https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94573
Bug ID: 94573
Summary: Optimizer produces suboptimal code related to
-fstore-merging
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: zhongyunde at tom dot com
Target Milestone: ---
For the following code, we can known init the array C000016DD is always
consecutive, so we can use the more bigger mode size.
test base on the x86-64 gcc 9.2 on https://gcc.godbolt.org/, now it is still
handled DWORD by DWORD, and we except optimize it with QWORD or more bigger
size.
extern signed int C000016DD[43][12];
void C00001F93(int index)
{
C000016DD[index][0] = 0;
C000016DD[index][1] = 0;
C000016DD[index][2] = 0;
C000016DD[index][3] = 0;
C000016DD[index][4] = 0;
C000016DD[index][5] = 0;
C000016DD[index][6] = 0;
C000016DD[index][7] = 0;
return;
}
============= related assemble =============
C00001F93(int):
movsx rdi, edi
lea rax, [rdi+rdi*2]
sal rax, 4
mov DWORD PTR C000016DD[rax], 0
mov DWORD PTR C000016DD[rax+4], 0
mov DWORD PTR C000016DD[rax+8], 0
mov DWORD PTR C000016DD[rax+12], 0
mov DWORD PTR C000016DD[rax+16], 0
mov DWORD PTR C000016DD[rax+20], 0
mov DWORD PTR C000016DD[rax+24], 0
mov DWORD PTR C000016DD[rax+28], 0
ret
