| /* Conditional Dead Call Elimination pass for the GNU compiler. |
| Copyright (C) 2008-2017 Free Software Foundation, Inc. |
| Contributed by Xinliang David Li <davidxl@google.com> |
| |
| 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 "tree.h" |
| #include "gimple.h" |
| #include "cfghooks.h" |
| #include "tree-pass.h" |
| #include "ssa.h" |
| #include "gimple-pretty-print.h" |
| #include "fold-const.h" |
| #include "stor-layout.h" |
| #include "gimple-iterator.h" |
| #include "tree-cfg.h" |
| #include "tree-into-ssa.h" |
| #include "builtins.h" |
| #include "internal-fn.h" |
| #include "tree-dfa.h" |
| |
| |
| /* This pass serves two closely-related purposes: |
| |
| 1. It conditionally executes calls that set errno if (a) the result of |
| the call is unused and (b) a simple range check on the arguments can |
| detect most cases where errno does not need to be set. |
| |
| This is the "conditional dead-code elimination" that gave the pass |
| its original name, since the call is dead for most argument values. |
| The calls for which it helps are usually part of the C++ abstraction |
| penalty exposed after inlining. |
| |
| 2. It looks for calls to built-in functions that set errno and whose |
| result is used. It checks whether there is an associated internal |
| function that doesn't set errno and whether the target supports |
| that internal function. If so, the pass uses the internal function |
| to compute the result of the built-in function but still arranges |
| for errno to be set when necessary. There are two ways of setting |
| errno: |
| |
| a. by protecting the original call with the same argument checks as (1) |
| |
| b. by protecting the original call with a check that the result |
| of the internal function is not equal to itself (i.e. is NaN). |
| |
| (b) requires that NaNs are the only erroneous results. It is not |
| appropriate for functions like log, which returns ERANGE for zero |
| arguments. (b) is also likely to perform worse than (a) because it |
| requires the result to be calculated first. The pass therefore uses |
| (a) when it can and uses (b) as a fallback. |
| |
| For (b) the pass can replace the original call with a call to |
| IFN_SET_EDOM, if the target supports direct assignments to errno. |
| |
| In both cases, arguments that require errno to be set should occur |
| rarely in practice. Checks of the errno result should also be rare, |
| but the compiler would need powerful interprocedural analysis to |
| prove that errno is not checked. It's much easier to add argument |
| checks or result checks instead. |
| |
| An example of (1) is: |
| |
| log (x); // Mostly dead call |
| ==> |
| if (__builtin_islessequal (x, 0)) |
| log (x); |
| |
| With this change, call to log (x) is effectively eliminated, as |
| in the majority of the cases, log won't be called with x out of |
| range. The branch is totally predictable, so the branch cost |
| is low. |
| |
| An example of (2) is: |
| |
| y = sqrt (x); |
| ==> |
| y = IFN_SQRT (x); |
| if (__builtin_isless (x, 0)) |
| sqrt (x); |
| |
| In the vast majority of cases we should then never need to call sqrt. |
| |
| Note that library functions are not supposed to clear errno to zero without |
| error. See IEEE Std 1003.1, section 2.3 Error Numbers, and section 7.5:3 of |
| ISO/IEC 9899 (C99). |
| |
| The condition wrapping the builtin call is conservatively set to avoid too |
| aggressive (wrong) shrink wrapping. */ |
| |
| |
| /* A structure for representing input domain of |
| a function argument in integer. If the lower |
| bound is -inf, has_lb is set to false. If the |
| upper bound is +inf, has_ub is false. |
| is_lb_inclusive and is_ub_inclusive are flags |
| to indicate if lb and ub value are inclusive |
| respectively. */ |
| |
| struct inp_domain |
| { |
| int lb; |
| int ub; |
| bool has_lb; |
| bool has_ub; |
| bool is_lb_inclusive; |
| bool is_ub_inclusive; |
| }; |
| |
| /* A helper function to construct and return an input |
| domain object. LB is the lower bound, HAS_LB is |
| a boolean flag indicating if the lower bound exists, |
| and LB_INCLUSIVE is a boolean flag indicating if the |
| lower bound is inclusive or not. UB, HAS_UB, and |
| UB_INCLUSIVE have the same meaning, but for upper |
| bound of the domain. */ |
| |
| static inp_domain |
| get_domain (int lb, bool has_lb, bool lb_inclusive, |
| int ub, bool has_ub, bool ub_inclusive) |
| { |
| inp_domain domain; |
| domain.lb = lb; |
| domain.has_lb = has_lb; |
| domain.is_lb_inclusive = lb_inclusive; |
| domain.ub = ub; |
| domain.has_ub = has_ub; |
| domain.is_ub_inclusive = ub_inclusive; |
| return domain; |
| } |
| |
| /* A helper function to check the target format for the |
| argument type. In this implementation, only IEEE formats |
| are supported. ARG is the call argument to be checked. |
| Returns true if the format is supported. To support other |
| target formats, function get_no_error_domain needs to be |
| enhanced to have range bounds properly computed. Since |
| the check is cheap (very small number of candidates |
| to be checked), the result is not cached for each float type. */ |
| |
| static bool |
| check_target_format (tree arg) |
| { |
| tree type; |
| machine_mode mode; |
| const struct real_format *rfmt; |
| |
| type = TREE_TYPE (arg); |
| mode = TYPE_MODE (type); |
| rfmt = REAL_MODE_FORMAT (mode); |
| if ((mode == SFmode |
| && (rfmt == &ieee_single_format || rfmt == &mips_single_format |
| || rfmt == &motorola_single_format)) |
| || (mode == DFmode |
| && (rfmt == &ieee_double_format || rfmt == &mips_double_format |
| || rfmt == &motorola_double_format)) |
| /* For long double, we can not really check XFmode |
| which is only defined on intel platforms. |
| Candidate pre-selection using builtin function |
| code guarantees that we are checking formats |
| for long double modes: double, quad, and extended. */ |
| || (mode != SFmode && mode != DFmode |
| && (rfmt == &ieee_quad_format |
| || rfmt == &mips_quad_format |
| || rfmt == &ieee_extended_motorola_format |
| || rfmt == &ieee_extended_intel_96_format |
| || rfmt == &ieee_extended_intel_128_format |
| || rfmt == &ieee_extended_intel_96_round_53_format))) |
| return true; |
| |
| return false; |
| } |
| |
| |
| /* A helper function to help select calls to pow that are suitable for |
| conditional DCE transformation. It looks for pow calls that can be |
| guided with simple conditions. Such calls either have constant base |
| values or base values converted from integers. Returns true if |
| the pow call POW_CALL is a candidate. */ |
| |
| /* The maximum integer bit size for base argument of a pow call |
| that is suitable for shrink-wrapping transformation. */ |
| #define MAX_BASE_INT_BIT_SIZE 32 |
| |
| static bool |
| check_pow (gcall *pow_call) |
| { |
| tree base, expn; |
| enum tree_code bc, ec; |
| |
| if (gimple_call_num_args (pow_call) != 2) |
| return false; |
| |
| base = gimple_call_arg (pow_call, 0); |
| expn = gimple_call_arg (pow_call, 1); |
| |
| if (!check_target_format (expn)) |
| return false; |
| |
| bc = TREE_CODE (base); |
| ec = TREE_CODE (expn); |
| |
| /* Folding candidates are not interesting. |
| Can actually assert that it is already folded. */ |
| if (ec == REAL_CST && bc == REAL_CST) |
| return false; |
| |
| if (bc == REAL_CST) |
| { |
| /* Only handle a fixed range of constant. */ |
| REAL_VALUE_TYPE mv; |
| REAL_VALUE_TYPE bcv = TREE_REAL_CST (base); |
| if (real_equal (&bcv, &dconst1)) |
| return false; |
| if (real_less (&bcv, &dconst1)) |
| return false; |
| real_from_integer (&mv, TYPE_MODE (TREE_TYPE (base)), 256, UNSIGNED); |
| if (real_less (&mv, &bcv)) |
| return false; |
| return true; |
| } |
| else if (bc == SSA_NAME) |
| { |
| tree base_val0, type; |
| gimple *base_def; |
| int bit_sz; |
| |
| /* Only handles cases where base value is converted |
| from integer values. */ |
| base_def = SSA_NAME_DEF_STMT (base); |
| if (gimple_code (base_def) != GIMPLE_ASSIGN) |
| return false; |
| |
| if (gimple_assign_rhs_code (base_def) != FLOAT_EXPR) |
| return false; |
| base_val0 = gimple_assign_rhs1 (base_def); |
| |
| type = TREE_TYPE (base_val0); |
| if (TREE_CODE (type) != INTEGER_TYPE) |
| return false; |
| bit_sz = TYPE_PRECISION (type); |
| /* If the type of the base is too wide, |
| the resulting shrink wrapping condition |
| will be too conservative. */ |
| if (bit_sz > MAX_BASE_INT_BIT_SIZE) |
| return false; |
| |
| return true; |
| } |
| else |
| return false; |
| } |
| |
| /* A helper function to help select candidate function calls that are |
| suitable for conditional DCE. Candidate functions must have single |
| valid input domain in this implementation except for pow (see check_pow). |
| Returns true if the function call is a candidate. */ |
| |
| static bool |
| check_builtin_call (gcall *bcall) |
| { |
| tree arg; |
| |
| arg = gimple_call_arg (bcall, 0); |
| return check_target_format (arg); |
| } |
| |
| /* Return true if built-in function call CALL calls a math function |
| and if we know how to test the range of its arguments to detect _most_ |
| situations in which errno is not set. The test must err on the side |
| of treating non-erroneous values as potentially erroneous. */ |
| |
| static bool |
| can_test_argument_range (gcall *call) |
| { |
| switch (DECL_FUNCTION_CODE (gimple_call_fndecl (call))) |
| { |
| /* Trig functions. */ |
| CASE_FLT_FN (BUILT_IN_ACOS): |
| CASE_FLT_FN (BUILT_IN_ASIN): |
| /* Hyperbolic functions. */ |
| CASE_FLT_FN (BUILT_IN_ACOSH): |
| CASE_FLT_FN (BUILT_IN_ATANH): |
| CASE_FLT_FN (BUILT_IN_COSH): |
| CASE_FLT_FN (BUILT_IN_SINH): |
| /* Log functions. */ |
| CASE_FLT_FN (BUILT_IN_LOG): |
| CASE_FLT_FN (BUILT_IN_LOG2): |
| CASE_FLT_FN (BUILT_IN_LOG10): |
| CASE_FLT_FN (BUILT_IN_LOG1P): |
| /* Exp functions. */ |
| CASE_FLT_FN (BUILT_IN_EXP): |
| CASE_FLT_FN (BUILT_IN_EXP2): |
| CASE_FLT_FN (BUILT_IN_EXP10): |
| CASE_FLT_FN (BUILT_IN_EXPM1): |
| CASE_FLT_FN (BUILT_IN_POW10): |
| /* Sqrt. */ |
| CASE_FLT_FN (BUILT_IN_SQRT): |
| return check_builtin_call (call); |
| /* Special one: two argument pow. */ |
| case BUILT_IN_POW: |
| return check_pow (call); |
| default: |
| break; |
| } |
| |
| return false; |
| } |
| |
| /* Return true if CALL can produce a domain error (EDOM) but can never |
| produce a pole, range overflow or range underflow error (all ERANGE). |
| This means that we can tell whether a function would have set errno |
| by testing whether the result is a NaN. */ |
| |
| static bool |
| edom_only_function (gcall *call) |
| { |
| switch (DECL_FUNCTION_CODE (gimple_call_fndecl (call))) |
| { |
| CASE_FLT_FN (BUILT_IN_ACOS): |
| CASE_FLT_FN (BUILT_IN_ASIN): |
| CASE_FLT_FN (BUILT_IN_ATAN): |
| CASE_FLT_FN (BUILT_IN_COS): |
| CASE_FLT_FN (BUILT_IN_SIGNIFICAND): |
| CASE_FLT_FN (BUILT_IN_SIN): |
| CASE_FLT_FN (BUILT_IN_SQRT): |
| CASE_FLT_FN (BUILT_IN_FMOD): |
| CASE_FLT_FN (BUILT_IN_REMAINDER): |
| return true; |
| |
| default: |
| return false; |
| } |
| } |
| |
| /* Return true if it is structurally possible to guard CALL. */ |
| |
| static bool |
| can_guard_call_p (gimple *call) |
| { |
| return (!stmt_ends_bb_p (call) |
| || find_fallthru_edge (gimple_bb (call)->succs)); |
| } |
| |
| /* A helper function to generate gimple statements for one bound |
| comparison, so that the built-in function is called whenever |
| TCODE <ARG, LBUB> is *false*. TEMP_NAME1/TEMP_NAME2 are names |
| of the temporaries, CONDS is a vector holding the produced GIMPLE |
| statements, and NCONDS points to the variable holding the number of |
| logical comparisons. CONDS is either empty or a list ended with a |
| null tree. */ |
| |
| static void |
| gen_one_condition (tree arg, int lbub, |
| enum tree_code tcode, |
| const char *temp_name1, |
| const char *temp_name2, |
| vec<gimple *> conds, |
| unsigned *nconds) |
| { |
| tree lbub_real_cst, lbub_cst, float_type; |
| tree temp, tempn, tempc, tempcn; |
| gassign *stmt1; |
| gassign *stmt2; |
| gcond *stmt3; |
| |
| float_type = TREE_TYPE (arg); |
| lbub_cst = build_int_cst (integer_type_node, lbub); |
| lbub_real_cst = build_real_from_int_cst (float_type, lbub_cst); |
| |
| temp = create_tmp_var (float_type, temp_name1); |
| stmt1 = gimple_build_assign (temp, arg); |
| tempn = make_ssa_name (temp, stmt1); |
| gimple_assign_set_lhs (stmt1, tempn); |
| |
| tempc = create_tmp_var (boolean_type_node, temp_name2); |
| stmt2 = gimple_build_assign (tempc, |
| fold_build2 (tcode, |
| boolean_type_node, |
| tempn, lbub_real_cst)); |
| tempcn = make_ssa_name (tempc, stmt2); |
| gimple_assign_set_lhs (stmt2, tempcn); |
| |
| stmt3 = gimple_build_cond_from_tree (tempcn, NULL_TREE, NULL_TREE); |
| conds.quick_push (stmt1); |
| conds.quick_push (stmt2); |
| conds.quick_push (stmt3); |
| (*nconds)++; |
| } |
| |
| /* A helper function to generate GIMPLE statements for |
| out of input domain check. ARG is the call argument |
| to be runtime checked, DOMAIN holds the valid domain |
| for the given function, CONDS points to the vector |
| holding the result GIMPLE statements. *NCONDS is |
| the number of logical comparisons. This function |
| produces no more than two logical comparisons, one |
| for lower bound check, one for upper bound check. */ |
| |
| static void |
| gen_conditions_for_domain (tree arg, inp_domain domain, |
| vec<gimple *> conds, |
| unsigned *nconds) |
| { |
| if (domain.has_lb) |
| gen_one_condition (arg, domain.lb, |
| (domain.is_lb_inclusive |
| ? UNGE_EXPR : UNGT_EXPR), |
| "DCE_COND_LB", "DCE_COND_LB_TEST", |
| conds, nconds); |
| |
| if (domain.has_ub) |
| { |
| /* Now push a separator. */ |
| if (domain.has_lb) |
| conds.quick_push (NULL); |
| |
| gen_one_condition (arg, domain.ub, |
| (domain.is_ub_inclusive |
| ? UNLE_EXPR : UNLT_EXPR), |
| "DCE_COND_UB", "DCE_COND_UB_TEST", |
| conds, nconds); |
| } |
| } |
| |
| |
| /* A helper function to generate condition |
| code for the y argument in call pow (some_const, y). |
| See candidate selection in check_pow. Since the |
| candidates' base values have a limited range, |
| the guarded code generated for y are simple: |
