gcc/ipa-icf-gimple.c

/* Interprocedural Identical Code Folding pass
   Copyright (C) 2014-2021 Free Software Foundation, Inc.

   Contributed by Jan Hubicka <hubicka@ucw.cz> and Martin Liska <mliska@suse.cz>

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 "rtl.h"
#include "tree.h"
#include "gimple.h"
#include "tree-pass.h"
#include "ssa.h"
#include "cgraph.h"
#include "data-streamer.h"
#include "gimple-pretty-print.h"
#include "fold-const.h"
#include "gimple-iterator.h"
#include "ipa-utils.h"
#include "tree-eh.h"
#include "builtins.h"
#include "cfgloop.h"
#include "attribs.h"
#include "gimple-walk.h"

#include "tree-ssa-alias-compare.h"
#include "ipa-icf-gimple.h"

namespace ipa_icf_gimple {

/* Initialize internal structures for a given SOURCE_FUNC_DECL and
   TARGET_FUNC_DECL. Strict polymorphic comparison is processed if
   an option COMPARE_POLYMORPHIC is true. For special cases, one can
   set IGNORE_LABELS to skip label comparison.
   Similarly, IGNORE_SOURCE_DECLS and IGNORE_TARGET_DECLS are sets
   of declarations that can be skipped.  */

func_checker::func_checker (tree source_func_decl, tree target_func_decl,
			    bool ignore_labels, bool tbaa,
			    hash_set<symtab_node *> *ignored_source_nodes,
			    hash_set<symtab_node *> *ignored_target_nodes)
  : m_source_func_decl (source_func_decl), m_target_func_decl (target_func_decl),
    m_ignored_source_nodes (ignored_source_nodes),
    m_ignored_target_nodes (ignored_target_nodes),
    m_ignore_labels (ignore_labels), m_tbaa (tbaa)
{
  function *source_func = DECL_STRUCT_FUNCTION (source_func_decl);
  function *target_func = DECL_STRUCT_FUNCTION (target_func_decl);

  unsigned ssa_source = SSANAMES (source_func)->length ();
  unsigned ssa_target = SSANAMES (target_func)->length ();

  m_source_ssa_names.create (ssa_source);
  m_target_ssa_names.create (ssa_target);

  for (unsigned i = 0; i < ssa_source; i++)
    m_source_ssa_names.safe_push (-1);

  for (unsigned i = 0; i < ssa_target; i++)
    m_target_ssa_names.safe_push (-1);
}

/* Memory release routine.  */

func_checker::~func_checker ()
{
  m_source_ssa_names.release();
  m_target_ssa_names.release();
}

/* Verifies that trees T1 and T2 are equivalent from perspective of ICF.  */

bool
func_checker::compare_ssa_name (const_tree t1, const_tree t2)
{
  gcc_assert (TREE_CODE (t1) == SSA_NAME);
  gcc_assert (TREE_CODE (t2) == SSA_NAME);

  unsigned i1 = SSA_NAME_VERSION (t1);
  unsigned i2 = SSA_NAME_VERSION (t2);

  if (SSA_NAME_IS_DEFAULT_DEF (t1) != SSA_NAME_IS_DEFAULT_DEF (t2))
    return false;

  if (m_source_ssa_names[i1] == -1)
    m_source_ssa_names[i1] = i2;
  else if (m_source_ssa_names[i1] != (int) i2)
    return false;

  if(m_target_ssa_names[i2] == -1)
    m_target_ssa_names[i2] = i1;
  else if (m_target_ssa_names[i2] != (int) i1)
    return false;

  if (SSA_NAME_IS_DEFAULT_DEF (t1))
    {
      tree b1 = SSA_NAME_VAR (t1);
      tree b2 = SSA_NAME_VAR (t2);

      return compare_operand (b1, b2, OP_NORMAL);
    }

  return true;
}

/* Verification function for edges E1 and E2.  */

bool
func_checker::compare_edge (edge e1, edge e2)
{
  if (e1->flags != e2->flags)
    return false;

  bool existed_p;

  edge &slot = m_edge_map.get_or_insert (e1, &existed_p);
  if (existed_p)
    return return_with_debug (slot == e2);
  else
    slot = e2;

