diff options
Diffstat (limited to 'lib/Target/X86/README-SSE.txt')
| -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. + +//===---------------------------------------------------------------------===// |