| /* Alias analysis for GNU C |
| Copyright (C) 1997-2020 Free Software Foundation, Inc. |
| Contributed by John Carr (jfc@mit.edu). |
| |
| This file is part of GCC. |
| |
| GCC is free software; you can redistribute it and/or modify it under |
| the terms of the GNU General Public License as published by the Free |
| Software Foundation; either version 3, or (at your option) any later |
| version. |
| |
| GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
| WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GCC; see the file COPYING3. If not see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "backend.h" |
| #include "target.h" |
| #include "rtl.h" |
| #include "tree.h" |
| #include "gimple.h" |
| #include "df.h" |
| #include "memmodel.h" |
| #include "tm_p.h" |
| #include "gimple-ssa.h" |
| #include "emit-rtl.h" |
| #include "alias.h" |
| #include "fold-const.h" |
| #include "varasm.h" |
| #include "cselib.h" |
| #include "langhooks.h" |
| #include "cfganal.h" |
| #include "rtl-iter.h" |
| #include "cgraph.h" |
| #include "ipa-utils.h" |
| |
| /* The aliasing API provided here solves related but different problems: |
| |
| Say there exists (in c) |
| |
| struct X { |
| struct Y y1; |
| struct Z z2; |
| } x1, *px1, *px2; |
| |
| struct Y y2, *py; |
| struct Z z2, *pz; |
| |
| |
| py = &x1.y1; |
| px2 = &x1; |
| |
| Consider the four questions: |
| |
| Can a store to x1 interfere with px2->y1? |
| Can a store to x1 interfere with px2->z2? |
| Can a store to x1 change the value pointed to by with py? |
| Can a store to x1 change the value pointed to by with pz? |
| |
| The answer to these questions can be yes, yes, yes, and maybe. |
| |
| The first two questions can be answered with a simple examination |
| of the type system. If structure X contains a field of type Y then |
| a store through a pointer to an X can overwrite any field that is |
| contained (recursively) in an X (unless we know that px1 != px2). |
| |
| The last two questions can be solved in the same way as the first |
| two questions but this is too conservative. The observation is |
| that in some cases we can know which (if any) fields are addressed |
| and if those addresses are used in bad ways. This analysis may be |
| language specific. In C, arbitrary operations may be applied to |
| pointers. However, there is some indication that this may be too |
| conservative for some C++ types. |
| |
| The pass ipa-type-escape does this analysis for the types whose |
| instances do not escape across the compilation boundary. |
| |
| Historically in GCC, these two problems were combined and a single |
| data structure that was used to represent the solution to these |
| problems. We now have two similar but different data structures, |
| The data structure to solve the last two questions is similar to |
| the first, but does not contain the fields whose address are never |
| taken. For types that do escape the compilation unit, the data |
| structures will have identical information. |
| */ |
| |
| /* The alias sets assigned to MEMs assist the back-end in determining |
| which MEMs can alias which other MEMs. In general, two MEMs in |
| different alias sets cannot alias each other, with one important |
| exception. Consider something like: |
| |
| struct S { int i; double d; }; |
| |
| a store to an `S' can alias something of either type `int' or type |
| `double'. (However, a store to an `int' cannot alias a `double' |
| and vice versa.) We indicate this via a tree structure that looks |
| like: |
| struct S |
| / \ |
| / \ |
| |/_ _\| |
| int double |
| |
| (The arrows are directed and point downwards.) |
| In this situation we say the alias set for `struct S' is the |
| `superset' and that those for `int' and `double' are `subsets'. |
| |
| To see whether two alias sets can point to the same memory, we must |
| see if either alias set is a subset of the other. We need not trace |
| past immediate descendants, however, since we propagate all |
| grandchildren up one level. |
| |
| Alias set zero is implicitly a superset of all other alias sets. |
| However, this is no actual entry for alias set zero. It is an |
| error to attempt to explicitly construct a subset of zero. */ |
| |
| struct alias_set_hash : int_hash <int, INT_MIN, INT_MIN + 1> {}; |
| |
| struct GTY(()) alias_set_entry { |
| /* The alias set number, as stored in MEM_ALIAS_SET. */ |
| alias_set_type alias_set; |
| |
| /* Nonzero if would have a child of zero: this effectively makes this |
| alias set the same as alias set zero. */ |
| bool has_zero_child; |
| /* Nonzero if alias set corresponds to pointer type itself (i.e. not to |
| aggregate contaiing pointer. |
| This is used for a special case where we need an universal pointer type |
| compatible with all other pointer types. */ |
| bool is_pointer; |
| /* Nonzero if is_pointer or if one of childs have has_pointer set. */ |
| bool has_pointer; |
| |
| /* The children of the alias set. These are not just the immediate |
| children, but, in fact, all descendants. So, if we have: |
| |
| struct T { struct S s; float f; } |
| |
| continuing our example above, the children here will be all of |
| `int', `double', `float', and `struct S'. */ |
| hash_map<alias_set_hash, int> *children; |
| }; |
| |
| static int rtx_equal_for_memref_p (const_rtx, const_rtx); |
| static void record_set (rtx, const_rtx, void *); |
| static int base_alias_check (rtx, rtx, rtx, rtx, machine_mode, |
| machine_mode); |
| static rtx find_base_value (rtx); |
| static int mems_in_disjoint_alias_sets_p (const_rtx, const_rtx); |
| static alias_set_entry *get_alias_set_entry (alias_set_type); |
| static tree decl_for_component_ref (tree); |
| static int write_dependence_p (const_rtx, |
| const_rtx, machine_mode, rtx, |
| bool, bool, bool); |
| static int compare_base_symbol_refs (const_rtx, const_rtx); |
| |
| static void memory_modified_1 (rtx, const_rtx, void *); |
| |
| /* Query statistics for the different low-level disambiguators. |
| A high-level query may trigger multiple of them. */ |
| |
| static struct { |
| unsigned long long num_alias_zero; |
| unsigned long long num_same_alias_set; |
| unsigned long long num_same_objects; |
| unsigned long long num_volatile; |
| unsigned long long num_dag; |
| unsigned long long num_universal; |
| unsigned long long num_disambiguated; |
| } alias_stats; |
| |
| |
| /* Set up all info needed to perform alias analysis on memory references. */ |
| |
| /* Returns the size in bytes of the mode of X. */ |
| #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X))) |
| |
| /* Cap the number of passes we make over the insns propagating alias |
| information through set chains. |
| ??? 10 is a completely arbitrary choice. This should be based on the |
| maximum loop depth in the CFG, but we do not have this information |
| available (even if current_loops _is_ available). */ |
| #define MAX_ALIAS_LOOP_PASSES 10 |
| |
| /* reg_base_value[N] gives an address to which register N is related. |
| If all sets after the first add or subtract to the current value |
| or otherwise modify it so it does not point to a different top level |
| object, reg_base_value[N] is equal to the address part of the source |
| of the first set. |
| |
| A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS |
| expressions represent three types of base: |
| |
| 1. incoming arguments. There is just one ADDRESS to represent all |
| arguments, since we do not know at this level whether accesses |
| based on different arguments can alias. The ADDRESS has id 0. |
| |
| 2. stack_pointer_rtx, frame_pointer_rtx, hard_frame_pointer_rtx |
| (if distinct from frame_pointer_rtx) and arg_pointer_rtx. |
| Each of these rtxes has a separate ADDRESS associated with it, |
| each with a negative id. |
| |
| GCC is (and is required to be) precise in which register it |
| chooses to access a particular region of stack. We can therefore |
| assume that accesses based on one of these rtxes do not alias |
| accesses based on another of these rtxes. |
| |
| 3. bases that are derived from malloc()ed memory (REG_NOALIAS). |
| Each such piece of memory has a separate ADDRESS associated |
| with it, each with an id greater than 0. |
| |
| Accesses based on one ADDRESS do not alias accesses based on other |
| ADDRESSes. Accesses based on ADDRESSes in groups (2) and (3) do not |
| alias globals either; the ADDRESSes have Pmode to indicate this. |
| The ADDRESS in group (1) _may_ alias globals; it has VOIDmode to |
| indicate this. */ |
| |
| static GTY(()) vec<rtx, va_gc> *reg_base_value; |
| static rtx *new_reg_base_value; |
| |
| /* The single VOIDmode ADDRESS that represents all argument bases. |
| It has id 0. */ |
| static GTY(()) rtx arg_base_value; |
| |
| /* Used to allocate unique ids to each REG_NOALIAS ADDRESS. */ |
| static int unique_id; |
| |
| /* We preserve the copy of old array around to avoid amount of garbage |
| produced. About 8% of garbage produced were attributed to this |
| array. */ |
| static GTY((deletable)) vec<rtx, va_gc> *old_reg_base_value; |
| |
| /* Values of XINT (address, 0) of Pmode ADDRESS rtxes for special |
| registers. */ |
| #define UNIQUE_BASE_VALUE_SP -1 |
| #define UNIQUE_BASE_VALUE_ARGP -2 |
| #define UNIQUE_BASE_VALUE_FP -3 |
| #define UNIQUE_BASE_VALUE_HFP -4 |
| |
| #define static_reg_base_value \ |
| (this_target_rtl->x_static_reg_base_value) |
| |
| #define REG_BASE_VALUE(X) \ |
| (REGNO (X) < vec_safe_length (reg_base_value) \ |
| ? (*reg_base_value)[REGNO (X)] : 0) |
| |
| /* Vector indexed by N giving the initial (unchanging) value known for |
| pseudo-register N. This vector is initialized in init_alias_analysis, |
| and does not change until end_alias_analysis is called. */ |
| static GTY(()) vec<rtx, va_gc> *reg_known_value; |
| |
| /* Vector recording for each reg_known_value whether it is due to a |
| REG_EQUIV note. Future passes (viz., reload) may replace the |
| pseudo with the equivalent expression and so we account for the |
| dependences that would be introduced if that happens. |
| |
| The REG_EQUIV notes created in assign_parms may mention the arg |
| pointer, and there are explicit insns in the RTL that modify the |
| arg pointer. Thus we must ensure that such insns don't get |
| scheduled across each other because that would invalidate the |
| REG_EQUIV notes. One could argue that the REG_EQUIV notes are |
| wrong, but solving the problem in the scheduler will likely give |
| better code, so we do it here. */ |
| static sbitmap reg_known_equiv_p; |
| |
| /* True when scanning insns from the start of the rtl to the |
| NOTE_INSN_FUNCTION_BEG note. */ |
| static bool copying_arguments; |
| |
| |
| /* The splay-tree used to store the various alias set entries. */ |
| static GTY (()) vec<alias_set_entry *, va_gc> *alias_sets; |
| |
| /* Build a decomposed reference object for querying the alias-oracle |
| from the MEM rtx and store it in *REF. |
| Returns false if MEM is not suitable for the alias-oracle. */ |
| |
| static bool |
| ao_ref_from_mem (ao_ref *ref, const_rtx mem) |
| { |
| tree expr = MEM_EXPR (mem); |
| tree base; |
| |
| if (!expr) |
| return false; |
| |
| ao_ref_init (ref, expr); |
| |
| /* Get the base of the reference and see if we have to reject or |
| adjust it. */ |
| base = ao_ref_base (ref); |
| if (base == NULL_TREE) |
| return false; |
| |
| /* The tree oracle doesn't like bases that are neither decls |
| nor indirect references of SSA names. */ |
| if (!(DECL_P (base) |
| || (TREE_CODE (base) == MEM_REF |
| && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) |
| || (TREE_CODE (base) == TARGET_MEM_REF |
| && TREE_CODE (TMR_BASE (base)) == SSA_NAME))) |
| return false; |
| |
| ref->ref_alias_set = MEM_ALIAS_SET (mem); |
| |
| /* If MEM_OFFSET or MEM_SIZE are unknown what we got from MEM_EXPR |
| is conservative, so trust it. */ |
| if (!MEM_OFFSET_KNOWN_P (mem) |
| || !MEM_SIZE_KNOWN_P (mem)) |
| return true; |
| |
| /* If MEM_OFFSET/MEM_SIZE get us outside of ref->offset/ref->max_size |
| drop ref->ref. */ |
| if (maybe_lt (MEM_OFFSET (mem), 0) |
| || (ref->max_size_known_p () |
| && maybe_gt ((MEM_OFFSET (mem) + MEM_SIZE (mem)) * BITS_PER_UNIT, |
| ref->max_size))) |
| ref->ref = NULL_TREE; |
| |
| /* Refine size and offset we got from analyzing MEM_EXPR by using |
| MEM_SIZE and MEM_OFFSET. */ |
| |
| ref->offset += MEM_OFFSET (mem) * BITS_PER_UNIT; |
| ref->size = MEM_SIZE (mem) * BITS_PER_UNIT; |
| |
| /* The MEM may extend into adjacent fields, so adjust max_size if |
| necessary. */ |
| if (ref->max_size_known_p ()) |
| ref->max_size = upper_bound (ref->max_size, ref->size); |
| |
| /* If MEM_OFFSET and MEM_SIZE might get us outside of the base object of |
| the MEM_EXPR punt. This happens for STRICT_ALIGNMENT targets a lot. */ |
| if (MEM_EXPR (mem) != get_spill_slot_decl (false) |
| && (maybe_lt (ref->offset, 0) |
| || (DECL_P (ref->base) |
