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tree-optimization/93538 - add missing comparison folding case

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This adds back a folding that worked in GCC 4.5 times by amending
the pattern that handles other cases of address vs. SSA name
comparisons.

2020-02-04  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/93538
	* match.pd (addr EQ/NE ptr): Amend to handle &ptr->x EQ/NE ptr.

	* gcc.dg/tree-ssa/forwprop-38.c: New testcase.
This commit is contained in:
Richard Biener 2020-02-04 15:17:01 +01:00
parent 9bc5bea1f3
commit 5124c34fcc
4 changed files with 45 additions and 11 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2020-02-04 Richard Biener <rguenther@suse.de>
PR tree-optimization/93538
* match.pd (addr EQ/NE ptr): Amend to handle &ptr->x EQ/NE ptr.
2020-02-04 Richard Biener <rguenther@suse.de>
PR tree-optimization/91123

33
gcc/match.pd
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@ -4267,19 +4267,30 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
{ constant_boolean_node (above ? false : true, type); }))))))))))))
(for cmp (eq ne)
/* A local variable can never be pointed to by
the default SSA name of an incoming parameter.
SSA names are canonicalized to 2nd place. */
(simplify
/* SSA names are canonicalized to 2nd place. */
(cmp addr@0 SSA_NAME@1)
(if (SSA_NAME_IS_DEFAULT_DEF (@1)
&& TREE_CODE (SSA_NAME_VAR (@1)) == PARM_DECL)
(with { tree base = get_base_address (TREE_OPERAND (@0, 0)); }
(if (TREE_CODE (base) == VAR_DECL
&& auto_var_in_fn_p (base, current_function_decl))
(if (cmp == NE_EXPR)
{ constant_boolean_node (true, type); }
{ constant_boolean_node (false, type); }))))))
(with
{ poly_int64 off; tree base; }
/* A local variable can never be pointed to by
the default SSA name of an incoming parameter. */
(if (SSA_NAME_IS_DEFAULT_DEF (@1)
&& TREE_CODE (SSA_NAME_VAR (@1)) == PARM_DECL
&& (base = get_base_address (TREE_OPERAND (@0, 0)))
&& TREE_CODE (base) == VAR_DECL
&& auto_var_in_fn_p (base, current_function_decl))
(if (cmp == NE_EXPR)
{ constant_boolean_node (true, type); }
{ constant_boolean_node (false, type); })
/* If the address is based on @1 decide using the offset. */
(if ((base = get_addr_base_and_unit_offset (TREE_OPERAND (@0, 0), &off))
&& TREE_CODE (base) == MEM_REF
&& TREE_OPERAND (base, 0) == @1)
(with { off += mem_ref_offset (base).force_shwi (); }
(if (known_ne (off, 0))
{ constant_boolean_node (cmp == NE_EXPR, type); }
(if (known_eq (off, 0))
{ constant_boolean_node (cmp == EQ_EXPR, type); }))))))))
/* Equality compare simplifications from fold_binary */
(for cmp (eq ne)

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2020-02-04 Richard Biener <rguenther@suse.de>
PR tree-optimization/93538
* gcc.dg/tree-ssa/forwprop-38.c: New testcase.
2020-02-04 Jakub Jelinek <jakub@redhat.com>
* c-c++-common/cpp/has-include-1.c: New test.

13
gcc/testsuite/gcc.dg/tree-ssa/forwprop-38.c Normal file
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@ -0,0 +1,13 @@
/* { dg-do compile } */
/* { dg-options "-O -fdump-tree-forwprop1" } */
struct A { int a[1]; };
void f (struct A *p)
{
void *q = p->a;
if (p != q)
__builtin_abort ();
}
/* { dg-final { scan-tree-dump-not "abort" "forwprop1" } } */