diff --git a/lib/Analysis/DependenceGraphBuilder.cpp b/lib/Analysis/DependenceGraphBuilder.cpp index fbf0f665159..04a34472659 100644 --- a/lib/Analysis/DependenceGraphBuilder.cpp +++ b/lib/Analysis/DependenceGraphBuilder.cpp @@ -140,75 +140,74 @@ template void AbstractDependenceGraphBuilder::createPiBlocks() { if (*N == PiNode || NodesInSCC.count(N)) continue; - for (NodeType *SCCNode : NL) { + enum Direction { + Incoming, // Incoming edges to the SCC + Outgoing, // Edges going ot of the SCC + DirectionCount // To make the enum usable as an array index. + }; - enum Direction { - Incoming, // Incoming edges to the SCC - Outgoing, // Edges going ot of the SCC - DirectionCount // To make the enum usable as an array index. - }; + // Use these flags to help us avoid creating redundant edges. If there + // are more than one edges from an outside node to inside nodes, we only + // keep one edge from that node to the pi-block node. Similarly, if + // there are more than one edges from inside nodes to an outside node, + // we only keep one edge from the pi-block node to the outside node. + // There is a flag defined for each direction (incoming vs outgoing) and + // for each type of edge supported, using a two-dimensional boolean + // array. + using EdgeKind = typename EdgeType::EdgeKind; + EnumeratedArray EdgeAlreadyCreated[DirectionCount]{false, + false}; - // Use these flags to help us avoid creating redundant edges. If there - // are more than one edges from an outside node to inside nodes, we only - // keep one edge from that node to the pi-block node. Similarly, if - // there are more than one edges from inside nodes to an outside node, - // we only keep one edge from the pi-block node to the outside node. - // There is a flag defined for each direction (incoming vs outgoing) and - // for each type of edge supported, using a two-dimensional boolean - // array. - using EdgeKind = typename EdgeType::EdgeKind; - EnumeratedArray EdgeAlreadyCreated[DirectionCount]{ - false, false}; + auto createEdgeOfKind = [this](NodeType &Src, NodeType &Dst, + const EdgeKind K) { + switch (K) { + case EdgeKind::RegisterDefUse: + createDefUseEdge(Src, Dst); + break; + case EdgeKind::MemoryDependence: + createMemoryEdge(Src, Dst); + break; + case EdgeKind::Rooted: + createRootedEdge(Src, Dst); + break; + default: + llvm_unreachable("Unsupported type of edge."); + } + }; - auto createEdgeOfKind = [this](NodeType &Src, NodeType &Dst, - const EdgeKind K) { - switch (K) { - case EdgeKind::RegisterDefUse: - createDefUseEdge(Src, Dst); - break; - case EdgeKind::MemoryDependence: - createMemoryEdge(Src, Dst); - break; - case EdgeKind::Rooted: - createRootedEdge(Src, Dst); - break; - default: - llvm_unreachable("Unsupported type of edge."); - } - }; + auto reconnectEdges = [&](NodeType *Src, NodeType *Dst, NodeType *New, + const Direction Dir) { + if (!Src->hasEdgeTo(*Dst)) + return; + LLVM_DEBUG( + dbgs() << "reconnecting(" + << (Dir == Direction::Incoming ? "incoming)" : "outgoing)") + << ":\nSrc:" << *Src << "\nDst:" << *Dst << "\nNew:" << *New + << "\n"); + assert((Dir == Direction::Incoming || Dir == Direction::Outgoing) && + "Invalid direction."); - auto reconnectEdges = [&](NodeType *Src, NodeType *Dst, NodeType *New, - const Direction Dir) { - if (!Src->hasEdgeTo(*Dst)) - return; - LLVM_DEBUG(dbgs() - << "reconnecting(" - << (Dir == Direction::Incoming ? "incoming)" : "outgoing)") - << ":\nSrc:" << *Src << "\nDst:" << *Dst - << "\nNew:" << *New << "\n"); - assert((Dir == Direction::Incoming || Dir == Direction::Outgoing) && - "Invalid direction."); - - SmallVector EL; - Src->findEdgesTo(*Dst, EL); - for (EdgeType *OldEdge : EL) { - EdgeKind Kind = OldEdge->getKind(); - if (!EdgeAlreadyCreated[Dir][Kind]) { - if (Dir == Direction::Incoming) { - createEdgeOfKind(*Src, *New, Kind); - LLVM_DEBUG(dbgs() << "created edge from Src to New.