- Bug fixes.
- Allow icmp rewrite using an iv / stride of a smaller integer type.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43480 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 01ba7b3..57ddc67 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -1476,6 +1476,8 @@
uint64_t SignBit = 1ULL << (BitWidth-1);
const Type *CmpTy = C->getType();
const Type *NewCmpTy = NULL;
+ unsigned TyBits = CmpTy->getPrimitiveSizeInBits();
+ unsigned NewTyBits = 0;
int64_t NewCmpVal = CmpVal;
SCEVHandle *NewStride = NULL;
Value *NewIncV = NULL;
@@ -1521,7 +1523,31 @@
}
NewCmpTy = NewIncV->getType();
- if (RequiresTypeConversion(CmpTy, NewCmpTy)) {
+ NewTyBits = isa<PointerType>(NewCmpTy)
+ ? UIntPtrTy->getPrimitiveSizeInBits()
+ : NewCmpTy->getPrimitiveSizeInBits();
+ if (RequiresTypeConversion(NewCmpTy, CmpTy)) {
+ // Check if it is possible to rewrite it using a 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) {
+ NewCmpVal = CmpVal;
+ 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)) {
NewCmpVal = CmpVal;
continue;
}
@@ -1552,13 +1578,12 @@
if (NewCmpVal != CmpVal) {
// Create a new compare instruction using new stride / iv.
ICmpInst *OldCond = Cond;
- Value *RHS = ConstantInt::get(C->getType(), NewCmpVal);
- // Both sides of a ICmpInst must be of the same type.
- if (NewCmpTy != CmpTy) {
- if (isa<PointerType>(NewCmpTy) && !isa<PointerType>(CmpTy))
- RHS= SCEVExpander::InsertCastOfTo(Instruction::IntToPtr, RHS, NewCmpTy);
- else
- RHS = SCEVExpander::InsertCastOfTo(Instruction::BitCast, RHS, NewCmpTy);
+ Value *RHS;
+ if (!isa<PointerType>(NewCmpTy))
+ RHS = ConstantInt::get(NewCmpTy, NewCmpVal);
+ else {
+ RHS = ConstantInt::get(UIntPtrTy, NewCmpVal);
+ RHS = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr, RHS, NewCmpTy);
}
// Insert new compare instruction.
Cond = new ICmpInst(Predicate, NewIncV, RHS);
@@ -1572,8 +1597,11 @@
OldCond->eraseFromParent();
IVUsesByStride[*CondStride].Users.pop_back();
- SCEVHandle NewOffset = SE->getMulExpr(CondUse->Offset,
- SE->getConstant(ConstantInt::get(CondUse->Offset->getType(), Scale)));
+ 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, NewIncV);
CondUse = &IVUsesByStride[*NewStride].Users.back();
CondStride = NewStride;