diff --git a/lib/Target/X86/README-SSE.txt b/lib/Target/X86/README-SSE.txt index bab5373d652..2b7f9ae4392 100644 --- a/lib/Target/X86/README-SSE.txt +++ b/lib/Target/X86/README-SSE.txt @@ -530,3 +530,45 @@ to loads from constant pool. Floating point max / min are commutable when -enable-unsafe-fp-path is specified. We should turn int_x86_sse_max_ss and X86ISD::FMIN etc. into other nodes which are selected to max / min instructions that are marked commutable. + +//===---------------------------------------------------------------------===// + +We should compile this: +#include +typedef union { + int i[4]; + float f[4]; + __m128 v; +} vector4_t; +void swizzle (const void *a, vector4_t * b, vector4_t * c) { + b->v = _mm_loadl_pi (b->v, (__m64 *) a); + c->v = _mm_loadl_pi (c->v, ((__m64 *) a) + 1); +} + +to: + +_swizzle: + movl 4(%esp), %eax + movl 8(%esp), %edx + movl 12(%esp), %ecx + movlps (%eax), %xmm0 + movlps %xmm0, (%edx) + movlps 8(%eax), %xmm0 + movlps %xmm0, (%ecx) + ret + +not: + +swizzle: + movl 8(%esp), %eax + movaps (%eax), %xmm0 + movl 4(%esp), %ecx + movlps (%ecx), %xmm0 + movaps %xmm0, (%eax) + movl 12(%esp), %eax + movaps (%eax), %xmm0 + movlps 8(%ecx), %xmm0 + movaps %xmm0, (%eax) + ret + +