From 7c76c876e917a1f20a788f602cc78fff7d0a2a65 Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Tue, 10 Oct 2023 11:09:16 +0200
Subject: [PATCH] Fix missed CSE with a BLKmode entity
The following fixes fallout of r10-7145-g1dc00a8ec9aeba which made
us cautionous about CSEing a load to an object that has padding bits.
The added check also triggers for BLKmode entities like STRING_CSTs
but by definition a BLKmode entity does not have padding bits.
PR tree-optimization/111751
* tree-ssa-sccvn.cc (visit_reference_op_load): Exempt
BLKmode result from the padding bits check.
---
gcc/tree-ssa-sccvn.cc | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index d2aab38c2d20..ce8ae8c67539 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -5747,8 +5747,9 @@ visit_reference_op_load (tree lhs, tree op, gimple *stmt)
{
/* Avoid the type punning in case the result mode has padding where
the op we lookup has not. */
- if (maybe_lt (GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (result))),
- GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (op)))))
+ if (TYPE_MODE (TREE_TYPE (result)) != BLKmode
+ && maybe_lt (GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (result))),
+ GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (op)))))
result = NULL_TREE;
else
{
--
GitLab