  /* TODO: filter edge probabilities for profile feedback match.  */

  return true;
}

/* Verification function for declaration trees T1 and T2 that
   come from functions FUNC1 and FUNC2.  */

bool
func_checker::compare_decl (const_tree t1, const_tree t2)
{
  if (!auto_var_in_fn_p (t1, m_source_func_decl)
      || !auto_var_in_fn_p (t2, m_target_func_decl))
    return return_with_debug (t1 == t2);

  tree_code t = TREE_CODE (t1);
  if ((t == VAR_DECL || t == PARM_DECL || t == RESULT_DECL)
      && DECL_BY_REFERENCE (t1) != DECL_BY_REFERENCE (t2))
    return return_false_with_msg ("DECL_BY_REFERENCE flags are different");

  /* We do not really need to check types of variables, since they are just
     blocks of memory and we verify types of the accesses to them.
     However do compare types of other kinds of decls
     (parm decls and result decl types may affect ABI convetions).  */
  if (t != VAR_DECL)
    {
      if (!compatible_types_p (TREE_TYPE (t1), TREE_TYPE (t2)))
	return return_false ();
    }
  else
    {
      if (!operand_equal_p (DECL_SIZE (t1), DECL_SIZE (t2),
			    OEP_MATCH_SIDE_EFFECTS))
	return return_false_with_msg ("DECL_SIZEs are different");
    }

  bool existed_p;
  const_tree &slot = m_decl_map.get_or_insert (t1, &existed_p);
  if (existed_p)
    return return_with_debug (slot == t2);
  else
    slot = t2;

  return true;
}

/* Return true if T1 and T2 are same for purposes of ipa-polymorphic-call
   analysis.  COMPARE_PTR indicates if types of pointers needs to be
   considered.  */

bool
func_checker::compatible_polymorphic_types_p (tree t1, tree t2,
					      bool compare_ptr)
{
  gcc_assert (TREE_CODE (t1) != FUNCTION_TYPE && TREE_CODE (t1) != METHOD_TYPE);

  /* Pointer types generally give no information.  */
  if (POINTER_TYPE_P (t1))
    {
      if (!compare_ptr)
	return true;
      return func_checker::compatible_polymorphic_types_p (TREE_TYPE (t1),
							   TREE_TYPE (t2),
							   false);
    }

  /* If types contain a polymorphic types, match them.  */
  bool c1 = contains_polymorphic_type_p (t1);
  bool c2 = contains_polymorphic_type_p (t2);
  if (!c1 && !c2)
    return true;
  if (!c1 || !c2)
    return return_false_with_msg ("one type is not polymorphic");
  if (!types_must_be_same_for_odr (t1, t2))
    return return_false_with_msg ("types are not same for ODR");
  return true;
}

/* Return true if types are compatible from perspective of ICF.  */
bool
func_checker::compatible_types_p (tree t1, tree t2)
{
  if (TREE_CODE (t1) != TREE_CODE (t2))
    return return_false_with_msg ("different tree types");

  if (TYPE_RESTRICT (t1) != TYPE_RESTRICT (t2))
    return return_false_with_msg ("restrict flags are different");

  if (!types_compatible_p (t1, t2))
    return return_false_with_msg ("types are not compatible");

  return true;
}

/* Add hash of ARG to HSTATE. FLAGS have same meaning
   as for operand_equal_p.  Works only if operand acces type is OP_NORMAL.  */

void
func_checker::hash_operand (const_tree arg, inchash::hash &hstate,
			    unsigned int flags)
{
  if (arg == NULL_TREE)
    {
      hstate.merge_hash (0);
      return;
    }

  switch (TREE_CODE (arg))
    {
    case PARM_DECL:
      {
	unsigned int index = 0;
	if (DECL_CONTEXT (arg))
	  for (tree p = DECL_ARGUMENTS (DECL_CONTEXT (arg));
	       p && index < 32; p = DECL_CHAIN (p), index++)
	    if (p == arg)
	      break;
	hstate.add_int (PARM_DECL);
	hstate.add_int (index);
      }
      return;
    case FUNCTION_DECL:
    case VAR_DECL:
    case LABEL_DECL:
    case RESULT_DECL:
    case CONST_DECL:
      hstate.add_int (TREE_CODE (arg));
      return;
    case SSA_NAME:
      hstate.add_int (SSA_NAME);
      if (SSA_NAME_IS_DEFAULT_DEF (arg))
	hash_operand (SSA_NAME_VAR (arg), hstate, flags);
      return;
    case FIELD_DECL:
      inchash::add_expr (DECL_FIELD_OFFSET (arg), hstate, flags);
      inchash::add_expr (DECL_FIELD_BIT_OFFSET (arg), hstate, flags);
      return;
    default:
      break;
    }

