[forwarded from http://bugs.debian.org/560812]
With the following simple test file, the 3DNow! generated code is
incorrect, with final _m_pfsub generated as pfsubr %mm0,%mm0, thus
producing completely incorrect result.
seen with current branches and trunk.
Matthias
*** main.c
#include <mm3dnow.h>
void Butterfly_3(__m64 *D,__m64 SC,unsigned int IStep,unsigned int Off)
{ __m64 T,T1,T2;
T = _m_pfmul(D[Off+1], SC);
T1 = D[Off+0];
D[Off+0] = _m_pfadd(T1, T);
D[Off+1] = _m_pfsub(T1, T);
}
The command line is:
gcc -march=athlon -S -O3 main.c
The generated code is:
*** main.s
.file "main.c"
.text
.p2align 4,,15
.globl Butterfly_3
.type Butterfly_3, @function
Butterfly_3:
pushl %ebp
movl %esp, %ebp
movl 8(%ebp), %edx
movl 16(%ebp), %ecx
leal 8(%edx,%ecx,8), %eax
leal (%edx,%ecx,8), %edx
pfmul (%eax), %mm0
movq (%edx), %mm1
movq %mm1, %mm2
pfadd %mm0, %mm2
pfsubr %mm0, %mm0
movq %mm2, (%edx)
movq %mm0, (%eax)
leave
ret
.size Butterfly_3, .-Butterfly_3
.ident "GCC: (Debian 4.4.2-4) 4.4.2"
.section .note.GNU-stack,"",@progbits
--
Summary: Incorrect 3DNow! code generated
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: debian-gcc at lists dot debian dot org
GCC target triplet: i486-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42549
