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[Bug target/80080] S390: Isses with emitted cs-instructions for __atomic builtins.
- From: "vogt at linux dot vnet.ibm.com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 22 Mar 2017 13:12:49 +0000
- Subject: [Bug target/80080] S390: Isses with emitted cs-instructions for __atomic builtins.
- Auto-submitted: auto-generated
- References: <bug-80080-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80080
--- Comment #8 from Dominik Vogt <vogt at linux dot vnet.ibm.com> ---
The patch has a performance regression on s390x.
.L1
lr %r3,%r1
cs %r1,%r4,0(%r2)
jne .L1
becomes
.L1
cs %r1,%r3,0(%r2)
ipm %r4
sra %r4,28
cijne %r4,0,.L1
Although this can be fixed on s390/s390x in a follow-up patch, I cannot really
prove that something similar won't happen on other targets without testing
them.