https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113827
Bug ID: 113827
Summary: MrBayes benchmark redundant load
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: rdapp at gcc dot gnu.org
CC: juzhe.zhong at rivai dot ai, law at gcc dot gnu.org,
pan2.li at intel dot com
Blocks: 79704
Target Milestone: ---
Target: riscv
A hot block in the MrBayes benchmark (as used in the Phoronix testsuite) has a
redundant scalar load when vectorized.
Minimal example, compiled with -march=rv64gcv -O3
int foo (float **a, float f, int n)
{
for (int i = 0; i < n; i++)
{
a[i][0] /= f;
a[i][1] /= f;
a[i][2] /= f;
a[i][3] /= f;
a[i] += 4;
}
}
GCC:
.L3:
ld a5,0(a0)
vle32.v v1,0(a5)
vfmul.vv v1,v1,v2
vse32.v v1,0(a5)
addi a5,a5,16
sd a5,0(a0)
addi a0,a0,8
bne a0,a4,.L3
The value of a5 doesn't change after the store to 0(a0).
LLVM:
.L3
vle32.v v8,(a1)
addi a3,a1,16
sd a3,0(a2)
vfdiv.vf v8,v8,fa5
addi a2,a2,8
vse32.v v8,(a1)
bne a2,a0,.L3
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79704
[Bug 79704] [meta-bug] Phoronix Test Suite compiler performance issues