  /* In gimple all clobbers can be considered equal: while comparaing two
     gimple clobbers we match the left hand memory accesses.  */
  if (TREE_CLOBBER_P (arg))
    {
      hstate.add_int (0xc10bbe5);
      return;
    }
  gcc_assert (!DECL_P (arg));
  gcc_assert (!TYPE_P (arg));

  return operand_compare::hash_operand (arg, hstate, flags);
}

/* Add hash of ARG accesses according to ACCESS to HSTATE.
   FLAGS have same meaning as for operand_equal_p.  */

void
func_checker::hash_operand (const_tree arg, inchash::hash &hstate,
			    unsigned int flags, operand_access_type access)
{
  if (access == OP_MEMORY)
    {
      ao_ref ref;
      ao_ref_init (&ref, const_cast <tree> (arg));
      return hash_ao_ref (&ref, lto_streaming_expected_p (), m_tbaa, hstate);
    }
  else
    return hash_operand (arg, hstate, flags);
}

bool
func_checker::operand_equal_p (const_tree t1, const_tree t2,
			       unsigned int flags)
{
  bool r;
  if (verify_hash_value (t1, t2, flags, &r))
    return r;

  if (t1 == t2)
    return true;
  else if (!t1 || !t2)
    return false;

  if (TREE_CODE (t1) != TREE_CODE (t2))
    return return_false ();

  switch (TREE_CODE (t1))
    {
    case FUNCTION_DECL:
      /* All function decls are in the symbol table and known to match
	 before we start comparing bodies.  */
      return true;
    case VAR_DECL:
      return return_with_debug (compare_variable_decl (t1, t2));
    case LABEL_DECL:
      {
	int *bb1 = m_label_bb_map.get (t1);
	int *bb2 = m_label_bb_map.get (t2);
	/* Labels can point to another function (non-local GOTOs).  */
	return return_with_debug (bb1 != NULL && bb2 != NULL && *bb1 == *bb2);
      }

    case PARM_DECL:
    case RESULT_DECL:
    case CONST_DECL:
      return compare_decl (t1, t2);
    case SSA_NAME:
      return compare_ssa_name (t1, t2);
    default:
      break;
    }
  /* In gimple all clobbers can be considered equal.  We match the left hand
     memory accesses.  */
  if (TREE_CLOBBER_P (t1) || TREE_CLOBBER_P (t2))
    return TREE_CLOBBER_P (t1) == TREE_CLOBBER_P (t2);

  return operand_compare::operand_equal_p (t1, t2, flags);
}

/* Function responsible for comparison of various operands T1 and T2
   which are accessed as ACCESS.
   If these components, from functions FUNC1 and FUNC2, are equal, true
   is returned.  */

bool
func_checker::compare_operand (tree t1, tree t2, operand_access_type access)
{
  if (!t1 && !t2)
    return true;
  else if (!t1 || !t2)
    return false;
  if (access == OP_MEMORY)
    {
      ao_ref ref1, ref2;
      ao_ref_init (&ref1, const_cast <tree> (t1));
      ao_ref_init (&ref2, const_cast <tree> (t2));
      int flags = compare_ao_refs (&ref1, &ref2,
				   lto_streaming_expected_p (), m_tbaa);

      if (!flags)
	return true;
      if (flags & SEMANTICS)
	return return_false_with_msg
		("compare_ao_refs failed (semantic difference)");
      if (flags & BASE_ALIAS_SET)
	return return_false_with_msg
		("compare_ao_refs failed (base alias set difference)");
      if (flags & REF_ALIAS_SET)
	return return_false_with_msg
		 ("compare_ao_refs failed (ref alias set difference)");
      if (flags & ACCESS_PATH)
	return return_false_with_msg
		 ("compare_ao_refs failed (access path difference)");
      if (flags & DEPENDENCE_CLIQUE)
	return return_false_with_msg
		 ("compare_ao_refs failed (dependence clique difference)");
      gcc_unreachable ();
    }
  else
    {
      if (operand_equal_p (t1, t2, OEP_MATCH_SIDE_EFFECTS))
	return true;
      return return_false_with_msg
		 ("operand_equal_p failed");
    }
}

