[LSR] Pointers with different address spaces are considered incompatible.

Summary:
Function isCompatibleIVType is already used as a guard before the call to

 SE.getMinusSCEV(OperExpr, PrevExpr);

in LSRInstance::ChainInstruction. getMinusSCEV requires the expressions
to be of the same type, so we now consider two pointers with different
address spaces to be incompatible, since it is possible that the pointers
in fact have different sizes.

Reviewers: qcolombet, eli.friedman

Reviewed By: qcolombet

Subscribers: nhaehnle, Ka-Ka, llvm-commits, mzolotukhin

Differential Revision: https://reviews.llvm.org/D29885

llvm-svn: 295033

1 files changed, 6 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index a59d901d76e..baef7b9a196 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -2559,7 +2559,12 @@ static Value *getWideOperand(Value *Oper) {
 static bool isCompatibleIVType(Value *LVal, Value *RVal) {
   Type *LType = LVal->getType();
   Type *RType = RVal->getType();
-  return (LType == RType) || (LType->isPointerTy() && RType->isPointerTy());
+  return (LType == RType) || (LType->isPointerTy() && RType->isPointerTy() &&
+                              // Different address spaces means (possibly)
+                              // different types of the pointer implementation,
+                              // e.g. i16 vs i32 so disallow that.
+                              (LType->getPointerAddressSpace() ==
+                               RType->getPointerAddressSpace()));
 }
 
 /// Return an approximation of this SCEV expression's "base", or NULL for any