| if (__builtin_isgreater (y, max_y)) |
| pow (const, y); |
| Note max_y can be computed separately for each |
| const base, but in this implementation, we |
| choose to compute it using the max base |
| in the allowed range for the purpose of |
| simplicity. BASE is the constant base value, |
| EXPN is the expression for the exponent argument, |
| *CONDS is the vector to hold resulting statements, |
| and *NCONDS is the number of logical conditions. */ |
| |
| static void |
| gen_conditions_for_pow_cst_base (tree base, tree expn, |
| vec<gimple *> conds, |
| unsigned *nconds) |
| { |
| inp_domain exp_domain; |
| /* Validate the range of the base constant to make |
| sure it is consistent with check_pow. */ |
| REAL_VALUE_TYPE mv; |
| REAL_VALUE_TYPE bcv = TREE_REAL_CST (base); |
| gcc_assert (!real_equal (&bcv, &dconst1) |
| && !real_less (&bcv, &dconst1)); |
| real_from_integer (&mv, TYPE_MODE (TREE_TYPE (base)), 256, UNSIGNED); |
| gcc_assert (!real_less (&mv, &bcv)); |
| |
| exp_domain = get_domain (0, false, false, |
| 127, true, false); |
| |
| gen_conditions_for_domain (expn, exp_domain, |
| conds, nconds); |
| } |
| |
| /* Generate error condition code for pow calls with |
| non constant base values. The candidates selected |
| have their base argument value converted from |
| integer (see check_pow) value (1, 2, 4 bytes), and |
| the max exp value is computed based on the size |
| of the integer type (i.e. max possible base value). |
| The resulting input domain for exp argument is thus |
| conservative (smaller than the max value allowed by |
| the runtime value of the base). BASE is the integer |
| base value, EXPN is the expression for the exponent |
| argument, *CONDS is the vector to hold resulting |
| statements, and *NCONDS is the number of logical |
| conditions. */ |
| |
| static void |
| gen_conditions_for_pow_int_base (tree base, tree expn, |
| vec<gimple *> conds, |
| unsigned *nconds) |
| { |
| gimple *base_def; |
| tree base_val0; |
| tree int_type; |
| tree temp, tempn; |
| tree cst0; |
| gimple *stmt1, *stmt2; |
| int bit_sz, max_exp; |
| inp_domain exp_domain; |
| |
| base_def = SSA_NAME_DEF_STMT (base); |
| base_val0 = gimple_assign_rhs1 (base_def); |
| int_type = TREE_TYPE (base_val0); |
| bit_sz = TYPE_PRECISION (int_type); |
| gcc_assert (bit_sz > 0 |
| && bit_sz <= MAX_BASE_INT_BIT_SIZE); |
| |
| /* Determine the max exp argument value according to |
| the size of the base integer. The max exp value |
| is conservatively estimated assuming IEEE754 double |
| precision format. */ |
| if (bit_sz == 8) |
| max_exp = 128; |
| else if (bit_sz == 16) |
| max_exp = 64; |
| else |
| { |
| gcc_assert (bit_sz == MAX_BASE_INT_BIT_SIZE); |
| max_exp = 32; |
| } |
| |
| /* For pow ((double)x, y), generate the following conditions: |
| cond 1: |
| temp1 = x; |
| if (__builtin_islessequal (temp1, 0)) |
| |
| cond 2: |
| temp2 = y; |
| if (__builtin_isgreater (temp2, max_exp_real_cst)) */ |
| |
| /* Generate condition in reverse order -- first |
| the condition for the exp argument. */ |
| |
| exp_domain = get_domain (0, false, false, |
| max_exp, true, true); |
| |
| gen_conditions_for_domain (expn, exp_domain, |
| conds, nconds); |
| |
| /* Now generate condition for the base argument. |
| Note it does not use the helper function |
| gen_conditions_for_domain because the base |
| type is integer. */ |
| |
| /* Push a separator. */ |
| conds.quick_push (NULL); |
| |
| temp = create_tmp_var (int_type, "DCE_COND1"); |
| cst0 = build_int_cst (int_type, 0); |
| stmt1 = gimple_build_assign (temp, base_val0); |
| tempn = make_ssa_name (temp, stmt1); |
| gimple_assign_set_lhs (stmt1, tempn); |
| stmt2 = gimple_build_cond (GT_EXPR, tempn, cst0, NULL_TREE, NULL_TREE); |
| |
| conds.quick_push (stmt1); |
| conds.quick_push (stmt2); |
| (*nconds)++; |
| } |
| |
| /* Method to generate conditional statements for guarding conditionally |
| dead calls to pow. One or more statements can be generated for |
| each logical condition. Statement groups of different conditions |
| are separated by a NULL tree and they are stored in the vec |
| conds. The number of logical conditions are stored in *nconds. |
| |
| See C99 standard, 7.12.7.4:2, for description of pow (x, y). |
| The precise condition for domain errors are complex. In this |
| implementation, a simplified (but conservative) valid domain |
| for x and y are used: x is positive to avoid dom errors, while |
| y is smaller than a upper bound (depending on x) to avoid range |
| errors. Runtime code is generated to check x (if not constant) |
| and y against the valid domain. If it is out, jump to the call, |
