Revert back to r1.21, which was the last revision of predsimplify that

passes llvm-gcc bootstrap.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31146 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 109 insertions, 134 deletions

diff --git a/lib/Transforms/Scalar/PredicateSimplifier.cpp b/lib/Transforms/Scalar/PredicateSimplifier.cpp
index c91642fd13..4d86f6aa46 100644
--- a/lib/Transforms/Scalar/PredicateSimplifier.cpp
+++ b/lib/Transforms/Scalar/PredicateSimplifier.cpp
@@ -41,7 +41,6 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/InstVisitor.h"
 #include <iostream>
-#include <list>
 using namespace llvm;
 
 typedef DominatorTree::Node DTNodeType;
@@ -75,14 +74,14 @@ namespace {
       return leaders.empty();
     }
 
-    iterator findLeader(ElemTy &e) {
+    iterator findLeader(ElemTy e) {
       typename std::map<ElemTy, unsigned>::iterator MI = mapping.find(e);
       if (MI == mapping.end()) return 0;
 
       return MI->second;
     }
 
-    const_iterator findLeader(ElemTy &e) const {
+    const_iterator findLeader(ElemTy e) const {
       typename std::map<ElemTy, unsigned>::const_iterator MI =
           mapping.find(e);
       if (MI == mapping.end()) return 0;
@@ -117,11 +116,6 @@ namespace {
 
     // Mutators
 
-    void remove(ElemTy &e) {
-      ElemTy E = e;      // The parameter to erase must not be a reference to
-      mapping.erase(E);  // an element contained in the map.
-    }
-
     /// Combine two sets referring to the same element, inserting the
     /// elements as needed. Returns a valid iterator iff two already
     /// existing disjoint synonym sets were combined. The iterator
@@ -130,7 +124,7 @@ namespace {
 
     /// Returns an iterator pointing to the synonym set containing
     /// element e. If none exists, a new one is created and returned.
-    iterator findOrInsert(ElemTy &e) {
+    iterator findOrInsert(ElemTy e) {
       iterator I = findLeader(e);
       if (I) return I;
 
@@ -209,19 +203,6 @@ namespace {
       return union_find.empty();
     }
 
-    void remove(Value *V) {
-      SynonymIterator I = union_find.findLeader(V);
-      if (!I) return;
-
-      union_find.remove(V);
-
-      for (PropertyIterator PI = Properties.begin(), PE = Properties.end();
-           PI != PE;) {
-        Property &P = *PI++;
-        if (P.I1 == I || P.I2 == I) Properties.erase(PI);
-      }
-    }
-
     void addEqual(Value *V1, Value *V2) {
       // If %x = 0. and %y = -0., seteq %x, %y is true, but
       // copysign(%x) is not the same as copysign(%y).
@@ -230,10 +211,6 @@ namespace {
       order(V1, V2);
       if (isa<Constant>(V2)) return; // refuse to set false == true.
 
-      if (union_find.findLeader(V1) &&
-          union_find.findLeader(V1) == union_find.findLeader(V2))
-        return; // no-op
-
       SynonymIterator deleted = union_find.unionSets(V1, V2);
       if (deleted) {
         SynonymIterator replacement = union_find.findLeader(V1);
@@ -257,7 +234,7 @@ namespace {
       if (isa<Constant>(V1) && isa<Constant>(V2)) return;
 
       if (findProperty(NE, V1, V2) != Properties.end())
-        return; // no-op.
+        return; // found.
 
       // Add the property.
       SynonymIterator I1 = union_find.findOrInsert(V1),
@@ -331,73 +308,6 @@ namespace {
       }
     }
 
