https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97071
Bug ID: 97071
Summary: Fails to CSE / inherit constant pool load
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rguenth at gcc dot gnu.org
Target Milestone: ---
double foo (double x)
{
return x * -3. + 3.;
}
compiles to
0: addis 2,12,.TOC.-.LCF0@ha
addi 2,2,.TOC.-.LCF0@l
.localentry foo,.-foo
addis 9,2,.LC0@toc@ha
lfd 12,.LC0@toc@l(9)
addis 9,2,.LC2@toc@ha
lfd 0,.LC2@toc@l(9)
fmadd 1,1,12,0
blr
...
.LC0:
.long 0
.long -1073217536
.align 3
.LC2:
.long 0
.long 1074266112
but CSE or reload inheritance could have replaced the add of + 3. with
subtraction of the available -3. constant. Might be more difficult to
pull off on x86 where the add/mul has memory operands.
