Recommit r333268: [IPSCCP] Use PredicateInfo to propagate facts from cmp instructions.

This patch updates IPSCCP to use PredicateInfo to propagate
facts to true branches predicated by EQ and to false branches
predicated by NE.

As a follow up, we should be able to extend it to also propagate additional
facts about nonnull.

Reviewers: davide, mssimpso, dberlin, efriedma

Reviewed By: davide, dberlin

Differential Revision: https://reviews.llvm.org/D45330

llvm-svn: 333740

8 files changed, 155 insertions, 15 deletions

diff --git a/llvm/include/llvm/Transforms/Scalar/SCCP.h b/llvm/include/llvm/Transforms/Scalar/SCCP.h
index 2a294c95a17..e434d41d034 100644
--- a/llvm/include/llvm/Transforms/Scalar/SCCP.h
+++ b/llvm/include/llvm/Transforms/Scalar/SCCP.h
@@ -21,11 +21,13 @@
 #ifndef LLVM_TRANSFORMS_SCALAR_SCCP_H
 #define LLVM_TRANSFORMS_SCALAR_SCCP_H
 
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/PassManager.h"
+#include "llvm/Transforms/Utils/PredicateInfo.h"
 
 namespace llvm {
 
@@ -37,7 +39,9 @@ public:
   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
 };
 
-bool runIPSCCP(Module &M, const DataLayout &DL, const TargetLibraryInfo *TLI);
+bool runIPSCCP(
+    Module &M, const DataLayout &DL, const TargetLibraryInfo *TLI,
+    function_ref<std::unique_ptr<PredicateInfo>(Function &)> getPredicateInfo);
 } // end namespace llvm
 
 #endif // LLVM_TRANSFORMS_SCALAR_SCCP_H
diff --git a/llvm/lib/Transforms/IPO/SCCP.cpp b/llvm/lib/Transforms/IPO/SCCP.cpp
index cc53c4b8c46..e2bb6f185c3 100644
--- a/llvm/lib/Transforms/IPO/SCCP.cpp
+++ b/llvm/lib/Transforms/IPO/SCCP.cpp
@@ -1,4 +1,5 @@
 #include "llvm/Transforms/IPO/SCCP.h"
+#include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/Transforms/Scalar/SCCP.h"
@@ -8,7 +9,15 @@ using namespace llvm;
 PreservedAnalyses IPSCCPPass::run(Module &M, ModuleAnalysisManager &AM) {
   const DataLayout &DL = M.getDataLayout();
   auto &TLI = AM.getResult<TargetLibraryAnalysis>(M);
-  if (!runIPSCCP(M, DL, &TLI))
+  auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
+  auto getPredicateInfo =
+      [&FAM](Function &F) -> std::unique_ptr<PredicateInfo> {
+    return make_unique<PredicateInfo>(F,
+                                      FAM.getResult<DominatorTreeAnalysis>(F),
+                                      FAM.getResult<AssumptionAnalysis>(F));
+  };
+
+  if (!runIPSCCP(M, DL, &TLI, getPredicateInfo))
     return PreservedAnalyses::all();
   return PreservedAnalyses::none();
 }
@@ -34,10 +43,20 @@ public:
     const DataLayout &DL = M.getDataLayout();
     const TargetLibraryInfo *TLI =
         &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
-    return runIPSCCP(M, DL, TLI);
+
+    auto getPredicateInfo =
+        [this](Function &F) -> std::unique_ptr<PredicateInfo> {
+      return make_unique<PredicateInfo>(
+          F, this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree(),
+          this->getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F));
+    };
+
+    return runIPSCCP(M, DL, TLI, getPredicateInfo);
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<AssumptionCacheTracker>();
+    AU.addRequired<DominatorTreeWrapperPass>();
     AU.addRequired<TargetLibraryInfoWrapperPass>();
   }
 };
@@ -49,6 +68,7 @@ char IPSCCPLegacyPass::ID = 0;
 INITIALIZE_PASS_BEGIN(IPSCCPLegacyPass, "ipsccp",
                       "Interprocedural Sparse Conditional Constant Propagation",
                       false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
 INITIALIZE_PASS_END(IPSCCPLegacyPass, "ipsccp",
                     "Interprocedural Sparse Conditional Constant Propagation",
diff --git a/llvm/lib/Transforms/Scalar/SCCP.cpp b/llvm/lib/Transforms/Scalar/SCCP.cpp
index 27c51f07f1f..e0bd3480c2d 100644
--- a/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -55,6 +55,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/PredicateInfo.h"
 #include <cassert>
 #include <utility>
 #include <vector>
@@ -248,7 +249,21 @@ class SCCPSolver : public InstVisitor<SCCPSolver> {
   using Edge = std::pair<BasicBlock *, BasicBlock *>;
   DenseSet<Edge> KnownFeasibleEdges;
 
