PR4548: optimize zext+udiv+trunc to udiv.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75539 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index c93994f..838b33c 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -7974,6 +7974,23 @@
CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
NumCastsRemoved);
+ case Instruction::UDiv:
+ case Instruction::URem: {
+ // UDiv and URem can be truncated if all the truncated bits are zero.
+ uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
+ uint32_t BitWidth = Ty->getScalarSizeInBits();
+ if (BitWidth < OrigBitWidth) {
+ APInt Mask = APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth);
+ if (MaskedValueIsZero(I->getOperand(0), Mask) &&
+ MaskedValueIsZero(I->getOperand(1), Mask)) {
+ return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
+ NumCastsRemoved) &&
+ CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
+ NumCastsRemoved);
+ }
+ }
+ break;
+ }
case Instruction::Shl:
// If we are truncating the result of this SHL, and if it's a shift of a
// constant amount, we can always perform a SHL in a smaller type.
@@ -8060,7 +8077,9 @@
case Instruction::Xor:
case Instruction::AShr:
case Instruction::LShr:
- case Instruction::Shl: {
+ case Instruction::Shl:
+ case Instruction::UDiv:
+ case Instruction::URem: {
Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);