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author | Chris Lattner <sabre@nondot.org> | 2008-05-13 18:48:54 +0000 |
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committer | Chris Lattner <sabre@nondot.org> | 2008-05-13 18:48:54 +0000 |
commit | 7171c836a93024d523b457b5a98782fa7ad5c97b (patch) | |
tree | 1aa4ec3766ccb1a25c056d55c7225c383fc4dc38 /lib | |
parent | c3dac5cbfe1f7ce35bc8129a4e0d5d58bfd130ea (diff) | |
download | external_llvm-7171c836a93024d523b457b5a98782fa7ad5c97b.zip external_llvm-7171c836a93024d523b457b5a98782fa7ad5c97b.tar.gz external_llvm-7171c836a93024d523b457b5a98782fa7ad5c97b.tar.bz2 |
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51060 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r-- | lib/Target/X86/README-SSE.txt | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/lib/Target/X86/README-SSE.txt b/lib/Target/X86/README-SSE.txt index 5c681e0..5f114a8 100644 --- a/lib/Target/X86/README-SSE.txt +++ b/lib/Target/X86/README-SSE.txt @@ -764,4 +764,28 @@ madd: //===---------------------------------------------------------------------===// +Consider: +#include <emmintrin.h> +__m128 foo2 (float x) { + return _mm_set_ps (0, 0, x, 0); +} + +In x86-32 mode, we generate this spiffy code: + +_foo2: + movss 4(%esp), %xmm0 + pshufd $81, %xmm0, %xmm0 + ret + +in x86-64 mode, we generate this code, which could be better: + +_foo2: + xorps %xmm1, %xmm1 + movss %xmm0, %xmm1 + pshufd $81, %xmm1, %xmm0 + ret + +In sse4 mode, we could use insertps to make both better. + +//===---------------------------------------------------------------------===// |