| otherwise the call is bypassed. POW_CALL is the call statement, |
| *CONDS is a vector holding the resulting condition statements, |
| and *NCONDS is the number of logical conditions. */ |
| |
| static void |
| gen_conditions_for_pow (gcall *pow_call, vec<gimple *> conds, |
| unsigned *nconds) |
| { |
| tree base, expn; |
| enum tree_code bc; |
| |
| gcc_checking_assert (check_pow (pow_call)); |
| |
| *nconds = 0; |
| |
| base = gimple_call_arg (pow_call, 0); |
| expn = gimple_call_arg (pow_call, 1); |
| |
| bc = TREE_CODE (base); |
| |
| if (bc == REAL_CST) |
| gen_conditions_for_pow_cst_base (base, expn, conds, nconds); |
| else if (bc == SSA_NAME) |
| gen_conditions_for_pow_int_base (base, expn, conds, nconds); |
| else |
| gcc_unreachable (); |
| } |
| |
| /* A helper routine to help computing the valid input domain |
| for a builtin function. See C99 7.12.7 for details. In this |
| implementation, we only handle single region domain. The |
| resulting region can be conservative (smaller) than the actual |
| one and rounded to integers. Some of the bounds are documented |
| in the standard, while other limit constants are computed |
| assuming IEEE floating point format (for SF and DF modes). |
| Since IEEE only sets minimum requirements for long double format, |
| different long double formats exist under different implementations |
| (e.g, 64 bit double precision (DF), 80 bit double-extended |
| precision (XF), and 128 bit quad precision (QF) ). For simplicity, |
| in this implementation, the computed bounds for long double assume |
| 64 bit format (DF), and are therefore conservative. Another |
| assumption is that single precision float type is always SF mode, |
| and double type is DF mode. This function is quite |
| implementation specific, so it may not be suitable to be part of |
| builtins.c. This needs to be revisited later to see if it can |
| be leveraged in x87 assembly expansion. */ |
| |
| static inp_domain |
| get_no_error_domain (enum built_in_function fnc) |
| { |
| switch (fnc) |
| { |
| /* Trig functions: return [-1, +1] */ |
| CASE_FLT_FN (BUILT_IN_ACOS): |
| CASE_FLT_FN (BUILT_IN_ASIN): |
| return get_domain (-1, true, true, |
| 1, true, true); |
| /* Hyperbolic functions. */ |
| CASE_FLT_FN (BUILT_IN_ACOSH): |
| /* acosh: [1, +inf) */ |
| return get_domain (1, true, true, |
| 1, false, false); |
| CASE_FLT_FN (BUILT_IN_ATANH): |
| /* atanh: (-1, +1) */ |
| return get_domain (-1, true, false, |
| 1, true, false); |
| case BUILT_IN_COSHF: |
| case BUILT_IN_SINHF: |
| /* coshf: (-89, +89) */ |
| return get_domain (-89, true, false, |
| 89, true, false); |
| case BUILT_IN_COSH: |
| case BUILT_IN_SINH: |
| case BUILT_IN_COSHL: |
| case BUILT_IN_SINHL: |
| /* cosh: (-710, +710) */ |
| return get_domain (-710, true, false, |
| 710, true, false); |
| /* Log functions: (0, +inf) */ |
| CASE_FLT_FN (BUILT_IN_LOG): |
| CASE_FLT_FN (BUILT_IN_LOG2): |
| CASE_FLT_FN (BUILT_IN_LOG10): |
| return get_domain (0, true, false, |
| 0, false, false); |
| CASE_FLT_FN (BUILT_IN_LOG1P): |
| return get_domain (-1, true, false, |
| 0, false, false); |
| /* Exp functions. */ |
| case BUILT_IN_EXPF: |
| case BUILT_IN_EXPM1F: |
| /* expf: (-inf, 88) */ |
| return get_domain (-1, false, false, |
| 88, true, false); |
| case BUILT_IN_EXP: |
| case BUILT_IN_EXPM1: |
| case BUILT_IN_EXPL: |
| case BUILT_IN_EXPM1L: |
| /* exp: (-inf, 709) */ |
| return get_domain (-1, false, false, |
| 709, true, false); |
| case BUILT_IN_EXP2F: |
| /* exp2f: (-inf, 128) */ |
| return get_domain (-1, false, false, |
| 128, true, false); |
| case BUILT_IN_EXP2: |
| case BUILT_IN_EXP2L: |
| /* exp2: (-inf, 1024) */ |
| return get_domain (-1, false, false, |
| 1024, true, false); |
| case BUILT_IN_EXP10F: |
| case BUILT_IN_POW10F: |
| /* exp10f: (-inf, 38) */ |
| return get_domain (-1, false, false, |
| 38, true, false); |
| case BUILT_IN_EXP10: |
| case BUILT_IN_POW10: |
| case BUILT_IN_EXP10L: |
| case BUILT_IN_POW10L: |
| /* exp10: (-inf, 308) */ |
| return get_domain (-1, false, false, |
| 308, true, false); |
| /* sqrt: [0, +inf) */ |
| CASE_FLT_FN (BUILT_IN_SQRT): |
| return get_domain (0, true, true, |
| 0, false, false); |
| default: |
| gcc_unreachable (); |
| } |
| |
| gcc_unreachable (); |
| } |
| |
| /* The function to generate shrink wrap conditions for a partially |
| dead builtin call whose return value is not used anywhere, |
| but has to be kept live due to potential error condition. |
| BI_CALL is the builtin call, CONDS is the vector of statements |
| for condition code, NCODES is the pointer to the number of |
| logical conditions. Statements belonging to different logical |
| condition are separated by NULL tree in the vector. */ |
| |
| static void |
