Generalize the ChangeCompareStride code, in preparation for

handling non-constant strides. No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65363 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 96 insertions, 94 deletions

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index e32cacc441..0d6df2fbae 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -2133,15 +2133,12 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
     return Cond;
   const SCEVConstant *SC = dyn_cast<SCEVConstant>(*CondStride);
   if (!SC) return Cond;
-  ConstantInt *C = dyn_cast<ConstantInt>(Cond->getOperand(1));
-  if (!C) return Cond;
 
   ICmpInst::Predicate Predicate = Cond->getPredicate();
   int64_t CmpSSInt = SC->getValue()->getSExtValue();
-  int64_t CmpVal = C->getValue().getSExtValue();
-  unsigned BitWidth = C->getValue().getBitWidth();
+  unsigned BitWidth = (*CondStride)->getBitWidth();
   uint64_t SignBit = 1ULL << (BitWidth-1);
-  const Type *CmpTy = C->getType();
+  const Type *CmpTy = Cond->getOperand(0)->getType();
   const Type *NewCmpTy = NULL;
   unsigned TyBits = CmpTy->getPrimitiveSizeInBits();
   unsigned NewTyBits = 0;
@@ -2149,102 +2146,112 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
   Value *NewCmpLHS = NULL;
   Value *NewCmpRHS = NULL;
   int64_t Scale = 1;
+  SCEVHandle NewOffset = SE->getIntegerSCEV(0, UIntPtrTy);
+  std::stable_sort(StrideOrder.begin(), StrideOrder.end(), StrideCompare());
 
-  // Check stride constant and the comparision constant signs to detect
-  // overflow.
-  if ((CmpVal & SignBit) != (CmpSSInt & SignBit))
-    return Cond;
+  if (ConstantInt *C = dyn_cast<ConstantInt>(Cond->getOperand(1))) {
+    int64_t CmpVal = C->getValue().getSExtValue();
 
-  // Look for a suitable stride / iv as replacement.
-  std::stable_sort(StrideOrder.begin(), StrideOrder.end(), StrideCompare());
-  for (unsigned i = 0, e = StrideOrder.size(); i != e; ++i) {
-    std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI = 
-      IVUsesByStride.find(StrideOrder[i]);
-    if (!isa<SCEVConstant>(SI->first))
-      continue;
-    int64_t SSInt = cast<SCEVConstant>(SI->first)->getValue()->getSExtValue();
-    if (abs(SSInt) <= abs(CmpSSInt) || (SSInt % CmpSSInt) != 0)
-      continue;
+    // Check stride constant and the comparision constant signs to detect
+    // overflow.
+    if ((CmpVal & SignBit) != (CmpSSInt & SignBit))
+      return Cond;
 
-    Scale = SSInt / CmpSSInt;
-    int64_t NewCmpVal = CmpVal * Scale;
-    APInt Mul = APInt(BitWidth, NewCmpVal);
-    // Check for overflow.
-    if (Mul.getSExtValue() != NewCmpVal)
-      continue;
+    // Look for a suitable stride / iv as replacement.
+    for (unsigned i = 0, e = StrideOrder.size(); i != e; ++i) {
+      std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI = 
+        IVUsesByStride.find(StrideOrder[i]);
+      if (!isa<SCEVConstant>(SI->first))
+        continue;
+      int64_t SSInt = cast<SCEVConstant>(SI->first)->getValue()->getSExtValue();
+      if (abs(SSInt) <= abs(CmpSSInt) || (SSInt % CmpSSInt) != 0)
+        continue;
 
-    // Watch out for overflow.
-    if (ICmpInst::isSignedPredicate(Predicate) &&
-        (CmpVal & SignBit) != (NewCmpVal & SignBit))
-      continue;
+      Scale = SSInt / CmpSSInt;
+      int64_t NewCmpVal = CmpVal * Scale;
+      APInt Mul = APInt(BitWidth, NewCmpVal);
+      // Check for overflow.
+      if (Mul.getSExtValue() != NewCmpVal)
+        continue;
 
-    if (NewCmpVal == CmpVal)
-      continue;
-    // Pick the best iv to use trying to avoid a cast.
-    NewCmpLHS = NULL;
-    for (std::vector<IVStrideUse>::iterator UI = SI->second.Users.begin(),
-           E = SI->second.Users.end(); UI != E; ++UI) {
-      NewCmpLHS = UI->OperandValToReplace;
-      if (NewCmpLHS->getType() == CmpTy)
-        break;
-    }
-    if (!NewCmpLHS)
-      continue;
+      // Watch out for overflow.
+      if (ICmpInst::isSignedPredicate(Predicate) &&
+          (CmpVal & SignBit) != (NewCmpVal & SignBit))
+        continue;
 
-    NewCmpTy = NewCmpLHS->getType();
-    NewTyBits = isa<PointerType>(NewCmpTy)
-      ? UIntPtrTy->getPrimitiveSizeInBits()
-      : NewCmpTy->getPrimitiveSizeInBits();
-    if (RequiresTypeConversion(NewCmpTy, CmpTy)) {
-      // Check if it is possible to rewrite it using
-      // an iv / stride of a smaller integer type.
-      bool TruncOk = false;
-      if (NewCmpTy->isInteger()) {
-        unsigned Bits = NewTyBits;
-        if (ICmpInst::isSignedPredicate(Predicate))
-          --Bits;
-        uint64_t Mask = (1ULL << Bits) - 1;
-        if (((uint64_t)NewCmpVal & Mask) == (uint64_t)NewCmpVal)
-          TruncOk = true;
+      if (NewCmpVal == CmpVal)
+        continue;
+      // Pick the best iv to use trying to avoid a cast.
+      NewCmpLHS = NULL;
+      for (std::vector<IVStrideUse>::iterator UI = SI->second.Users.begin(),
+             E = SI->second.Users.end(); UI != E; ++UI) {
+        NewCmpLHS = UI->OperandValToReplace;
+        if (NewCmpLHS->getType() == CmpTy)
+          break;
       }
-      if (!TruncOk)
+      if (!NewCmpLHS)
         continue;
-    }
 