+  DenseMap<Function *, std::unique_ptr<PredicateInfo>> PredInfos;
+  DenseMap<Value *, SmallPtrSet<User *, 2>> AdditionalUsers;
+
 public:
+  void addPredInfo(Function &F, std::unique_ptr<PredicateInfo> PI) {
+    PredInfos[&F] = std::move(PI);
+  }
+
+  const PredicateBase *getPredicateInfoFor(Instruction *I) {
+    auto PI = PredInfos.find(I->getParent()->getParent());
+    if (PI == PredInfos.end())
+      return nullptr;
+    return PI->second->getPredicateInfoFor(I);
+  }
+
   SCCPSolver(const DataLayout &DL, const TargetLibraryInfo *tli)
       : DL(DL), TLI(tli) {}
 
@@ -563,6 +578,26 @@ private:
       visit(*I);
   }
 
+  // Add U as additional user of V.
+  void addAdditionalUser(Value *V, User *U) {
+    auto Iter = AdditionalUsers.insert({V, {}});
+    Iter.first->second.insert(U);
+  }
+
+  // Mark I's users as changed, including AdditionalUsers.
+  void markUsersAsChanged(Value *I) {
+    for (User *U : I->users())
+      if (auto *UI = dyn_cast<Instruction>(U))
+        OperandChangedState(UI);
+
+    auto Iter = AdditionalUsers.find(I);
+    if (Iter != AdditionalUsers.end()) {
+      for (User *U : Iter->second)
+        if (auto *UI = dyn_cast<Instruction>(U))
+          OperandChangedState(UI);
+    }
+  }
+
 private:
   friend class InstVisitor<SCCPSolver>;
 
@@ -1157,6 +1192,59 @@ void SCCPSolver::visitCallSite(CallSite CS) {
   Function *F = CS.getCalledFunction();
   Instruction *I = CS.getInstruction();
 
