diff --git a/llvm/lib/Transforms/Utils/LowerSwitch.cpp b/llvm/lib/Transforms/Utils/LowerSwitch.cpp --- a/llvm/lib/Transforms/Utils/LowerSwitch.cpp +++ b/llvm/lib/Transforms/Utils/LowerSwitch.cpp @@ -370,7 +370,7 @@ const unsigned NumSimpleCases = Clusterify(Cases, SI); IntegerType *IT = cast(SI->getCondition()->getType()); const unsigned BitWidth = IT->getBitWidth(); - APInt SignedZero(BitWidth, 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 @@ -431,7 +431,7 @@ if (DefaultIsUnreachableFromSwitch) { DenseMap Popularity; - APInt MaxPop(SignedZero); + APInt MaxPop(UnsignedZero); BasicBlock *PopSucc = nullptr; APInt SignedMax = APInt::getSignedMaxValue(BitWidth); @@ -457,11 +457,11 @@ } // 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; } @@ -486,8 +486,6 @@ // 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; }); @@ -498,8 +496,9 @@ 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; } diff --git a/llvm/test/Transforms/LowerSwitch/pr59316.ll b/llvm/test/Transforms/LowerSwitch/pr59316.ll --- a/llvm/test/Transforms/LowerSwitch/pr59316.ll +++ b/llvm/test/Transforms/LowerSwitch/pr59316.ll @@ -62,3 +62,32 @@ 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