diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Analysis/MemoryDependenceAnalysis.cpp | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp index 0890489c557..2436543a816 100644 --- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp +++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp @@ -638,6 +638,15 @@ MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom( if (isInvariantLoad) continue; + // A release fence requires that all stores complete before it, but does + // not prevent the reordering of following loads or stores 'before' the + // fence. As a result, we look past it when finding a dependency for + // loads. DSE uses this to find preceeding stores to delete and thus we + // can't bypass the fence if the query instruction is a store. + if (FenceInst *FI = dyn_cast<FenceInst>(Inst)) + if (isLoad && FI->getOrdering() == Release) + continue; + // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer. ModRefInfo MR = AA.getModRefInfo(Inst, MemLoc); // If necessary, perform additional analysis. |