| && (DECL_SIZE (ref->base) == NULL_TREE |
| || !poly_int_tree_p (DECL_SIZE (ref->base)) |
| || maybe_lt (wi::to_poly_offset (DECL_SIZE (ref->base)), |
| ref->offset + ref->size))))) |
| return false; |
| |
| return true; |
| } |
| |
| /* Query the alias-oracle on whether the two memory rtx X and MEM may |
| alias. If TBAA_P is set also apply TBAA. Returns true if the |
| two rtxen may alias, false otherwise. */ |
| |
| static bool |
| rtx_refs_may_alias_p (const_rtx x, const_rtx mem, bool tbaa_p) |
| { |
| ao_ref ref1, ref2; |
| |
| if (!ao_ref_from_mem (&ref1, x) |
| || !ao_ref_from_mem (&ref2, mem)) |
| return true; |
| |
| return refs_may_alias_p_1 (&ref1, &ref2, |
| tbaa_p |
| && MEM_ALIAS_SET (x) != 0 |
| && MEM_ALIAS_SET (mem) != 0); |
| } |
| |
| /* Return true if the ref EARLIER behaves the same as LATER with respect |
| to TBAA for every memory reference that might follow LATER. */ |
| |
| bool |
| refs_same_for_tbaa_p (tree earlier, tree later) |
| { |
| ao_ref earlier_ref, later_ref; |
| ao_ref_init (&earlier_ref, earlier); |
| ao_ref_init (&later_ref, later); |
| alias_set_type earlier_set = ao_ref_alias_set (&earlier_ref); |
| alias_set_type later_set = ao_ref_alias_set (&later_ref); |
| if (!(earlier_set == later_set |
| || alias_set_subset_of (later_set, earlier_set))) |
| return false; |
| alias_set_type later_base_set = ao_ref_base_alias_set (&later_ref); |
| alias_set_type earlier_base_set = ao_ref_base_alias_set (&earlier_ref); |
| return (earlier_base_set == later_base_set |
| || alias_set_subset_of (later_base_set, earlier_base_set)); |
| } |
| |
| /* Returns a pointer to the alias set entry for ALIAS_SET, if there is |
| such an entry, or NULL otherwise. */ |
| |
| static inline alias_set_entry * |
| get_alias_set_entry (alias_set_type alias_set) |
| { |
| return (*alias_sets)[alias_set]; |
| } |
| |
| /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that |
| the two MEMs cannot alias each other. */ |
| |
| static inline int |
| mems_in_disjoint_alias_sets_p (const_rtx mem1, const_rtx mem2) |
| { |
| return (flag_strict_aliasing |
| && ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), |
| MEM_ALIAS_SET (mem2))); |
| } |
| |
| /* Return true if the first alias set is a subset of the second. */ |
| |
| bool |
| alias_set_subset_of (alias_set_type set1, alias_set_type set2) |
| { |
| alias_set_entry *ase2; |
| |
| /* Disable TBAA oracle with !flag_strict_aliasing. */ |
| if (!flag_strict_aliasing) |
| return true; |
| |
| /* Everything is a subset of the "aliases everything" set. */ |
| if (set2 == 0) |
| return true; |
| |
| /* Check if set1 is a subset of set2. */ |
| ase2 = get_alias_set_entry (set2); |
| if (ase2 != 0 |
| && (ase2->has_zero_child |
| || (ase2->children && ase2->children->get (set1)))) |
| return true; |
| |
| /* As a special case we consider alias set of "void *" to be both subset |
| and superset of every alias set of a pointer. This extra symmetry does |
| not matter for alias_sets_conflict_p but it makes aliasing_component_refs_p |
| to return true on the following testcase: |
| |
| void *ptr; |
| char **ptr2=(char **)&ptr; |
| *ptr2 = ... |
| |
| Additionally if a set contains universal pointer, we consider every pointer |
| to be a subset of it, but we do not represent this explicitely - doing so |
| would require us to update transitive closure each time we introduce new |
| pointer type. This makes aliasing_component_refs_p to return true |
| on the following testcase: |
| |
| struct a {void *ptr;} |
| char **ptr = (char **)&a.ptr; |
| ptr = ... |
| |
| This makes void * truly universal pointer type. See pointer handling in |
| get_alias_set for more details. */ |
| if (ase2 && ase2->has_pointer) |
| { |
| alias_set_entry *ase1 = get_alias_set_entry (set1); |
| |
| if (ase1 && ase1->is_pointer) |
| { |
| alias_set_type voidptr_set = TYPE_ALIAS_SET (ptr_type_node); |
| /* If one is ptr_type_node and other is pointer, then we consider |
| them subset of each other. */ |
| if (set1 == voidptr_set || set2 == voidptr_set) |
| return true; |
| /* If SET2 contains universal pointer's alias set, then we consdier |
| every (non-universal) pointer. */ |
| if (ase2->children && set1 != voidptr_set |
| && ase2->children->get (voidptr_set)) |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| /* Return 1 if the two specified alias sets may conflict. */ |
| |
| int |
| alias_sets_conflict_p (alias_set_type set1, alias_set_type set2) |
| { |
| alias_set_entry *ase1; |
| alias_set_entry *ase2; |
| |
| /* The easy case. */ |
| if (alias_sets_must_conflict_p (set1, set2)) |
| return 1; |
| |
| /* See if the first alias set is a subset of the second. */ |
| ase1 = get_alias_set_entry (set1); |
| if (ase1 != 0 |
| && ase1->children && ase1->children->get (set2)) |
| { |
| ++alias_stats.num_dag; |
| return 1; |
| } |
| |
| /* Now do the same, but with the alias sets reversed. */ |
| ase2 = get_alias_set_entry (set2); |
| if (ase2 != 0 |
| && ase2->children && ase2->children->get (set1)) |
| { |
| ++alias_stats.num_dag; |
| return 1; |
| } |
| |
| /* We want void * to be compatible with any other pointer without |
| really dropping it to alias set 0. Doing so would make it |
| compatible with all non-pointer types too. |
| |
| This is not strictly necessary by the C/C++ language |
| standards, but avoids common type punning mistakes. In |
| addition to that, we need the existence of such universal |
| pointer to implement Fortran's C_PTR type (which is defined as |
| type compatible with all C pointers). */ |
| if (ase1 && ase2 && ase1->has_pointer && ase2->has_pointer) |
| { |
| alias_set_type voidptr_set = TYPE_ALIAS_SET (ptr_type_node); |
| |
| /* If one of the sets corresponds to universal pointer, |
| we consider it to conflict with anything that is |
| or contains pointer. */ |
| if (set1 == voidptr_set || set2 == voidptr_set) |
| { |
| ++alias_stats.num_universal; |
| return true; |
| } |
| /* If one of sets is (non-universal) pointer and the other |
| contains universal pointer, we also get conflict. */ |
| if (ase1->is_pointer && set2 != voidptr_set |
| && ase2->children && ase2->children->get (voidptr_set)) |
| { |
| ++alias_stats.num_universal; |
| return true; |
| } |
| if (ase2->is_pointer && set1 != voidptr_set |
| && ase1->children && ase1->children->get (voidptr_set)) |
| { |
| ++alias_stats.num_universal; |
| return true; |
| } |
| } |
| |
| ++alias_stats.num_disambiguated; |
| |
| /* The two alias sets are distinct and neither one is the |
| child of the other. Therefore, they cannot conflict. */ |
| return 0; |
| } |
| |
| /* Return 1 if the two specified alias sets will always conflict. */ |
| |
| int |
| alias_sets_must_conflict_p (alias_set_type set1, alias_set_type set2) |
| { |
| /* Disable TBAA oracle with !flag_strict_aliasing. */ |
| if (!flag_strict_aliasing) |
| return 1; |
| if (set1 == 0 || set2 == 0) |
| { |
| ++alias_stats.num_alias_zero; |
| return 1; |
| } |
| if (set1 == set2) |
| { |
| ++alias_stats.num_same_alias_set; |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| /* Return 1 if any MEM object of type T1 will always conflict (using the |
| dependency routines in this file) with any MEM object of type T2. |
| This is used when allocating temporary storage. If T1 and/or T2 are |
| NULL_TREE, it means we know nothing about the storage. */ |
| |
| int |
| objects_must_conflict_p (tree t1, tree t2) |
| { |
| alias_set_type set1, set2; |
| |
| /* If neither has a type specified, we don't know if they'll conflict |
| because we may be using them to store objects of various types, for |
| example the argument and local variables areas of inlined functions. */ |
| if (t1 == 0 && t2 == 0) |
| return 0; |
| |
| /* If they are the same type, they must conflict. */ |
| if (t1 == t2) |
| { |
| ++alias_stats.num_same_objects; |
| return 1; |
| } |
| /* Likewise if both are volatile. */ |
| if (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2)) |
| { |
| ++alias_stats.num_volatile; |
| return 1; |
| } |
| |
| set1 = t1 ? get_alias_set (t1) : 0; |
| set2 = t2 ? get_alias_set (t2) : 0; |
| |
| /* We can't use alias_sets_conflict_p because we must make sure |
| that every subtype of t1 will conflict with every subtype of |
| t2 for which a pair of subobjects of these respective subtypes |
| overlaps on the stack. */ |
| return alias_sets_must_conflict_p (set1, set2); |
| } |
| |
| /* Return true if T is an end of the access path which can be used |
| by type based alias oracle. */ |
| |
| bool |
| ends_tbaa_access_path_p (const_tree t) |
| { |
| switch (TREE_CODE (t)) |
| { |
| case COMPONENT_REF: |
| if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1))) |
| return true; |
| /* Permit type-punning when accessing a union, provided the access |
| is directly through the union. For example, this code does not |
| permit taking the address of a union member and then storing |
| through it. Even the type-punning allowed here is a GCC |
| extension, albeit a common and useful one; the C standard says |
| that such accesses have implementation-defined behavior. */ |
| else if (TREE_CODE (TREE_TYPE (TREE_OPERAND (t, 0))) == UNION_TYPE) |
| return true; |
| break; |
| |
| case ARRAY_REF: |
| case ARRAY_RANGE_REF: |
| if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0)))) |
| return true; |
| break; |
| |
| case REALPART_EXPR: |
| case IMAGPART_EXPR: |
| break; |
| |
| case BIT_FIELD_REF: |
| case VIEW_CONVERT_EXPR: |
| /* Bitfields and casts are never addressable. */ |
| return true; |
| break; |
| |
| default: |
| gcc_unreachable (); |
| } |
| return false; |
| } |
| |
| /* Return the outermost parent of component present in the chain of |
| component references handled by get_inner_reference in T with the |
| following property: |
| - the component is non-addressable |
| or NULL_TREE if no such parent exists. In the former cases, the alias |
| set of this parent is the alias set that must be used for T itself. */ |
| |
| tree |
| component_uses_parent_alias_set_from (const_tree t) |
| { |
| const_tree found = NULL_TREE; |
| |
| while (handled_component_p (t)) |
| { |
| if (ends_tbaa_access_path_p (t)) |
| found = t; |
| |
| t = TREE_OPERAND (t, 0); |
| } |
| |
| if (found) |
| return TREE_OPERAND (found, 0); |
| |
| return NULL_TREE; |
| } |
| |
| |
| /* Return whether the pointer-type T effective for aliasing may |
| access everything and thus the reference has to be assigned |
| alias-set zero. */ |
| |
| static bool |
| ref_all_alias_ptr_type_p (const_tree t) |
| { |
| return (TREE_CODE (TREE_TYPE (t)) == VOID_TYPE |
| || TYPE_REF_CAN_ALIAS_ALL (t)); |
| } |
| |
| /* Return the alias set for the memory pointed to by T, which may be |
| either a type or an expression. Return -1 if there is nothing |
| special about dereferencing T. */ |
| |
| static alias_set_type |
| get_deref_alias_set_1 (tree t) |
| { |
| /* All we care about is the type. */ |
| if (! TYPE_P (t)) |
| t = TREE_TYPE (t); |
| |
| /* If we have an INDIRECT_REF via a void pointer, we don't |
| know anything about what that might alias. Likewise if the |
| pointer is marked that way. */ |
| if (ref_all_alias_ptr_type_p (t)) |
| return 0; |
| |
| return -1; |
| } |
| |
| /* Return the alias set for the memory pointed to by T, which may be |
| either a type or an expression. */ |
| |
| alias_set_type |
| get_deref_alias_set (tree t) |
| { |
| /* If we're not doing any alias analysis, just assume everything |
| aliases everything else. */ |
| if (!flag_strict_aliasing) |
| return 0; |
| |
| alias_set_type set = get_deref_alias_set_1 (t); |
| |
| /* Fall back to the alias-set of the pointed-to type. */ |
| if (set == -1) |
| { |
| if (! TYPE_P (t)) |
| t = TREE_TYPE (t); |
| set = get_alias_set (TREE_TYPE (t)); |
| } |
| |
| return set; |
| } |
| |
| /* Return the pointer-type relevant for TBAA purposes from the |
| memory reference tree *T or NULL_TREE in which case *T is |
| adjusted to point to the outermost component reference that |
| can be used for assigning an alias set. */ |
| |
| static tree |
| reference_alias_ptr_type_1 (tree *t) |
| { |
| tree inner; |
| |
| /* Get the base object of the reference. */ |
| inner = *t; |
| while (handled_component_p (inner)) |
| { |
| /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use |
| the type of any component references that wrap it to |
| determine the alias-set. */ |
| if (TREE_CODE (inner) == VIEW_CONVERT_EXPR) |
| *t = TREE_OPERAND (inner, 0); |
| inner = TREE_OPERAND (inner, 0); |
| } |
| |
| /* Handle pointer dereferences here, they can override the |
| alias-set. */ |
| if (INDIRECT_REF_P (inner) |
| && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner, 0)))) |
| return TREE_TYPE (TREE_OPERAND (inner, 0)); |
| else if (TREE_CODE (inner) == TARGET_MEM_REF) |
| return TREE_TYPE (TMR_OFFSET (inner)); |
| else if (TREE_CODE (inner) == MEM_REF |
| && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner, 1)))) |
| return TREE_TYPE (TREE_OPERAND (inner, 1)); |
| |
| /* If the innermost reference is a MEM_REF that has a |
| conversion embedded treat it like a VIEW_CONVERT_EXPR above, |
| using the memory access type for determining the alias-set. */ |
| if (TREE_CODE (inner) == MEM_REF |
| && (TYPE_MAIN_VARIANT (TREE_TYPE (inner)) |
| != TYPE_MAIN_VARIANT |
| (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner, 1)))))) |
| return TREE_TYPE (TREE_OPERAND (inner, 1)); |
| |
| /* Otherwise, pick up the outermost object that we could have |
| a pointer to. */ |
| tree tem = component_uses_parent_alias_set_from (*t); |
| if (tem) |
| *t = tem; |
| |
| return NULL_TREE; |
| } |
| |
| /* Return the pointer-type relevant for TBAA purposes from the |
| gimple memory reference tree T. This is the type to be used for |
| the offset operand of MEM_REF or TARGET_MEM_REF replacements of T |
| and guarantees that get_alias_set will return the same alias |
| set for T and the replacement. */ |
| |
| tree |
| reference_alias_ptr_type (tree t) |
| { |
| /* If the frontend assigns this alias-set zero, preserve that. */ |
| if (lang_hooks.get_alias_set (t) == 0) |
| return ptr_type_node; |
| |
| tree ptype = reference_alias_ptr_type_1 (&t); |
| /* If there is a given pointer type for aliasing purposes, return it. */ |
| if (ptype != NULL_TREE) |
| return ptype; |
| |
| /* Otherwise build one from the outermost component reference we |
| may use. */ |
| if (TREE_CODE (t) == MEM_REF |
| || TREE_CODE (t) == TARGET_MEM_REF) |
| return TREE_TYPE (TREE_OPERAND (t, 1)); |
| else |
| return build_pointer_type (TYPE_MAIN_VARIANT (TREE_TYPE (t))); |
| } |
| |
| /* Return whether the pointer-types T1 and T2 used to determine |
| two alias sets of two references will yield the same answer |
| from get_deref_alias_set. */ |
| |
| bool |
| alias_ptr_types_compatible_p (tree t1, tree t2) |
| { |
| if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2)) |
| return true; |
| |
| if (ref_all_alias_ptr_type_p (t1) |
| || ref_all_alias_ptr_type_p (t2)) |
| return false; |
| |
| /* This function originally abstracts from simply comparing |
| get_deref_alias_set so that we are sure this still computes |
| the same result after LTO type merging is applied. |
| When in LTO type merging is done we can actually do this compare. |
| */ |
| if (in_lto_p) |
| return get_deref_alias_set (t1) == get_deref_alias_set (t2); |
| else |
| return (TYPE_MAIN_VARIANT (TREE_TYPE (t1)) |
| == TYPE_MAIN_VARIANT (TREE_TYPE (t2))); |
| } |
| |
| /* Create emptry alias set entry. */ |
| |
| alias_set_entry * |
| init_alias_set_entry (alias_set_type set) |
| { |
| alias_set_entry *ase = ggc_alloc<alias_set_entry> (); |
| ase->alias_set = set; |
| ase->children = NULL; |
| ase->has_zero_child = false; |
| ase->is_pointer = false; |
| ase->has_pointer = false; |
| gcc_checking_assert (!get_alias_set_entry (set)); |
| (*alias_sets)[set] = ase; |
| return ase; |
| } |
| |
| /* Return the alias set for T, which may be either a type or an |
| expression. Call language-specific routine for help, if needed. */ |
| |
| alias_set_type |
| get_alias_set (tree t) |
| { |
| alias_set_type set; |
| |
| /* We cannot give up with -fno-strict-aliasing because we need to build |
| proper type representations for possible functions which are built with |
| -fstrict-aliasing. */ |
| |
| /* return 0 if this or its type is an error. */ |
| if (t == error_mark_node |
| || (! TYPE_P (t) |
| && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node))) |
| return 0; |
| |
| /* We can be passed either an expression or a type. This and the |
| language-specific routine may make mutually-recursive calls to each other |
| to figure out what to do. At each juncture, we see if this is a tree |
| that the language may need to handle specially. First handle things that |
| aren't types. */ |
| if (! TYPE_P (t)) |
| { |
| /* Give the language a chance to do something with this tree |
| before we look at it. */ |
| STRIP_NOPS (t); |
| set = lang_hooks.get_alias_set (t); |
| if (set != -1) |
| return set; |
| |
| /* Get the alias pointer-type to use or the outermost object |
| that we could have a pointer to. */ |
| tree ptype = reference_alias_ptr_type_1 (&t); |
| if (ptype != NULL) |
| return get_deref_alias_set (ptype); |
| |
| /* If we've already determined the alias set for a decl, just return |
| it. This is necessary for C++ anonymous unions, whose component |
| variables don't look like union members (boo!). */ |
| if (VAR_P (t) |
| && DECL_RTL_SET_P (t) && MEM_P (DECL_RTL (t))) |
| return MEM_ALIAS_SET (DECL_RTL (t)); |
| |
| /* Now all we care about is the type. */ |
| t = TREE_TYPE (t); |
| } |
| |
| /* Variant qualifiers don't affect the alias set, so get the main |
| variant. */ |
| t = TYPE_MAIN_VARIANT (t); |
| |
| if (AGGREGATE_TYPE_P (t) |
| && TYPE_TYPELESS_STORAGE (t)) |
| return 0; |
| |
| /* Always use the canonical type as well. If this is a type that |
| requires structural comparisons to identify compatible types |
| use alias set zero. */ |
| if (TYPE_STRUCTURAL_EQUALITY_P (t)) |
| { |
| /* Allow the language to specify another alias set for this |
| type. */ |
| set = lang_hooks.get_alias_set (t); |
| if (set != -1) |
| return set; |
| /* Handle structure type equality for pointer types, arrays and vectors. |
| This is easy to do, because the code below ignores canonical types on |
| these anyway. This is important for LTO, where TYPE_CANONICAL for |
| pointers cannot be meaningfully computed by the frontend. */ |
| if (canonical_type_used_p (t)) |
| { |
| /* In LTO we set canonical types for all types where it makes |
| sense to do so. Double check we did not miss some type. */ |
| gcc_checking_assert (!in_lto_p || !type_with_alias_set_p (t)); |
| return 0; |
| } |
| } |
| else |
| { |
| t = TYPE_CANONICAL (t); |
| gcc_checking_assert (!TYPE_STRUCTURAL_EQUALITY_P (t)); |
| } |
| |
| /* If this is a type with a known alias set, return it. */ |
| gcc_checking_assert (t == TYPE_MAIN_VARIANT (t)); |
| if (TYPE_ALIAS_SET_KNOWN_P (t)) |
| return TYPE_ALIAS_SET (t); |
| |
| /* We don't want to set TYPE_ALIAS_SET for incomplete types. */ |
| if (!COMPLETE_TYPE_P (t)) |
| { |
| /* For arrays with unknown size the conservative answer is the |
| alias set of the element type. */ |
| if (TREE_CODE (t) == ARRAY_TYPE) |
| return get_alias_set (TREE_TYPE (t)); |
| |
| /* But return zero as a conservative answer for incomplete types. */ |
| return 0; |
| } |
| |
| /* See if the language has special handling for this type. */ |
| set = lang_hooks.get_alias_set (t); |
| if (set != -1) |
| return set; |
| |
| /* There are no objects of FUNCTION_TYPE, so there's no point in |
| using up an alias set for them. (There are, of course, pointers |
| and references to functions, but that's different.) */ |
| else if (TREE_CODE (t) == FUNCTION_TYPE || TREE_CODE (t) == METHOD_TYPE) |
| set = 0; |
| |
| /* Unless the language specifies otherwise, let vector types alias |
| their components. This avoids some nasty type punning issues in |
| normal usage. And indeed lets vectors be treated more like an |
| array slice. */ |
| else if (TREE_CODE (t) == VECTOR_TYPE) |
| set = get_alias_set (TREE_TYPE (t)); |
| |
| /* Unless the language specifies otherwise, treat array types the |
| same as their components. This avoids the asymmetry we get |
| through recording the components. Consider accessing a |
| character(kind=1) through a reference to a character(kind=1)[1:1]. |
| Or consider if we want to assign integer(kind=4)[0:D.1387] and |
| integer(kind=4)[4] the same alias set or not. |
| Just be pragmatic here and make sure the array and its element |
| type get the same alias set assigned. */ |
| else if (TREE_CODE (t) == ARRAY_TYPE |
| && (!TYPE_NONALIASED_COMPONENT (t) |
| || TYPE_STRUCTURAL_EQUALITY_P (t))) |
| set = get_alias_set (TREE_TYPE (t)); |
| |
| /* From the former common C and C++ langhook implementation: |
| |
| Unfortunately, there is no canonical form of a pointer type. |
| In particular, if we have `typedef int I', then `int *', and |
| `I *' are different types. So, we have to pick a canonical |
| representative. We do this below. |
| |
| Technically, this approach is actually more conservative that |
| it needs to be. In particular, `const int *' and `int *' |
| should be in different alias sets, according to the C and C++ |
| standard, since their types are not the same, and so, |
| technically, an `int **' and `const int **' cannot point at |
| the same thing. |
| |
| But, the standard is wrong. In particular, this code is |
| legal C++: |
| |
| int *ip; |
| int **ipp = &ip; |
| const int* const* cipp = ipp; |
| And, it doesn't make sense for that to be legal unless you |
| can dereference IPP and CIPP. So, we ignore cv-qualifiers on |
| the pointed-to types. This issue has been reported to the |
| C++ committee. |
| |
| For this reason go to canonical type of the unqalified pointer type. |
| Until GCC 6 this code set all pointers sets to have alias set of |
| ptr_type_node but that is a bad idea, because it prevents disabiguations |
| in between pointers. For Firefox this accounts about 20% of all |
| disambiguations in the program. */ |
| else if (POINTER_TYPE_P (t) && t != ptr_type_node) |
| { |
| tree p; |
| auto_vec <bool, 8> reference; |
| |
| /* Unnest all pointers and references. |
| We also want to make pointer to array/vector equivalent to pointer to |
| its element (see the reasoning above). Skip all those types, too. */ |
| for (p = t; POINTER_TYPE_P (p) |
| || (TREE_CODE (p) == ARRAY_TYPE |
| && (!TYPE_NONALIASED_COMPONENT (p) |
| || !COMPLETE_TYPE_P (p) |
| || TYPE_STRUCTURAL_EQUALITY_P (p))) |
| || TREE_CODE (p) == VECTOR_TYPE; |
| p = TREE_TYPE (p)) |
| { |
| /* Ada supports recursive pointers. Instead of doing recursion |
| check, just give up once the preallocated space of 8 elements |
| is up. In this case just punt to void * alias set. */ |
| if (reference.length () == 8) |
| { |
| p = ptr_type_node; |
| break; |
| } |
| if (TREE_CODE (p) == REFERENCE_TYPE) |
| /* In LTO we want languages that use references to be compatible |
| with languages that use pointers. */ |
| reference.safe_push (true && !in_lto_p); |
| if (TREE_CODE (p) == POINTER_TYPE) |
| reference.safe_push (false); |
| } |
| p = TYPE_MAIN_VARIANT (p); |
| |
| /* In LTO for C++ programs we can turn incomplete types to complete |
| using ODR name lookup. */ |
| if (in_lto_p && TYPE_STRUCTURAL_EQUALITY_P (p) && odr_type_p (p)) |
| { |
| p = prevailing_odr_type (p); |
| gcc_checking_assert (TYPE_MAIN_VARIANT (p) == p); |
| } |
| |
| /* Make void * compatible with char * and also void **. |
| Programs are commonly violating TBAA by this. |
| |
| We also make void * to conflict with every pointer |
| (see record_component_aliases) and thus it is safe it to use it for |
| pointers to types with TYPE_STRUCTURAL_EQUALITY_P. */ |
| if (TREE_CODE (p) == VOID_TYPE || TYPE_STRUCTURAL_EQUALITY_P (p)) |
| set = get_alias_set (ptr_type_node); |
| else |
| { |
| /* Rebuild pointer type starting from canonical types using |
| unqualified pointers and references only. This way all such |
| pointers will have the same alias set and will conflict with |
| each other. |
| |
| Most of time we already have pointers or references of a given type. |
| If not we build new one just to be sure that if someone later |
| (probably only middle-end can, as we should assign all alias |
| classes only after finishing translation unit) builds the pointer |
| type, the canonical type will match. */ |
| p = TYPE_CANONICAL (p); |
| while (!reference.is_empty ()) |
| { |
| if (reference.pop ()) |
| p = build_reference_type (p); |
| else |
| p = build_pointer_type (p); |
| gcc_checking_assert (p == TYPE_MAIN_VARIANT (p)); |
| /* build_pointer_type should always return the canonical type. |
| For LTO TYPE_CANOINCAL may be NULL, because we do not compute |
| them. Be sure that frontends do not glob canonical types of |
| pointers in unexpected way and that p == TYPE_CANONICAL (p) |
| in all other cases. */ |
| gcc_checking_assert (!TYPE_CANONICAL (p) |
| || p == TYPE_CANONICAL (p)); |
| } |
| |
| /* Assign the alias set to both p and t. |
| We cannot call get_alias_set (p) here as that would trigger |
| infinite recursion when p == t. In other cases it would just |
| trigger unnecesary legwork of rebuilding the pointer again. */ |
| gcc_checking_assert (p == TYPE_MAIN_VARIANT (p)); |
| if (TYPE_ALIAS_SET_KNOWN_P (p)) |
| set = TYPE_ALIAS_SET (p); |
| else |
| { |
| set = new_alias_set (); |
| TYPE_ALIAS_SET (p) = set; |
| } |
| } |
| } |
| /* Alias set of ptr_type_node is special and serve as universal pointer which |
| is TBAA compatible with every other pointer type. Be sure we have the |
| alias set built even for LTO which otherwise keeps all TYPE_CANONICAL |
