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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131659 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 4b8a67d94d4dfc6056f14c84cc4cb80e6cd889cd..243937705aceaa4f4a0bedc959523415f27dd1d2 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -597,6 +597,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
   case Intrinsic::x86_sse41_pmovzxbw:
   case Intrinsic::x86_sse41_pmovzxwd:
   case Intrinsic::x86_sse41_pmovzxdq: {
+    // pmov{s|z}x ignores the upper half of their input vectors.
     unsigned VWidth =
       cast<VectorType>(II->getArgOperand(0)->getType())->getNumElements();
     unsigned LowHalfElts = VWidth / 2;