https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78639
Bug ID: 78639
Summary: Power9 bad code generation for cactusADM benchmark
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: meissner at gcc dot gnu.org
Target Milestone: ---
I was building the Spec 2006 benchmark targeting the forthcoming power9
processor and I noticed the cactusADM benchmark did not build.
The bug is due to my change on November 21st, 2016 (subversion id 242679). If
a DImode value in an Altivec register is to be stored with a register+register
address, the compiler generated STXSD (register+offset) instead of STXSDX
(register+register).
In the movdi_internal64 pattern, I deleted a 'w' from the STXSD constraint,
which meant the constraint was using "Y" instead of "wY". "Y" allows reg+reg,
while "wY" does not (and also enforces a stricter alignment check).