-    // Don't rewrite if use offset is non-constant and the new type is
-    // of a different type.
-    // FIXME: too conservative?
-    if (NewTyBits != TyBits && !isa<SCEVConstant>(CondUse->Offset))
-      continue;
+      NewCmpTy = NewCmpLHS->getType();
+      NewTyBits = isa<PointerType>(NewCmpTy)
+        ? UIntPtrTy->getPrimitiveSizeInBits()
+        : NewCmpTy->getPrimitiveSizeInBits();
+      if (RequiresTypeConversion(NewCmpTy, CmpTy)) {
+        // Check if it is possible to rewrite it using
+        // an iv / stride of a smaller integer type.
+        bool TruncOk = false;
+        if (NewCmpTy->isInteger()) {
+          unsigned Bits = NewTyBits;
+          if (ICmpInst::isSignedPredicate(Predicate))
+            --Bits;
+          uint64_t Mask = (1ULL << Bits) - 1;
+          if (((uint64_t)NewCmpVal & Mask) == (uint64_t)NewCmpVal)
+            TruncOk = true;
+        }
+        if (!TruncOk)
+          continue;
+      }
 
-    bool AllUsesAreAddresses = true;
-    bool AllUsesAreOutsideLoop = true;
-    std::vector<BasedUser> UsersToProcess;
-    SCEVHandle CommonExprs = CollectIVUsers(SI->first, SI->second, L,
-                                            AllUsesAreAddresses,
-                                            AllUsesAreOutsideLoop,
-                                            UsersToProcess);
-    // Avoid rewriting the compare instruction with an iv of new stride
-    // if it's likely the new stride uses will be rewritten using the
-    // stride of the compare instruction.
-    if (AllUsesAreAddresses &&
-        ValidStride(!CommonExprs->isZero(), Scale, UsersToProcess))
-      continue;
+      // Don't rewrite if use offset is non-constant and the new type is
+      // of a different type.
+      // FIXME: too conservative?
+      if (NewTyBits != TyBits && !isa<SCEVConstant>(CondUse->Offset))
+        continue;
 
-    // If scale is negative, use swapped predicate unless it's testing
-    // for equality.
-    if (Scale < 0 && !Cond->isEquality())
-      Predicate = ICmpInst::getSwappedPredicate(Predicate);
-
-    NewStride = &StrideOrder[i];
-    if (!isa<PointerType>(NewCmpTy))
-      NewCmpRHS = ConstantInt::get(NewCmpTy, NewCmpVal);
-    else {
-      NewCmpRHS = ConstantInt::get(UIntPtrTy, NewCmpVal);
-      NewCmpRHS = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr,
-                                               NewCmpRHS, NewCmpTy);
+      bool AllUsesAreAddresses = true;
+      bool AllUsesAreOutsideLoop = true;
+      std::vector<BasedUser> UsersToProcess;
+      SCEVHandle CommonExprs = CollectIVUsers(SI->first, SI->second, L,
+                                              AllUsesAreAddresses,
+                                              AllUsesAreOutsideLoop,
+                                              UsersToProcess);
+      // Avoid rewriting the compare instruction with an iv of new stride
+      // if it's likely the new stride uses will be rewritten using the
+      // stride of the compare instruction.
+      if (AllUsesAreAddresses &&
+          ValidStride(!CommonExprs->isZero(), Scale, UsersToProcess))
+        continue;
+
+      // If scale is negative, use swapped predicate unless it's testing
+      // for equality.
+      if (Scale < 0 && !Cond->isEquality())
+        Predicate = ICmpInst::getSwappedPredicate(Predicate);
+
+      NewStride = &StrideOrder[i];
+      if (!isa<PointerType>(NewCmpTy))
+        NewCmpRHS = ConstantInt::get(NewCmpTy, NewCmpVal);
+      else {
+        NewCmpRHS = ConstantInt::get(UIntPtrTy, NewCmpVal);
+        NewCmpRHS = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr,
+                                                 NewCmpRHS, NewCmpTy);
+      }
+      NewOffset = TyBits == NewTyBits
+        ? SE->getMulExpr(CondUse->Offset,
+                         SE->getConstant(ConstantInt::get(CmpTy, Scale)))
+        : SE->getConstant(ConstantInt::get(NewCmpTy,
+          cast<SCEVConstant>(CondUse->Offset)->getValue()->getSExtValue()*Scale));
+      break;
     }
-    break;
   }
 
   // Forgo this transformation if it the increment happens to be
@@ -2275,11 +2282,6 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
     OldCond->eraseFromParent();
 
     IVUsesByStride[*CondStride].Users.pop_back();
-    SCEVHandle NewOffset = TyBits == NewTyBits
-      ? SE->getMulExpr(CondUse->Offset,
-                       SE->getConstant(ConstantInt::get(CmpTy, Scale)))
-      : SE->getConstant(ConstantInt::get(NewCmpTy,
-        cast<SCEVConstant>(CondUse->Offset)->getValue()->getSExtValue()*Scale));
     IVUsesByStride[*NewStride].addUser(NewOffset, Cond, NewCmpLHS);
     CondUse = &IVUsesByStride[*NewStride].Users.back();
     CondStride = NewStride;