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//===---------------------------------------------------------------------===//
// Random ideas for the X86 backend: MMX-specific stuff.
//===---------------------------------------------------------------------===//
//===---------------------------------------------------------------------===//
This:
#include <mmintrin.h>
__v2si qux(int A) {
return (__v2si){ 0, A };
}
is compiled into:
_qux:
subl $28, %esp
movl 32(%esp), %eax
movd %eax, %mm0
movq %mm0, (%esp)
movl (%esp), %eax
movl %eax, 20(%esp)
movq %mm0, 8(%esp)
movl 12(%esp), %eax
movl %eax, 16(%esp)
movq 16(%esp), %mm0
addl $28, %esp
ret
Yuck!
GCC gives us:
_qux:
subl $12, %esp
movl 16(%esp), %eax
movl 20(%esp), %edx
movl $0, (%eax)
movl %edx, 4(%eax)
addl $12, %esp
ret $4
//===---------------------------------------------------------------------===//
int main() {
__m64 A[1] = { _mm_cvtsi32_si64(1) };
__m64 B[1] = { _mm_cvtsi32_si64(10) };
__m64 sum = _mm_cvtsi32_si64(0);
sum = __builtin_ia32_paddq(__builtin_ia32_paddq(A[0], B[0]), sum);
printf("Sum = %d\n", _mm_cvtsi64_si32(sum));
return 0;
}
Generates:
movl $11, %eax
### movd %eax, %mm0
### movq %mm0, 8(%esp)
### movl 8(%esp), %eax
movl %eax, 4(%esp)
movl $_str, (%esp)
call L_printf$stub
xorl %eax, %eax
addl $28, %esp
These instructions are unnecessary.
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