| gen_shrink_wrap_conditions (gcall *bi_call, vec<gimple *> conds, |
| unsigned int *nconds) |
| { |
| gcall *call; |
| tree fn; |
| enum built_in_function fnc; |
| |
| gcc_assert (nconds && conds.exists ()); |
| gcc_assert (conds.length () == 0); |
| gcc_assert (is_gimple_call (bi_call)); |
| |
| call = bi_call; |
| fn = gimple_call_fndecl (call); |
| gcc_assert (fn && DECL_BUILT_IN (fn)); |
| fnc = DECL_FUNCTION_CODE (fn); |
| *nconds = 0; |
| |
| if (fnc == BUILT_IN_POW) |
| gen_conditions_for_pow (call, conds, nconds); |
| else |
| { |
| tree arg; |
| inp_domain domain = get_no_error_domain (fnc); |
| *nconds = 0; |
| arg = gimple_call_arg (bi_call, 0); |
| gen_conditions_for_domain (arg, domain, conds, nconds); |
| } |
| |
| return; |
| } |
| |
| |
| /* Probability of the branch (to the call) is taken. */ |
| #define ERR_PROB 0.01 |
| |
| /* Shrink-wrap BI_CALL so that it is only called when one of the NCONDS |
| conditions in CONDS is false. */ |
| |
| static void |
| shrink_wrap_one_built_in_call_with_conds (gcall *bi_call, vec <gimple *> conds, |
| unsigned int nconds) |
| { |
| gimple_stmt_iterator bi_call_bsi; |
| basic_block bi_call_bb, join_tgt_bb, guard_bb; |
| edge join_tgt_in_edge_from_call, join_tgt_in_edge_fall_thru; |
| edge bi_call_in_edge0, guard_bb_in_edge; |
| unsigned tn_cond_stmts; |
| unsigned ci; |
| gimple *cond_expr = NULL; |
| gimple *cond_expr_start; |
| |
| /* The cfg we want to create looks like this: |
| |
| [guard n-1] <- guard_bb (old block) |
| | \ |
| | [guard n-2] } |
| | / \ } |
| | / ... } new blocks |
| | / [guard 0] } |
| | / / | } |
| [ call ] | <- bi_call_bb } |
| | \ | |
| | \ | |
| | [ join ] <- join_tgt_bb (old iff call must end bb) |
| | |
| possible EH edges (only if [join] is old) |
| |
| When [join] is new, the immediate dominators for these blocks are: |
| |
| 1. [guard n-1]: unchanged |
| 2. [call]: [guard n-1] |
| 3. [guard m]: [guard m+1] for 0 <= m <= n-2 |
| 4. [join]: [guard n-1] |
| |
| We punt for the more complex case case of [join] being old and |
| simply free the dominance info. We also punt on postdominators, |
| which aren't expected to be available at this point anyway. */ |
| bi_call_bb = gimple_bb (bi_call); |
| |
| /* Now find the join target bb -- split bi_call_bb if needed. */ |
| if (stmt_ends_bb_p (bi_call)) |
| { |
| /* We checked that there was a fallthrough edge in |
| can_guard_call_p. */ |
| join_tgt_in_edge_from_call = find_fallthru_edge (bi_call_bb->succs); |
| gcc_assert (join_tgt_in_edge_from_call); |
| /* We don't want to handle PHIs. */ |
| if (EDGE_COUNT (join_tgt_in_edge_from_call->dest->preds) > 1) |
| join_tgt_bb = split_edge (join_tgt_in_edge_from_call); |
| else |
| { |
| join_tgt_bb = join_tgt_in_edge_from_call->dest; |
| /* We may have degenerate PHIs in the destination. Propagate |
| those out. */ |
| for (gphi_iterator i = gsi_start_phis (join_tgt_bb); !gsi_end_p (i);) |
| { |
| gphi *phi = i.phi (); |
| replace_uses_by (gimple_phi_result (phi), |
| gimple_phi_arg_def (phi, 0)); |
| remove_phi_node (&i, true); |
| } |
| } |
| } |
| else |
| { |
| join_tgt_in_edge_from_call = split_block (bi_call_bb, bi_call); |
| join_tgt_bb = join_tgt_in_edge_from_call->dest; |
| } |
| |
| bi_call_bsi = gsi_for_stmt (bi_call); |
| |
| /* Now it is time to insert the first conditional expression |
| into bi_call_bb and split this bb so that bi_call is |
| shrink-wrapped. */ |
| tn_cond_stmts = conds.length (); |
| cond_expr = NULL; |
| cond_expr_start = conds[0]; |
| for (ci = 0; ci < tn_cond_stmts; ci++) |
| { |
| gimple *c = conds[ci]; |
| gcc_assert (c || ci != 0); |
| if (!c) |
| break; |
| gsi_insert_before (&bi_call_bsi, c, GSI_SAME_STMT); |
| cond_expr = c; |
| } |
| ci++; |
| gcc_assert (cond_expr && gimple_code (cond_expr) == GIMPLE_COND); |
| |
| typedef std::pair<edge, edge> edge_pair; |
| auto_vec<edge_pair, 8> edges; |
| |
| bi_call_in_edge0 = split_block (bi_call_bb, cond_expr); |
| bi_call_in_edge0->flags &= ~EDGE_FALLTHRU; |
| bi_call_in_edge0->flags |= EDGE_FALSE_VALUE; |
| guard_bb = bi_call_bb; |
| bi_call_bb = bi_call_in_edge0->dest; |
| join_tgt_in_edge_fall_thru = make_edge (guard_bb, join_tgt_bb, |
| EDGE_TRUE_VALUE); |
| |
| edges.reserve (nconds); |
| edges.quick_push (edge_pair (bi_call_in_edge0, join_tgt_in_edge_fall_thru)); |
| |
| /* Code generation for the rest of the conditions */ |
| for (unsigned int i = 1; i < nconds; ++i) |
| { |
| unsigned ci0; |
| edge bi_call_in_edge; |
| gimple_stmt_iterator guard_bsi = gsi_for_stmt (cond_expr_start); |
| ci0 = ci; |
| cond_expr_start = conds[ci0]; |
| for (; ci < tn_cond_stmts; ci++) |
| { |
| gimple *c = conds[ci]; |
| gcc_assert (c || ci != ci0); |
| if (!c) |
