diff options
| -rw-r--r-- | lib/Analysis/AliasAnalysis.cpp | 21 | ||||
| -rw-r--r-- | lib/Analysis/BasicAliasAnalysis.cpp | 16 | ||||
| -rw-r--r-- | test/Analysis/BasicAA/cas.ll | 14 |
3 files changed, 51 insertions, 0 deletions
diff --git a/lib/Analysis/AliasAnalysis.cpp b/lib/Analysis/AliasAnalysis.cpp index 2571492..3e46fcc 100644 --- a/lib/Analysis/AliasAnalysis.cpp +++ b/lib/Analysis/AliasAnalysis.cpp @@ -150,6 +150,27 @@ AliasAnalysis::getModRefBehavior(CallSite CS, AliasAnalysis::ModRefBehavior AliasAnalysis::getModRefBehavior(Function *F, std::vector<PointerAccessInfo> *Info) { + if (F->isIntrinsic()) { + switch (F->getIntrinsicID()) { + case Intrinsic::atomic_cmp_swap: + case Intrinsic::atomic_load_add: + case Intrinsic::atomic_load_and: + case Intrinsic::atomic_load_max: + case Intrinsic::atomic_load_min: + case Intrinsic::atomic_load_nand: + case Intrinsic::atomic_load_or: + case Intrinsic::atomic_load_sub: + case Intrinsic::atomic_load_umax: + case Intrinsic::atomic_load_umin: + case Intrinsic::atomic_load_xor: + case Intrinsic::atomic_swap: + // CAS and related intrinsics only access their arguments. + return AliasAnalysis::AccessesArguments; + default: + break; + } + } + if (F->doesNotAccessMemory()) // Can't do better than this. return DoesNotAccessMemory; diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index ccbe338..317e9d9 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -256,6 +256,22 @@ bool BasicAliasAnalysis::pointsToConstantMemory(const Value *P) { // AliasAnalysis::ModRefResult BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) { + // If the function only accesses its arguments, it suffices to check that + // P does not alias any of those arguments. + if (AliasAnalysis::getModRefBehavior(CS, 0) == + AliasAnalysis::AccessesArguments) { + bool doesAlias = false; + for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end(); + AI != AE; ++AI) + if (alias(*AI, ~0U, P, Size) != NoAlias) { + doesAlias = true; + break; + } + + if (!doesAlias) + return NoModRef; + } + if (!isa<Constant>(P)) { const Value *Object = P->getUnderlyingObject(); diff --git a/test/Analysis/BasicAA/cas.ll b/test/Analysis/BasicAA/cas.ll new file mode 100644 index 0000000..9bbb5e7 --- /dev/null +++ b/test/Analysis/BasicAA/cas.ll @@ -0,0 +1,14 @@ +; RUN: llvm-as < %s | opt -basicaa -gvn | llvm-dis | grep load | count 1 + +@flag0 = internal global i32 zeroinitializer +@turn = internal global i32 zeroinitializer + + +define i32 @main() { + %a = load i32* @flag0 + %b = tail call i32 @llvm.atomic.swap.i32.p0i32(i32* @turn, i32 1) + %c = load i32* @flag0 + ret i32 %c +} + +declare i32 @llvm.atomic.swap.i32.p0i32(i32*, i32) nounwind
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