https://gcc.gnu.org/g:47cd06042237bf2d4f05b8355362bc038f6fa445
commit r13-8693-g47cd06042237bf2d4f05b8355362bc038f6fa445
Author: Richard Biener <rguent...@suse.de>
Date: Wed Jan 31 11:28:50 2024 +0100
tree-optimization/113630 - invalid code hoisting
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.
(cherry picked from commit 724b64304ff5c8ac08a913509afd6fde38d7b767)
Diff:
---
gcc/testsuite/gcc.dg/torture/pr113630.c | 4 ++++
gcc/tree-ssa-pre.cc | 14 ++++++++++++++
2 files changed, 18 insertions(+)
diff --git a/gcc/testsuite/gcc.dg/torture/pr113630.c
b/gcc/testsuite/gcc.dg/torture/pr113630.c
new file mode 100644
index 00000000000..72ebdefae27
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr113630.c
@@ -0,0 +1,4 @@
+/* { dg-do run { target { { *-*-linux* *-*-gnu* *-*-uclinux* } && mmap } } } */
+/* { dg-additional-options "-fno-strict-aliasing" } */
+
+#include "pr110799.c"
diff --git a/gcc/tree-ssa-pre.cc b/gcc/tree-ssa-pre.cc
index dfcc9ec4711..9e9a2f9d26a 100644
--- a/gcc/tree-ssa-pre.cc
+++ b/gcc/tree-ssa-pre.cc
@@ -4224,6 +4224,20 @@ 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
