https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109766
Bug ID: 109766
Summary: Passing doubles through the stack generates a stack
adjustment pear each such argument at -Os/-Oz.
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: pskocik at gmail dot com
Target Milestone: ---
/*
Passing doubles through the stack generates a stack adjustment pear each such
argument at -Os/-Oz.
These stack adjustments are only coalesced at -O1/-O2/-O3, leaving -Os/-Oz
with larger code.
*/
#define $expr(...) (__extension__({__VA_ARGS__;}))
#define $regF0 $expr(register double x __asm("xmm0"); x)
#define $regF1 $expr(register double x __asm("xmm1"); x)
#define $regF2 $expr(register double x __asm("xmm2"); x)
#define $regF3 $expr(register double x __asm("xmm3"); x)
#define $regF4 $expr(register double x __asm("xmm4"); x)
#define $regF5 $expr(register double x __asm("xmm5"); x)
#define $regF6 $expr(register double x __asm("xmm6"); x)
#define $regF7 $expr(register double x __asm("xmm7"); x)
void func(char const*Fmt, ...);
void callfunc(char const*Fmt, double D0, double D1, double D2, double D3,
double D4, double D5, double D6, double D7){
func(Fmt,$regF0,$regF1,$regF2,$regF3,$regF4,$regF5,$regF6,$regF7,
D0,D1,D2,D3,D4,D5,D6,D7);
/*
//gcc @ -Os/-Oz
0000000000000000 <callfunc>:
0: 50 push %rax
1: b0 08 mov $0x8,%al
3: 48 8d 64 24 f8 lea -0x8(%rsp),%rsp
8: 66 0f d6 3c 24 movq %xmm7,(%rsp)
d: 48 8d 64 24 f8 lea -0x8(%rsp),%rsp
12: 66 0f d6 34 24 movq %xmm6,(%rsp)
17: 48 8d 64 24 f8 lea -0x8(%rsp),%rsp
1c: 66 0f d6 2c 24 movq %xmm5,(%rsp)
21: 48 8d 64 24 f8 lea -0x8(%rsp),%rsp
26: 66 0f d6 24 24 movq %xmm4,(%rsp)
2b: 48 8d 64 24 f8 lea -0x8(%rsp),%rsp
30: 66 0f d6 1c 24 movq %xmm3,(%rsp)
35: 48 8d 64 24 f8 lea -0x8(%rsp),%rsp
3a: 66 0f d6 14 24 movq %xmm2,(%rsp)
3f: 48 8d 64 24 f8 lea -0x8(%rsp),%rsp
44: 66 0f d6 0c 24 movq %xmm1,(%rsp)
49: 48 8d 64 24 f8 lea -0x8(%rsp),%rsp
4e: 66 0f d6 04 24 movq %xmm0,(%rsp)
53: e8 00 00 00 00 callq 58 <callfunc+0x58>
54: R_X86_64_PLT32 func-0x4
58: 48 83 c4 48 add $0x48,%rsp
5c: c3 retq
$sz(callfunc)=93
//clang @ -Os/-Oz
0000000000000000 <callfunc>:
0: 48 83 ec 48 sub $0x48,%rsp
4: f2 0f 11 7c 24 38 movsd %xmm7,0x38(%rsp)
a: f2 0f 11 74 24 30 movsd %xmm6,0x30(%rsp)
10: f2 0f 11 6c 24 28 movsd %xmm5,0x28(%rsp)
16: f2 0f 11 64 24 20 movsd %xmm4,0x20(%rsp)
1c: f2 0f 11 5c 24 18 movsd %xmm3,0x18(%rsp)
22: f2 0f 11 54 24 10 movsd %xmm2,0x10(%rsp)
28: f2 0f 11 4c 24 08 movsd %xmm1,0x8(%rsp)
2e: f2 0f 11 04 24 movsd %xmm0,(%rsp)
33: b0 08 mov $0x8,%al
35: e8 00 00 00 00 callq 3a <callfunc+0x3a>
36: R_X86_64_PLT32 func-0x4
3a: 48 83 c4 48 add $0x48,%rsp
3e: c3 retq
$sz(callfunc)=63
//gcc @ -O1
0000000000000000 <callfunc>:
0: 48 83 ec 48 sub $0x48,%rsp
4: f2 0f 11 7c 24 38 movsd %xmm7,0x38(%rsp)
a: f2 0f 11 74 24 30 movsd %xmm6,0x30(%rsp)
10: f2 0f 11 6c 24 28 movsd %xmm5,0x28(%rsp)
16: f2 0f 11 64 24 20 movsd %xmm4,0x20(%rsp)
1c: f2 0f 11 5c 24 18 movsd %xmm3,0x18(%rsp)
22: f2 0f 11 54 24 10 movsd %xmm2,0x10(%rsp)
28: f2 0f 11 4c 24 08 movsd %xmm1,0x8(%rsp)
2e: f2 0f 11 04 24 movsd %xmm0,(%rsp)
33: b8 08 00 00 00 mov $0x8,%eax
38: e8 00 00 00 00 callq 3d <callfunc+0x3d>
39: R_X86_64_PLT32 func-0x4
3d: 48 83 c4 48 add $0x48,%rsp
41: c3 retq
$sz(callfunc)=66
*/
}
https://godbolt.org/z/d8T3hxqWK