-    void addToResolve(Value *V, std::list<Value *> &WorkList) {
-      if (!isa<Constant>(V) && !isa<BasicBlock>(V)) {
-        for (Value::use_iterator UI = V->use_begin(), UE = V->use_end();
-             UI != UE; ++UI) {
-          if (!isa<Constant>(*UI) && !isa<BasicBlock>(*UI)) {
-            WorkList.push_back(*UI);
-          }
-        }
-      }
-    }
-
-    void resolve(std::list<Value *> &WorkList) {
-      if (WorkList.empty()) return;
-
-      Value *V = WorkList.front();
-      WorkList.pop_front();
-
-      if (empty()) return;
-
-      Instruction *I = dyn_cast<Instruction>(V);
-      if (!I) return;
-
-      if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
-        Value *lhs = canonicalize(BO->getOperand(0)),
-              *rhs = canonicalize(BO->getOperand(1));
-
-        ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(lhs),
-                         *CI2 = dyn_cast<ConstantIntegral>(rhs);
-
-        if (CI1 && CI2) {
-          addToResolve(BO, WorkList);
-          addEqual(BO, ConstantExpr::get(BO->getOpcode(), CI1, CI2));
-        } else if (SetCondInst *SCI = dyn_cast<SetCondInst>(BO)) {
-          PropertySet::ConstPropertyIterator NE =
-             findProperty(PropertySet::NE, lhs, rhs);
-
-          if (NE != Properties.end()) {
-            switch (SCI->getOpcode()) {
-            case Instruction::SetEQ:
-              addToResolve(SCI, WorkList);
-              addEqual(SCI, ConstantBool::getFalse());
-              break;
-            case Instruction::SetNE:
-              addToResolve(SCI, WorkList);
-              addEqual(SCI, ConstantBool::getTrue());
-              break;
-            case Instruction::SetLE:
-            case Instruction::SetGE:
-            case Instruction::SetLT:
-            case Instruction::SetGT:
-              break;
-            default:
-              assert(0 && "Unknown opcode in SetCondInst.");
-              break;
-            }
-          }
-        }
-      } else if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
-        Value *Condition = canonicalize(SI->getCondition());
-        if (ConstantBool *CB = dyn_cast<ConstantBool>(Condition)) {
-          addToResolve(SI, WorkList);
-          addEqual(SI, CB->getValue() ? SI->getTrueValue() : SI->getFalseValue());
-        }
-      }
-      if (!WorkList.empty()) resolve(WorkList);
-    }
-
     // Finds the properties implied by an equivalence and adds them too.
     // Example: ("seteq %a, %b", true,  EQ) --> (%a, %b, EQ)
     //          ("seteq %a, %b", false, EQ) --> (%a, %b, NE)
@@ -424,45 +334,32 @@ namespace {
           if (V1 == ConstantBool::getFalse())
             add(Opcode, BO->getOperand(0), BO->getOperand(1), true);
           break;
-        case Instruction::And: {
-          ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V1);
-          if (CI && CI->isAllOnesValue()) {
+        case Instruction::And:
+          if (V1 == ConstantBool::getTrue()) {
             add(Opcode, V1, BO->getOperand(0), false);
             add(Opcode, V1, BO->getOperand(1), false);
           }
-        } break;
-        case Instruction::Or: {
-          ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V1);
-          if (CI && CI->isNullValue()) {
+          break;
+        case Instruction::Or:
+          if (V1 == ConstantBool::getFalse()) {
             add(Opcode, V1, BO->getOperand(0), false);
             add(Opcode, V1, BO->getOperand(1), false);
           }
-        } break;
-        case Instruction::Xor: {
-          if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V1)) {
-            const Type *Ty = BO->getType();
-            if (CI->isAllOnesValue()) {
-              if (BO->getOperand(0) == V1)
-                add(Opcode, Constant::getNullValue(Ty),
-                    BO->getOperand(1), false);
-              if (BO->getOperand(1) == V1)
-                add(Opcode, Constant::getNullValue(Ty),
-                    BO->getOperand(0), false);
-            }
-            if (CI->isNullValue()) {
-              ConstantIntegral *Op0 =
-                  dyn_cast<ConstantIntegral>(BO->getOperand(0));
-              ConstantIntegral *Op1 =
-                  dyn_cast<ConstantIntegral>(BO->getOperand(1));
-              if (Op0 && Op0->isAllOnesValue())
-                add(Opcode, ConstantIntegral::getAllOnesValue(Ty),
-                    BO->getOperand(1), false);
-              if (Op1 && Op1->isAllOnesValue())
-                add(Opcode, ConstantIntegral::getAllOnesValue(Ty),
-                    BO->getOperand(0), false);
-            }
+          break;
+        case Instruction::Xor:
+          if (V1 == ConstantBool::getTrue()) {
+            if (BO->getOperand(0) == V1)
+              add(Opcode, ConstantBool::getFalse(), BO->getOperand(1), false);
+            if (BO->getOperand(1) == V1)
+              add(Opcode, ConstantBool::getFalse(), BO->getOperand(0), false);
+          }
+          if (V1 == ConstantBool::getFalse()) {
+            if (BO->getOperand(0) == ConstantBool::getTrue())
+              add(Opcode, ConstantBool::getTrue(), BO->getOperand(1), false);
+            if (BO->getOperand(1) == ConstantBool::getTrue())
+              add(Opcode, ConstantBool::getTrue(), BO->getOperand(0), false);
           }
-        } break;
+          break;
         default:
           break;
         }
@@ -479,11 +376,6 @@ namespace {
         else if (Opcode == EQ)
           assert("Result of select not equal to either value.");
       }
-
-      std::list<Value *> WorkList;
-      addToResolve(V1, WorkList);
-      addToResolve(V2, WorkList);
-      resolve(WorkList);
     }
 
