AMDGPU: Fix converting unanalyzable global loads to SMRD

Not all memory dependence queries succeed, so this needs to
be conservative if it fails.

llvm-svn: 307861

1 files changed, 5 insertions, 4 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUAnnotateUniformValues.cpp b/llvm/lib/Target/AMDGPU/AMDGPUAnnotateUniformValues.cpp
index 6f002860044..ed537082664 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUAnnotateUniformValues.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUAnnotateUniformValues.cpp
@@ -108,10 +108,11 @@ bool AMDGPUAnnotateUniformValues::isClobberedInFunction(LoadInst * Load) {
   DFS(Start, Checklist);
   for (auto &BB : Checklist) {
     BasicBlock::iterator StartIt = (!L && (BB == Load->getParent())) ?
-     BasicBlock::iterator(Load) : BB->end();
-     if (MDR->getPointerDependencyFrom(MemoryLocation(Ptr),
-       true, StartIt, BB, Load).isClobber())
-       return true;
+      BasicBlock::iterator(Load) : BB->end();
+    auto Q = MDR->getPointerDependencyFrom(MemoryLocation(Ptr), true,
+                                           StartIt, BB, Load);
+    if (Q.isClobber() || Q.isUnknown())
+      return true;
   }
   return false;
 }