Generalize the zext(trunc(t) & C) instcombine to work even with
C is not a low-bits mask, and add a similar instcombine for
zext((trunc(t) & C) ^ C).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73705 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index bf287f2..5bd17e0 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -8564,20 +8564,33 @@
}
}
- // zext(trunc(t) & C) -> (t & C) if C is a mask.
+ // zext(trunc(t) & C) -> (t & zext(C)).
if (SrcI && SrcI->getOpcode() == Instruction::And && SrcI->hasOneUse())
if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
if (TruncInst *TI = dyn_cast<TruncInst>(SrcI->getOperand(0))) {
Value *TI0 = TI->getOperand(0);
- if (TI0->getType() == CI.getType()) {
- unsigned TO = C->getValue().countTrailingOnes();
- if (APIntOps::isMask(TO, C->getValue()))
- return
- BinaryOperator::Create(Instruction::And, TI0,
- ConstantExpr::getZExt(C, CI.getType()));
- }
+ if (TI0->getType() == CI.getType())
+ return
+ BinaryOperator::CreateAnd(TI0,
+ ConstantExpr::getZExt(C, CI.getType()));
}
+ // zext((trunc(t) & C) ^ C) -> ((t & zext(C)) ^ zext(C)).
+ if (SrcI && SrcI->getOpcode() == Instruction::Xor && SrcI->hasOneUse())
+ if (ConstantInt *C = dyn_cast<ConstantInt>(SrcI->getOperand(1)))
+ if (BinaryOperator *And = dyn_cast<BinaryOperator>(SrcI->getOperand(0)))
+ if (And->getOpcode() == Instruction::And && And->hasOneUse() &&
+ And->getOperand(1) == C)
+ if (TruncInst *TI = dyn_cast<TruncInst>(And->getOperand(0))) {
+ Value *TI0 = TI->getOperand(0);
+ if (TI0->getType() == CI.getType()) {
+ Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
+ Instruction *NewAnd = BinaryOperator::CreateAnd(TI0, ZC, "tmp");
+ InsertNewInstBefore(NewAnd, *And);
+ return BinaryOperator::CreateXor(NewAnd, ZC);
+ }
+ }
+
return 0;
}