https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77416
Bug ID: 77416
Summary: LRA rematerializing use of CA reg across function call
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pthaugen at gcc dot gnu.org
CC: bergner at gcc dot gnu.org, dje.gcc at gmail dot com,
vmakarov at gcc dot gnu.org, wschmidt at gcc dot gnu.org
Target Milestone: ---
Host: powerpc64-unknown-linux-gnu
Target: powerpc64-unknown-linux-gnu
Build: powerpc64-unknown-linux-gnu
Created attachment 39521
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39521&action=edit
reduced testcase
CPU2006 benchmark 445.gobmk started failing verification of output starting
with r239105 (switch rs6000 port to LRA). I tracked it down to code where LRA
is rematerializing the use of the CA reg across a function call, which is not
valid since a call can clobber it.
Before the switch to LRA we saw the following code:
addic 9,9,-1
addze 9,16
stw 9,492(1)
... code with function call(s)
lwz 9,492(1)
After LRA switch the code looks like this:
addic 9,9,-1
addze 9,16
stw 9,492(1)
... code with function call(s)
addze 9,16
Compile options for reduced testcase: gcc -S -O2 -m32 -mcpu=power7
