[Bug rtl-optimization/82454] New: Possible future performance regression in x86 for 64-bit constant expansions
sudi.das at arm dot com
gcc-bugzilla@gcc.gnu.org
Fri Oct 6 16:57:00 GMT 2017
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82454
Bug ID: 82454
Summary: Possible future performance regression in x86 for
64-bit constant expansions
Product: gcc
Version: 7.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: sudi.das at arm dot com
Target Milestone: ---
Created attachment 42317
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42317&action=edit
test1
As per the discussions on
https://gcc.gnu.org/ml/gcc-patches/2017-04/msg00570.html
https://gcc.gnu.org/ml/gcc-patches/2017-08/msg00039.html
https://gcc.gnu.org/ml/gcc-patches/2017-09/msg01736.html
The patch to add a simplification of 1U << (31 - x) for PR 80131, may lead to a
performance regression for x86.
I am adding the tests that Jakub mentioned as a runtime performance regression
tests.
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