| break; |
| gsi_insert_before (&guard_bsi, c, GSI_SAME_STMT); |
| cond_expr = c; |
| } |
| ci++; |
| gcc_assert (cond_expr && gimple_code (cond_expr) == GIMPLE_COND); |
| guard_bb_in_edge = split_block (guard_bb, cond_expr); |
| guard_bb_in_edge->flags &= ~EDGE_FALLTHRU; |
| guard_bb_in_edge->flags |= EDGE_TRUE_VALUE; |
| |
| bi_call_in_edge = make_edge (guard_bb, bi_call_bb, EDGE_FALSE_VALUE); |
| edges.quick_push (edge_pair (bi_call_in_edge, guard_bb_in_edge)); |
| } |
| |
| /* Now update the probability and profile information, processing the |
| guards in order of execution. |
| |
| There are two approaches we could take here. On the one hand we |
| could assign a probability of X to the call block and distribute |
| that probability among its incoming edges. On the other hand we |
| could assign a probability of X to each individual call edge. |
| |
| The choice only affects calls that have more than one condition. |
| In those cases, the second approach would give the call block |
| a greater probability than the first. However, the difference |
| is only small, and our chosen X is a pure guess anyway. |
| |
| Here we take the second approach because it's slightly simpler |
| and because it's easy to see that it doesn't lose profile counts. */ |
| bi_call_bb->count = 0; |
| bi_call_bb->frequency = 0; |
| while (!edges.is_empty ()) |
| { |
| edge_pair e = edges.pop (); |
| edge call_edge = e.first; |
| edge nocall_edge = e.second; |
| basic_block src_bb = call_edge->src; |
| gcc_assert (src_bb == nocall_edge->src); |
| |
| call_edge->probability = REG_BR_PROB_BASE * ERR_PROB; |
| call_edge->count = apply_probability (src_bb->count, |
| call_edge->probability); |
| nocall_edge->probability = inverse_probability (call_edge->probability); |
| nocall_edge->count = src_bb->count - call_edge->count; |
| |
| unsigned int call_frequency = apply_probability (src_bb->frequency, |
| call_edge->probability); |
| |
| bi_call_bb->count += call_edge->count; |
| bi_call_bb->frequency += call_frequency; |
| |
| if (nocall_edge->dest != join_tgt_bb) |
| { |
| nocall_edge->dest->count = nocall_edge->count; |
| nocall_edge->dest->frequency = src_bb->frequency - call_frequency; |
| } |
| } |
| |
| if (dom_info_available_p (CDI_DOMINATORS)) |
| { |
| /* The split_blocks leave [guard 0] as the immediate dominator |
| of [call] and [call] as the immediate dominator of [join]. |
| Fix them up. */ |
| set_immediate_dominator (CDI_DOMINATORS, bi_call_bb, guard_bb); |
| set_immediate_dominator (CDI_DOMINATORS, join_tgt_bb, guard_bb); |
| } |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| location_t loc; |
| loc = gimple_location (bi_call); |
| fprintf (dump_file, |
| "%s:%d: note: function call is shrink-wrapped" |
| " into error conditions.\n", |
| LOCATION_FILE (loc), LOCATION_LINE (loc)); |
| } |
| } |
| |
| /* Shrink-wrap BI_CALL so that it is only called when it might set errno |
| (but is always called if it would set errno). */ |
| |
| static void |
| shrink_wrap_one_built_in_call (gcall *bi_call) |
| { |
| unsigned nconds = 0; |
| auto_vec<gimple *, 12> conds; |
| gen_shrink_wrap_conditions (bi_call, conds, &nconds); |
| gcc_assert (nconds != 0); |
| shrink_wrap_one_built_in_call_with_conds (bi_call, conds, nconds); |
| } |
| |
| /* Return true if built-in function call CALL could be implemented using |
| a combination of an internal function to compute the result and a |
| separate call to set errno. */ |
| |
| static bool |
| can_use_internal_fn (gcall *call) |
| { |
| /* Only replace calls that set errno. */ |
| if (!gimple_vdef (call)) |
| return false; |
| |
| /* See whether there is an internal function for this built-in. */ |
| if (replacement_internal_fn (call) == IFN_LAST) |
| return false; |
| |
| /* See whether we can catch all cases where errno would be set, |
| while still avoiding the call in most cases. */ |
| if (!can_test_argument_range (call) |
| && !edom_only_function (call)) |
| return false; |
| |
| return true; |
| } |
| |
| /* Implement built-in function call CALL using an internal function. */ |
| |
| static void |
| use_internal_fn (gcall *call) |
| { |
| /* We'll be inserting another call with the same arguments after the |
| lhs has been set, so prevent any possible coalescing failure from |
| having both values live at once. See PR 71020. */ |
| replace_abnormal_ssa_names (call); |
| |
| unsigned nconds = 0; |
| auto_vec<gimple *, 12> conds; |
| if (can_test_argument_range (call)) |
| { |
| gen_shrink_wrap_conditions (call, conds, &nconds); |
| gcc_assert (nconds != 0); |
| } |
| else |
| gcc_assert (edom_only_function (call)); |
| |
| internal_fn ifn = replacement_internal_fn (call); |