     DominatorTree *DT;
@@ -514,6 +406,26 @@ namespace {
     virtual void getAnalysisUsage(AnalysisUsage &AU) const;
 
   private:
+    /// Backwards - Try to replace the Use of the instruction with
+    /// something simpler. This resolves a value by walking backwards
+    /// through its definition and the operands of that definition to
+    /// see if any values can now be solved for with the properties
+    /// that are in effect now, but weren't at definition time.
+    class Backwards : public InstVisitor<Backwards, Value &> {
+      friend class InstVisitor<Backwards, Value &>;
+      const PropertySet &KP;
+
+      Value &visitSetCondInst(SetCondInst &SCI);
+      Value &visitBinaryOperator(BinaryOperator &BO);
+      Value &visitSelectInst(SelectInst &SI);
+      Value &visitInstruction(Instruction &I);
+
+    public:
+      explicit Backwards(const PropertySet &KP) : KP(KP) {}
+
+      Value *resolve(Value *V);
+    };
+
     /// Forwards - Adds new properties into PropertySet and uses them to
     /// simplify instructions. Because new properties sometimes apply to
     /// a transition from one BasicBlock to another, this will use the
@@ -628,6 +540,69 @@ void PredicateSimplifier::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addPreservedID(BreakCriticalEdgesID);
 }
 
+Value &PredicateSimplifier::Backwards::visitSetCondInst(SetCondInst &SCI) {
+  Value &vBO = visitBinaryOperator(SCI);
+  if (&vBO !=  &SCI) return vBO;
+
+  Value *SCI0 = resolve(SCI.getOperand(0)),
+        *SCI1 = resolve(SCI.getOperand(1));
+
+  PropertySet::ConstPropertyIterator NE =
+      KP.findProperty(PropertySet::NE, SCI0, SCI1);
+
+  if (NE != KP.Properties.end()) {
+    switch (SCI.getOpcode()) {
+      case Instruction::SetEQ: return *ConstantBool::getFalse();
+      case Instruction::SetNE: return *ConstantBool::getTrue();
+      case Instruction::SetLE:
+      case Instruction::SetGE:
+      case Instruction::SetLT:
+      case Instruction::SetGT:
+        break;
+      default:
+        assert(0 && "Unknown opcode in SetCondInst.");
+        break;
+    }
+  }
+  return SCI;
+}
+
+Value &PredicateSimplifier::Backwards::visitBinaryOperator(BinaryOperator &BO) {
+  Value *V = KP.canonicalize(&BO);
+  if (V != &BO) return *V;
+
+  Value *lhs = resolve(BO.getOperand(0)),
+        *rhs = resolve(BO.getOperand(1));
+
+  ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(lhs),
+                   *CI2 = dyn_cast<ConstantIntegral>(rhs);
+
+  if (CI1 && CI2) return *ConstantExpr::get(BO.getOpcode(), CI1, CI2);
+
+  return BO;
+}
+
+Value &PredicateSimplifier::Backwards::visitSelectInst(SelectInst &SI) {
+  Value *V = KP.canonicalize(&SI);
+  if (V != &SI) return *V;
+
+  Value *Condition = resolve(SI.getCondition());
+  if (ConstantBool *CB = dyn_cast<ConstantBool>(Condition))
+    return *resolve(CB->getValue() ? SI.getTrueValue() : SI.getFalseValue());
+  return SI;
+}
+
+Value &PredicateSimplifier::Backwards::visitInstruction(Instruction &I) {
+  return *KP.canonicalize(&I);
+}
+
+Value *PredicateSimplifier::Backwards::resolve(Value *V) {
+  if (isa<Constant>(V) || isa<BasicBlock>(V) || KP.empty()) return V;
+
+  if (Instruction *I = dyn_cast<Instruction>(V)) return &visit(*I);
+  return KP.canonicalize(V);
+}
+
 void PredicateSimplifier::visitBasicBlock(BasicBlock *BB,
                                           PropertySet &KnownProperties) {
   for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
@@ -638,12 +613,12 @@ void PredicateSimplifier::visitBasicBlock(BasicBlock *BB,
 void PredicateSimplifier::visitInstruction(Instruction *I,
                                            PropertySet &KnownProperties) {
   // Try to replace the whole instruction.
-  Value *V = KnownProperties.canonicalize(I);
+  Backwards resolve(KnownProperties);
+  Value *V = resolve.resolve(I);
   if (V != I) {
     modified = true;
     ++NumInstruction;
     DEBUG(std::cerr << "Removing " << *I);
-    KnownProperties.remove(I);
     I->replaceAllUsesWith(V);
     I->eraseFromParent();
     return;
@@ -652,7 +627,7 @@ void PredicateSimplifier::visitInstruction(Instruction *I,
   // Try to substitute operands.
   for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
     Value *Oper = I->getOperand(i);
-    Value *V = KnownProperties.canonicalize(Oper);
+    Value *V = resolve.resolve(Oper);
     if (V != Oper) {
       modified = true;
       ++NumVarsReplaced;