revert r297155 because there's a clang test that depends on InstCombine:

tools/clang/test/CodeGen/zvector.c

llvm-svn: 297166

1 files changed, 0 insertions, 20 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index a1ac64dda35..e60687fa7ad 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -463,23 +463,6 @@ Instruction *InstCombiner::shrinkBitwiseLogic(TruncInst &Trunc) {
   return BinaryOperator::Create(LogicOp->getOpcode(), NarrowOp0, NarrowC);
 }
 
-/// Try to narrow the width of a splat shuffle. This could be generalized to any
-/// shuffle with a constant operand, but we limit the transform to avoid
-/// creating a shuffle type that targets may not be able to lower effectively.
-static Instruction *shrinkSplatShuffle(TruncInst &Trunc,
-                                       InstCombiner::BuilderTy &Builder) {
-  auto *Shuf = dyn_cast<ShuffleVectorInst>(Trunc.getOperand(0));
-  if (Shuf && Shuf->hasOneUse() && isa<UndefValue>(Shuf->getOperand(1)) &&
-      Shuf->getMask()->getSplatValue()) {
-    // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Undef, SplatMask
-    Constant *NarrowUndef = UndefValue::get(Trunc.getType());
-    Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType());
-    return new ShuffleVectorInst(NarrowOp, NarrowUndef, Shuf->getMask());
-  }
-
-  return nullptr;
-}
-
 Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
   if (Instruction *Result = commonCastTransforms(CI))
     return Result;
@@ -571,9 +554,6 @@ Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
   if (Instruction *I = shrinkBitwiseLogic(CI))
     return I;
 
-  if (Instruction *I = shrinkSplatShuffle(CI, *Builder))
-    return I;
-
   if (Src->hasOneUse() && isa<IntegerType>(SrcTy) &&
       shouldChangeType(SrcTy, DestTy)) {
     // Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the