[x86, InstCombine] delete x86 SSE2 masked store with zero mask

This follows up on the related AVX instruction transforms, but this
one is too strange to do anything more with. Intel's behavioral
description of this instruction in its Software Developer's Manual
is tragi-comic.

llvm-svn: 263340

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index b8396eee844..f6ed6900a6a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -876,6 +876,11 @@ static bool simplifyX86MaskedStore(IntrinsicInst &II, InstCombiner &IC) {
     return true;
   }
 
+  // The SSE2 version is too weird (eg, unaligned but non-temporal) to do
+  // anything else at this level.
+  if (II.getIntrinsicID() == Intrinsic::x86_sse2_maskmov_dqu)
+    return false;
+
   auto *ConstMask = dyn_cast<ConstantDataVector>(Mask);
   if (!ConstMask)
     return false;
@@ -1674,6 +1679,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
       return I;
     break;
 
+  case Intrinsic::x86_sse2_maskmov_dqu:
   case Intrinsic::x86_avx_maskstore_ps:
   case Intrinsic::x86_avx_maskstore_pd:
   case Intrinsic::x86_avx_maskstore_ps_256: