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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27567 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-04-10 21:51:03 +00:00
parent 8ebd7f937b
commit a956db2a63
1 changed files with 23 additions and 0 deletions
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23
lib/Target/X86/README.txt
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@ -675,6 +675,29 @@ Perhaps use pxor / xorp* to clear a XMM register first?
//===---------------------------------------------------------------------===//
Better codegen for:
void f(float a, float b, vector float * out) { *out = (vector float){ a, 0.0, 0.0, b}; }
void f(float a, float b, vector float * out) { *out = (vector float){ a, b, 0.0, 0}; }
For the later we generate:
_f:
pxor %xmm0, %xmm0
movss 8(%esp), %xmm1
movaps %xmm0, %xmm2
unpcklps %xmm1, %xmm2
movss 4(%esp), %xmm1
unpcklps %xmm0, %xmm1
unpcklps %xmm2, %xmm1
movl 12(%esp), %eax
movaps %xmm1, (%eax)
ret
This seems like it should use shufps, one for each of a & b.
//===---------------------------------------------------------------------===//
Adding to the list of cmp / test poor codegen issues:
int test(__m128 *A, __m128 *B) {