From 758abf1ae3139a5e3d556fd2cc5636c813629547 Mon Sep 17 00:00:00 2001 From: Alexandre Oliva Date: Wed, 6 Jan 2021 08:05:40 -0300 Subject: [PATCH] add alignment to enable store merging in strict-alignment targets In g++.dg/opt/store-merging-2.C, the natural alignment of types T and S is a single byte, so we shouldn't expect store merging on strict-alignment platforms. Indeed, without something like the adjust-alignment pass to bump up the alignment of the automatic variable, as in GCC 10, the optimization does not occur. This patch adjusts the test so that the required alignment is expressly stated, and so we don't rely on its accidentally being there to get the desired optimization. for gcc/testsuite/ChangeLog * g++.dg/opt/store-merging-2.C: Add the required alignment. --- gcc/testsuite/g++.dg/opt/store-merging-2.C | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/gcc/testsuite/g++.dg/opt/store-merging-2.C b/gcc/testsuite/g++.dg/opt/store-merging-2.C index 3c17033764b..b1ad7018a17 100644 --- a/gcc/testsuite/g++.dg/opt/store-merging-2.C +++ b/gcc/testsuite/g++.dg/opt/store-merging-2.C @@ -4,7 +4,9 @@ // { dg-options "-O2 -flifetime-dse=2 -fdump-tree-store-merging-details" } // { dg-final { scan-tree-dump "New sequence of 2 stores to replace old one of 3 stores" "store-merging" } } -struct T { char a[128]; }; +/* The alignment is necessary for store-merging to take place on + strict-alignment targets. */ +struct __attribute__ ((__aligned__ (4))) T { char a[128]; }; struct S { S () : a () { a.a[12] = 0; a.a[13] = 1; a.a[14] = 0; a.a[15] = 6; } T a; }; void foo (S &); void bar (void) { S s; foo (s); } -- 2.30.2