[Bug c++/88521] gcc 9.0 from r266355 miscompile x265 for mingw-w64 target

[mateuszb at poczta dot onet.pl]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88521

--- Comment #7 from mateuszb at poczta dot onet.pl ---
W dniu 17.12.2018 o 13:52, umesh.kalappa0 at gmail dot com pisze:
> mateuszb,
> Please can you provide us the sample file to investigate more on this .

I'm not assembly expert, but this looks to me as a bug:
$ cat t.c
float fun1(void)
{
    return 4.14f;
}
Mateusz@Mateusz-i7 /c/temp
$ gcc -c -O2 -o t354.o t.c

Mateusz@Mateusz-i7 /c/temp
$ objdump -d t354.o

t354.o:     file format pe-x86-64


Disassembly of section .text:

0000000000000000 <fun1>:
   0:   f3 0f 10 05 00 00 00    movss  0x0(%rip),%xmm0        # 8 <fun1+0x8>
   7:   00
   8:   c3                      retq
   9:   90                      nop
   a:   90                      nop
   b:   90                      nop
   c:   90                      nop
   d:   90                      nop
   e:   90                      nop
   f:   90                      nop

Mateusz@Mateusz-i7 /c/temp
$ m64- 355

Mateusz@Mateusz-i7 /c/temp
$ gcc -c -O2 -o t355.o t.c

Mateusz@Mateusz-i7 /c/temp
$ objdump -d t355.o

t355.o:     file format pe-x86-64


Disassembly of section .text:

0000000000000000 <fun1>:
   0:   8b 05 00 00 00 00       mov    0x0(%rip),%eax        # 6 <fun1+0x6>
   6:   c3                      retq
   7:   90                      nop
   8:   90                      nop
   9:   90                      nop
   a:   90                      nop
   b:   90                      nop
   c:   90                      nop
   d:   90                      nop
   e:   90                      nop
   f:   90                      nop

This patch is really intended to change abi for float return (without struct)?