[Bug target/18562] SSE constant vector initialization produces dead constant values on stack

[uros at kss-loka dot si]

------- Additional Comments From uros at kss-loka dot si  2005-01-12 10:54 
-------
Another testcase that I think should be optimized:
#include <xmmintrin.h>

__m128 test() {
        float val1[4] = {0.0f, 0.0f, 0.0f, 0.0f};

        return _mm_loadu_ps(val1);
}

This is currently compiled to:
test:
        pushl  %ebp
        movl   $0x00000000, %eax
        movl   %esp, %ebp
        subl   $16, %esp
        movl   %eax, -16(%ebp)
        movl   %eax, -12(%ebp)
        movl   %eax, -8(%ebp)
        movl   %eax, -4(%ebp)
        movups -16(%ebp), %xmm0
        leave
        ret

But I think gcc it should produce something like:
test:
        pushl  %ebp
        xorps  %xmm0, %xmm0
        movl   %esp, %ebp
        subl   $16, %esp
(*)     movups %xmm0, -16(%ebp)
        leave
        ret

Perhaps even the store to stack is not necessary in this particular case.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18562