[llvm-commits] [llvm] r139768 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp test/Transforms/InstCombine/vec_demanded_elts.ll

[Eli Friedman]

Author: efriedma
Date: Wed Sep 14 20:14:29 2011
New Revision: 139768

URL: http://llvm.org/viewvc/llvm-project?rev=139768&view=rev
Log:
Make demanded-elt simplification for shufflevector slightly stronger.  Spotted by inspection.


Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
    llvm/trunk/test/Transforms/InstCombine/vec_demanded_elts.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp?rev=139768&r1=139767&r2=139768&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp Wed Sep 14 20:14:29 2011
@@ -962,6 +962,9 @@
       unsigned MaskVal = Shuffle->getMaskValue(i);
       if (MaskVal == -1u) {
         UndefElts.setBit(i);
+      } else if (!DemandedElts[i]) {
+        NewUndefElts = true;
+        UndefElts.setBit(i);
       } else if (MaskVal < LHSVWidth) {
         if (UndefElts4[MaskVal]) {
           NewUndefElts = true;

Modified: llvm/trunk/test/Transforms/InstCombine/vec_demanded_elts.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/vec_demanded_elts.ll?rev=139768&r1=139767&r2=139768&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/vec_demanded_elts.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/vec_demanded_elts.ll Wed Sep 14 20:14:29 2011
@@ -152,3 +152,14 @@
 	ret <4 x i32> %0
 }
 declare <4 x i32> @llvm.x86.sse41.pmovzxwd(<8 x i16>) nounwind readnone
+
+define <4 x float> @dead_shuffle_elt(<4 x float> %x, <2 x float> %y) nounwind {
+entry:
+; CHECK: define <4 x float> @dead_shuffle_elt
+; CHECK: shufflevector <2 x float> %y, <2 x float> undef, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
+  %shuffle.i = shufflevector <2 x float> %y, <2 x float> %y, <4 x i32> <i32 0, i32 1, i32 0, i32 1>
+  %shuffle9.i = shufflevector <4 x float> %x, <4 x float> %shuffle.i, <4 x i32> <i32 4, i32 5, i32 2, i32 3>
+  ret <4 x float> %shuffle9.i
+}
+
+