| of pointer types NULL. */ |
| else if (t == ptr_type_node) |
| set = new_alias_set (); |
| |
| /* Otherwise make a new alias set for this type. */ |
| else |
| { |
| /* Each canonical type gets its own alias set, so canonical types |
| shouldn't form a tree. It doesn't really matter for types |
| we handle specially above, so only check it where it possibly |
| would result in a bogus alias set. */ |
| gcc_checking_assert (TYPE_CANONICAL (t) == t); |
| |
| set = new_alias_set (); |
| } |
| |
| TYPE_ALIAS_SET (t) = set; |
| |
| /* If this is an aggregate type or a complex type, we must record any |
| component aliasing information. */ |
| if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE) |
| record_component_aliases (t); |
| |
| /* We treat pointer types specially in alias_set_subset_of. */ |
| if (POINTER_TYPE_P (t) && set) |
| { |
| alias_set_entry *ase = get_alias_set_entry (set); |
| if (!ase) |
| ase = init_alias_set_entry (set); |
| ase->is_pointer = true; |
| ase->has_pointer = true; |
| } |
| |
| return set; |
| } |
| |
| /* Return a brand-new alias set. */ |
| |
| alias_set_type |
| new_alias_set (void) |
| { |
| if (alias_sets == 0) |
| vec_safe_push (alias_sets, (alias_set_entry *) NULL); |
| vec_safe_push (alias_sets, (alias_set_entry *) NULL); |
| return alias_sets->length () - 1; |
| } |
| |
| /* Indicate that things in SUBSET can alias things in SUPERSET, but that |
| not everything that aliases SUPERSET also aliases SUBSET. For example, |
| in C, a store to an `int' can alias a load of a structure containing an |
| `int', and vice versa. But it can't alias a load of a 'double' member |
| of the same structure. Here, the structure would be the SUPERSET and |
| `int' the SUBSET. This relationship is also described in the comment at |
| the beginning of this file. |
| |
| This function should be called only once per SUPERSET/SUBSET pair. |
| |
| It is illegal for SUPERSET to be zero; everything is implicitly a |
| subset of alias set zero. */ |
| |
| void |
| record_alias_subset (alias_set_type superset, alias_set_type subset) |
| { |
| alias_set_entry *superset_entry; |
| alias_set_entry *subset_entry; |
| |
| /* It is possible in complex type situations for both sets to be the same, |
| in which case we can ignore this operation. */ |
| if (superset == subset) |
| return; |
| |
| gcc_assert (superset); |
| |
| superset_entry = get_alias_set_entry (superset); |
| if (superset_entry == 0) |
| { |
| /* Create an entry for the SUPERSET, so that we have a place to |
| attach the SUBSET. */ |
| superset_entry = init_alias_set_entry (superset); |
| } |
| |
| if (subset == 0) |
| superset_entry->has_zero_child = 1; |
| else |
| { |
| if (!superset_entry->children) |
| superset_entry->children |
| = hash_map<alias_set_hash, int>::create_ggc (64); |
| |
| /* Enter the SUBSET itself as a child of the SUPERSET. If it was |
| already there we're done. */ |
| if (superset_entry->children->put (subset, 0)) |
| return; |
| |
| subset_entry = get_alias_set_entry (subset); |
| /* If there is an entry for the subset, enter all of its children |
| (if they are not already present) as children of the SUPERSET. */ |
| if (subset_entry) |
| { |
| if (subset_entry->has_zero_child) |
| superset_entry->has_zero_child = true; |
| if (subset_entry->has_pointer) |
| superset_entry->has_pointer = true; |
| |
| if (subset_entry->children) |
| { |
| hash_map<alias_set_hash, int>::iterator iter |
| = subset_entry->children->begin (); |
| for (; iter != subset_entry->children->end (); ++iter) |
| superset_entry->children->put ((*iter).first, (*iter).second); |
| } |
| } |
| } |
| } |
| |
| /* Record that component types of TYPE, if any, are part of SUPERSET for |
| aliasing purposes. For record types, we only record component types |
| for fields that are not marked non-addressable. For array types, we |
| only record the component type if it is not marked non-aliased. */ |
| |
| void |
| record_component_aliases (tree type, alias_set_type superset) |
| { |
| tree field; |
| |
| if (superset == 0) |
| return; |
| |
| switch (TREE_CODE (type)) |
| { |
| case RECORD_TYPE: |
| case UNION_TYPE: |
| case QUAL_UNION_TYPE: |
| { |
| /* LTO non-ODR type merging does not make any difference between |
| component pointer types. We may have |
| |
| struct foo {int *a;}; |
| |
| as TYPE_CANONICAL of |
| |
| struct bar {float *a;}; |
| |
| Because accesses to int * and float * do not alias, we would get |
| false negative when accessing the same memory location by |
| float ** and bar *. We thus record the canonical type as: |
| |
| struct {void *a;}; |
| |
| void * is special cased and works as a universal pointer type. |
| Accesses to it conflicts with accesses to any other pointer |
| type. */ |
| bool void_pointers = in_lto_p |
| && (!odr_type_p (type) |
| || !odr_based_tbaa_p (type)); |
| for (field = TYPE_FIELDS (type); field != 0; field = DECL_CHAIN (field)) |
| if (TREE_CODE (field) == FIELD_DECL && !DECL_NONADDRESSABLE_P (field)) |
| { |
| tree t = TREE_TYPE (field); |
| if (void_pointers) |
| { |
| /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their |
| element type and that type has to be normalized to void *, |
| too, in the case it is a pointer. */ |
| while (!canonical_type_used_p (t) && !POINTER_TYPE_P (t)) |
| { |
| gcc_checking_assert (TYPE_STRUCTURAL_EQUALITY_P (t)); |
| t = TREE_TYPE (t); |
| } |
| if (POINTER_TYPE_P (t)) |
| t = ptr_type_node; |
| else if (flag_checking) |
| gcc_checking_assert (get_alias_set (t) |
| == get_alias_set (TREE_TYPE (field))); |
| } |
| |
| alias_set_type set = get_alias_set (t); |
| record_alias_subset (superset, set); |
| /* If the field has alias-set zero make sure to still record |
| any componets of it. This makes sure that for |
| struct A { |
| struct B { |
| int i; |
| char c[4]; |
| } b; |
| }; |
| in C++ even though 'B' has alias-set zero because |
| TYPE_TYPELESS_STORAGE is set, 'A' has the alias-set of |
| 'int' as subset. */ |
| if (set == 0) |
| record_component_aliases (t, superset); |
| } |
| } |
| break; |
| |
| case COMPLEX_TYPE: |
| record_alias_subset (superset, get_alias_set (TREE_TYPE (type))); |
| break; |
| |
| /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their |
| element type. */ |
| |
| default: |
| break; |
| } |
| } |
| |
| /* Record that component types of TYPE, if any, are part of that type for |
| aliasing purposes. For record types, we only record component types |
| for fields that are not marked non-addressable. For array types, we |
| only record the component type if it is not marked non-aliased. */ |
| |
| void |
| record_component_aliases (tree type) |
| { |
| alias_set_type superset = get_alias_set (type); |
| record_component_aliases (type, superset); |
| } |
| |
| |
| /* Allocate an alias set for use in storing and reading from the varargs |
| spill area. */ |
| |
| static GTY(()) alias_set_type varargs_set = -1; |
| |
| alias_set_type |
| get_varargs_alias_set (void) |
| { |
| #if 1 |
| /* We now lower VA_ARG_EXPR, and there's currently no way to attach the |
| varargs alias set to an INDIRECT_REF (FIXME!), so we can't |
| consistently use the varargs alias set for loads from the varargs |
| area. So don't use it anywhere. */ |
| return 0; |
| #else |
| if (varargs_set == -1) |
| varargs_set = new_alias_set (); |
| |
| return varargs_set; |
| #endif |
| } |
| |
| /* Likewise, but used for the fixed portions of the frame, e.g., register |
| save areas. */ |
| |
| static GTY(()) alias_set_type frame_set = -1; |
| |
| alias_set_type |
| get_frame_alias_set (void) |
| { |
| if (frame_set == -1) |
| frame_set = new_alias_set (); |
| |
| return frame_set; |
| } |
| |
| /* Create a new, unique base with id ID. */ |
| |
| static rtx |
| unique_base_value (HOST_WIDE_INT id) |
| { |
| return gen_rtx_ADDRESS (Pmode, id); |
| } |
| |
| /* Return true if accesses based on any other base value cannot alias |
| those based on X. */ |
| |
| static bool |
| unique_base_value_p (rtx x) |
| { |
| return GET_CODE (x) == ADDRESS && GET_MODE (x) == Pmode; |
| } |
| |
| /* Return true if X is known to be a base value. */ |
| |
| static bool |
| known_base_value_p (rtx x) |
| { |
| switch (GET_CODE (x)) |
| { |
| case LABEL_REF: |
| case SYMBOL_REF: |
| return true; |
| |
| case ADDRESS: |
| /* Arguments may or may not be bases; we don't know for sure. */ |
| return GET_MODE (x) != VOIDmode; |
| |
| default: |
| return false; |
| } |
| } |
| |
| /* Inside SRC, the source of a SET, find a base address. */ |
| |
| static rtx |
| find_base_value (rtx src) |
| { |
| unsigned int regno; |
| scalar_int_mode int_mode; |
| |
| #if defined (FIND_BASE_TERM) |
| /* Try machine-dependent ways to find the base term. */ |
| src = FIND_BASE_TERM (src); |
| #endif |
| |
| switch (GET_CODE (src)) |
| { |
| case SYMBOL_REF: |
| case LABEL_REF: |
| return src; |
| |
| case REG: |
| regno = REGNO (src); |
| /* At the start of a function, argument registers have known base |
| values which may be lost later. Returning an ADDRESS |
| expression here allows optimization based on argument values |
| even when the argument registers are used for other purposes. */ |
| if (regno < FIRST_PSEUDO_REGISTER && copying_arguments) |
| return new_reg_base_value[regno]; |
| |
| /* If a pseudo has a known base value, return it. Do not do this |
| for non-fixed hard regs since it can result in a circular |
| dependency chain for registers which have values at function entry. |
| |
| The test above is not sufficient because the scheduler may move |
| a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */ |
| if ((regno >= FIRST_PSEUDO_REGISTER || fixed_regs[regno]) |
| && regno < vec_safe_length (reg_base_value)) |
| { |
| /* If we're inside init_alias_analysis, use new_reg_base_value |
| to reduce the number of relaxation iterations. */ |
| if (new_reg_base_value && new_reg_base_value[regno] |
| && DF_REG_DEF_COUNT (regno) == 1) |
| return new_reg_base_value[regno]; |
| |
| if ((*reg_base_value)[regno]) |
| return (*reg_base_value)[regno]; |
| } |
| |
| return 0; |
| |
| case MEM: |
| /* Check for an argument passed in memory. Only record in the |
| copying-arguments block; it is too hard to track changes |
| otherwise. */ |
| if (copying_arguments |
| && (XEXP (src, 0) == arg_pointer_rtx |
| || (GET_CODE (XEXP (src, 0)) == PLUS |
| && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx))) |
| return arg_base_value; |
| return 0; |
| |
| case CONST: |
| src = XEXP (src, 0); |
| if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS) |
| break; |
| |
| /* fall through */ |
| |
| case PLUS: |
| case MINUS: |
| { |
| rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1); |
| |
| /* If either operand is a REG that is a known pointer, then it |
| is the base. */ |
| if (REG_P (src_0) && REG_POINTER (src_0)) |
| return find_base_value (src_0); |
| if (REG_P (src_1) && REG_POINTER (src_1)) |
| return find_base_value (src_1); |
| |
| /* If either operand is a REG, then see if we already have |
| a known value for it. */ |
| if (REG_P (src_0)) |
| { |
| temp = find_base_value (src_0); |
| if (temp != 0) |
| src_0 = temp; |
| } |
| |
| if (REG_P (src_1)) |
| { |
| temp = find_base_value (src_1); |
| if (temp!= 0) |
| src_1 = temp; |
| } |
| |
| /* If either base is named object or a special address |
| (like an argument or stack reference), then use it for the |
| base term. */ |
| if (src_0 != 0 && known_base_value_p (src_0)) |
| return src_0; |
| |
| if (src_1 != 0 && known_base_value_p (src_1)) |
| return src_1; |
| |
| /* Guess which operand is the base address: |
| If either operand is a symbol, then it is the base. If |
| either operand is a CONST_INT, then the other is the base. */ |
| if (CONST_INT_P (src_1) || CONSTANT_P (src_0)) |
| return find_base_value (src_0); |
| else if (CONST_INT_P (src_0) || CONSTANT_P (src_1)) |
| return find_base_value (src_1); |
| |
| return 0; |
| } |
| |
| case LO_SUM: |
| /* The standard form is (lo_sum reg sym) so look only at the |
| second operand. */ |
| return find_base_value (XEXP (src, 1)); |
| |
| case AND: |
| /* Look through aligning ANDs. And AND with zero or one with |
| the LSB set isn't one (see for example PR92462). */ |
| if (CONST_INT_P (XEXP (src, 1)) |
| && INTVAL (XEXP (src, 1)) != 0 |
| && (INTVAL (XEXP (src, 1)) & 1) == 0) |
| return find_base_value (XEXP (src, 0)); |
| return 0; |
| |
| case TRUNCATE: |
| /* As we do not know which address space the pointer is referring to, we can |
| handle this only if the target does not support different pointer or |
| address modes depending on the address space. */ |
| if (!target_default_pointer_address_modes_p ()) |
| break; |
| if (!is_a <scalar_int_mode> (GET_MODE (src), &int_mode) |
| || GET_MODE_PRECISION (int_mode) < GET_MODE_PRECISION (Pmode)) |
| break; |
| /* Fall through. */ |
| case HIGH: |
| case PRE_INC: |
| case PRE_DEC: |