+  if (auto *II = dyn_cast<IntrinsicInst>(I)) {
+    if (II->getIntrinsicID() == Intrinsic::ssa_copy) {
+      if (ValueState[I].isOverdefined())
+        return;
+
+      auto *PI = getPredicateInfoFor(I);
+      if (!PI)
+        return;
+
+      auto *PBranch = dyn_cast<PredicateBranch>(getPredicateInfoFor(I));
+      if (!PBranch)
+        return mergeInValue(ValueState[I], I, getValueState(PI->OriginalOp));
+
+      Value *CopyOf = I->getOperand(0);
+      Value *Cond = PBranch->Condition;
+
+      // Everything below relies on the condition being a comparison.
+      auto *Cmp = dyn_cast<CmpInst>(Cond);
+      if (!Cmp)
+        return mergeInValue(ValueState[I], I, getValueState(PI->OriginalOp));
+
+      Value *CmpOp0 = Cmp->getOperand(0);
+      Value *CmpOp1 = Cmp->getOperand(1);
+      if (CopyOf != CmpOp0 && CopyOf != CmpOp1)
+        return mergeInValue(ValueState[I], I, getValueState(PI->OriginalOp));
+
+      if (CmpOp0 != CopyOf)
+        std::swap(CmpOp0, CmpOp1);
+
+      LatticeVal OriginalVal = getValueState(CopyOf);
+      LatticeVal EqVal = getValueState(CmpOp1);
+      LatticeVal &IV = ValueState[I];
+      if (PBranch->TrueEdge && Cmp->getPredicate() == CmpInst::ICMP_EQ) {
+        addAdditionalUser(CmpOp1, I);
+        if (OriginalVal.isConstant())
+          mergeInValue(IV, I, OriginalVal);
+        else
+          mergeInValue(IV, I, EqVal);
+        return;
+      }
+      if (!PBranch->TrueEdge && Cmp->getPredicate() == CmpInst::ICMP_NE) {
+        addAdditionalUser(CmpOp1, I);
+        if (OriginalVal.isConstant())
+          mergeInValue(IV, I, OriginalVal);
+        else
+          mergeInValue(IV, I, EqVal);
+        return;
+      }
+
+      return mergeInValue(IV, I, getValueState(PBranch->OriginalOp));
+    }
+  }
+
   // The common case is that we aren't tracking the callee, either because we
   // are not doing interprocedural analysis or the callee is indirect, or is
   // external.  Handle these cases first.
@@ -1268,9 +1356,7 @@ void SCCPSolver::Solve() {
       // since all of its users will have already been marked as overdefined
       // Update all of the users of this instruction's value.
       //
-      for (User *U : I->users())
-        if (auto *UI = dyn_cast<Instruction>(U))
-          OperandChangedState(UI);
+      markUsersAsChanged(I);
     }
 
     // Process the instruction work list.
@@ -1287,9 +1373,7 @@ void SCCPSolver::Solve() {
       // Update all of the users of this instruction's value.
       //
       if (I->getType()->isStructTy() || !getValueState(I).isOverdefined())
-        for (User *U : I->users())
-          if (auto *UI = dyn_cast<Instruction>(U))
-            OperandChangedState(UI);
+        markUsersAsChanged(I);
     }
 
     // Process the basic block work list.
@@ -1855,8 +1939,9 @@ static void findReturnsToZap(Function &F,
   }
 }
 
-bool llvm::runIPSCCP(Module &M, const DataLayout &DL,
-                     const TargetLibraryInfo *TLI) {
+bool llvm::runIPSCCP(
+    Module &M, const DataLayout &DL, const TargetLibraryInfo *TLI,
+    function_ref<std::unique_ptr<PredicateInfo>(Function &)> getPredicateInfo) {
   SCCPSolver Solver(DL, TLI);
 
   // Loop over all functions, marking arguments to those with their addresses
@@ -1865,6 +1950,7 @@ bool llvm::runIPSCCP(Module &M, const DataLayout &DL,
     if (F.isDeclaration())
       continue;
 
+    Solver.addPredInfo(F, getPredicateInfo(F));
     // Determine if we can track the function's return values. If so, add the
     // function to the solver's set of return-tracked functions.
     if (canTrackReturnsInterprocedurally(&F))
@@ -1983,6 +2069,24 @@ bool llvm::runIPSCCP(Module &M, const DataLayout &DL,
       F.getBasicBlockList().erase(DeadBB);
     }
     BlocksToErase.clear();
+
+    for (BasicBlock &BB : F) {
+      for (BasicBlock::iterator BI = BB.begin(), E = BB.end(); BI != E;) {
+        Instruction *Inst = &*BI++;
+        if (const PredicateBase *PI = Solver.getPredicateInfoFor(Inst)) {
+          if (auto *II = dyn_cast<IntrinsicInst>(Inst)) {
+            if (II->getIntrinsicID() == Intrinsic::ssa_copy) {
+              Value *Op = II->getOperand(0);
+              Inst->replaceAllUsesWith(Op);
+              Inst->eraseFromParent();
+              continue;
+            }
+          }
+          Inst->replaceAllUsesWith(PI->OriginalOp);
+          Inst->eraseFromParent();
+        }
+      }
+    }
   }
 