bool
func_checker::compare_asm_inputs_outputs (tree t1, tree t2,
					  operand_access_type_map *map)
{
  gcc_assert (TREE_CODE (t1) == TREE_LIST);
  gcc_assert (TREE_CODE (t2) == TREE_LIST);

  for (; t1; t1 = TREE_CHAIN (t1))
    {
      if (!t2)
	return false;

      if (!compare_operand (TREE_VALUE (t1), TREE_VALUE (t2),
			    get_operand_access_type (map, t1)))
	return return_false ();

      tree p1 = TREE_PURPOSE (t1);
      tree p2 = TREE_PURPOSE (t2);

      gcc_assert (TREE_CODE (p1) == TREE_LIST);
      gcc_assert (TREE_CODE (p2) == TREE_LIST);

      if (strcmp (TREE_STRING_POINTER (TREE_VALUE (p1)),
		  TREE_STRING_POINTER (TREE_VALUE (p2))) != 0)
	return return_false ();

      t2 = TREE_CHAIN (t2);
    }

  if (t2)
    return return_false ();

  return true;
}

/* Verifies that trees T1 and T2 do correspond.  */

bool
func_checker::compare_variable_decl (const_tree t1, const_tree t2)
{
  bool ret = false;

  if (t1 == t2)
    return true;

  if (DECL_ALIGN (t1) != DECL_ALIGN (t2))
    return return_false_with_msg ("alignments are different");

  if (DECL_HARD_REGISTER (t1) != DECL_HARD_REGISTER (t2))
    return return_false_with_msg ("DECL_HARD_REGISTER are different");

  if (DECL_HARD_REGISTER (t1)
      && DECL_ASSEMBLER_NAME_RAW (t1) != DECL_ASSEMBLER_NAME_RAW (t2))
    return return_false_with_msg ("HARD REGISTERS are different");

  /* Symbol table variables are known to match before we start comparing
     bodies.  */
  if (decl_in_symtab_p (t1))
    return decl_in_symtab_p (t2);
  ret = compare_decl (t1, t2);

  return return_with_debug (ret);
}

/* Compare loop information for basic blocks BB1 and BB2.  */

bool
func_checker::compare_loops (basic_block bb1, basic_block bb2)
{
  if ((bb1->loop_father == NULL) != (bb2->loop_father == NULL))
    return return_false ();

  class loop *l1 = bb1->loop_father;
  class loop *l2 = bb2->loop_father;
  if (l1 == NULL)
    return true;

  if ((bb1 == l1->header) != (bb2 == l2->header))
    return return_false_with_msg ("header");
  if ((bb1 == l1->latch) != (bb2 == l2->latch))
    return return_false_with_msg ("latch");
  if (l1->simdlen != l2->simdlen)
    return return_false_with_msg ("simdlen");
  if (l1->safelen != l2->safelen)
    return return_false_with_msg ("safelen");
  if (l1->can_be_parallel != l2->can_be_parallel)
    return return_false_with_msg ("can_be_parallel");
  if (l1->dont_vectorize != l2->dont_vectorize)
    return return_false_with_msg ("dont_vectorize");
  if (l1->force_vectorize != l2->force_vectorize)
    return return_false_with_msg ("force_vectorize");
  if (l1->finite_p != l2->finite_p)
    return return_false_with_msg ("finite_p");
  if (l1->unroll != l2->unroll)
    return return_false_with_msg ("unroll");
  if (!compare_variable_decl (l1->simduid, l2->simduid))
    return return_false_with_msg ("simduid");

  return true;
}

/* Function visits all gimple labels and creates corresponding
   mapping between basic blocks and labels.  */

void
func_checker::parse_labels (sem_bb *bb)
{
  for (gimple_stmt_iterator gsi = gsi_start_bb (bb->bb); !gsi_end_p (gsi);
       gsi_next (&gsi))
    {
      gimple *stmt = gsi_stmt (gsi);

      if (glabel *label_stmt = dyn_cast <glabel *> (stmt))
	{
	  const_tree t = gimple_label_label (label_stmt);
	  gcc_assert (TREE_CODE (t) == LABEL_DECL);

	  m_label_bb_map.put (t, bb->bb->index);
	}
    }
}

/* Basic block equivalence comparison function that returns true if
   basic blocks BB1 and BB2 (from functions FUNC1 and FUNC2) correspond.