| case POST_INC: |
| case POST_DEC: |
| case PRE_MODIFY: |
| case POST_MODIFY: |
| return find_base_value (XEXP (src, 0)); |
| |
| case ZERO_EXTEND: |
| case SIGN_EXTEND: /* used for NT/Alpha pointers */ |
| /* As we do not know which address space the pointer is referring to, we can |
| handle this only if the target does not support different pointer or |
| address modes depending on the address space. */ |
| if (!target_default_pointer_address_modes_p ()) |
| break; |
| |
| { |
| rtx temp = find_base_value (XEXP (src, 0)); |
| |
| if (temp != 0 && CONSTANT_P (temp)) |
| temp = convert_memory_address (Pmode, temp); |
| |
| return temp; |
| } |
| |
| default: |
| break; |
| } |
| |
| return 0; |
| } |
| |
| /* Called from init_alias_analysis indirectly through note_stores, |
| or directly if DEST is a register with a REG_NOALIAS note attached. |
| SET is null in the latter case. */ |
| |
| /* While scanning insns to find base values, reg_seen[N] is nonzero if |
| register N has been set in this function. */ |
| static sbitmap reg_seen; |
| |
| static void |
| record_set (rtx dest, const_rtx set, void *data ATTRIBUTE_UNUSED) |
| { |
| unsigned regno; |
| rtx src; |
| int n; |
| |
| if (!REG_P (dest)) |
| return; |
| |
| regno = REGNO (dest); |
| |
| gcc_checking_assert (regno < reg_base_value->length ()); |
| |
| n = REG_NREGS (dest); |
| if (n != 1) |
| { |
| while (--n >= 0) |
| { |
| bitmap_set_bit (reg_seen, regno + n); |
| new_reg_base_value[regno + n] = 0; |
| } |
| return; |
| } |
| |
| if (set) |
| { |
| /* A CLOBBER wipes out any old value but does not prevent a previously |
| unset register from acquiring a base address (i.e. reg_seen is not |
| set). */ |
| if (GET_CODE (set) == CLOBBER) |
| { |
| new_reg_base_value[regno] = 0; |
| return; |
| } |
| |
| src = SET_SRC (set); |
| } |
| else |
| { |
| /* There's a REG_NOALIAS note against DEST. */ |
| if (bitmap_bit_p (reg_seen, regno)) |
| { |
| new_reg_base_value[regno] = 0; |
| return; |
| } |
| bitmap_set_bit (reg_seen, regno); |
| new_reg_base_value[regno] = unique_base_value (unique_id++); |
| return; |
| } |
| |
| /* If this is not the first set of REGNO, see whether the new value |
| is related to the old one. There are two cases of interest: |
| |
| (1) The register might be assigned an entirely new value |
| that has the same base term as the original set. |
| |
| (2) The set might be a simple self-modification that |
| cannot change REGNO's base value. |
| |
| If neither case holds, reject the original base value as invalid. |
| Note that the following situation is not detected: |
| |
| extern int x, y; int *p = &x; p += (&y-&x); |
| |
| ANSI C does not allow computing the difference of addresses |
| of distinct top level objects. */ |
| if (new_reg_base_value[regno] != 0 |
| && find_base_value (src) != new_reg_base_value[regno]) |
| switch (GET_CODE (src)) |
| { |
| case LO_SUM: |
| case MINUS: |
| if (XEXP (src, 0) != dest && XEXP (src, 1) != dest) |
| new_reg_base_value[regno] = 0; |
| break; |
| case PLUS: |
| /* If the value we add in the PLUS is also a valid base value, |
| this might be the actual base value, and the original value |
| an index. */ |
| { |
| rtx other = NULL_RTX; |
| |
| if (XEXP (src, 0) == dest) |
| other = XEXP (src, 1); |
| else if (XEXP (src, 1) == dest) |
| other = XEXP (src, 0); |
| |
| if (! other || find_base_value (other)) |
| new_reg_base_value[regno] = 0; |
| break; |
| } |
| case AND: |
| if (XEXP (src, 0) != dest || !CONST_INT_P (XEXP (src, 1))) |
| new_reg_base_value[regno] = 0; |
| break; |
| default: |
| new_reg_base_value[regno] = 0; |
| break; |
| } |
| /* If this is the first set of a register, record the value. */ |
| else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno]) |
| && ! bitmap_bit_p (reg_seen, regno) && new_reg_base_value[regno] == 0) |
| new_reg_base_value[regno] = find_base_value (src); |
| |
| bitmap_set_bit (reg_seen, regno); |
| } |
| |
| /* Return REG_BASE_VALUE for REGNO. Selective scheduler uses this to avoid |
| using hard registers with non-null REG_BASE_VALUE for renaming. */ |
| rtx |
| get_reg_base_value (unsigned int regno) |
| { |
| return (*reg_base_value)[regno]; |
| } |
| |
| /* If a value is known for REGNO, return it. */ |
| |
| rtx |
| get_reg_known_value (unsigned int regno) |
| { |
| if (regno >= FIRST_PSEUDO_REGISTER) |
| { |
| regno -= FIRST_PSEUDO_REGISTER; |
| if (regno < vec_safe_length (reg_known_value)) |
| return (*reg_known_value)[regno]; |
| } |
| return NULL; |
| } |
| |
| /* Set it. */ |
| |
| static void |
| set_reg_known_value (unsigned int regno, rtx val) |
| { |
| if (regno >= FIRST_PSEUDO_REGISTER) |
| { |
| regno -= FIRST_PSEUDO_REGISTER; |
| if (regno < vec_safe_length (reg_known_value)) |
| (*reg_known_value)[regno] = val; |
| } |
| } |
| |
| /* Similarly for reg_known_equiv_p. */ |
| |
| bool |
| get_reg_known_equiv_p (unsigned int regno) |
| { |
| if (regno >= FIRST_PSEUDO_REGISTER) |
| { |
| regno -= FIRST_PSEUDO_REGISTER; |
| if (regno < vec_safe_length (reg_known_value)) |
| return bitmap_bit_p (reg_known_equiv_p, regno); |
| } |
| return false; |
| } |
| |
| static void |
| set_reg_known_equiv_p (unsigned int regno, bool val) |
| { |
| if (regno >= FIRST_PSEUDO_REGISTER) |
| { |
| regno -= FIRST_PSEUDO_REGISTER; |
| if (regno < vec_safe_length (reg_known_value)) |
| { |
| if (val) |
| bitmap_set_bit (reg_known_equiv_p, regno); |
| else |
| bitmap_clear_bit (reg_known_equiv_p, regno); |
| } |
| } |
| } |
| |
| |
| /* Returns a canonical version of X, from the point of view alias |
| analysis. (For example, if X is a MEM whose address is a register, |
| and the register has a known value (say a SYMBOL_REF), then a MEM |
| whose address is the SYMBOL_REF is returned.) */ |
| |
| rtx |
| canon_rtx (rtx x) |
| { |
| /* Recursively look for equivalences. */ |
| if (REG_P (x) && REGNO (x) >= FIRST_PSEUDO_REGISTER) |
| { |
| rtx t = get_reg_known_value (REGNO (x)); |
| if (t == x) |
| return x; |
| if (t) |
| return canon_rtx (t); |
| } |
| |
| if (GET_CODE (x) == PLUS) |
| { |
| rtx x0 = canon_rtx (XEXP (x, 0)); |
| rtx x1 = canon_rtx (XEXP (x, 1)); |
| |
| if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1)) |
| return simplify_gen_binary (PLUS, GET_MODE (x), x0, x1); |
| } |
| |
| /* This gives us much better alias analysis when called from |
| the loop optimizer. Note we want to leave the original |
| MEM alone, but need to return the canonicalized MEM with |
| all the flags with their original values. */ |
| else if (MEM_P (x)) |
| x = replace_equiv_address_nv (x, canon_rtx (XEXP (x, 0))); |
| |
| return x; |
| } |
| |
| /* Return 1 if X and Y are identical-looking rtx's. |
| Expect that X and Y has been already canonicalized. |
| |
| We use the data in reg_known_value above to see if two registers with |
| different numbers are, in fact, equivalent. */ |
| |
| static int |
| rtx_equal_for_memref_p (const_rtx x, const_rtx y) |
| { |
| int i; |
| int j; |
| enum rtx_code code; |
| const char *fmt; |
| |
| if (x == 0 && y == 0) |
| return 1; |
| if (x == 0 || y == 0) |
| return 0; |
| |
| if (x == y) |
| return 1; |
| |
| code = GET_CODE (x); |
| /* Rtx's of different codes cannot be equal. */ |
| if (code != GET_CODE (y)) |
| return 0; |
| |
| /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. |
| (REG:SI x) and (REG:HI x) are NOT equivalent. */ |
| |
| if (GET_MODE (x) != GET_MODE (y)) |
| return 0; |
| |
| /* Some RTL can be compared without a recursive examination. */ |
| switch (code) |
| { |
| case REG: |
| return REGNO (x) == REGNO (y); |
| |
| case LABEL_REF: |
| return label_ref_label (x) == label_ref_label (y); |
| |
| case SYMBOL_REF: |
| return compare_base_symbol_refs (x, y) == 1; |
| |
| case ENTRY_VALUE: |
| /* This is magic, don't go through canonicalization et al. */ |
| return rtx_equal_p (ENTRY_VALUE_EXP (x), ENTRY_VALUE_EXP (y)); |
| |
| case VALUE: |
| CASE_CONST_UNIQUE: |
| /* Pointer equality guarantees equality for these nodes. */ |
| return 0; |
| |
| default: |
| break; |
| } |
| |
| /* canon_rtx knows how to handle plus. No need to canonicalize. */ |
| if (code == PLUS) |
| return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)) |
| && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1))) |
| || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1)) |
| && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0)))); |
| /* For commutative operations, the RTX match if the operand match in any |
| order. Also handle the simple binary and unary cases without a loop. */ |
| if (COMMUTATIVE_P (x)) |
| { |
| rtx xop0 = canon_rtx (XEXP (x, 0)); |
| rtx yop0 = canon_rtx (XEXP (y, 0)); |
| rtx yop1 = canon_rtx (XEXP (y, 1)); |
| |
| return ((rtx_equal_for_memref_p (xop0, yop0) |
| && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), yop1)) |
| || (rtx_equal_for_memref_p (xop0, yop1) |
| && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), yop0))); |
| } |
| else if (NON_COMMUTATIVE_P (x)) |
| { |
| return (rtx_equal_for_memref_p (canon_rtx (XEXP (x, 0)), |
| canon_rtx (XEXP (y, 0))) |
| && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), |
| canon_rtx (XEXP (y, 1)))); |
| } |
| else if (UNARY_P (x)) |
| return rtx_equal_for_memref_p (canon_rtx (XEXP (x, 0)), |
| canon_rtx (XEXP (y, 0))); |
| |
| /* Compare the elements. If any pair of corresponding elements |
| fail to match, return 0 for the whole things. |
| |
| Limit cases to types which actually appear in addresses. */ |
| |
| fmt = GET_RTX_FORMAT (code); |
| for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) |
| { |
| switch (fmt[i]) |
| { |
| case 'i': |
| if (XINT (x, i) != XINT (y, i)) |
| return 0; |
| break; |
| |
| case 'p': |
| if (maybe_ne (SUBREG_BYTE (x), SUBREG_BYTE (y))) |
| return 0; |
| break; |
| |
| case 'E': |
| /* Two vectors must have the same length. */ |
| if (XVECLEN (x, i) != XVECLEN (y, i)) |
| return 0; |
| |
| /* And the corresponding elements must match. */ |
| for (j = 0; j < XVECLEN (x, i); j++) |
| if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x, i, j)), |
| canon_rtx (XVECEXP (y, i, j))) == 0) |
| return 0; |
| break; |
| |
| case 'e': |
| if (rtx_equal_for_memref_p (canon_rtx (XEXP (x, i)), |
| canon_rtx (XEXP (y, i))) == 0) |
| return 0; |
| break; |
| |
| /* This can happen for asm operands. */ |
| case 's': |
| if (strcmp (XSTR (x, i), XSTR (y, i))) |
| return 0; |
| break; |
| |
| /* This can happen for an asm which clobbers memory. */ |
| case '0': |
| break; |
| |
| /* It is believed that rtx's at this level will never |
| contain anything but integers and other rtx's, |
| except for within LABEL_REFs and SYMBOL_REFs. */ |
| default: |
| gcc_unreachable (); |
| } |
| } |
| return 1; |
| } |
| |
| static rtx |
| find_base_term (rtx x, vec<std::pair<cselib_val *, |
| struct elt_loc_list *> > &visited_vals) |
| { |
| cselib_val *val; |
| struct elt_loc_list *l, *f; |
| rtx ret; |
| scalar_int_mode int_mode; |
| |
| #if defined (FIND_BASE_TERM) |
| /* Try machine-dependent ways to find the base term. */ |
| x = FIND_BASE_TERM (x); |
| #endif |
| |
| switch (GET_CODE (x)) |
| { |
| case REG: |
| return REG_BASE_VALUE (x); |
| |
| case TRUNCATE: |
| /* As we do not know which address space the pointer is referring to, we can |
| handle this only if the target does not support different pointer or |
| address modes depending on the address space. */ |
| if (!target_default_pointer_address_modes_p ()) |
| return 0; |
| if (!is_a <scalar_int_mode> (GET_MODE (x), &int_mode) |
| || GET_MODE_PRECISION (int_mode) < GET_MODE_PRECISION (Pmode)) |
| return 0; |
| /* Fall through. */ |
| case HIGH: |
| case PRE_INC: |
| case PRE_DEC: |
| case POST_INC: |
| case POST_DEC: |
| case PRE_MODIFY: |
| case POST_MODIFY: |
| return find_base_term (XEXP (x, 0), visited_vals); |
| |
| case ZERO_EXTEND: |
| case SIGN_EXTEND: /* Used for Alpha/NT pointers */ |
| /* As we do not know which address space the pointer is referring to, we can |
| handle this only if the target does not support different pointer or |
| address modes depending on the address space. */ |
| if (!target_default_pointer_address_modes_p ()) |
| return 0; |
| |
| { |
| rtx temp = find_base_term (XEXP (x, 0), visited_vals); |
| |
| if (temp != 0 && CONSTANT_P (temp)) |
| temp = convert_memory_address (Pmode, temp); |
| |
| return temp; |
| } |
| |
| case VALUE: |
| val = CSELIB_VAL_PTR (x); |
| ret = NULL_RTX; |
| |
| if (!val) |
| return ret; |
| |
| if (cselib_sp_based_value_p (val)) |
| return static_reg_base_value[STACK_POINTER_REGNUM]; |
| |
| if (visited_vals.length () > (unsigned) param_max_find_base_term_values) |
| return ret; |
| |
| f = val->locs; |
| /* Reset val->locs to avoid infinite recursion. */ |
| if (f) |
| visited_vals.safe_push (std::make_pair (val, f)); |
| val->locs = NULL; |
| |
| for (l = f; l; l = l->next) |
| if (GET_CODE (l->loc) == VALUE |
| && CSELIB_VAL_PTR (l->loc)->locs |
