[Instruction] Introduce getAtomicSyncScopeID()

An analysis may just be interested in checking if an instruction is
atomic but system scoped or single-thread scoped, like ThreadSanitizer's
isAtomic(). Unfortunately Instruction::isAtomic() can only answer the
"atomic" part of the question, but to also check scope becomes rather
verbose.

To simplify and reduce redundancy, introduce a common helper
getAtomicSyncScopeID() which returns the scope of an atomic operation.
Start using it in ThreadSanitizer.

NFCI.

Reviewed By: dvyukov

Differential Revision: https://reviews.llvm.org/D121910

1 files changed, 8 insertions, 13 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
index cd1e854..ade0316 100644
--- a/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
@@ -526,19 +526,14 @@ void ThreadSanitizer::chooseInstructionsToInstrument(
   Local.clear();
 }
 
-static bool isAtomic(Instruction *I) {
+static bool isTsanAtomic(const Instruction *I) {
   // TODO: Ask TTI whether synchronization scope is between threads.
-  if (LoadInst *LI = dyn_cast<LoadInst>(I))
-    return LI->isAtomic() && LI->getSyncScopeID() != SyncScope::SingleThread;
-  if (StoreInst *SI = dyn_cast<StoreInst>(I))
-    return SI->isAtomic() && SI->getSyncScopeID() != SyncScope::SingleThread;
-  if (isa<AtomicRMWInst>(I))
-    return true;
-  if (isa<AtomicCmpXchgInst>(I))
-    return true;
-  if (isa<FenceInst>(I))
-    return true;
-  return false;
+  auto SSID = getAtomicSyncScopeID(I);
+  if (!SSID.hasValue())
+    return false;
+  if (isa<LoadInst>(I) || isa<StoreInst>(I))
+    return SSID.getValue() != SyncScope::SingleThread;
+  return true;
 }
 
 void ThreadSanitizer::InsertRuntimeIgnores(Function &F) {
@@ -580,7 +575,7 @@ bool ThreadSanitizer::sanitizeFunction(Function &F,
   // Traverse all instructions, collect loads/stores/returns, check for calls.
   for (auto &BB : F) {
     for (auto &Inst : BB) {
-      if (isAtomic(&Inst))
+      if (isTsanAtomic(&Inst))
         AtomicAccesses.push_back(&Inst);
       else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
         LocalLoadsAndStores.push_back(&Inst);