const unsigned NumSimpleCases = Clusterify(Cases, SI);
IntegerType *IT = cast<IntegerType>(SI->getCondition()->getType());
const unsigned BitWidth = IT->getBitWidth();
- APInt SignedZero(BitWidth, 0);
+ // Explictly use higher precision to prevent unsigned overflow where
+ // `UnsignedMax - 0 + 1 == 0`
+ APInt UnsignedZero(BitWidth + 1, 0);
APInt UnsignedMax = APInt::getMaxValue(BitWidth);
LLVM_DEBUG(dbgs() << "Clusterify finished. Total clusters: " << Cases.size()
<< ". Total non-default cases: " << NumSimpleCases
if (DefaultIsUnreachableFromSwitch) {
DenseMap<BasicBlock *, APInt> Popularity;
- APInt MaxPop(SignedZero);
+ APInt MaxPop(UnsignedZero);
BasicBlock *PopSucc = nullptr;
APInt SignedMax = APInt::getSignedMaxValue(BitWidth);
}
// Count popularity.
- APInt N = High - Low + 1;
- assert(N.sge(SignedZero) && "Popularity shouldn't be negative.");
+ assert(High.sge(Low) && "Popularity shouldn't be negative.");
+ APInt N = High.sext(BitWidth + 1) - Low.sext(BitWidth + 1) + 1;
// Explict insert to make sure the bitwidth of APInts match
- APInt &Pop = Popularity.insert({I.BB, APInt(SignedZero)}).first->second;
- if ((Pop += N).sgt(MaxPop)) {
+ APInt &Pop = Popularity.insert({I.BB, APInt(UnsignedZero)}).first->second;
+ if ((Pop += N).ugt(MaxPop)) {
MaxPop = Pop;
PopSucc = I.BB;
}
// Use the most popular block as the new default, reducing the number of
// cases.
- assert(MaxPop.sgt(SignedZero) && PopSucc &&
- "Max populartion shouldn't be negative.");
Default = PopSucc;
llvm::erase_if(Cases,
[PopSucc](const CaseRange &R) { return R.BB == PopSucc; });
SI->eraseFromParent();
// As all the cases have been replaced with a single branch, only keep
// one entry in the PHI nodes.
- for (APInt I(SignedZero); I.slt(MaxPop - 1); ++I)
- PopSucc->removePredecessor(OrigBlock);
+ if (!MaxPop.isZero())
+ for (APInt I(UnsignedZero); I.ult(MaxPop - 1); ++I)
+ PopSucc->removePredecessor(OrigBlock);
return;
}
BB1: ; preds = %BB
unreachable
}
+
+define void @f_i1() {
+entry:
+ switch i1 false, label %sw.bb [
+ i1 false, label %sw.bb12
+ ]
+
+sw.bb: ; preds = %entry
+ unreachable
+
+sw.bb12: ; preds = %entry
+ unreachable
+}
+
+define void @f_i2(i2 %cond) {
+entry:
+ switch i2 %cond, label %sw.bb [
+ i2 0, label %sw.bb12
+ i2 1, label %sw.bb12
+ i2 2, label %sw.bb12
+ i2 3, label %sw.bb12
+ ]
+
+sw.bb: ; preds = %entry
+ unreachable
+
+sw.bb12: ; preds = %entry
+ unreachable
+}
\ No newline at end of file