   // If we inferred constant or undef return values for a function, we replaced
diff --git a/llvm/test/Other/new-pm-lto-defaults.ll b/llvm/test/Other/new-pm-lto-defaults.ll
index 0633db5bb84..f78c3e8e9fa 100644
--- a/llvm/test/Other/new-pm-lto-defaults.ll
+++ b/llvm/test/Other/new-pm-lto-defaults.ll
@@ -41,6 +41,8 @@
 ; CHECK-O2-NEXT: Running analysis: ProfileSummaryAnalysis
 ; CHECK-O2-NEXT: Running analysis: OptimizationRemarkEmitterAnalysis
 ; CHECK-O2-NEXT: Running pass: IPSCCPPass
+; CHECK-O2-DAG: Running analysis: AssumptionAnalysis on foo
+; CHECK-O2-DAG: Running analysis: DominatorTreeAnalysis on foo
 ; CHECK-O2-NEXT: Running pass: CalledValuePropagationPass
 ; CHECK-O-NEXT: Running pass: ModuleToPostOrderCGSCCPassAdaptor<{{.*}}PostOrderFunctionAttrsPass>
 ; CHECK-O-NEXT: Running analysis: InnerAnalysisManagerProxy<{{.*}}SCC
@@ -56,8 +58,6 @@
 ; CHECK-O-NEXT: Running pass: WholeProgramDevirtPass
 ; CHECK-O2-NEXT: Running pass: GlobalOptPass
 ; CHECK-O2-NEXT: Running pass: ModuleToFunctionPassAdaptor<{{.*}}PromotePass>
-; CHECK-O2-NEXT: Running analysis: DominatorTreeAnalysis
-; CHECK-O2-NEXT: Running analysis: AssumptionAnalysis
 ; CHECK-O2-NEXT: Running pass: ConstantMergePass
 ; CHECK-O2-NEXT: Running pass: DeadArgumentEliminationPass
 ; CHECK-O2-NEXT: Running pass: ModuleToFunctionPassAdaptor<{{.*}}PassManager{{.*}}>
diff --git a/llvm/test/Other/opt-O2-pipeline.ll b/llvm/test/Other/opt-O2-pipeline.ll
index 445450f7e00..5a7a3d6618d 100644
--- a/llvm/test/Other/opt-O2-pipeline.ll
+++ b/llvm/test/Other/opt-O2-pipeline.ll
@@ -28,6 +28,7 @@
 ; CHECK-NEXT:     Force set function attributes
 ; CHECK-NEXT:     Infer set function attributes
 ; CHECK-NEXT:     Interprocedural Sparse Conditional Constant Propagation
+; CHECK-NEXT:       Unnamed pass: implement Pass::getPassName()
 ; CHECK-NEXT:     Called Value Propagation
 ; CHECK-NEXT:     Global Variable Optimizer
 ; CHECK-NEXT:       Unnamed pass: implement Pass::getPassName()
@@ -276,6 +277,9 @@
 ; CHECK-NEXT:       Module Verifier
 ; CHECK-NEXT:     Bitcode Writer
 ; CHECK-NEXT: Pass Arguments:
+; CHECK-NEXT:  FunctionPass Manager
+; CHECK-NEXT:     Dominator Tree Construction
+; CHECK-NEXT: Pass Arguments:
 ; CHECK-NEXT: Target Library Information
 ; CHECK-NEXT:   FunctionPass Manager
 ; CHECK-NEXT:     Dominator Tree Construction
diff --git a/llvm/test/Other/opt-O3-pipeline.ll b/llvm/test/Other/opt-O3-pipeline.ll
index 1dacd2b3a2e..b7e189ffd73 100644
--- a/llvm/test/Other/opt-O3-pipeline.ll
+++ b/llvm/test/Other/opt-O3-pipeline.ll
@@ -30,6 +30,7 @@
 ; CHECK-NEXT:     FunctionPass Manager
