https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88496
Bug ID: 88496
Summary: Unnecessary stack adjustment with -mavx512f
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: hjl.tools at gmail dot com
CC: ubizjak at gmail dot com, wei3.xiao at intel dot com,
xuepeng.guo at intel dot com
Target Milestone: ---
Target: i386,x86-64
[hjl@gnu-cfl-1 gcc]$ cat /tmp/x.i
struct B
{
char a[12];
int b;
};
struct B
f2 (void)
{
struct B x = {};
return x;
}
[hjl@gnu-cfl-1 gcc]$ ./xgcc -B./ -O2 -S /tmp/x.i -mavx2
[hjl@gnu-cfl-1 gcc]$ cat x.s
.file "x.i"
.text
.p2align 4
.globl f2
.type f2, @function
f2:
.LFB0:
.cfi_startproc
xorl %eax, %eax
xorl %edx, %edx
ret
.cfi_endproc
.LFE0:
.size f2, .-f2
.ident "GCC: (GNU) 9.0.0 20181214 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-cfl-1 gcc]$ ./xgcc -B./ -O2 -S /tmp/x.i -mavx512f
[hjl@gnu-cfl-1 gcc]$ cat x.s
.file "x.i"
.text
.p2align 4
.globl f2
.type f2, @function
f2:
.LFB0:
.cfi_startproc
subq $16, %rsp
.cfi_def_cfa_offset 24
xorl %eax, %eax
xorl %edx, %edx
addq $16, %rsp
.cfi_def_cfa_offset 8
ret
.cfi_endproc
.LFE0:
.size f2, .-f2
.ident "GCC: (GNU) 9.0.0 20181214 (experimental)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-cfl-1 gcc]$
subq and addq aren't necessary.
