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tree-optimization/113630 - invalid code hoisting

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The following avoids code hoisting (but also PRE insertion) of
expressions that got value-numbered to another one that are not
a valid replacement (but still compute the same value).  This time
because the access path ends in a structure with different size,
meaning we consider a related access as not trapping because of the
size of the base of the access.

	PR tree-optimization/113630
	* tree-ssa-pre.cc (compute_avail): Avoid registering a
	reference with a representation with not matching base
	access size.

	* gcc.dg/torture/pr113630.c: New testcase.
This commit is contained in:
Richard Biener 2024-01-31 11:28:50 +01:00
parent b59775b642
commit 724b64304f
2 changed files with 18 additions and 0 deletions
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4
gcc/testsuite/gcc.dg/torture/pr113630.c Normal file
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@ -0,0 +1,4 @@
/* { dg-do run { target { { *-*-linux* *-*-gnu* *-*-uclinux* } && mmap } } } */
/* { dg-additional-options "-fno-strict-aliasing" } */
#include "pr110799.c"

14
gcc/tree-ssa-pre.cc
View file

@ -4281,6 +4281,20 @@ compute_avail (function *fun)
= wide_int_to_tree (ptr_type_node,
wi::to_wide (ref1->op2));
}
/* We also need to make sure that the access path
ends in an access of the same size as otherwise
we might assume an access may not trap while in
fact it might. That's independent of whether
TBAA is in effect. */
if (TYPE_SIZE (ref1->type) != TYPE_SIZE (ref2->type)
&& (! TYPE_SIZE (ref1->type)
|| ! TYPE_SIZE (ref2->type)
|| ! operand_equal_p (TYPE_SIZE (ref1->type),
TYPE_SIZE (ref2->type))))
{
operands.release ();
continue;
}
operands.release ();
result = get_or_alloc_expr_for_reference