   In general, a collection of equivalence dictionaries is built for types
   like SSA names, declarations (VAR_DECL, PARM_DECL, ..). This infrastructure
   is utilized by every statement-by-statement comparison function.  */

bool
func_checker::compare_bb (sem_bb *bb1, sem_bb *bb2)
{
  gimple_stmt_iterator gsi1, gsi2;
  gimple *s1, *s2;

  gsi1 = gsi_start_nondebug_bb (bb1->bb);
  gsi2 = gsi_start_nondebug_bb (bb2->bb);

  while (!gsi_end_p (gsi1))
    {
      if (gsi_end_p (gsi2))
	return return_false ();

      s1 = gsi_stmt (gsi1);
      s2 = gsi_stmt (gsi2);

      int eh1 = lookup_stmt_eh_lp_fn
		(DECL_STRUCT_FUNCTION (m_source_func_decl), s1);
      int eh2 = lookup_stmt_eh_lp_fn
		(DECL_STRUCT_FUNCTION (m_target_func_decl), s2);

      if (eh1 != eh2)
	return return_false_with_msg ("EH regions are different");

      if (gimple_code (s1) != gimple_code (s2))
	return return_false_with_msg ("gimple codes are different");

      switch (gimple_code (s1))
	{
	case GIMPLE_CALL:
	  if (!compare_gimple_call (as_a <gcall *> (s1),
				    as_a <gcall *> (s2)))
	    return return_different_stmts (s1, s2, "GIMPLE_CALL");
	  break;
	case GIMPLE_ASSIGN:
	  if (!compare_gimple_assign (s1, s2))
	    return return_different_stmts (s1, s2, "GIMPLE_ASSIGN");
	  break;
	case GIMPLE_COND:
	  if (!compare_gimple_cond (s1, s2))
	    return return_different_stmts (s1, s2, "GIMPLE_COND");
	  break;
	case GIMPLE_SWITCH:
	  if (!compare_gimple_switch (as_a <gswitch *> (s1),
				      as_a <gswitch *> (s2)))
	    return return_different_stmts (s1, s2, "GIMPLE_SWITCH");
	  break;
	case GIMPLE_DEBUG:
	  break;
	case GIMPLE_EH_DISPATCH:
	  if (gimple_eh_dispatch_region (as_a <geh_dispatch *> (s1))
	      != gimple_eh_dispatch_region (as_a <geh_dispatch *> (s2)))
	    return return_different_stmts (s1, s2, "GIMPLE_EH_DISPATCH");
	  break;
	case GIMPLE_RESX:
	  if (!compare_gimple_resx (as_a <gresx *> (s1),
				    as_a <gresx *> (s2)))
	    return return_different_stmts (s1, s2, "GIMPLE_RESX");
	  break;
	case GIMPLE_LABEL:
	  if (!compare_gimple_label (as_a <glabel *> (s1),
				     as_a <glabel *> (s2)))
	    return return_different_stmts (s1, s2, "GIMPLE_LABEL");
	  break;
	case GIMPLE_RETURN:
	  if (!compare_gimple_return (as_a <greturn *> (s1),
				      as_a <greturn *> (s2)))
	    return return_different_stmts (s1, s2, "GIMPLE_RETURN");
	  break;
	case GIMPLE_GOTO:
	  if (!compare_gimple_goto (s1, s2))
	    return return_different_stmts (s1, s2, "GIMPLE_GOTO");
	  break;
	case GIMPLE_ASM:
	  if (!compare_gimple_asm (as_a <gasm *> (s1),
				   as_a <gasm *> (s2)))
	    return return_different_stmts (s1, s2, "GIMPLE_ASM");
	  break;
	case GIMPLE_PREDICT:
	case GIMPLE_NOP:
	  break;
	default:
	  return return_false_with_msg ("Unknown GIMPLE code reached");
	}

