Author: hans Date: Tue Jan 17 18:12:25 2017 New Revision: 292307 URL: http://llvm.org/viewvc/llvm-project?rev=292307&view=rev Log: Merging r291968 and r291979: ------------------------------------------------------------------------ r291968 | dannyb | 2017-01-13 14:40:01 -0800 (Fri, 13 Jan 2017) | 23 lines
NewGVN: Move leaders around properly to ensure we have a canonical dominating leader. Fixes PR 31613. Summary: This is a testcase where phi node cycling happens, and because we do not order the leaders by domination or anything similar, the leader keeps changing. Using std::set for the members is too expensive, and we actually don't need them sorted all the time, only at leader changes. We could keep both a set and a vector, and keep them mostly sorted and resort as necessary, or use a set and a fibheap, but all of this seems premature. After running some statistics, we are able to avoid the vast majority of sorting by keeping a "next leader" field. Most congruence classes only have leader changes once or twice during GVN. Reviewers: davide Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D28594 ------------------------------------------------------------------------ ------------------------------------------------------------------------ r291979 | dannyb | 2017-01-13 15:54:10 -0800 (Fri, 13 Jan 2017) | 1 line NewGVN: Fix PR31613 test regex naming ------------------------------------------------------------------------ Added: llvm/branches/release_40/test/Transforms/NewGVN/pr31613.ll - copied, changed from r291968, llvm/trunk/test/Transforms/NewGVN/pr31613.ll Modified: llvm/branches/release_40/ (props changed) llvm/branches/release_40/lib/Transforms/Scalar/NewGVN.cpp Propchange: llvm/branches/release_40/ ------------------------------------------------------------------------------ --- svn:mergeinfo (original) +++ svn:mergeinfo Tue Jan 17 18:12:25 2017 @@ -1,3 +1,3 @@ /llvm/branches/Apple/Pertwee:110850,110961 /llvm/branches/type-system-rewrite:133420-134817 -/llvm/trunk:155241,291863,291875,292242,292255 +/llvm/trunk:155241,291863,291875,291968,291979,292242,292255 Modified: llvm/branches/release_40/lib/Transforms/Scalar/NewGVN.cpp URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_40/lib/Transforms/Scalar/NewGVN.cpp?rev=292307&r1=292306&r2=292307&view=diff ============================================================================== --- llvm/branches/release_40/lib/Transforms/Scalar/NewGVN.cpp (original) +++ llvm/branches/release_40/lib/Transforms/Scalar/NewGVN.cpp Tue Jan 17 18:12:25 2017 @@ -81,6 +81,10 @@ STATISTIC(NumGVNOpsSimplified, "Number o STATISTIC(NumGVNPhisAllSame, "Number of PHIs whos arguments are all the same"); STATISTIC(NumGVNMaxIterations, "Maximum Number of iterations it took to converge GVN"); +STATISTIC(NumGVNLeaderChanges, "Number of leader changes"); +STATISTIC(NumGVNSortedLeaderChanges, "Number of sorted leader changes"); +STATISTIC(NumGVNAvoidedSortedLeaderChanges, + "Number of avoided sorted leader changes"); //===----------------------------------------------------------------------===// // GVN Pass @@ -139,6 +143,10 @@ struct CongruenceClass { // This is used so we can detect store equivalence changes properly. int StoreCount = 0; + // The most dominating leader after our current leader, because the member set + // is not sorted and is expensive to keep sorted all the time. + std::pair<Value *, unsigned int> NextLeader = {nullptr, ~0U}; + explicit CongruenceClass(unsigned ID) : ID(ID) {} CongruenceClass(unsigned ID, Value *Leader, const Expression *E) : ID(ID), RepLeader(Leader), DefiningExpr(E) {} @@ -320,8 +328,8 @@ private: // Templated to allow them to work both on BB's and BB-edges. template <class T> Value *lookupOperandLeader(Value *, const User *, const T &) const; - void performCongruenceFinding(Value *, const Expression *); - void moveValueToNewCongruenceClass(Value *, CongruenceClass *, + void performCongruenceFinding(Instruction *, const Expression *); + void moveValueToNewCongruenceClass(Instruction *, CongruenceClass *, CongruenceClass *); // Reachability handling. void updateReachableEdge(BasicBlock *, BasicBlock *); @@ -1056,20 +1064,43 @@ void NewGVN::markLeaderChangeTouched(Con // Move a value, currently in OldClass, to be part of NewClass // Update OldClass for the move (including changing leaders, etc) -void NewGVN::moveValueToNewCongruenceClass(Value *V, CongruenceClass *OldClass, +void NewGVN::moveValueToNewCongruenceClass(Instruction *I, + CongruenceClass *OldClass, CongruenceClass *NewClass) { - DEBUG(dbgs() << "New congruence class for " << V << " is " << NewClass->ID + DEBUG(dbgs() << "New congruence class for " << I << " is " << NewClass->ID << "\n"); - OldClass->Members.erase(V); - NewClass->Members.insert(V); - if (isa<StoreInst>(V)) { + + if (I == OldClass->NextLeader.first) + OldClass->NextLeader = {nullptr, ~0U}; + + // The new instruction and new class leader may either be siblings in the + // dominator tree, or the new class leader should dominate the new member + // instruction. We simply check that the member instruction does not properly + // dominate the new class leader. + assert( + !isa<Instruction>(NewClass->RepLeader) || !NewClass->RepLeader || + I == NewClass->RepLeader || + !DT->properlyDominates( + I->getParent(), + cast<Instruction>(NewClass->RepLeader)->getParent()) && + "New class for instruction should not be dominated by instruction"); + + if (NewClass->RepLeader != I) { + auto DFSNum = InstrDFS.lookup(I); + if (DFSNum < NewClass->NextLeader.second) + NewClass->NextLeader = {I, DFSNum}; + } + + OldClass->Members.erase(I); + NewClass->Members.insert(I); + if (isa<StoreInst>(I)) { --OldClass->StoreCount; assert(OldClass->StoreCount >= 0); ++NewClass->StoreCount; assert(NewClass->StoreCount > 0); } - ValueToClass[V] = NewClass; + ValueToClass[I] = NewClass; // See if we destroyed the class or need to swap leaders. if (OldClass->Members.empty() && OldClass != InitialClass) { if (OldClass->DefiningExpr) { @@ -1078,25 +1109,48 @@ void NewGVN::moveValueToNewCongruenceCla << " from table\n"); ExpressionToClass.erase(OldClass->DefiningExpr); } - } else if (OldClass->RepLeader == V) { + } else if (OldClass->RepLeader == I) { // When the leader changes, the value numbering of // everything may change due to symbolization changes, so we need to // reprocess. - OldClass->RepLeader = *(OldClass->Members.begin()); + DEBUG(dbgs() << "Leader change!\n"); + ++NumGVNLeaderChanges; + // We don't need to sort members if there is only 1, and we don't care about + // sorting the initial class because everything either gets out of it or is + // unreachable. + if (OldClass->Members.size() == 1 || OldClass == InitialClass) { + OldClass->RepLeader = *(OldClass->Members.begin()); + } else if (OldClass->NextLeader.first) { + ++NumGVNAvoidedSortedLeaderChanges; + OldClass->RepLeader = OldClass->NextLeader.first; + OldClass->NextLeader = {nullptr, ~0U}; + } else { + ++NumGVNSortedLeaderChanges; + // TODO: If this ends up to slow, we can maintain a dual structure for + // member testing/insertion, or keep things mostly sorted, and sort only + // here, or .... + std::pair<Value *, unsigned> MinDFS = {nullptr, ~0U}; + for (const auto X : OldClass->Members) { + auto DFSNum = InstrDFS.lookup(X); + if (DFSNum < MinDFS.second) + MinDFS = {X, DFSNum}; + } + OldClass->RepLeader = MinDFS.first; + } markLeaderChangeTouched(OldClass); } } // Perform congruence finding on a given value numbering expression. -void NewGVN::performCongruenceFinding(Value *V, const Expression *E) { - ValueToExpression[V] = E; +void NewGVN::performCongruenceFinding(Instruction *I, const Expression *E) { + ValueToExpression[I] = E; // This is guaranteed to return something, since it will at least find // INITIAL. - CongruenceClass *VClass = ValueToClass[V]; - assert(VClass && "Should have found a vclass"); + CongruenceClass *IClass = ValueToClass[I]; + assert(IClass && "Should have found a IClass"); // Dead classes should have been eliminated from the mapping. - assert(!VClass->Dead && "Found a dead class"); + assert(!IClass->Dead && "Found a dead class"); CongruenceClass *EClass; if (const auto *VE = dyn_cast<VariableExpression>(E)) { @@ -1118,13 +1172,13 @@ void NewGVN::performCongruenceFinding(Va