2 files changed, 22 insertions, 16 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 2de83a01062..98e3fde95b3 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1097,20 +1097,11 @@ static Instruction *foldLogicCastConstant(BinaryOperator &Logic, CastInst *Cast,
   Type *DestTy = Logic.getType();
   Type *SrcTy = Cast->getSrcTy();
 
-  // If the first operand is bitcast, move the logic operation ahead of the
-  // bitcast (do the logic operation in the original type). This can eliminate
-  // bitcasts and allow combines that would otherwise be impeded by the bitcast.
+  // Move the logic operation ahead of a zext if the constant is unchanged in
+  // the smaller source type. Performing the logic in a smaller type may provide
+  // more information to later folds, and the smaller logic instruction may be
+  // cheaper (particularly in the case of vectors).
   Value *X;
-  if (match(Cast, m_BitCast(m_Value(X)))) {
-    Value *NewConstant = ConstantExpr::getBitCast(C, SrcTy);
-    Value *NewOp = Builder->CreateBinOp(LogicOpc, X, NewConstant);
-    return CastInst::CreateBitOrPointerCast(NewOp, DestTy);
-  }
-
-  // Similarly, move the logic operation ahead of a zext if the constant is
-  // unchanged in the smaller source type. Performing the logic in a smaller
-  // type may provide more information to later folds, and the smaller logic
-  // instruction may be cheaper (particularly in the case of vectors).
   if (match(Cast, m_OneUse(m_ZExt(m_Value(X))))) {
     Constant *TruncC = ConstantExpr::getTrunc(C, SrcTy);
     Constant *ZextTruncC = ConstantExpr::getZExt(TruncC, DestTy);
@@ -1579,11 +1570,14 @@ static Value *getSelectCondition(Value *A, Value *B,
 
   // If A and B are sign-extended, look through the sexts to find the booleans.
   Value *Cond;
+  Value *NotB;
   if (match(A, m_SExt(m_Value(Cond))) &&
       Cond->getType()->getScalarType()->isIntegerTy(1) &&
-      match(B, m_CombineOr(m_Not(m_SExt(m_Specific(Cond))),
-                           m_SExt(m_Not(m_Specific(Cond))))))
-    return Cond;
+      match(B, m_OneUse(m_Not(m_Value(NotB))))) {
+    NotB = peekThroughBitcast(NotB, true);
+    if (match(NotB, m_SExt(m_Specific(Cond))))
+      return Cond;
+  }
 
   // All scalar (and most vector) possibilities should be handled now.
   // Try more matches that only apply to non-splat constant vectors.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 38e95fb1163..d3049389dfb 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1896,6 +1896,18 @@ static Instruction *foldBitCastBitwiseLogic(BitCastInst &BitCast,
     return BinaryOperator::Create(BO->getOpcode(), CastedOp0, X);
   }
 
+  // Canonicalize vector bitcasts to come before vector bitwise logic with a
+  // constant. This eases recognition of special constants for later ops.
+  // Example:
+  // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
+  Constant *C;
+  if (match(BO->getOperand(1), m_Constant(C))) {
+    // bitcast (logic X, C) --> logic (bitcast X, C')
+    Value *CastedOp0 = Builder.CreateBitCast(BO->getOperand(0), DestTy);
+    Value *CastedC = ConstantExpr::getBitCast(C, DestTy);
+    return BinaryOperator::Create(BO->getOpcode(), CastedOp0, CastedC);
+  }
+
   return nullptr;
 }