[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

2 files changed, 37 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
diff --git a/llvm/test/Transforms/LoopStrengthReduce/AMDGPU/different-addrspace-crash.ll b/llvm/test/Transforms/LoopStrengthReduce/AMDGPU/different-addrspace-crash.ll
new file mode 100644
index 00000000000..89b62632cac
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/AMDGPU/different-addrspace-crash.ll
@@ -0,0 +1,31 @@
+; RUN: llc < %s | FileCheck %s
+
+target datalayout = "e-p:32:32-p1:64:64-p2:64:64-p3:32:32-p4:64:64-p5:32:32-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64"
+target triple = "amdgcn--"
+
+; We need to compile this for a target where we have different address spaces,
+; and where pointers in those address spaces have different size.
+; E.g. for amdgcn-- pointers in address space 0 are 32 bits and pointers in
+; address space 1 are 64 bits.
+
+; We shouldn't crash. Check that we get a loop with the two stores.
+;CHECK-LABEL: foo:
+;CHECK: [[LOOP_LABEL:BB[0-9]+_[0-9]+]]:
+;CHECK: buffer_store_dword
+;CHECK: buffer_store_dword
+;CHECK: s_branch [[LOOP_LABEL]]
+
+define void @foo() {
+entry:
+  br label %loop
+
+loop:
+  %idx0 = phi i32 [ %next_idx0, %loop ], [ 0, %entry ]
+  %0 = getelementptr inbounds i32, i32* null, i32 %idx0
+  %1 = getelementptr inbounds i32, i32 addrspace(1)* null, i32 %idx0
+  store i32 1, i32* %0
+  store i32 7, i32 addrspace(1)* %1
+  %next_idx0 = add nuw nsw i32 %idx0, 1
+  br label %loop
+}
+