NewClass->RepLeader = lookupOperandLeader(SI->getValueOperand(), SI, SI->getParent()); } else { - NewClass->RepLeader = V; + NewClass->RepLeader = I; } assert(!isa<VariableExpression>(E) && "VariableExpression should have been handled already"); EClass = NewClass; - DEBUG(dbgs() << "Created new congruence class for " << *V + DEBUG(dbgs() << "Created new congruence class for " << *I << " using expression " << *E << " at " << NewClass->ID << " and leader " << *(NewClass->RepLeader) << "\n"); DEBUG(dbgs() << "Hash value was " << E->getHashValue() << "\n"); @@ -1140,36 +1194,31 @@ void NewGVN::performCongruenceFinding(Va assert(!EClass->Dead && "We accidentally looked up a dead class"); } } - bool ClassChanged = VClass != EClass; - bool LeaderChanged = LeaderChanges.erase(V); + bool ClassChanged = IClass != EClass; + bool LeaderChanged = LeaderChanges.erase(I); if (ClassChanged || LeaderChanged) { DEBUG(dbgs() << "Found class " << EClass->ID << " for expression " << E << "\n"); if (ClassChanged) - - moveValueToNewCongruenceClass(V, VClass, EClass); - - - markUsersTouched(V); - if (auto *I = dyn_cast<Instruction>(V)) { - if (MemoryAccess *MA = MSSA->getMemoryAccess(I)) { - // If this is a MemoryDef, we need to update the equivalence table. If - // we determined the expression is congruent to a different memory - // state, use that different memory state. If we determined it didn't, - // we update that as well. Right now, we only support store - // expressions. - if (!isa<MemoryUse>(MA) && isa<StoreExpression>(E) && - EClass->Members.size() != 1) { - auto *DefAccess = cast<StoreExpression>(E)->getDefiningAccess(); - setMemoryAccessEquivTo(MA, DefAccess != MA ? DefAccess : nullptr); - } else { - setMemoryAccessEquivTo(MA, nullptr); - } - markMemoryUsersTouched(MA); + moveValueToNewCongruenceClass(I, IClass, EClass); + markUsersTouched(I); + if (MemoryAccess *MA = MSSA->getMemoryAccess(I)) { + // If this is a MemoryDef, we need to update the equivalence table. If + // we determined the expression is congruent to a different memory + // state, use that different memory state. If we determined it didn't, + // we update that as well. Right now, we only support store + // expressions. + if (!isa<MemoryUse>(MA) && isa<StoreExpression>(E) && + EClass->Members.size() != 1) { + auto *DefAccess = cast<StoreExpression>(E)->getDefiningAccess(); + setMemoryAccessEquivTo(MA, DefAccess != MA ? DefAccess : nullptr); + } else { + setMemoryAccessEquivTo(MA, nullptr); } + markMemoryUsersTouched(MA); } - } else if (StoreInst *SI = dyn_cast<StoreInst>(V)) { + } else if (auto *SI = dyn_cast<StoreInst>(I)) { // There is, sadly, one complicating thing for stores. Stores do not // produce values, only consume them. However, in order to make loads and // stores value number the same, we ignore the value operand of the store. Copied: llvm/branches/release_40/test/Transforms/NewGVN/pr31613.ll (from r291968, llvm/trunk/test/Transforms/NewGVN/pr31613.ll) URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_40/test/Transforms/NewGVN/pr31613.ll?p2=llvm/branches/release_40/test/Transforms/NewGVN/pr31613.ll&p1=llvm/trunk/test/Transforms/NewGVN/pr31613.ll&r1=291968&r2=292307&rev=292307&view=diff ============================================================================== --- llvm/trunk/test/Transforms/NewGVN/pr31613.ll (original) +++ llvm/branches/release_40/test/Transforms/NewGVN/pr31613.ll Tue Jan 17 18:12:25 2017 @@ -85,7 +85,7 @@ define void @e() { ; CHECK: l: ; CHECK-NEXT: br label [[R:%.*]] ; CHECK: q: -; CHECK-NEXT: [[M:%.*]] = load [[STRUCT_A*:%.*]], [[STRUCT_A**:%.*]] null +; CHECK-NEXT: [[M:%.*]] = load %struct.a*, %struct.a** null ; CHECK-NEXT: br label [[R]] ; CHECK: r: ; CHECK-NEXT: switch i32 undef, label [[N:%.*]] [ @@ -95,7 +95,7 @@ define void @e() { ; CHECK-NEXT: store i32 undef, i32* [[F]], !g !0 ; CHECK-NEXT: br label [[H]] ; CHECK: n: -; CHECK-NEXT: [[O:%.*]] = load [[STRUCT_A*]], [[STRUCT_A**]] null +; CHECK-NEXT: [[O:%.*]] = load %struct.a*, %struct.a** null ; CHECK-NEXT: ret void ; %f = alloca i32 _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
