https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100697
Bug ID: 100697
Summary: Missing fwprop for argument register
Product: gcc
Version: 10.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: zhongyunde at huawei dot com
Target Milestone: ---
cat test.c
extern double top[100];
int foo (long long j, double a) {
top[j] += a;
return 0;
}
gcc10.3 -g0 -O3 -march=armv8.2-a test.c -save-temps -S, can also be test base
on https://gcc.godbolt.org.
.type foo, %function
foo:
.LFB0:
.cfi_startproc
mov x2, x0 -- redundant could be fwprop
adrp x1, top
add x1, x1, :lo12:top
mov w0, 0
ldr d1, [x1, x2, lsl 3]
fadd d0, d1, d0
str d0, [x1, x2, lsl 3]
ret
If x0 fwprop into both ldr and str, then the insn mov x2, x0 can be deleted.
