Use switch instead of if. No functionality change.

[oota-llvm.git] / lib / Transforms / Scalar / Reassociate.cpp

diff --git a/lib/Transforms/Scalar/Reassociate.cpp b/lib/Transforms/Scalar/Reassociate.cpp
index 493930b3885ad3a65fcf49dd66b51e03bd02e8ff..328a9c5755b383474c4192e13f233f69e84073d2 100644 (file)
--- a/lib/Transforms/Scalar/Reassociate.cpp
+++ b/lib/Transforms/Scalar/Reassociate.cpp
@@ -122,7 +122,6 @@ namespace {
   class XorOpnd {
   public:
     XorOpnd(Value *V);
-    const XorOpnd &operator=(const XorOpnd &That);
 
     bool isInvalid() const { return SymbolicPart == 0; }
     bool isOrExpr() const { return isOr; }
@@ -199,7 +198,7 @@ namespace {
 }
 
 XorOpnd::XorOpnd(Value *V) {
-  assert(!isa<Constant>(V) && "No constant");
+  assert(!isa<ConstantInt>(V) && "No ConstantInt");
   OrigVal = V;
   Instruction *I = dyn_cast<Instruction>(V);
   SymbolicRank = 0;
@@ -225,15 +224,6 @@ XorOpnd::XorOpnd(Value *V) {
   isOr = true;
 }
 
-const XorOpnd &XorOpnd::operator=(const XorOpnd &That) {
-  OrigVal = That.OrigVal;
-  SymbolicPart = That.SymbolicPart;
-  ConstPart = That.ConstPart;
-  SymbolicRank = That.SymbolicRank;
-  isOr = That.isOr;
-  return *this;
-}
-
 char Reassociate::ID = 0;
 INITIALIZE_PASS(Reassociate, "reassociate",
                 "Reassociate expressions", false, false)
@@ -251,21 +241,24 @@ static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode) {
 }
 
 static bool isUnmovableInstruction(Instruction *I) {
-  if (I->getOpcode() == Instruction::PHI ||
-      I->getOpcode() == Instruction::LandingPad ||
-      I->getOpcode() == Instruction::Alloca ||
-      I->getOpcode() == Instruction::Load ||
-      I->getOpcode() == Instruction::Invoke ||
-      (I->getOpcode() == Instruction::Call &&
-       !isa<DbgInfoIntrinsic>(I)) ||
-      I->getOpcode() == Instruction::UDiv ||
-      I->getOpcode() == Instruction::SDiv ||
-      I->getOpcode() == Instruction::FDiv ||
-      I->getOpcode() == Instruction::URem ||
-      I->getOpcode() == Instruction::SRem ||
-      I->getOpcode() == Instruction::FRem)
+  switch (I->getOpcode()) {
+  case Instruction::PHI:
+  case Instruction::LandingPad:
+  case Instruction::Alloca:
+  case Instruction::Load:
+  case Instruction::Invoke:
+  case Instruction::UDiv:
+  case Instruction::SDiv:
+  case Instruction::FDiv:
+  case Instruction::URem:
+  case Instruction::SRem:
+  case Instruction::FRem:
     return true;
-  return false;
+  case Instruction::Call:
+    return !isa<DbgInfoIntrinsic>(I);
+  default:
+    return false;
+  }
 }
 
 void Reassociate::BuildRankMap(Function &F) {
@@ -1195,9 +1188,6 @@ bool Reassociate::CombineXorOpnd(Instruction *I, XorOpnd *Opnd1, XorOpnd *Opnd2,
   if (X != Opnd2->getSymbolicPart())
     return false;
 
-  const APInt &C1 = Opnd1->getConstPart();
-  const APInt &C2 = Opnd2->getConstPart();
-
   // This many instruction become dead.(At least "Opnd1 ^ Opnd2" will die.)
   int DeadInstNum = 1;
   if (Opnd1->getValue()->hasOneUse())
@@ -1215,6 +1205,8 @@ bool Reassociate::CombineXorOpnd(Instruction *I, XorOpnd *Opnd1, XorOpnd *Opnd2,
     if (Opnd2->isOrExpr())
       std::swap(Opnd1, Opnd2);
 
+    const APInt &C1 = Opnd1->getConstPart();
+    const APInt &C2 = Opnd2->getConstPart();
     APInt C3((~C1) ^ C2);
 
     // Do not increase code size!
@@ -1230,6 +1222,8 @@ bool Reassociate::CombineXorOpnd(Instruction *I, XorOpnd *Opnd1, XorOpnd *Opnd2,
   } else if (Opnd1->isOrExpr()) {
     // Xor-Rule 3: (x | c1) ^ (x | c2) = (x & c3) ^ c3 where c3 = c1 ^ c2
     //
+    const APInt &C1 = Opnd1->getConstPart();
+    const APInt &C2 = Opnd2->getConstPart();
     APInt C3 = C1 ^ C2;
     
     // Do not increase code size
@@ -1244,6 +1238,8 @@ bool Reassociate::CombineXorOpnd(Instruction *I, XorOpnd *Opnd1, XorOpnd *Opnd2,
   } else {
     // Xor-Rule 4: (x & c1) ^ (x & c2) = (x & (c1^c2))
     //
+    const APInt &C1 = Opnd1->getConstPart();
+    const APInt &C2 = Opnd2->getConstPart();
     APInt C3 = C1 ^ C2;
     Res = createAndInstr(I, X, C3);
   }
@@ -1281,11 +1277,18 @@ Value *Reassociate::OptimizeXor(Instruction *I,
       XorOpnd O(V);
       O.setSymbolicRank(getRank(O.getSymbolicPart()));
       Opnds.push_back(O);
-      OpndPtrs.push_back(&Opnds.back());
     } else
       ConstOpnd ^= cast<ConstantInt>(V)->getValue();
   }
 
+  // NOTE: From this point on, do *NOT* add/delete element to/from "Opnds".
+  //  It would otherwise invalidate the "Opnds"'s iterator, and hence invalidate
+  //  the "OpndPtrs" as well. For the similar reason, do not fuse this loop
+  //  with the previous loop --- the iterator of the "Opnds" may be invalidated
+  //  when new elements are added to the vector.
+  for (unsigned i = 0, e = Opnds.size(); i != e; ++i)
+    OpndPtrs.push_back(&Opnds[i]);
+
   // Step 2: Sort the Xor-Operands in a way such that the operands containing
   //  the same symbolic value cluster together. For instance, the input operand
   //  sequence ("x | 123", "y & 456", "x & 789") will be sorted into: