在 2018/9/19 16:52, lokesh janghel 写道:
Hi,
I am starting to looking into this issue.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85667#c0
We did some analysis about that issue and found that the problem occurs may
be in the code generation phase in GCC.
ABI says that struct type uses the integer register (like clang )or memory
to return not the SSE registers.
Before we go ahead and fix this issue and we would like to know the
community views/comments on the same.
This happens on not only x64, but x86 too:
```
typedef struct
{
float x;
} Float;
#ifdef _MSC_VER
# define MSABI
#else
# define MSABI __attribute__((ms_abi))
#endif
Float MSABI fn1()
{
Float v;
v.x = 3.145;
return v;
}
```
```
E:\Desktop>cl /nologo /c /O2 /Fo:test-cl.obj test.c && objdump
-dMintel-mneomic test-cl.obj
test-cl.obj: file format pe-i386
Disassembly of section .text$mn:
00000000 <_fn1>:
0: 51 push ecx
1: c7 04 24 ae 47 49 40 mov DWORD PTR [esp],0x404947ae
8: 8b 04 24 mov eax,DWORD PTR [esp]
b: 59 pop ecx
c: c3 ret
E:\Desktop>gcc -c -O2 -o test-gcc.o test.c && objdump -dMintel-mneomic
test-gcc.o
test-gcc.o: file format pe-i386
Disassembly of section .text:
00000000 <_fn1>:
0: d9 05 00 00 00 00 fld DWORD PTR ds:0x0
6: c3 ret
7: 90 nop
E:\Desktop>
```
--
Best regards,
LH_Mouse