| && !CSELIB_VAL_PTR (l->loc)->locs->next |
| && CSELIB_VAL_PTR (l->loc)->locs->loc == x) |
| continue; |
| else if ((ret = find_base_term (l->loc, visited_vals)) != 0) |
| break; |
| |
| return ret; |
| |
| case LO_SUM: |
| /* The standard form is (lo_sum reg sym) so look only at the |
| second operand. */ |
| return find_base_term (XEXP (x, 1), visited_vals); |
| |
| case CONST: |
| x = XEXP (x, 0); |
| if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS) |
| return 0; |
| /* Fall through. */ |
| case PLUS: |
| case MINUS: |
| { |
| rtx tmp1 = XEXP (x, 0); |
| rtx tmp2 = XEXP (x, 1); |
| |
| /* This is a little bit tricky since we have to determine which of |
| the two operands represents the real base address. Otherwise this |
| routine may return the index register instead of the base register. |
| |
| That may cause us to believe no aliasing was possible, when in |
| fact aliasing is possible. |
| |
| We use a few simple tests to guess the base register. Additional |
| tests can certainly be added. For example, if one of the operands |
| is a shift or multiply, then it must be the index register and the |
| other operand is the base register. */ |
| |
| if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2)) |
| return find_base_term (tmp2, visited_vals); |
| |
| /* If either operand is known to be a pointer, then prefer it |
| to determine the base term. */ |
| if (REG_P (tmp1) && REG_POINTER (tmp1)) |
| ; |
| else if (REG_P (tmp2) && REG_POINTER (tmp2)) |
| std::swap (tmp1, tmp2); |
| /* If second argument is constant which has base term, prefer it |
| over variable tmp1. See PR64025. */ |
| else if (CONSTANT_P (tmp2) && !CONST_INT_P (tmp2)) |
| std::swap (tmp1, tmp2); |
| |
| /* Go ahead and find the base term for both operands. If either base |
| term is from a pointer or is a named object or a special address |
| (like an argument or stack reference), then use it for the |
| base term. */ |
| rtx base = find_base_term (tmp1, visited_vals); |
| if (base != NULL_RTX |
| && ((REG_P (tmp1) && REG_POINTER (tmp1)) |
| || known_base_value_p (base))) |
| return base; |
| base = find_base_term (tmp2, visited_vals); |
| if (base != NULL_RTX |
| && ((REG_P (tmp2) && REG_POINTER (tmp2)) |
| || known_base_value_p (base))) |
| return base; |
| |
| /* We could not determine which of the two operands was the |
| base register and which was the index. So we can determine |
| nothing from the base alias check. */ |
| return 0; |
| } |
| |
| case AND: |
| /* Look through aligning ANDs. And AND with zero or one with |
| the LSB set isn't one (see for example PR92462). */ |
| if (CONST_INT_P (XEXP (x, 1)) |
| && INTVAL (XEXP (x, 1)) != 0 |
| && (INTVAL (XEXP (x, 1)) & 1) == 0) |
| return find_base_term (XEXP (x, 0), visited_vals); |
| return 0; |
| |
| case SYMBOL_REF: |
| case LABEL_REF: |
| return x; |
| |
| default: |
| return 0; |
| } |
| } |
| |
| /* Wrapper around the worker above which removes locs from visited VALUEs |
| to avoid visiting them multiple times. We unwind that changes here. */ |
| |
| static rtx |
| find_base_term (rtx x) |
| { |
| auto_vec<std::pair<cselib_val *, struct elt_loc_list *>, 32> visited_vals; |
| rtx res = find_base_term (x, visited_vals); |
| for (unsigned i = 0; i < visited_vals.length (); ++i) |
| visited_vals[i].first->locs = visited_vals[i].second; |
| return res; |
| } |
| |
| /* Return true if accesses to address X may alias accesses based |
| on the stack pointer. */ |
| |
| bool |
| may_be_sp_based_p (rtx x) |
| { |
| rtx base = find_base_term (x); |
| return !base || base == static_reg_base_value[STACK_POINTER_REGNUM]; |
| } |
| |
| /* BASE1 and BASE2 are decls. Return 1 if they refer to same object, 0 |
| if they refer to different objects and -1 if we cannot decide. */ |
| |
| int |
| compare_base_decls (tree base1, tree base2) |
| { |
| int ret; |
| gcc_checking_assert (DECL_P (base1) && DECL_P (base2)); |
| if (base1 == base2) |
| return 1; |
| |
| /* If we have two register decls with register specification we |
| cannot decide unless their assembler names are the same. */ |
| if (DECL_REGISTER (base1) |
| && DECL_REGISTER (base2) |
| && HAS_DECL_ASSEMBLER_NAME_P (base1) |
| && HAS_DECL_ASSEMBLER_NAME_P (base2) |
| && DECL_ASSEMBLER_NAME_SET_P (base1) |
| && DECL_ASSEMBLER_NAME_SET_P (base2)) |
| { |
| if (DECL_ASSEMBLER_NAME_RAW (base1) == DECL_ASSEMBLER_NAME_RAW (base2)) |
| return 1; |
| return -1; |
| } |
| |
| /* Declarations of non-automatic variables may have aliases. All other |
| decls are unique. */ |
| if (!decl_in_symtab_p (base1) |
| || !decl_in_symtab_p (base2)) |
| return 0; |
| |
| /* Don't cause symbols to be inserted by the act of checking. */ |
| symtab_node *node1 = symtab_node::get (base1); |
| if (!node1) |
| return 0; |
| symtab_node *node2 = symtab_node::get (base2); |
| if (!node2) |
| return 0; |
| |
| ret = node1->equal_address_to (node2, true); |
| return ret; |
| } |
| |
| /* Same as compare_base_decls but for SYMBOL_REF. */ |
| |
| static int |
| compare_base_symbol_refs (const_rtx x_base, const_rtx y_base) |
| { |
| tree x_decl = SYMBOL_REF_DECL (x_base); |
| tree y_decl = SYMBOL_REF_DECL (y_base); |
| bool binds_def = true; |
| |
| if (XSTR (x_base, 0) == XSTR (y_base, 0)) |
| return 1; |
| if (x_decl && y_decl) |
| return compare_base_decls (x_decl, y_decl); |
| if (x_decl || y_decl) |
| { |
| if (!x_decl) |
| { |
| std::swap (x_decl, y_decl); |
| std::swap (x_base, y_base); |
| } |
| /* We handle specially only section anchors and assume that other |
| labels may overlap with user variables in an arbitrary way. */ |
| if (!SYMBOL_REF_HAS_BLOCK_INFO_P (y_base)) |
| return -1; |
| /* Anchors contains static VAR_DECLs and CONST_DECLs. We are safe |
| to ignore CONST_DECLs because they are readonly. */ |
| if (!VAR_P (x_decl) |
| || (!TREE_STATIC (x_decl) && !TREE_PUBLIC (x_decl))) |
| return 0; |
| |
| symtab_node *x_node = symtab_node::get_create (x_decl) |
| ->ultimate_alias_target (); |
| /* External variable cannot be in section anchor. */ |
| if (!x_node->definition) |
| return 0; |
| x_base = XEXP (DECL_RTL (x_node->decl), 0); |
| /* If not in anchor, we can disambiguate. */ |
| if (!SYMBOL_REF_HAS_BLOCK_INFO_P (x_base)) |
| return 0; |
| |
| /* We have an alias of anchored variable. If it can be interposed; |
| we must assume it may or may not alias its anchor. */ |
| binds_def = decl_binds_to_current_def_p (x_decl); |
| } |
| /* If we have variable in section anchor, we can compare by offset. */ |
| if (SYMBOL_REF_HAS_BLOCK_INFO_P (x_base) |
| && SYMBOL_REF_HAS_BLOCK_INFO_P (y_base)) |
| { |
| if (SYMBOL_REF_BLOCK (x_base) != SYMBOL_REF_BLOCK (y_base)) |
| return 0; |
| if (SYMBOL_REF_BLOCK_OFFSET (x_base) == SYMBOL_REF_BLOCK_OFFSET (y_base)) |
| return binds_def ? 1 : -1; |
| if (SYMBOL_REF_ANCHOR_P (x_base) != SYMBOL_REF_ANCHOR_P (y_base)) |
| return -1; |
| return 0; |
| } |
| /* In general we assume that memory locations pointed to by different labels |
| may overlap in undefined ways. */ |
| return -1; |
| } |
| |
| /* Return 0 if the addresses X and Y are known to point to different |
| objects, 1 if they might be pointers to the same object. */ |
| |
| static int |
| base_alias_check (rtx x, rtx x_base, rtx y, rtx y_base, |
| machine_mode x_mode, machine_mode y_mode) |
| { |
| /* If the address itself has no known base see if a known equivalent |
| value has one. If either address still has no known base, nothing |
| is known about aliasing. */ |
| if (x_base == 0) |
| { |
| rtx x_c; |
| |
| if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x) |
| return 1; |
| |
| x_base = find_base_term (x_c); |
| if (x_base == 0) |
| return 1; |
| } |
| |
| if (y_base == 0) |
| { |
| rtx y_c; |
| if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y) |
| return 1; |
| |
| y_base = find_base_term (y_c); |
| if (y_base == 0) |
| return 1; |
| } |
| |
| /* If the base addresses are equal nothing is known about aliasing. */ |
| if (rtx_equal_p (x_base, y_base)) |
| return 1; |
| |
| /* The base addresses are different expressions. If they are not accessed |
| via AND, there is no conflict. We can bring knowledge of object |
| alignment into play here. For example, on alpha, "char a, b;" can |
| alias one another, though "char a; long b;" cannot. AND addresses may |
| implicitly alias surrounding objects; i.e. unaligned access in DImode |
| via AND address can alias all surrounding object types except those |
| with aligment 8 or higher. */ |
| if (GET_CODE (x) == AND && GET_CODE (y) == AND) |
| return 1; |
| if (GET_CODE (x) == AND |
| && (!CONST_INT_P (XEXP (x, 1)) |
| || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1)))) |
| return 1; |
| if (GET_CODE (y) == AND |
| && (!CONST_INT_P (XEXP (y, 1)) |
| || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1)))) |
| return 1; |
| |
| /* Differing symbols not accessed via AND never alias. */ |
| if (GET_CODE (x_base) == SYMBOL_REF && GET_CODE (y_base) == SYMBOL_REF) |
| return compare_base_symbol_refs (x_base, y_base) != 0; |
| |
| if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS) |
| return 0; |
| |
| if (unique_base_value_p (x_base) || unique_base_value_p (y_base)) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* Return TRUE if EXPR refers to a VALUE whose uid is greater than |
| (or equal to) that of V. */ |
| |
| static bool |
| refs_newer_value_p (const_rtx expr, rtx v) |
| { |
| int minuid = CSELIB_VAL_PTR (v)->uid; |
| subrtx_iterator::array_type array; |
| FOR_EACH_SUBRTX (iter, array, expr, NONCONST) |
| if (GET_CODE (*iter) == VALUE && CSELIB_VAL_PTR (*iter)->uid >= minuid) |
| return true; |
| return false; |
| } |
| |
| /* Convert the address X into something we can use. This is done by returning |
| it unchanged unless it is a VALUE or VALUE +/- constant; for VALUE |
| we call cselib to get a more useful rtx. */ |
| |
| rtx |
| get_addr (rtx x) |
| { |
| cselib_val *v; |
| struct elt_loc_list *l; |
| |
| if (GET_CODE (x) != VALUE) |
| { |
| if ((GET_CODE (x) == PLUS || GET_CODE (x) == MINUS) |
| && GET_CODE (XEXP (x, 0)) == VALUE |
| && CONST_SCALAR_INT_P (XEXP (x, 1))) |
| { |
| rtx op0 = get_addr (XEXP (x, 0)); |
| if (op0 != XEXP (x, 0)) |
| { |
| poly_int64 c; |
| if (GET_CODE (x) == PLUS |
| && poly_int_rtx_p (XEXP (x, 1), &c)) |
| return plus_constant (GET_MODE (x), op0, c); |
| return simplify_gen_binary (GET_CODE (x), GET_MODE (x), |
| op0, XEXP (x, 1)); |
| } |
| } |
| return x; |
| } |
| v = CSELIB_VAL_PTR (x); |
| if (v) |
| { |
| bool have_equivs = cselib_have_permanent_equivalences (); |
| if (have_equivs) |
| v = canonical_cselib_val (v); |
| for (l = v->locs; l; l = l->next) |
| if (CONSTANT_P (l->loc)) |
| return l->loc; |
| for (l = v->locs; l; l = l->next) |
| if (!REG_P (l->loc) && !MEM_P (l->loc) |
| /* Avoid infinite recursion when potentially dealing with |
| var-tracking artificial equivalences, by skipping the |
| equivalences themselves, and not choosing expressions |
| that refer to newer VALUEs. */ |
| && (!have_equivs |
| || (GET_CODE (l->loc) != VALUE |
| && !refs_newer_value_p (l->loc, x)))) |
| return l->loc; |
| if (have_equivs) |
| { |
| for (l = v->locs; l; l = l->next) |
| if (REG_P (l->loc) |
| || (GET_CODE (l->loc) != VALUE |
| && !refs_newer_value_p (l->loc, x))) |
| return l->loc; |
| /* Return the canonical value. */ |
| return v->val_rtx; |
| } |
| if (v->locs) |
| return v->locs->loc; |
| } |
| return x; |
| } |
| |
| /* Return the address of the (N_REFS + 1)th memory reference to ADDR |
| where SIZE is the size in bytes of the memory reference. If ADDR |
| is not modified by the memory reference then ADDR is returned. */ |
| |
| static rtx |
| addr_side_effect_eval (rtx addr, poly_int64 size, int n_refs) |
| { |
| poly_int64 offset = 0; |
| |
| switch (GET_CODE (addr)) |
| { |
| case PRE_INC: |
| offset = (n_refs + 1) * size; |
| break; |
| case PRE_DEC: |
| offset = -(n_refs + 1) * size; |
| break; |
| case POST_INC: |
| offset = n_refs * size; |
| break; |
| case POST_DEC: |
| offset = -n_refs * size; |
| break; |
| |
| default: |
| return addr; |
| } |
| |
| addr = plus_constant (GET_MODE (addr), XEXP (addr, 0), offset); |
| addr = canon_rtx (addr); |
| |
| return addr; |
| } |
| |
| /* Return TRUE if an object X sized at XSIZE bytes and another object |
| Y sized at YSIZE bytes, starting C bytes after X, may overlap. If |
| any of the sizes is zero, assume an overlap, otherwise use the |
| absolute value of the sizes as the actual sizes. */ |
| |
| static inline bool |
| offset_overlap_p (poly_int64 c, poly_int64 xsize, poly_int64 ysize) |
| { |
| if (known_eq (xsize, 0) || known_eq (ysize, 0)) |
| return true; |
| |
| if (maybe_ge (c, 0)) |
| return maybe_gt (maybe_lt (xsize, 0) ? -xsize : xsize, c); |
| else |
| return maybe_gt (maybe_lt (ysize, 0) ? -ysize : ysize, -c); |
| } |
| |
| /* Return one if X and Y (memory addresses) reference the |
