Index: llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp =================================================================== --- llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp +++ llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp @@ -201,8 +201,7 @@ mdconst::dyn_extract(WeightsNode->getOperand(i)); if (!Weight) return false; - Weights.push_back( - std::max(1, Weight->getLimitedValue(WeightLimit))); + Weights.push_back(Weight->getLimitedValue(WeightLimit)); } assert(Weights.size() == TI->getNumSuccessors() && "Checked above"); for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) @@ -553,7 +552,7 @@ uint32_t PrevSum = Sum; Sum += Weight; - assert(Sum > PrevSum); (void) PrevSum; + assert(Sum >= PrevSum); (void) PrevSum; } return Sum; @@ -616,14 +615,17 @@ uint32_t BranchProbabilityInfo:: getEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst) const { uint32_t Weight = 0; + bool FoundWeight = false; DenseMap::const_iterator MapI; for (succ_const_iterator I = succ_begin(Src), E = succ_end(Src); I != E; ++I) if (*I == Dst) { MapI = Weights.find(std::make_pair(Src, I.getSuccessorIndex())); - if (MapI != Weights.end()) + if (MapI != Weights.end()) { + FoundWeight = true; Weight += MapI->second; + } } - return (Weight == 0) ? DEFAULT_WEIGHT : Weight; + return (!FoundWeight) ? DEFAULT_WEIGHT : Weight; } /// Set the edge weight for a given edge specified by PredBlock and an index Index: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp =================================================================== --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -8009,7 +8009,11 @@ const ConstantInt *CaseVal = I.getCaseValue(); uint32_t Weight = 1; if (BPI) { - Weight = BPI->getEdgeWeight(SI.getParent(), I.getSuccessorIndex()); + // TODO - BPI used to guarantee non-zero weights, but this produces + // information loss (see PR 22718). Since we can't handle zero weights + // here, use the same flooring mechanism previously used by BPI. + Weight = std::max( + 1u, BPI->getEdgeWeight(SI.getParent(), I.getSuccessorIndex())); assert(Weight <= UINT32_MAX / SI.getNumSuccessors()); } Clusters.push_back(CaseCluster::range(CaseVal, CaseVal, Succ, Weight)); Index: llvm/trunk/test/Transforms/SampleProfile/branch.ll =================================================================== --- llvm/trunk/test/Transforms/SampleProfile/branch.ll +++ llvm/trunk/test/Transforms/SampleProfile/branch.ll @@ -36,8 +36,8 @@ tail call void @llvm.dbg.value(metadata i8** %argv, i64 0, metadata !14, metadata !DIExpression()), !dbg !27 %cmp = icmp slt i32 %argc, 2, !dbg !28 br i1 %cmp, label %return, label %if.end, !dbg !28 -; CHECK: edge entry -> return probability is 1 / 2 = 50% -; CHECK: edge entry -> if.end probability is 1 / 2 = 50% +; CHECK: edge entry -> return probability is 0 / 1 = 0% +; CHECK: edge entry -> if.end probability is 1 / 1 = 100% if.end: ; preds = %entry %arrayidx = getelementptr inbounds i8*, i8** %argv, i64 1, !dbg !30 @@ -46,8 +46,8 @@ tail call void @llvm.dbg.value(metadata i32 %call, i64 0, metadata !17, metadata !DIExpression()), !dbg !30 %cmp1 = icmp sgt i32 %call, 100, !dbg !35 br i1 %cmp1, label %for.body, label %if.end6, !dbg !35 -; CHECK: edge if.end -> for.body probability is 1 / 2 = 50% -; CHECK: edge if.end -> if.end6 probability is 1 / 2 = 50% +; CHECK: edge if.end -> for.body probability is 0 / 1 = 0% +; CHECK: edge if.end -> if.end6 probability is 1 / 1 = 100% for.body: ; preds = %if.end, %for.body %u.016 = phi i32 [ %inc, %for.body ], [ 0, %if.end ] @@ -65,8 +65,8 @@ tail call void @llvm.dbg.value(metadata i32 %inc, i64 0, metadata !21, metadata !DIExpression()), !dbg !38 %exitcond = icmp eq i32 %inc, %call, !dbg !38 br i1 %exitcond, label %if.end6, label %for.body, !dbg !38 -; CHECK: edge for.body -> if.end6 probability is 1 / 10227 = 0.00977804 -; CHECK: edge for.body -> for.body probability is 10226 / 10227 = 99.9902% [HOT edge] +; CHECK: edge for.body -> if.end6 probability is 0 / 10226 = 0% +; CHECK: edge for.body -> for.body probability is 10226 / 10226 = 100% [HOT edge] if.end6: ; preds = %for.body, %if.end %result.0 = phi double [ 0.000000e+00, %if.end ], [ %sub, %for.body ] Index: llvm/trunk/test/Transforms/SampleProfile/calls.ll =================================================================== --- llvm/trunk/test/Transforms/SampleProfile/calls.ll +++ llvm/trunk/test/Transforms/SampleProfile/calls.ll @@ -52,8 +52,8 @@ store i32 %inc, i32* %i, align 4, !dbg !14 %cmp = icmp slt i32 %0, 400000000, !dbg !14 br i1 %cmp, label %while.body, label %while.end, !dbg !14 -; CHECK: edge while.cond -> while.body probability is 5391 / 5392 = 99.9815% [HOT edge] -; CHECK: edge while.cond -> while.end probability is 1 / 5392 = 0.018546% +; CHECK: edge while.cond -> while.body probability is 5391 / 5391 = 100% [HOT edge] +; CHECK: edge while.cond -> while.end probability is 0 / 5391 = 0% while.body: ; preds = %while.cond %1 = load i32, i32* %i, align 4, !dbg !16 @@ -63,8 +63,8 @@ ; both branches out of while.body had the same weight. In reality, ; the edge while.body->if.then is taken most of the time. ; -; CHECK: edge while.body -> if.then probability is 5752 / 5753 = 99.9826% [HOT edge] -; CHECK: edge while.body -> if.else probability is 1 / 5753 = 0.0173822% +; CHECK: edge while.body -> if.then probability is 5752 / 5752 = 100% [HOT edge] +; CHECK: edge while.body -> if.else probability is 0 / 5752 = 0% if.then: ; preds = %while.body Index: llvm/trunk/test/Transforms/SampleProfile/propagate.ll =================================================================== --- llvm/trunk/test/Transforms/SampleProfile/propagate.ll +++ llvm/trunk/test/Transforms/SampleProfile/propagate.ll @@ -73,8 +73,8 @@ %5 = load i64, i64* %N.addr, align 8, !dbg !15 %cmp1 = icmp slt i64 %4, %5, !dbg !15 br i1 %cmp1, label %for.body, label %for.end18, !dbg !15 -; CHECK: edge for.cond -> for.body probability is 10 / 11 = 90.9091% [HOT edge] -; CHECK: edge for.cond -> for.end18 probability is 1 / 11 = 9.09091% +; CHECK: edge for.cond -> for.body probability is 10 / 10 = 100% [HOT edge] +; CHECK: edge for.cond -> for.end18 probability is 0 / 10 = 0% for.body: ; preds = %for.cond %6 = load i64, i64* %i, align 8, !dbg !18 @@ -119,8 +119,8 @@ %14 = load i64, i64* %i, align 8, !dbg !28 %cmp10 = icmp slt i64 %conv9, %14, !dbg !28 br i1 %cmp10, label %for.body11, label %for.end, !dbg !28 -; CHECK: edge for.cond8 -> for.body11 probability is 16191 / 16192 = 99.9938% [HOT edge] -; CHECK: edge for.cond8 -> for.end probability is 1 / 16192 = 0.00617589% +; CHECK: edge for.cond8 -> for.body11 probability is 16191 / 16191 = 100% [HOT edge] +; CHECK: edge for.cond8 -> for.end probability is 0 / 16191 = 0% for.body11: ; preds = %for.cond8 %15 = load i32, i32* %j, align 4, !dbg !31