 ; CHECK-NEXT:       Call-site splitting
 ; CHECK-NEXT:     Interprocedural Sparse Conditional Constant Propagation
+; CHECK-NEXT:       Unnamed pass: implement Pass::getPassName()
 ; CHECK-NEXT:     Called Value Propagation
 ; CHECK-NEXT:     Global Variable Optimizer
 ; CHECK-NEXT:       Unnamed pass: implement Pass::getPassName()
@@ -280,6 +281,9 @@
 ; CHECK-NEXT:       Module Verifier
 ; CHECK-NEXT:     Bitcode Writer
 ; CHECK-NEXT: Pass Arguments:
+; CHECK-NEXT:  FunctionPass Manager
+; CHECK-NEXT:     Dominator Tree Construction
+; CHECK-NEXT: Pass Arguments:
 ; CHECK-NEXT: Target Library Information
 ; CHECK-NEXT:   FunctionPass Manager
 ; CHECK-NEXT:     Dominator Tree Construction
diff --git a/llvm/test/Other/opt-Os-pipeline.ll b/llvm/test/Other/opt-Os-pipeline.ll
index b34dcf63e56..375f7b74ada 100644
--- a/llvm/test/Other/opt-Os-pipeline.ll
+++ b/llvm/test/Other/opt-Os-pipeline.ll
@@ -28,6 +28,7 @@
 ; CHECK-NEXT:     Force set function attributes
 ; CHECK-NEXT:     Infer set function attributes
 ; CHECK-NEXT:     Interprocedural Sparse Conditional Constant Propagation
+; CHECK-NEXT:       Unnamed pass: implement Pass::getPassName()
 ; CHECK-NEXT:     Called Value Propagation
 ; CHECK-NEXT:     Global Variable Optimizer
 ; CHECK-NEXT:       Unnamed pass: implement Pass::getPassName()
@@ -262,6 +263,9 @@
 ; CHECK-NEXT:       Module Verifier
 ; CHECK-NEXT:     Bitcode Writer
 ; CHECK-NEXT: Pass Arguments:
+; CHECK-NEXT:  FunctionPass Manager
+; CHECK-NEXT:     Dominator Tree Construction
+; CHECK-NEXT: Pass Arguments:
 ; CHECK-NEXT: Target Library Information
 ; CHECK-NEXT:   FunctionPass Manager
 ; CHECK-NEXT:     Dominator Tree Construction
diff --git a/llvm/test/Transforms/IPConstantProp/musttail-call.ll b/llvm/test/Transforms/IPConstantProp/musttail-call.ll
index 75877585710..567ca408099 100644
--- a/llvm/test/Transforms/IPConstantProp/musttail-call.ll
+++ b/llvm/test/Transforms/IPConstantProp/musttail-call.ll
@@ -9,7 +9,7 @@ define i8* @start(i8 %v) {
   %c1 = icmp eq i8 %v, 0
   br i1 %c1, label %true, label %false
 true:
-  ; CHECK: %ca = musttail call i8* @side_effects(i8 %v)
+  ; CHECK: %ca = musttail call i8* @side_effects(i8 0)
   ; CHECK: ret i8* %ca
   %ca = musttail call i8* @side_effects(i8 %v)
   ret i8* %ca
@@ -34,7 +34,7 @@ define internal i8* @side_effects(i8 %v) {
   ; is always `null`.
   ; The call can't be removed due to `external` call above, though.
 
-  ; CHECK: %ca = musttail call i8* @start(i8 %v)
+  ; CHECK: %ca = musttail call i8* @start(i8 0)
   %ca = musttail call i8* @start(i8 %v)
 
   ; Thus the result must be returned anyway