| same location in memory or if the references overlap. |
| Return zero if they do not overlap, else return |
| minus one in which case they still might reference the same location. |
| |
| C is an offset accumulator. When |
| C is nonzero, we are testing aliases between X and Y + C. |
| XSIZE is the size in bytes of the X reference, |
| similarly YSIZE is the size in bytes for Y. |
| Expect that canon_rtx has been already called for X and Y. |
| |
| If XSIZE or YSIZE is zero, we do not know the amount of memory being |
| referenced (the reference was BLKmode), so make the most pessimistic |
| assumptions. |
| |
| If XSIZE or YSIZE is negative, we may access memory outside the object |
| being referenced as a side effect. This can happen when using AND to |
| align memory references, as is done on the Alpha. |
| |
| Nice to notice that varying addresses cannot conflict with fp if no |
| local variables had their addresses taken, but that's too hard now. |
| |
| ??? Contrary to the tree alias oracle this does not return |
| one for X + non-constant and Y + non-constant when X and Y are equal. |
| If that is fixed the TBAA hack for union type-punning can be removed. */ |
| |
| static int |
| memrefs_conflict_p (poly_int64 xsize, rtx x, poly_int64 ysize, rtx y, |
| poly_int64 c) |
| { |
| if (GET_CODE (x) == VALUE) |
| { |
| if (REG_P (y)) |
| { |
| struct elt_loc_list *l = NULL; |
| if (CSELIB_VAL_PTR (x)) |
| for (l = canonical_cselib_val (CSELIB_VAL_PTR (x))->locs; |
| l; l = l->next) |
| if (REG_P (l->loc) && rtx_equal_for_memref_p (l->loc, y)) |
| break; |
| if (l) |
| x = y; |
| else |
| x = get_addr (x); |
| } |
| /* Don't call get_addr if y is the same VALUE. */ |
| else if (x != y) |
| x = get_addr (x); |
| } |
| if (GET_CODE (y) == VALUE) |
| { |
| if (REG_P (x)) |
| { |
| struct elt_loc_list *l = NULL; |
| if (CSELIB_VAL_PTR (y)) |
| for (l = canonical_cselib_val (CSELIB_VAL_PTR (y))->locs; |
| l; l = l->next) |
| if (REG_P (l->loc) && rtx_equal_for_memref_p (l->loc, x)) |
| break; |
| if (l) |
| y = x; |
| else |
| y = get_addr (y); |
| } |
| /* Don't call get_addr if x is the same VALUE. */ |
| else if (y != x) |
| y = get_addr (y); |
| } |
| if (GET_CODE (x) == HIGH) |
| x = XEXP (x, 0); |
| else if (GET_CODE (x) == LO_SUM) |
| x = XEXP (x, 1); |
| else |
| x = addr_side_effect_eval (x, maybe_lt (xsize, 0) ? -xsize : xsize, 0); |
| if (GET_CODE (y) == HIGH) |
| y = XEXP (y, 0); |
| else if (GET_CODE (y) == LO_SUM) |
| y = XEXP (y, 1); |
| else |
| y = addr_side_effect_eval (y, maybe_lt (ysize, 0) ? -ysize : ysize, 0); |
| |
| if (GET_CODE (x) == SYMBOL_REF && GET_CODE (y) == SYMBOL_REF) |
| { |
| int cmp = compare_base_symbol_refs (x,y); |
| |
| /* If both decls are the same, decide by offsets. */ |
| if (cmp == 1) |
| return offset_overlap_p (c, xsize, ysize); |
| /* Assume a potential overlap for symbolic addresses that went |
| through alignment adjustments (i.e., that have negative |
| sizes), because we can't know how far they are from each |
| other. */ |
| if (maybe_lt (xsize, 0) || maybe_lt (ysize, 0)) |
| return -1; |
| /* If decls are different or we know by offsets that there is no overlap, |
| we win. */ |
| if (!cmp || !offset_overlap_p (c, xsize, ysize)) |
| return 0; |
| /* Decls may or may not be different and offsets overlap....*/ |
| return -1; |
| } |
| else if (rtx_equal_for_memref_p (x, y)) |
| { |
| return offset_overlap_p (c, xsize, ysize); |
| } |
| |
| /* This code used to check for conflicts involving stack references and |
| globals but the base address alias code now handles these cases. */ |
| |
| if (GET_CODE (x) == PLUS) |
| { |
| /* The fact that X is canonicalized means that this |
| PLUS rtx is canonicalized. */ |
| rtx x0 = XEXP (x, 0); |
| rtx x1 = XEXP (x, 1); |
| |
| /* However, VALUEs might end up in different positions even in |
| canonical PLUSes. Comparing their addresses is enough. */ |
| if (x0 == y) |
| return memrefs_conflict_p (xsize, x1, ysize, const0_rtx, c); |
| else if (x1 == y) |
| return memrefs_conflict_p (xsize, x0, ysize, const0_rtx, c); |
| |
| poly_int64 cx1, cy1; |
| if (GET_CODE (y) == PLUS) |
| { |
| /* The fact that Y is canonicalized means that this |
| PLUS rtx is canonicalized. */ |
| rtx y0 = XEXP (y, 0); |
| rtx y1 = XEXP (y, 1); |
| |
| if (x0 == y1) |
| return memrefs_conflict_p (xsize, x1, ysize, y0, c); |
| if (x1 == y0) |
| return memrefs_conflict_p (xsize, x0, ysize, y1, c); |
| |
| if (rtx_equal_for_memref_p (x1, y1)) |
| return memrefs_conflict_p (xsize, x0, ysize, y0, c); |
| if (rtx_equal_for_memref_p (x0, y0)) |
| return memrefs_conflict_p (xsize, x1, ysize, y1, c); |
| if (poly_int_rtx_p (x1, &cx1)) |
| { |
| if (poly_int_rtx_p (y1, &cy1)) |
| return memrefs_conflict_p (xsize, x0, ysize, y0, |
| c - cx1 + cy1); |
| else |
| return memrefs_conflict_p (xsize, x0, ysize, y, c - cx1); |
| } |
| else if (poly_int_rtx_p (y1, &cy1)) |
| return memrefs_conflict_p (xsize, x, ysize, y0, c + cy1); |
| |
| return -1; |
| } |
| else if (poly_int_rtx_p (x1, &cx1)) |
| return memrefs_conflict_p (xsize, x0, ysize, y, c - cx1); |
| } |
| else if (GET_CODE (y) == PLUS) |
| { |
| /* The fact that Y is canonicalized means that this |
| PLUS rtx is canonicalized. */ |
| rtx y0 = XEXP (y, 0); |
| rtx y1 = XEXP (y, 1); |
| |
| if (x == y0) |
| return memrefs_conflict_p (xsize, const0_rtx, ysize, y1, c); |
| if (x == y1) |
| return memrefs_conflict_p (xsize, const0_rtx, ysize, y0, c); |
| |
| poly_int64 cy1; |
| if (poly_int_rtx_p (y1, &cy1)) |
| return memrefs_conflict_p (xsize, x, ysize, y0, c + cy1); |
| else |
| return -1; |
| } |
| |
| if (GET_CODE (x) == GET_CODE (y)) |
| switch (GET_CODE (x)) |
| { |
| case MULT: |
| { |
| /* Handle cases where we expect the second operands to be the |
| same, and check only whether the first operand would conflict |
| or not. */ |
| rtx x0, y0; |
| rtx x1 = canon_rtx (XEXP (x, 1)); |
| rtx y1 = canon_rtx (XEXP (y, 1)); |
| if (! rtx_equal_for_memref_p (x1, y1)) |
| return -1; |
| x0 = canon_rtx (XEXP (x, 0)); |
| y0 = canon_rtx (XEXP (y, 0)); |
| if (rtx_equal_for_memref_p (x0, y0)) |
| return offset_overlap_p (c, xsize, ysize); |
| |
| /* Can't properly adjust our sizes. */ |
| poly_int64 c1; |
| if (!poly_int_rtx_p (x1, &c1) |
| || !can_div_trunc_p (xsize, c1, &xsize) |
| || !can_div_trunc_p (ysize, c1, &ysize) |
| || !can_div_trunc_p (c, c1, &c)) |
| return -1; |
| return memrefs_conflict_p (xsize, x0, ysize, y0, c); |
| } |
| |
| default: |
| break; |
| } |
| |
| /* Deal with alignment ANDs by adjusting offset and size so as to |
| cover the maximum range, without taking any previously known |
| alignment into account. Make a size negative after such an |
| adjustments, so that, if we end up with e.g. two SYMBOL_REFs, we |
| assume a potential overlap, because they may end up in contiguous |
| memory locations and the stricter-alignment access may span over |
| part of both. */ |
| if (GET_CODE (x) == AND && CONST_INT_P (XEXP (x, 1))) |
| { |
| HOST_WIDE_INT sc = INTVAL (XEXP (x, 1)); |
| unsigned HOST_WIDE_INT uc = sc; |
| if (sc < 0 && pow2_or_zerop (-uc)) |
| { |
| if (maybe_gt (xsize, 0)) |
| xsize = -xsize; |
| if (maybe_ne (xsize, 0)) |
| xsize += sc + 1; |
| c -= sc + 1; |
| return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), |
| ysize, y, c); |
| } |
| } |
| if (GET_CODE (y) == AND && CONST_INT_P (XEXP (y, 1))) |
| { |
| HOST_WIDE_INT sc = INTVAL (XEXP (y, 1)); |
| unsigned HOST_WIDE_INT uc = sc; |
| if (sc < 0 && pow2_or_zerop (-uc)) |
| { |
| if (maybe_gt (ysize, 0)) |
| ysize = -ysize; |
| if (maybe_ne (ysize, 0)) |
| ysize += sc + 1; |
| c += sc + 1; |
| return memrefs_conflict_p (xsize, x, |
| ysize, canon_rtx (XEXP (y, 0)), c); |
| } |
| } |
| |
| if (CONSTANT_P (x)) |
| { |
| poly_int64 cx, cy; |
| if (poly_int_rtx_p (x, &cx) && poly_int_rtx_p (y, &cy)) |
| { |
| c += cy - cx; |
| return offset_overlap_p (c, xsize, ysize); |
| } |
| |
| if (GET_CODE (x) == CONST) |
| { |
| if (GET_CODE (y) == CONST) |
| return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), |
| ysize, canon_rtx (XEXP (y, 0)), c); |
| else |
| return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), |
| ysize, y, c); |
| } |
| if (GET_CODE (y) == CONST) |
| return memrefs_conflict_p (xsize, x, ysize, |
| canon_rtx (XEXP (y, 0)), c); |
| |
| /* Assume a potential overlap for symbolic addresses that went |
| through alignment adjustments (i.e., that have negative |
| sizes), because we can't know how far they are from each |
| other. */ |
| if (CONSTANT_P (y)) |
| return (maybe_lt (xsize, 0) |
| || maybe_lt (ysize, 0) |
| || offset_overlap_p (c, xsize, ysize)); |
| |
| return -1; |
| } |
| |
| return -1; |
| } |
| |
| /* Functions to compute memory dependencies. |
| |
| Since we process the insns in execution order, we can build tables |
| to keep track of what registers are fixed (and not aliased), what registers |
| are varying in known ways, and what registers are varying in unknown |
| ways. |
| |
| If both memory references are volatile, then there must always be a |
| dependence between the two references, since their order cannot be |
| changed. A volatile and non-volatile reference can be interchanged |
| though. |
| |
| We also must allow AND addresses, because they may generate accesses |
| outside the object being referenced. This is used to generate aligned |
| addresses from unaligned addresses, for instance, the alpha |
| storeqi_unaligned pattern. */ |
| |
| /* Read dependence: X is read after read in MEM takes place. There can |
| only be a dependence here if both reads are volatile, or if either is |
| an explicit barrier. */ |
| |
| int |
| read_dependence (const_rtx mem, const_rtx x) |
| { |
| if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) |
| return true; |
| if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER |
| || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) |
| return true; |
| return false; |
| } |
| |
| /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */ |
| |
| static tree |
| decl_for_component_ref (tree x) |
| { |
| do |
| { |
| x = TREE_OPERAND (x, 0); |
| } |
| while (x && TREE_CODE (x) == COMPONENT_REF); |
| |
| return x && DECL_P (x) ? x : NULL_TREE; |
| } |
| |
| /* Walk up the COMPONENT_REF list in X and adjust *OFFSET to compensate |
| for the offset of the field reference. *KNOWN_P says whether the |
| offset is known. */ |
| |
| static void |
| adjust_offset_for_component_ref (tree x, bool *known_p, |
| poly_int64 *offset) |
| { |
| if (!*known_p) |
| return; |
| do |
| { |
| tree xoffset = component_ref_field_offset (x); |
| tree field = TREE_OPERAND (x, 1); |
| if (!poly_int_tree_p (xoffset)) |
| { |
| *known_p = false; |
| return; |
| } |
| |
| poly_offset_int woffset |
| = (wi::to_poly_offset (xoffset) |
| + (wi::to_offset (DECL_FIELD_BIT_OFFSET (field)) |
| >> LOG2_BITS_PER_UNIT) |
| + *offset); |
| if (!woffset.to_shwi (offset)) |
| { |
| *known_p = false; |
| return; |
| } |
| |
| x = TREE_OPERAND (x, 0); |
| } |
| while (x && TREE_CODE (x) == COMPONENT_REF); |
| } |
| |
| /* Return nonzero if we can determine the exprs corresponding to memrefs |
| X and Y and they do not overlap. |
| If LOOP_VARIANT is set, skip offset-based disambiguation */ |
| |
| int |
| nonoverlapping_memrefs_p (const_rtx x, const_rtx y, bool loop_invariant) |
| { |
| tree exprx = MEM_EXPR (x), expry = MEM_EXPR (y); |
| rtx rtlx, rtly; |
| rtx basex, basey; |
| bool moffsetx_known_p, moffsety_known_p; |
| poly_int64 moffsetx = 0, moffsety = 0; |
| poly_int64 offsetx = 0, offsety = 0, sizex, sizey; |
| |
| /* Unless both have exprs, we can't tell anything. */ |
| if (exprx == 0 || expry == 0) |
| return 0; |
| |
| /* For spill-slot accesses make sure we have valid offsets. */ |
| if ((exprx == get_spill_slot_decl (false) |
| && ! MEM_OFFSET_KNOWN_P (x)) |
| || (expry == get_spill_slot_decl (false) |
| && ! MEM_OFFSET_KNOWN_P (y))) |
| return 0; |
| |
| /* If the field reference test failed, look at the DECLs involved. */ |
| moffsetx_known_p = MEM_OFFSET_KNOWN_P (x); |
| if (moffsetx_known_p) |
| moffsetx = MEM_OFFSET (x); |
| if (TREE_CODE (exprx) == COMPONENT_REF) |
| { |
| tree t = decl_for_component_ref (exprx); |
| if (! t) |
| return 0; |
| adjust_offset_for_component_ref (exprx, &moffsetx_known_p, &moffsetx); |
| exprx = t; |
| } |
| |
| moffsety_known_p = MEM_OFFSET_KNOWN_P (y); |
| if (moffsety_known_p) |
| moffsety = MEM_OFFSET (y); |
| if (TREE_CODE (expry) == COMPONENT_REF) |
| { |
| tree t = decl_for_component_ref (expry); |
| if (! t) |
| return 0; |
| adjust_offset_for_component_ref (expry, &moffsety_known_p, &moffsety); |
| expry = t; |
| } |
| |
| if (! DECL_P (exprx) || ! DECL_P (expry)) |
| return 0; |
| |
| /* If we refer to different gimple registers, or one gimple register |
| and one non-gimple-register, we know they can't overlap. First, |
| gimple registers don't have their addresses taken. Now, there |
