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From: "kretz at kde dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/94300] New: [10 Regression] memcpy vector load miscompiled during const-prop
Date: Tue, 24 Mar 2020 12:48:09 +0000 [thread overview]
Message-ID: <bug-94300-4@http.gcc.gnu.org/bugzilla/> (raw)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94300
Bug ID: 94300
Summary: [10 Regression] memcpy vector load miscompiled during
const-prop
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: kretz at kde dot org
Target Milestone: ---
Target: x86_64-*-*, i?86-*-*
Test case `-O1 -march=skylake-avx512`:
int main()
{
double mem[16];
using V [[gnu::vector_size(64)]] = double;
const V a{0, 1, 2, 3, 4, 5, 6, 7};
const V b{8, 9, 10, 11, 12, 13, 14, 15};
__builtin_memcpy(mem, &a, 64);
__builtin_memcpy(mem + 8, &b, 64);
V c = {};
__builtin_memcpy(&c, mem + 4, 64);
if (c[5] != double(9))
__builtin_abort();
}
>From my extended test case, where c would be {4, 5, 6, 7, 8, 15, 9, 10}. If GCC
is made to forget the contents of mem (e.g. inline-asm), the test does not
fail. GCC9 does not do constant evaluation of the code above and therefore
doesn't fail.
next reply other threads:[~2020-03-24 12:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 12:48 kretz at kde dot org [this message]
2020-03-24 13:17 ` [Bug tree-optimization/94300] [10 Regression] memcpy vector load miscompiled during const-prop since r10-6809-g7f5617b00445dcc8 marxin at gcc dot gnu.org
2020-03-24 14:02 ` jakub at gcc dot gnu.org
2020-03-24 14:53 ` jakub at gcc dot gnu.org
2020-03-25 8:17 ` cvs-commit at gcc dot gnu.org
2020-03-25 8:22 ` jakub at gcc dot gnu.org
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