https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108018
Bug ID: 108018
Summary: Wide immediate sequences not scheduled for POWER10
fusion
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: npiggin at gmail dot com
Target Milestone: ---
POWER10 has "wideimmediate" fusion sequences that include addi rx,ra,si ; addis
rx,rx,SI and addis rx,ra,si ; addi rx,rx,SI
--- test.c ---
static int foo, bar;
unsigned long test(void)
{
return (unsigned long)&foo + (unsigned long)&bar;
}
---
This test case when compiled with -O2 -mcpu=power10 -mno-pcrel results in
addis 2,12,.TOC.-.LCF0@ha
addi 2,2,.TOC.-.LCF0@l
addis 3,2,.LANCHOR0@toc@ha
addis 9,2,.LANCHOR0+4@toc@ha
addi 3,3,.LANCHOR0@toc@l
addi 9,9,.LANCHOR0+4@toc@l
add 3,3,9
blr
The TOC pointer generation is scheduled properly because it is the global entry
prologue, but the variable address generation is scheduled to favour
dependencies rather than the static fusion sequences that P10 has, which should
be preferable.