\n"); - } else if (Dir == Direction::Outgoing) { - createEdgeOfKind(*New, *Dst, Kind); - LLVM_DEBUG(dbgs() << "created edge from New to Dst.\n"); - } - EdgeAlreadyCreated[Dir][Kind] = true; + SmallVector EL; + Src->findEdgesTo(*Dst, EL); + for (EdgeType *OldEdge : EL) { + EdgeKind Kind = OldEdge->getKind(); + if (!EdgeAlreadyCreated[Dir][Kind]) { + if (Dir == Direction::Incoming) { + createEdgeOfKind(*Src, *New, Kind); + LLVM_DEBUG(dbgs() << "created edge from Src to New.\n"); + } else if (Dir == Direction::Outgoing) { + createEdgeOfKind(*New, *Dst, Kind); + LLVM_DEBUG(dbgs() << "created edge from New to Dst.\n"); } - Src->removeEdge(*OldEdge); - destroyEdge(*OldEdge); - LLVM_DEBUG(dbgs() << "removed old edge between Src and Dst.\n\n"); + EdgeAlreadyCreated[Dir][Kind] = true; } - }; + Src->removeEdge(*OldEdge); + destroyEdge(*OldEdge); + LLVM_DEBUG(dbgs() << "removed old edge between Src and Dst.\n\n"); + } + }; + for (NodeType *SCCNode : NL) { // Process incoming edges incident to the pi-block node. reconnectEdges(N, SCCNode, &PiNode, Direction::Incoming); diff --git a/unittests/Analysis/DDGTest.cpp b/unittests/Analysis/DDGTest.cpp index 9919d055d01..b1d35596c1e 100644 --- a/unittests/Analysis/DDGTest.cpp +++ b/unittests/Analysis/DDGTest.cpp @@ -128,3 +128,157 @@ TEST(DDGTest, getDependencies) { SE.getOne(DL.back()->getDistance(1)->getType())); }); } + +/// Test to make sure that when pi-blocks are formed, multiple edges of the same +/// kind and direction are collapsed into a single edge. +/// In the test below, %loadASubI belongs to an outside node, which has input +/// dependency with multiple load instructions in the pi-block containing +/// %loadBSubI. We expect a single memory dependence edge from the outside node +/// to this pi-block. The pi-block also contains %add and %add7 both of which +/// feed a phi in an outside node. We expect a single def-use edge from the +/// pi-block to the node containing that phi. +TEST(DDGTest, avoidDuplicateEdgesToFromPiBlocks) { + const char *ModuleStr = + "target datalayout = \"e-m:e-i64:64-n32:64-v256:256:256-v512:512:512\"\n" + "\n" + "define void @foo(float* noalias %A, float* noalias %B, float* noalias " + "%C, float* noalias %D, i32 signext %n) {\n" + "entry:\n" + " %cmp1 = icmp sgt i32 %n, 0\n" + " br i1 %cmp1, label %for.body.preheader, label %for.end\n" + "\n" + "for.body.preheader: ; preds = %entry\n" + " %wide.trip.count = zext i32 %n to i64\n" + " br label %for.body\n" + "\n" + "for.body: ; preds = " + "%for.body.preheader, %if.end\n" + " %indvars.iv = phi i64 [ 0, %for.body.preheader ], [ %indvars.iv.next, " + "%if.end ]\n" + " %arrayidx = getelementptr inbounds float, float* %A, i64 %indvars.iv\n" + " %loadASubI = load float, float* %arrayidx, align 4\n" + " %arrayidx2 = getelementptr inbounds float, float* %B, i64 " + "%indvars.iv\n" + " %loadBSubI = load float, float* %arrayidx2, align 4\n" + " %add = fadd fast float %loadASubI, %loadBSubI\n" + " %arrayidx4 = getelementptr inbounds float, float* %A, i64 " + "%indvars.iv\n" + " store float %add, float* %arrayidx4, align 4\n" + " %arrayidx6 = getelementptr inbounds float, float* %A, i64 " + "%indvars.iv\n" + " %0 = load float, float* %arrayidx6, align 4\n" + " %add7 = fadd fast float %0, 1.000000e+00\n" + " %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1\n" + " %arrayidx10 = getelementptr inbounds float, float* %B, i64 " + "%indvars.iv.next\n" + " store float %add7, float* %arrayidx10, align 4\n" + " %arrayidx12 = getelementptr inbounds float, float* %A, i64 " + "%indvars.iv\n" + " %1 = load float, float* %arrayidx12, align 4\n" + " %cmp13 = fcmp fast ogt float %1, 1.000000e+02\n" + " br i1 %cmp13, label %if.then, label %if.else\n" + "\n" + "if.then: ; preds = %for.body\n" + " br label %if.end\n" + "\n" + "if.else: ; preds = %for.body\n" + " br label %if.end\n" + "\n" + "if.end: ; preds = %if.else, " + "%if.then\n" + " %ff.0 = phi float [ %add, %if.then ], [ %add7, %if.else ]\n" + " store float %ff.0, float* %C, align 4\n" + " %exitcond = icmp ne i64 %indvars.iv.next, %wide.trip.count\n" + " br i1 %exitcond, label %for.body, label %for.end.loopexit\n" + "\n" + "for.end.loopexit: ; preds = %if.end\n" + " br label %for.end\n" + "\n" + "for.end: ; preds = " + "%for.end.loopexit, %entry\n" + " ret void\n" + "}\n"; + + LLVMContext Context; + std::unique_ptr M = makeLLVMModule(Context, ModuleStr); + + runTest( + *M, "foo", + [&](Function &F, LoopInfo &LI, DependenceInfo &DI, ScalarEvolution &SE) { + Loop *L = *LI.begin(); + assert(L && "expected the loop to be identified."); + + DataDependenceGraph DDG(*L, LI, DI); + + const DDGNode *LoadASubI = nullptr; + for (DDGNode *N : DDG) { + if (!isa(N)) + continue; + SmallVector IList; + N->collectInstructions([](const Instruction *I) { return true; }, + IList); + if (llvm::any_of(IList, [](Instruction *I) { + return I->getName() == "loadASubI"; + })) { + LoadASubI = N; + break; + } + } + assert(LoadASubI && "Did not find load of A[i]"); + + const PiBlockDDGNode *PiBlockWithBSubI = nullptr; + for (DDGNode *N : DDG) { + if (!isa(N)) + continue; + for (DDGNode *M : cast(N)->getNodes()) { + SmallVector IList; + M->collectInstructions([](const Instruction *I) { return true; }, + IList); + if (llvm::any_of(IList, [](Instruction *I) { + return I->getName() == "loadBSubI"; + })) { + PiBlockWithBSubI = static_cast(N); + break; + } + } + if (PiBlockWithBSubI) + break; + } + assert(PiBlockWithBSubI && + "Did not find pi-block containing load of B[i]"); + + const DDGNode *FFPhi = nullptr; + for (DDGNode *N : DDG) { + if (!isa(N)) + continue; + SmallVector IList; + N->collectInstructions([](const Instruction *I) { return true; }, + IList); + if (llvm::any_of(IList, [](Instruction *I) { + return I->getName() == "ff.0"; + })) { + FFPhi = N; + break; + } + } + assert(FFPhi && "Did not find ff.0 phi instruction"); + + // Expect a single memory edge from '%0 = A[i]' to the pi-block. This + // means the duplicate incoming memory edges are removed during pi-block + // formation. + SmallVector EL; + LoadASubI->findEdgesTo(*PiBlockWithBSubI, EL); + unsigned NumMemoryEdges = llvm::count_if( + EL, [](DDGEdge *Edge) { return Edge->isMemoryDependence(); }); + EXPECT_EQ(NumMemoryEdges, 1ull); + + /// Expect a single def-use edge from the pi-block to '%ff.0 = phi...`. + /// This means the duplicate outgoing def-use edges are removed during + /// pi-block formation. + EL.clear(); + PiBlockWithBSubI->findEdgesTo(*FFPhi, EL); + NumMemoryEdges = + llvm::count_if(EL, [](DDGEdge *Edge) { return Edge->isDefUse(); }); + EXPECT_EQ(NumMemoryEdges, 1ull); + }); +}