[InstCombine] allow more narrowing transforms for logic ops
We had a limited version of this for scalar 'and'; this expands
the transform to 'or' and 'xor' and allows vectors types too.
llvm-svn: 288273
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 491576e..c934550 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -443,6 +443,26 @@
return ExtractElementInst::Create(VecInput, IC.Builder->getInt32(Elt));
}
+/// Try to narrow the width of bitwise logic instructions with constants.
+Instruction *InstCombiner::shrinkBitwiseLogic(TruncInst &Trunc) {
+ Type *SrcTy = Trunc.getSrcTy();
+ Type *DestTy = Trunc.getType();
+ if (isa<IntegerType>(SrcTy) && !ShouldChangeType(SrcTy, DestTy))
+ return nullptr;
+
+ BinaryOperator *LogicOp;
+ Constant *C;
+ if (!match(Trunc.getOperand(0), m_OneUse(m_BinOp(LogicOp))) ||
+ !LogicOp->isBitwiseLogicOp() ||
+ !match(LogicOp->getOperand(1), m_Constant(C)))
+ return nullptr;
+
+ // trunc (logic X, C) --> logic (trunc X, C')
+ Constant *NarrowC = ConstantExpr::getTrunc(C, DestTy);
+ Value *NarrowOp0 = Builder->CreateTrunc(LogicOp->getOperand(0), DestTy);
+ return BinaryOperator::Create(LogicOp->getOpcode(), NarrowOp0, NarrowC);
+}
+
Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
if (Instruction *Result = commonCastTransforms(CI))
return Result;
@@ -531,17 +551,11 @@
}
}
+ if (Instruction *I = shrinkBitwiseLogic(CI))
+ return I;
+
if (Src->hasOneUse() && isa<IntegerType>(SrcTy) &&
ShouldChangeType(SrcTy, DestTy)) {
-
- // Transform "trunc (and X, cst)" -> "and (trunc X), cst" so long as the
- // dest type is native.
- if (match(Src, m_And(m_Value(A), m_ConstantInt(Cst)))) {
- Value *NewTrunc = Builder->CreateTrunc(A, DestTy, A->getName() + ".tr");
- return BinaryOperator::CreateAnd(NewTrunc,
- ConstantExpr::getTrunc(Cst, DestTy));
- }
-
// Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the
// dest type is native and cst < dest size.
if (match(Src, m_Shl(m_Value(A), m_ConstantInt(Cst))) &&
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index 176b7a0..e6b9bca 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -380,6 +380,7 @@
Instruction *scalarizePHI(ExtractElementInst &EI, PHINode *PN);
Value *EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask);
Instruction *foldCastedBitwiseLogic(BinaryOperator &I);
+ Instruction *shrinkBitwiseLogic(TruncInst &Trunc);
Instruction *optimizeBitCastFromPhi(CastInst &CI, PHINode *PN);
/// Determine if a pair of casts can be replaced by a single cast.