| could be more than one stack slot for (different versions of) the |
| same gimple register, but we can presumably tell they don't |
| overlap based on offsets from stack base addresses elsewhere. |
| It's important that we don't proceed to DECL_RTL, because gimple |
| registers may not pass DECL_RTL_SET_P, and make_decl_rtl won't be |
| able to do anything about them since no SSA information will have |
| remained to guide it. */ |
| if (is_gimple_reg (exprx) || is_gimple_reg (expry)) |
| return exprx != expry |
| || (moffsetx_known_p && moffsety_known_p |
| && MEM_SIZE_KNOWN_P (x) && MEM_SIZE_KNOWN_P (y) |
| && !offset_overlap_p (moffsety - moffsetx, |
| MEM_SIZE (x), MEM_SIZE (y))); |
| |
| /* With invalid code we can end up storing into the constant pool. |
| Bail out to avoid ICEing when creating RTL for this. |
| See gfortran.dg/lto/20091028-2_0.f90. */ |
| if (TREE_CODE (exprx) == CONST_DECL |
| || TREE_CODE (expry) == CONST_DECL) |
| return 1; |
| |
| /* If one decl is known to be a function or label in a function and |
| the other is some kind of data, they can't overlap. */ |
| if ((TREE_CODE (exprx) == FUNCTION_DECL |
| || TREE_CODE (exprx) == LABEL_DECL) |
| != (TREE_CODE (expry) == FUNCTION_DECL |
| || TREE_CODE (expry) == LABEL_DECL)) |
| return 1; |
| |
| /* If either of the decls doesn't have DECL_RTL set (e.g. marked as |
| living in multiple places), we can't tell anything. Exception |
| are FUNCTION_DECLs for which we can create DECL_RTL on demand. */ |
| if ((!DECL_RTL_SET_P (exprx) && TREE_CODE (exprx) != FUNCTION_DECL) |
| || (!DECL_RTL_SET_P (expry) && TREE_CODE (expry) != FUNCTION_DECL)) |
| return 0; |
| |
| rtlx = DECL_RTL (exprx); |
| rtly = DECL_RTL (expry); |
| |
| /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they |
| can't overlap unless they are the same because we never reuse that part |
| of the stack frame used for locals for spilled pseudos. */ |
| if ((!MEM_P (rtlx) || !MEM_P (rtly)) |
| && ! rtx_equal_p (rtlx, rtly)) |
| return 1; |
| |
| /* If we have MEMs referring to different address spaces (which can |
| potentially overlap), we cannot easily tell from the addresses |
| whether the references overlap. */ |
| if (MEM_P (rtlx) && MEM_P (rtly) |
| && MEM_ADDR_SPACE (rtlx) != MEM_ADDR_SPACE (rtly)) |
| return 0; |
| |
| /* Get the base and offsets of both decls. If either is a register, we |
| know both are and are the same, so use that as the base. The only |
| we can avoid overlap is if we can deduce that they are nonoverlapping |
| pieces of that decl, which is very rare. */ |
| basex = MEM_P (rtlx) ? XEXP (rtlx, 0) : rtlx; |
| basex = strip_offset_and_add (basex, &offsetx); |
| |
| basey = MEM_P (rtly) ? XEXP (rtly, 0) : rtly; |
| basey = strip_offset_and_add (basey, &offsety); |
| |
| /* If the bases are different, we know they do not overlap if both |
| are constants or if one is a constant and the other a pointer into the |
| stack frame. Otherwise a different base means we can't tell if they |
| overlap or not. */ |
| if (compare_base_decls (exprx, expry) == 0) |
| return ((CONSTANT_P (basex) && CONSTANT_P (basey)) |
| || (CONSTANT_P (basex) && REG_P (basey) |
| && REGNO_PTR_FRAME_P (REGNO (basey))) |
| || (CONSTANT_P (basey) && REG_P (basex) |
| && REGNO_PTR_FRAME_P (REGNO (basex)))); |
| |
| /* Offset based disambiguation not appropriate for loop invariant */ |
| if (loop_invariant) |
| return 0; |
| |
| /* Offset based disambiguation is OK even if we do not know that the |
| declarations are necessarily different |
| (i.e. compare_base_decls (exprx, expry) == -1) */ |
| |
| sizex = (!MEM_P (rtlx) ? poly_int64 (GET_MODE_SIZE (GET_MODE (rtlx))) |
| : MEM_SIZE_KNOWN_P (rtlx) ? MEM_SIZE (rtlx) |
| : -1); |
| sizey = (!MEM_P (rtly) ? poly_int64 (GET_MODE_SIZE (GET_MODE (rtly))) |
| : MEM_SIZE_KNOWN_P (rtly) ? MEM_SIZE (rtly) |
| : -1); |
| |
| /* If we have an offset for either memref, it can update the values computed |
| above. */ |
| if (moffsetx_known_p) |
| offsetx += moffsetx, sizex -= moffsetx; |
| if (moffsety_known_p) |
| offsety += moffsety, sizey -= moffsety; |
| |
| /* If a memref has both a size and an offset, we can use the smaller size. |
| We can't do this if the offset isn't known because we must view this |
| memref as being anywhere inside the DECL's MEM. */ |
| if (MEM_SIZE_KNOWN_P (x) && moffsetx_known_p) |
| sizex = MEM_SIZE (x); |
| if (MEM_SIZE_KNOWN_P (y) && moffsety_known_p) |
| sizey = MEM_SIZE (y); |
| |
| return !ranges_maybe_overlap_p (offsetx, sizex, offsety, sizey); |
| } |
| |
| /* Helper for true_dependence and canon_true_dependence. |
| Checks for true dependence: X is read after store in MEM takes place. |
| |
| If MEM_CANONICALIZED is FALSE, then X_ADDR and MEM_ADDR should be |
| NULL_RTX, and the canonical addresses of MEM and X are both computed |
| here. If MEM_CANONICALIZED, then MEM must be already canonicalized. |
| |
| If X_ADDR is non-NULL, it is used in preference of XEXP (x, 0). |
| |
| Returns 1 if there is a true dependence, 0 otherwise. */ |
| |
| static int |
| true_dependence_1 (const_rtx mem, machine_mode mem_mode, rtx mem_addr, |
| const_rtx x, rtx x_addr, bool mem_canonicalized) |
| { |
| rtx true_mem_addr; |
| rtx base; |
| int ret; |
| |
| gcc_checking_assert (mem_canonicalized ? (mem_addr != NULL_RTX) |
| : (mem_addr == NULL_RTX && x_addr == NULL_RTX)); |
| |
| if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) |
| return 1; |
| |
| /* (mem:BLK (scratch)) is a special mechanism to conflict with everything. |
| This is used in epilogue deallocation functions, and in cselib. */ |
| if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH) |
| return 1; |
| if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH) |
| return 1; |
| if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER |
| || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) |
| return 1; |
| |
| if (! x_addr) |
| x_addr = XEXP (x, 0); |
| x_addr = get_addr (x_addr); |
| |
| if (! mem_addr) |
| { |
| mem_addr = XEXP (mem, 0); |
| if (mem_mode == VOIDmode) |
| mem_mode = GET_MODE (mem); |
| } |
| true_mem_addr = get_addr (mem_addr); |
| |
| /* Read-only memory is by definition never modified, and therefore can't |
| conflict with anything. However, don't assume anything when AND |
| addresses are involved and leave to the code below to determine |
| dependence. We don't expect to find read-only set on MEM, but |
| stupid user tricks can produce them, so don't die. */ |
| if (MEM_READONLY_P (x) |
| && GET_CODE (x_addr) != AND |
| && GET_CODE (true_mem_addr) != AND) |
| return 0; |
| |
| /* If we have MEMs referring to different address spaces (which can |
| potentially overlap), we cannot easily tell from the addresses |
| whether the references overlap. */ |
| if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x)) |
| return 1; |
| |
| base = find_base_term (x_addr); |
| if (base && (GET_CODE (base) == LABEL_REF |
| || (GET_CODE (base) == SYMBOL_REF |
| && CONSTANT_POOL_ADDRESS_P (base)))) |
| return 0; |
| |
| rtx mem_base = find_base_term (true_mem_addr); |
| if (! base_alias_check (x_addr, base, true_mem_addr, mem_base, |
| GET_MODE (x), mem_mode)) |
| return 0; |
| |
| x_addr = canon_rtx (x_addr); |
| if (!mem_canonicalized) |
| mem_addr = canon_rtx (true_mem_addr); |
| |
| if ((ret = memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr, |
| SIZE_FOR_MODE (x), x_addr, 0)) != -1) |
| return ret; |
| |
| if (mems_in_disjoint_alias_sets_p (x, mem)) |
| return 0; |
| |
| if (nonoverlapping_memrefs_p (mem, x, false)) |
| return 0; |
| |
| return rtx_refs_may_alias_p (x, mem, true); |
| } |
| |
| /* True dependence: X is read after store in MEM takes place. */ |
| |
| int |
| true_dependence (const_rtx mem, machine_mode mem_mode, const_rtx x) |
| { |
| return true_dependence_1 (mem, mem_mode, NULL_RTX, |
| x, NULL_RTX, /*mem_canonicalized=*/false); |
| } |
| |
| /* Canonical true dependence: X is read after store in MEM takes place. |
| Variant of true_dependence which assumes MEM has already been |
| canonicalized (hence we no longer do that here). |
| The mem_addr argument has been added, since true_dependence_1 computed |
| this value prior to canonicalizing. */ |
| |
| int |
| canon_true_dependence (const_rtx mem, machine_mode mem_mode, rtx mem_addr, |
| const_rtx x, rtx x_addr) |
| { |
| return true_dependence_1 (mem, mem_mode, mem_addr, |
| x, x_addr, /*mem_canonicalized=*/true); |
| } |
| |
| /* Returns nonzero if a write to X might alias a previous read from |
| (or, if WRITEP is true, a write to) MEM. |
| If X_CANONCALIZED is true, then X_ADDR is the canonicalized address of X, |
| and X_MODE the mode for that access. |
| If MEM_CANONICALIZED is true, MEM is canonicalized. */ |
| |
| static int |
| write_dependence_p (const_rtx mem, |
| const_rtx x, machine_mode x_mode, rtx x_addr, |
| bool mem_canonicalized, bool x_canonicalized, bool writep) |
| { |
| rtx mem_addr; |
| rtx true_mem_addr, true_x_addr; |
| rtx base; |
| int ret; |
| |
| gcc_checking_assert (x_canonicalized |
| ? (x_addr != NULL_RTX |
| && (x_mode != VOIDmode || GET_MODE (x) == VOIDmode)) |
| : (x_addr == NULL_RTX && x_mode == VOIDmode)); |
| |
| if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) |
| return 1; |
| |
| /* (mem:BLK (scratch)) is a special mechanism to conflict with everything. |
| This is used in epilogue deallocation functions. */ |
| if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH) |
| return 1; |
| if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH) |
| return 1; |
| if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER |
| || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) |
| return 1; |
| |
| if (!x_addr) |
| x_addr = XEXP (x, 0); |
| true_x_addr = get_addr (x_addr); |
| |
| mem_addr = XEXP (mem, 0); |
| true_mem_addr = get_addr (mem_addr); |
| |
| /* A read from read-only memory can't conflict with read-write memory. |
| Don't assume anything when AND addresses are involved and leave to |
| the code below to determine dependence. */ |
| if (!writep |
| && MEM_READONLY_P (mem) |
| && GET_CODE (true_x_addr) != AND |
| && GET_CODE (true_mem_addr) != AND) |
| return 0; |
| |
| /* If we have MEMs referring to different address spaces (which can |
| potentially overlap), we cannot easily tell from the addresses |
| whether the references overlap. */ |
| if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x)) |
| return 1; |
| |
| base = find_base_term (true_mem_addr); |
| if (! writep |
| && base |
| && (GET_CODE (base) == LABEL_REF |
| || (GET_CODE (base) == SYMBOL_REF |
| && CONSTANT_POOL_ADDRESS_P (base)))) |
| return 0; |
| |
| rtx x_base = find_base_term (true_x_addr); |
| if (! base_alias_check (true_x_addr, x_base, true_mem_addr, base, |
| GET_MODE (x), GET_MODE (mem))) |
| return 0; |
| |
| if (!x_canonicalized) |
| { |
| x_addr = canon_rtx (true_x_addr); |
| x_mode = GET_MODE (x); |
| } |
| if (!mem_canonicalized) |
| mem_addr = canon_rtx (true_mem_addr); |
| |
| if ((ret = memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr, |
| GET_MODE_SIZE (x_mode), x_addr, 0)) != -1) |
| return ret; |
| |
| if (nonoverlapping_memrefs_p (x, mem, false)) |
| return 0; |
| |
| return rtx_refs_may_alias_p (x, mem, false); |
| } |
| |
| /* Anti dependence: X is written after read in MEM takes place. */ |
| |
| int |
| anti_dependence (const_rtx mem, const_rtx x) |
| { |
| return write_dependence_p (mem, x, VOIDmode, NULL_RTX, |
| /*mem_canonicalized=*/false, |
| /*x_canonicalized*/false, /*writep=*/false); |
| } |
| |
| /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X. |
| Also, consider X in X_MODE (which might be from an enclosing |
| STRICT_LOW_PART / ZERO_EXTRACT). |
| If MEM_CANONICALIZED is true, MEM is canonicalized. */ |
| |
| int |
| canon_anti_dependence (const_rtx mem, bool mem_canonicalized, |
| const_rtx x, machine_mode x_mode, rtx x_addr) |
| { |
| return write_dependence_p (mem, x, x_mode, x_addr, |
| mem_canonicalized, /*x_canonicalized=*/true, |
| /*writep=*/false); |
| } |
| |
| /* Output dependence: X is written after store in MEM takes place. */ |
| |
| int |
| output_dependence (const_rtx mem, const_rtx x) |
| { |
| return write_dependence_p (mem, x, VOIDmode, NULL_RTX, |
| /*mem_canonicalized=*/false, |
| /*x_canonicalized*/false, /*writep=*/true); |
| } |
| |
| /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X. |
| Also, consider X in X_MODE (which might be from an enclosing |
| STRICT_LOW_PART / ZERO_EXTRACT). |
| If MEM_CANONICALIZED is true, MEM is canonicalized. */ |
| |
| int |
| canon_output_dependence (const_rtx mem, bool mem_canonicalized, |
| const_rtx x, machine_mode x_mode, rtx x_addr) |
| { |
| return write_dependence_p (mem, x, x_mode, x_addr, |
| mem_canonicalized, /*x_canonicalized=*/true, |
| /*writep=*/true); |
| } |
| |
| |
| |
| /* Check whether X may be aliased with MEM. Don't do offset-based |
|