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* [Bug rtl-optimization/66391] New: suboptimal code for assignment of SImode struct with bitfields
@ 2015-06-03 6:56 bonzini at gnu dot org
2015-06-03 7:22 ` [Bug rtl-optimization/66391] " rguenth at gcc dot gnu.org
2021-08-19 0:47 ` [Bug middle-end/66391] " pinskia at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: bonzini at gnu dot org @ 2015-06-03 6:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66391
Bug ID: 66391
Summary: suboptimal code for assignment of SImode struct with
bitfields
Product: gcc
Version: 5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: bonzini at gnu dot org
Target Milestone: ---
This is caused by early SRA splitting elem's assignment into separate per-field
assignments.
struct x {
unsigned a : 6;
unsigned b : 26;
};
int f(struct x *x, unsigned a, unsigned b)
{
struct x elem = { .a = a, .b = b };
int i;
for (i = 0; i < 512; i++)
x[i] = elem;
}
Generated code:
.LFB0:
.cfi_startproc
leaq 2048(%rdi), %rcx
andl $63, %esi
sall $6, %edx
.p2align 4,,10
.p2align 3
.L2:
movzbl (%rdi), %eax
addq $4, %rdi
andl $-64, %eax
orl %esi, %eax
movb %al, -4(%rdi)
movl -4(%rdi), %eax
andl $63, %eax
orl %edx, %eax
movl %eax, -4(%rdi)
cmpq %rcx, %rdi
jne .L2
rep ret
.cfi_endproc
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-08-19 0:47 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2015-06-03 6:56 [Bug rtl-optimization/66391] New: suboptimal code for assignment of SImode struct with bitfields bonzini at gnu dot org
2015-06-03 7:22 ` [Bug rtl-optimization/66391] " rguenth at gcc dot gnu.org
2021-08-19 0:47 ` [Bug middle-end/66391] " pinskia at gcc dot gnu.org
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