[llvm-commits] CVS: llvm/lib/Target/X86/README-SSE.txt

[Chris Lattner]

Changes in directory llvm/lib/Target/X86:

README-SSE.txt updated: 1.14 -> 1.15
---
Log message:

a note


---
Diffs of the changes:  (+42 -0)

 README-SSE.txt |   42 ++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 42 insertions(+)


Index: llvm/lib/Target/X86/README-SSE.txt
diff -u llvm/lib/Target/X86/README-SSE.txt:1.14 llvm/lib/Target/X86/README-SSE.txt:1.15
--- llvm/lib/Target/X86/README-SSE.txt:1.14	Thu Dec 14 23:50:39 2006
+++ llvm/lib/Target/X86/README-SSE.txt	Tue Feb 27 11:21:09 2007
@@ -530,3 +530,45 @@
 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 <xmmintrin.h>
+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
+
+