| gcc_assert (ifn != IFN_LAST); |
| |
| /* Construct the new call, with the same arguments as the original one. */ |
| auto_vec <tree, 16> args; |
| unsigned int nargs = gimple_call_num_args (call); |
| for (unsigned int i = 0; i < nargs; ++i) |
| args.safe_push (gimple_call_arg (call, i)); |
| gcall *new_call = gimple_build_call_internal_vec (ifn, args); |
| gimple_set_location (new_call, gimple_location (call)); |
| |
| /* Transfer the LHS to the new call. */ |
| tree lhs = gimple_call_lhs (call); |
| gimple_call_set_lhs (new_call, lhs); |
| gimple_call_set_lhs (call, NULL_TREE); |
| SSA_NAME_DEF_STMT (lhs) = new_call; |
| |
| /* Insert the new call. */ |
| gimple_stmt_iterator gsi = gsi_for_stmt (call); |
| gsi_insert_before (&gsi, new_call, GSI_SAME_STMT); |
| |
| if (nconds == 0) |
| { |
| /* Skip the call if LHS == LHS. If we reach here, EDOM is the only |
| valid errno value and it is used iff the result is NaN. */ |
| conds.quick_push (gimple_build_cond (EQ_EXPR, lhs, lhs, |
| NULL_TREE, NULL_TREE)); |
| nconds++; |
| |
| /* Try replacing the original call with a direct assignment to |
| errno, via an internal function. */ |
| if (set_edom_supported_p () && !stmt_ends_bb_p (call)) |
| { |
| gimple_stmt_iterator gsi = gsi_for_stmt (call); |
| gcall *new_call = gimple_build_call_internal (IFN_SET_EDOM, 0); |
| gimple_set_vuse (new_call, gimple_vuse (call)); |
| gimple_set_vdef (new_call, gimple_vdef (call)); |
| SSA_NAME_DEF_STMT (gimple_vdef (new_call)) = new_call; |
| gimple_set_location (new_call, gimple_location (call)); |
| gsi_replace (&gsi, new_call, false); |
| call = new_call; |
| } |
| } |
| |
| shrink_wrap_one_built_in_call_with_conds (call, conds, nconds); |
| } |
| |
| /* The top level function for conditional dead code shrink |
| wrapping transformation. */ |
| |
| static void |
| shrink_wrap_conditional_dead_built_in_calls (vec<gcall *> calls) |
| { |
| unsigned i = 0; |
| |
| unsigned n = calls.length (); |
| for (; i < n ; i++) |
| { |
| gcall *bi_call = calls[i]; |
| if (gimple_call_lhs (bi_call)) |
| use_internal_fn (bi_call); |
| else |
| shrink_wrap_one_built_in_call (bi_call); |
| } |
| } |
| |
| namespace { |
| |
| const pass_data pass_data_call_cdce = |
| { |
| GIMPLE_PASS, /* type */ |
| "cdce", /* name */ |
| OPTGROUP_NONE, /* optinfo_flags */ |
| TV_TREE_CALL_CDCE, /* tv_id */ |
| ( PROP_cfg | PROP_ssa ), /* properties_required */ |
| 0, /* properties_provided */ |
| 0, /* properties_destroyed */ |
| 0, /* todo_flags_start */ |
| 0, /* todo_flags_finish */ |
| }; |
| |
| class pass_call_cdce : public gimple_opt_pass |
| { |
| public: |
| pass_call_cdce (gcc::context *ctxt) |
| : gimple_opt_pass (pass_data_call_cdce, ctxt) |
| {} |
| |
| /* opt_pass methods: */ |
| virtual bool gate (function *) |
| { |
| /* The limit constants used in the implementation |
| assume IEEE floating point format. Other formats |
| can be supported in the future if needed. */ |
| return flag_tree_builtin_call_dce != 0; |
| } |
| |
| virtual unsigned int execute (function *); |
| |
| }; // class pass_call_cdce |
| |
| unsigned int |
| pass_call_cdce::execute (function *fun) |
| { |
| basic_block bb; |
| gimple_stmt_iterator i; |
| auto_vec<gcall *> cond_dead_built_in_calls; |
| FOR_EACH_BB_FN (bb, fun) |
| { |
| /* Skip blocks that are being optimized for size, since our |
| transformation always increases code size. */ |
| if (optimize_bb_for_size_p (bb)) |
| continue; |
| |
| /* Collect dead call candidates. */ |
| for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i)) |
| { |
| gcall *stmt = dyn_cast <gcall *> (gsi_stmt (i)); |
| if (stmt |
| && gimple_call_builtin_p (stmt, BUILT_IN_NORMAL) |
| && (gimple_call_lhs (stmt) |
| ? can_use_internal_fn (stmt) |
| : can_test_argument_range (stmt)) |
| && can_guard_call_p (stmt)) |
| { |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "Found conditional dead call: "); |
| print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM); |
| fprintf (dump_file, "\n"); |
| } |
| if (!cond_dead_built_in_calls.exists ()) |
| cond_dead_built_in_calls.create (64); |
| cond_dead_built_in_calls.safe_push (stmt); |
| } |
| } |
| } |
| |
| if (!cond_dead_built_in_calls.exists ()) |
| return 0; |
| |
| shrink_wrap_conditional_dead_built_in_calls (cond_dead_built_in_calls); |
| free_dominance_info (CDI_POST_DOMINATORS); |
| /* As we introduced new control-flow we need to insert PHI-nodes |
| for the call-clobbers of the remaining call. */ |
| mark_virtual_operands_for_renaming (fun); |
| return TODO_update_ssa; |
| } |
| |
| } // anon namespace |
| |
| gimple_opt_pass * |
| make_pass_call_cdce (gcc::context *ctxt) |
| { |
| return new pass_call_cdce (ctxt); |
| } |