[llvm-commits] [llvm] r163103 - /llvm/trunk/lib/Target/X86/README-SSE.txt

Chris Lattner sabre at nondot.org
Sun Sep 2 19:58:21 PDT 2012


Author: lattner
Date: Sun Sep  2 21:58:21 2012
New Revision: 163103

URL: http://llvm.org/viewvc/llvm-project?rev=163103&view=rev
Log:
some peepholes that should match horizontal add/sub operations.

Modified:
    llvm/trunk/lib/Target/X86/README-SSE.txt

Modified: llvm/trunk/lib/Target/X86/README-SSE.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/README-SSE.txt?rev=163103&r1=163102&r2=163103&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/README-SSE.txt (original)
+++ llvm/trunk/lib/Target/X86/README-SSE.txt Sun Sep  2 21:58:21 2012
@@ -941,3 +941,15 @@
 cost of reduced accuracy.
 
 //===---------------------------------------------------------------------===//
+
+This function should be matched to haddpd when the appropriate CPU is enabled:
+
+#include <x86intrin.h>
+double f (__m128d p) {
+  return p[0] + p[1];
+}
+
+similarly, v[0]-v[1] should match to hsubpd, and {v[0]-v[1], w[0]-w[1]} should
+turn into hsubpd also.
+
+//===---------------------------------------------------------------------===//





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