aboutsummaryrefslogtreecommitdiff
path: root/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'llvm/lib/Transforms/Utils/SimplifyCFG.cpp')
-rw-r--r--llvm/lib/Transforms/Utils/SimplifyCFG.cpp18
1 files changed, 18 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 0e39284..a72af2b 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -25,6 +25,7 @@
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/EHPersonalities.h"
#include "llvm/Analysis/GuardUtils.h"
@@ -2250,6 +2251,23 @@ static Value *isSafeToSpeculateStore(Instruction *I, BasicBlock *BrBB,
return SI->getValueOperand();
return nullptr; // Unknown store.
}
+
+ if (auto *LI = dyn_cast<LoadInst>(&CurI)) {
+ if (LI->getPointerOperand() == StorePtr && LI->getType() == StoreTy &&
+ LI->isSimple()) {
+ // Local objects (created by an `alloca` instruction) are always
+ // writable, so once we are past a read from a location it is valid to
+ // also write to that same location.
+ // If the address of the local object never escapes the function, that
+ // means it's never concurrently read or written, hence moving the store
+ // from under the condition will not introduce a data race.
+ auto *AI = dyn_cast<AllocaInst>(getUnderlyingObject(StorePtr));
+ if (AI && !PointerMayBeCaptured(AI, false, true))
+ // Found a previous load, return it.
+ return LI;
+ }
+ // The load didn't work out, but we may still find a store.
+ }
}
return nullptr;