      gsi_next_nondebug (&gsi1);
      gsi_next_nondebug (&gsi2);
    }

  if (!gsi_end_p (gsi2))
    return return_false ();

  if (!compare_loops (bb1->bb, bb2->bb))
    return return_false ();

  return true;
}

/* Verifies for given GIMPLEs S1 and S2 that
   call statements are semantically equivalent.  */

bool
func_checker::compare_gimple_call (gcall *s1, gcall *s2)
{
  unsigned i;
  tree t1, t2;

  if (gimple_call_num_args (s1) != gimple_call_num_args (s2))
    return false;

  operand_access_type_map map (5);
  classify_operands (s1, &map);

  t1 = gimple_call_fn (s1);
  t2 = gimple_call_fn (s2);
  if (!compare_operand (t1, t2, get_operand_access_type (&map, t1)))
    return return_false ();

  /* Compare flags.  */
  if (gimple_call_internal_p (s1) != gimple_call_internal_p (s2)
      || gimple_call_ctrl_altering_p (s1) != gimple_call_ctrl_altering_p (s2)
      || gimple_call_tail_p (s1) != gimple_call_tail_p (s2)
      || gimple_call_return_slot_opt_p (s1) != gimple_call_return_slot_opt_p (s2)
      || gimple_call_from_thunk_p (s1) != gimple_call_from_thunk_p (s2)
      || gimple_call_from_new_or_delete (s1) != gimple_call_from_new_or_delete (s2)
      || gimple_call_va_arg_pack_p (s1) != gimple_call_va_arg_pack_p (s2)
      || gimple_call_alloca_for_var_p (s1) != gimple_call_alloca_for_var_p (s2))
    return false;

  if (gimple_call_internal_p (s1)
      && gimple_call_internal_fn (s1) != gimple_call_internal_fn (s2))
    return false;

  tree fntype1 = gimple_call_fntype (s1);
  tree fntype2 = gimple_call_fntype (s2);

  /* For direct calls we verify that types are compatible so if we matched
     callees, callers must match, too.  For indirect calls however verify
     function type.  */
  if (!gimple_call_fndecl (s1))
    {
      if ((fntype1 && !fntype2)
	  || (!fntype1 && fntype2)
	  || (fntype1 && !types_compatible_p (fntype1, fntype2)))
	return return_false_with_msg ("call function types are not compatible");
    }

  if (fntype1 && fntype2 && comp_type_attributes (fntype1, fntype2) != 1)
    return return_false_with_msg ("different fntype attributes");

  tree chain1 = gimple_call_chain (s1);
  tree chain2 = gimple_call_chain (s2);
  if ((chain1 && !chain2)
      || (!chain1 && chain2)
      || !compare_operand (chain1, chain2,
			   get_operand_access_type (&map, chain1)))
    return return_false_with_msg ("static call chains are different");

  /* Checking of argument.  */
  for (i = 0; i < gimple_call_num_args (s1); ++i)
    {
      t1 = gimple_call_arg (s1, i);
      t2 = gimple_call_arg (s2, i);

      if (!compare_operand (t1, t2, get_operand_access_type (&map, t1)))
	return return_false_with_msg ("GIMPLE call operands are different");
    }

  /* Return value checking.  */
  t1 = gimple_get_lhs (s1);
  t2 = gimple_get_lhs (s2);

  /* For internal calls, lhs types need to be verified, as neither fntype nor
     callee comparisons can catch that.  */
  if (gimple_call_internal_p (s1)
      && t1
      && t2
      && !compatible_types_p (TREE_TYPE (t1), TREE_TYPE (t2)))
    return return_false_with_msg ("GIMPLE internal call LHS type mismatch");

  return compare_operand (t1, t2, get_operand_access_type (&map, t1));
}


/* Verifies for given GIMPLEs S1 and S2 that
   assignment statements are semantically equivalent.  */

bool
func_checker::compare_gimple_assign (gimple *s1, gimple *s2)
{
  tree arg1, arg2;
  tree_code code1, code2;
  unsigned i;

  code1 = gimple_assign_rhs_code (s1);
  code2 = gimple_assign_rhs_code (s2);

  if (code1 != code2)
    return false;

  operand_access_type_map map (5);
  classify_operands (s1, &map);

  for (i = 0; i < gimple_num_ops (s1); i++)
    {
      arg1 = gimple_op (s1, i);
      arg2 = gimple_op (s2, i);

