From e6de9e39a8ac60a213538ea51e5ca07f517bfc5a Mon Sep 17 00:00:00 2001
From: Serge Pavlov <sepavloff@gmail.com>
Date: Wed, 14 May 2014 09:05:09 +0000
Subject: [PATCH] Fix the case when reordering shuffle and binop produces a
 constant.

This resolves PR19737.

llvm-svn: 208762
---
 .../InstCombine/InstructionCombining.cpp      | 26 +++++++++----------
 .../Transforms/InstCombine/vec_shuffle.ll     | 11 ++++++++
 2 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 8c0a249aee18..4c36887f6285 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1085,18 +1085,18 @@ Value *InstCombiner::Descale(Value *Val, APInt Scale, bool &NoSignedWrap) {
 
 /// \brief Creates node of binary operation with the same attributes as the
 /// specified one but with other operands.
-static BinaryOperator *CreateBinOpAsGiven(BinaryOperator &Inst, Value *LHS,
-                                          Value *RHS,
-                                          InstCombiner::BuilderTy *B) {
-  BinaryOperator *NewBO = cast<BinaryOperator>(B->CreateBinOp(Inst.getOpcode(),
-                                                              LHS, RHS));
-  if (isa<OverflowingBinaryOperator>(NewBO)) {
-    NewBO->setHasNoSignedWrap(Inst.hasNoSignedWrap());
-    NewBO->setHasNoUnsignedWrap(Inst.hasNoUnsignedWrap());
+static Value *CreateBinOpAsGiven(BinaryOperator &Inst, Value *LHS, Value *RHS,
+                                 InstCombiner::BuilderTy *B) {
+  Value *BORes = B->CreateBinOp(Inst.getOpcode(), LHS, RHS);
+  if (BinaryOperator *NewBO = dyn_cast<BinaryOperator>(BORes)) {
+    if (isa<OverflowingBinaryOperator>(NewBO)) {
+      NewBO->setHasNoSignedWrap(Inst.hasNoSignedWrap());
+      NewBO->setHasNoUnsignedWrap(Inst.hasNoUnsignedWrap());
+    }
+    if (isa<PossiblyExactOperator>(NewBO))
+      NewBO->setIsExact(Inst.isExact());
   }
-  if (isa<PossiblyExactOperator>(NewBO))
-    NewBO->setIsExact(Inst.isExact());
-  return NewBO;
+  return BORes;
 }
 
 /// \brief Makes transformation of binary operation specific for vector types.
@@ -1122,7 +1122,7 @@ Value *InstCombiner::SimplifyVectorOp(BinaryOperator &Inst) {
         isa<UndefValue>(RShuf->getOperand(1)) &&
         LShuf->getOperand(0)->getType() == RShuf->getOperand(0)->getType() &&
         LShuf->getMask() == RShuf->getMask()) {
-      BinaryOperator *NewBO = CreateBinOpAsGiven(Inst, LShuf->getOperand(0),
+      Value *NewBO = CreateBinOpAsGiven(Inst, LShuf->getOperand(0),
           RShuf->getOperand(0), Builder);
       Value *Res = Builder->CreateShuffleVector(NewBO,
           UndefValue::get(NewBO->getType()), LShuf->getMask());
@@ -1168,7 +1168,7 @@ Value *InstCombiner::SimplifyVectorOp(BinaryOperator &Inst) {
         NewLHS = Shuffle->getOperand(0);
         NewRHS = C2;
       }
-      BinaryOperator *NewBO = CreateBinOpAsGiven(Inst, NewLHS, NewRHS, Builder);
+      Value *NewBO = CreateBinOpAsGiven(Inst, NewLHS, NewRHS, Builder);
       Value *Res = Builder->CreateShuffleVector(NewBO,
           UndefValue::get(Inst.getType()), Shuffle->getMask());
       return Res;
diff --git a/llvm/test/Transforms/InstCombine/vec_shuffle.ll b/llvm/test/Transforms/InstCombine/vec_shuffle.ll
index 2e6f787f8334..fc0f8bd0aa99 100644
--- a/llvm/test/Transforms/InstCombine/vec_shuffle.ll
+++ b/llvm/test/Transforms/InstCombine/vec_shuffle.ll
@@ -394,3 +394,14 @@ define <8 x i8> @pr19730(<16 x i8> %in0) {
   %shuffle1 = shufflevector <8 x i8> %shuffle, <8 x i8> undef, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
   ret <8 x i8> %shuffle1
 }
+
+define i32 @pr19737(<4 x i32> %in0) {
+; CHECK-LABEL: @pr19737(
+; CHECK: [[VAR:%[a-zA-Z0-9.]+]] = extractelement <4 x i32> %in0, i32 0
+; CHECK: ret i32 [[VAR]]
+  %shuffle.i = shufflevector <4 x i32> zeroinitializer, <4 x i32> %in0, <4 x i32> <i32 0, i32 4, i32 2, i32 6>
+  %neg.i = xor <4 x i32> %shuffle.i, <i32 -1, i32 -1, i32 -1, i32 -1>
+  %and.i = and <4 x i32> %in0, %neg.i
+  %rv = extractelement <4 x i32> %and.i, i32 0
+  ret i32 %rv
+}