[MemorySSA] Don't hoist stores if interfering uses (as calls) exist.

llvm-svn: 373674

1 files changed, 11 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index 2e13e8e4150..262d64f1618 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -1248,12 +1248,22 @@ bool llvm::canSinkOrHoistInst(Instruction &I, AAResults *AA, DominatorTree *DT,
               // FIXME: More precise: no Uses that alias SI.
               if (!Flags->IsSink && !MSSA->dominates(SIMD, MU))
                 return false;
-            } else if (const auto *MD = dyn_cast<MemoryDef>(&MA))
+            } else if (const auto *MD = dyn_cast<MemoryDef>(&MA)) {
               if (auto *LI = dyn_cast<LoadInst>(MD->getMemoryInst())) {
                 (void)LI; // Silence warning.
                 assert(!LI->isUnordered() && "Expected unordered load");
                 return false;
               }
+              // Any call, while it may not be clobbering SI, it may be a use.
+              if (auto *CI = dyn_cast<CallInst>(MD->getMemoryInst())) {
+                // Check if the call may read from the memory locattion written
+                // to by SI. Check CI's attributes and arguments; the number of
+                // such checks performed is limited above by NoOfMemAccTooLarge.
+                ModRefInfo MRI = AA->getModRefInfo(CI, MemoryLocation::get(SI));
+                if (isModOrRefSet(MRI))
+                  return false;
+              }
+            }
         }
 
       auto *Source = MSSA->getSkipSelfWalker()->getClobberingMemoryAccess(SI);