optimize comparisons against cttz/ctlz/ctpop, patch by Alastair Lynn!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92745 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 90ab4f4..abbc89b 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1418,11 +1418,33 @@
}
} else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
// Handle icmp {eq|ne} <intrinsic>, intcst.
- if (II->getIntrinsicID() == Intrinsic::bswap) {
+ switch (II->getIntrinsicID()) {
+ case Intrinsic::bswap:
Worklist.Add(II);
ICI.setOperand(0, II->getOperand(1));
ICI.setOperand(1, ConstantInt::get(II->getContext(), RHSV.byteSwap()));
return &ICI;
+ case Intrinsic::ctlz:
+ case Intrinsic::cttz:
+ // ctz(A) == bitwidth(a) -> A == 0 and likewise for !=
+ if (RHSV == RHS->getType()->getBitWidth()) {
+ Worklist.Add(II);
+ ICI.setOperand(0, II->getOperand(1));
+ ICI.setOperand(1, ConstantInt::get(RHS->getType(), 0));
+ return &ICI;
+ }
+ break;
+ case Intrinsic::ctpop:
+ // popcount(A) == 0 -> A == 0 and likewise for !=
+ if (RHS->isZero()) {
+ Worklist.Add(II);
+ ICI.setOperand(0, II->getOperand(1));
+ ICI.setOperand(1, RHS);
+ return &ICI;
+ }
+ break;
+ default:
+ break;
}
}
}