[AMDGPU] stop image_store being moved illegally

Summary:
A recent change
321556: AMDGPU: Remove mayLoad/hasSideEffects from MIMG stores
can allow the machine instruction scheduler to move an image store past
an image load using the same descriptor.

V2: Fixed by marking image ops as mayAlias and isAliased. This may be
overly conservative, and we may need to revisit.
V3: Reverted test change done on 321556.

Reviewers: arsenm, nhaehnle, dstuttard

Subscribers: llvm-commits, t-tye, yaxunl, wdng, kzhuravl

Differential Revision: https://reviews.llvm.org/D41969

llvm-svn: 322419

1 files changed, 2 insertions, 6 deletions

diff --git a/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.h b/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.h
index 02e63f0258e..63875c55df0 100644
--- a/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.h
+++ b/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.h
@@ -50,15 +50,11 @@ public:
   }
 
   bool isAliased(const MachineFrameInfo *) const override {
-    // FIXME: If we ever change image intrinsics to accept fat pointers, then
-    // this could be true for some cases.
-    return false;
+    return true;
   }
 
   bool mayAlias(const MachineFrameInfo *) const override {
-    // FIXME: If we ever change image intrinsics to accept fat pointers, then
-    // this could be true for some cases.
-    return false;
+    return true;
   }
 };