      /* Compare types for LHS.  */
      if (i == 0 && !gimple_store_p (s1))
	{
	  if (!compatible_types_p (TREE_TYPE (arg1), TREE_TYPE (arg2)))
	    return return_false_with_msg ("GIMPLE LHS type mismatch");
	}

      if (!compare_operand (arg1, arg2, get_operand_access_type (&map, arg1)))
	return return_false_with_msg ("GIMPLE assignment operands "
				      "are different");
    }


  return true;
}

/* Verifies for given GIMPLEs S1 and S2 that
   condition statements are semantically equivalent.  */

bool
func_checker::compare_gimple_cond (gimple *s1, gimple *s2)
{
  tree t1, t2;
  tree_code code1, code2;

  code1 = gimple_cond_code (s1);
  code2 = gimple_cond_code (s2);

  if (code1 != code2)
    return false;

  t1 = gimple_cond_lhs (s1);
  t2 = gimple_cond_lhs (s2);

  if (!compare_operand (t1, t2, OP_NORMAL))
    return false;

  t1 = gimple_cond_rhs (s1);
  t2 = gimple_cond_rhs (s2);

  return compare_operand (t1, t2, OP_NORMAL);
}

/* Verifies for given GIMPLE_LABEL stmts S1 and S2 that
   label statements are semantically equivalent.  */

bool
func_checker::compare_gimple_label (const glabel *g1, const glabel *g2)
{
  if (m_ignore_labels)
    return true;

  tree t1 = gimple_label_label (g1);
  tree t2 = gimple_label_label (g2);

  if (FORCED_LABEL (t1) || FORCED_LABEL (t2))
    return return_false_with_msg ("FORCED_LABEL");

  /* As the pass build BB to label mapping, no further check is needed.  */
  return true;
}

/* Verifies for given GIMPLE_SWITCH stmts S1 and S2 that
   switch statements are semantically equivalent.  */

bool
func_checker::compare_gimple_switch (const gswitch *g1, const gswitch *g2)
{
  unsigned lsize1, lsize2, i;

  lsize1 = gimple_switch_num_labels (g1);
  lsize2 = gimple_switch_num_labels (g2);

  if (lsize1 != lsize2)
    return false;

  tree t1 = gimple_switch_index (g1);
  tree t2 = gimple_switch_index (g2);

  if (!compare_operand (t1, t2, OP_NORMAL))
    return false;

  for (i = 0; i < lsize1; i++)
    {
      tree label1 = gimple_switch_label (g1, i);
      tree label2 = gimple_switch_label (g2, i);

      /* Label LOW and HIGH comparison.  */
      tree low1 = CASE_LOW (label1);
      tree low2 = CASE_LOW (label2);

      if (!tree_int_cst_equal (low1, low2))
	return return_false_with_msg ("case low values are different");

      tree high1 = CASE_HIGH (label1);
      tree high2 = CASE_HIGH (label2);

      if (!tree_int_cst_equal (high1, high2))
	return return_false_with_msg ("case high values are different");

      if (TREE_CODE (label1) == CASE_LABEL_EXPR
	  && TREE_CODE (label2) == CASE_LABEL_EXPR)
	{
	  label1 = CASE_LABEL (label1);
	  label2 = CASE_LABEL (label2);

	  if (!compare_operand (label1, label2, OP_NORMAL))
	    return return_false_with_msg ("switch label_exprs are different");
	}
      else if (!tree_int_cst_equal (label1, label2))
	return return_false_with_msg ("switch labels are different");
    }

  return true;
}

/* Verifies for given GIMPLE_RETURN stmts S1 and S2 that
   return statements are semantically equivalent.  */

bool
func_checker::compare_gimple_return (const greturn *g1, const greturn *g2)
{
  tree t1, t2;

  t1 = gimple_return_retval (g1);
  t2 = gimple_return_retval (g2);

  /* Void return type.  */
  if (t1 == NULL && t2 == NULL)
    return true;
  else
    {
      operand_access_type_map map (3);
      return compare_operand (t1, t2, get_operand_access_type (&map, t1));
    }
}

/* Verifies for given GIMPLEs S1 and S2 that
   goto statements are semantically equivalent.  */

bool
func_checker::compare_gimple_goto (gimple *g1, gimple *g2)
{
  tree dest1, dest2;

  dest1 = gimple_goto_dest (g1);
  dest2 = gimple_goto_dest (g2);

  if (TREE_CODE (dest1) != TREE_CODE (dest2) || TREE_CODE (dest1) != SSA_NAME)
    return false;

  return compare_operand (dest1, dest2, OP_NORMAL);
}

/* Verifies for given GIMPLE_RESX stmts S1 and S2 that
   resx statements are semantically equivalent.  */

bool
func_checker::compare_gimple_resx (const gresx *g1, const gresx *g2)
{
  return gimple_resx_region (g1) == gimple_resx_region (g2);
}

/* Verifies for given GIMPLEs S1 and S2 that ASM statements are equivalent.
   For the beginning, the pass only supports equality for
   '__asm__ __volatile__ ("", "", "", "memory")'.  */

bool
func_checker::compare_gimple_asm (const gasm *g1, const gasm *g2)
{
  if (gimple_asm_volatile_p (g1) != gimple_asm_volatile_p (g2))
    return false;

  if (gimple_asm_input_p (g1) != gimple_asm_input_p (g2))
    return false;

  if (gimple_asm_inline_p (g1) != gimple_asm_inline_p (g2))
    return false;

  if (gimple_asm_ninputs (g1) != gimple_asm_ninputs (g2))
    return false;

  if (gimple_asm_noutputs (g1) != gimple_asm_noutputs (g2))
    return false;

  /* We do not suppport goto ASM statement comparison.  */
  if (gimple_asm_nlabels (g1) || gimple_asm_nlabels (g2))
    return false;

  if (gimple_asm_nclobbers (g1) != gimple_asm_nclobbers (g2))
    return false;

  if (strcmp (gimple_asm_string (g1), gimple_asm_string (g2)) != 0)
    return return_false_with_msg ("ASM strings are different");

  operand_access_type_map map (5);
  classify_operands (g1, &map);

  for (unsigned i = 0; i < gimple_asm_ninputs (g1); i++)
    {
      tree input1 = gimple_asm_input_op (g1, i);
      tree input2 = gimple_asm_input_op (g2, i);

      if (!compare_asm_inputs_outputs (input1, input2, &map))
	return return_false_with_msg ("ASM input is different");
    }

  for (unsigned i = 0; i < gimple_asm_noutputs (g1); i++)
    {
      tree output1 = gimple_asm_output_op (g1, i);
      tree output2 = gimple_asm_output_op (g2, i);

      if (!compare_asm_inputs_outputs (output1, output2, &map))
	return return_false_with_msg ("ASM output is different");
    }

  for (unsigned i = 0; i < gimple_asm_nclobbers (g1); i++)
    {
      tree clobber1 = gimple_asm_clobber_op (g1, i);
      tree clobber2 = gimple_asm_clobber_op (g2, i);

      if (!operand_equal_p (TREE_VALUE (clobber1), TREE_VALUE (clobber2),
			    OEP_ONLY_CONST))
	return return_false_with_msg ("ASM clobber is different");
    }

  return true;
}

/* Helper for func_checker::classify_operands.  Record that T is a load.  */

static bool
visit_load_store (gimple *, tree, tree t, void *data)
{
  func_checker::operand_access_type_map *map =
    (func_checker::operand_access_type_map *) data;
  map->add (t);
  return false;
}

/* Compute hash map determining access types of operands.  */

void
func_checker::classify_operands (const gimple *stmt,
				 operand_access_type_map *map)
{
  walk_stmt_load_store_ops (const_cast <gimple *> (stmt),
			    (void *)map, visit_load_store, visit_load_store);
}

/* Return access type of a given operand.  */

func_checker::operand_access_type
func_checker::get_operand_access_type (operand_access_type_map *map, tree t)
{
  if (map->contains (t))
    return OP_MEMORY;
  return OP_NORMAL;
}

} // ipa_icf_gimple namespace