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[Attributor] Cleanup detection of non-relaxed atomics in nosync inference 

The code was checking for cases which are disallowed by the verifier.  Delete dead code and adjust style.
This commit is contained in:
Philip Reames 2021-04-01 12:01:29 -07:00
parent 8e596f7e27
commit 1e69a5af92
1 changed files with 11 additions and 25 deletions
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36
llvm/lib/Transforms/IPO/AttributorAttributes.cpp
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@ -1290,6 +1290,15 @@ bool AANoSyncImpl::isNonRelaxedAtomic(Instruction *I) {
if (!I->isAtomic()) if (!I->isAtomic())
return false; return false;
if (auto *FI = dyn_cast<FenceInst>(I))
// All legal orderings for fence are stronger than monotonic.
return FI->getSyncScopeID() != SyncScope::SingleThread;
else if (auto *AI = dyn_cast<AtomicCmpXchgInst>(I)) {
// Unordered is not a legal ordering for cmpxchg.
return (AI->getSuccessOrdering() != AtomicOrdering::Monotonic ||
AI->getFailureOrdering() != AtomicOrdering::Monotonic);
}
AtomicOrdering Ordering; AtomicOrdering Ordering;
switch (I->getOpcode()) { switch (I->getOpcode()) {
case Instruction::AtomicRMW: case Instruction::AtomicRMW:
@ -1301,36 +1310,13 @@ bool AANoSyncImpl::isNonRelaxedAtomic(Instruction *I) {
case Instruction::Load: case Instruction::Load:
Ordering = cast<LoadInst>(I)->getOrdering(); Ordering = cast<LoadInst>(I)->getOrdering();
break; break;
case Instruction::Fence: {
auto *FI = cast<FenceInst>(I);
if (FI->getSyncScopeID() == SyncScope::SingleThread)
return false;
Ordering = FI->getOrdering();
break;
}
case Instruction::AtomicCmpXchg: {
AtomicOrdering Success = cast<AtomicCmpXchgInst>(I)->getSuccessOrdering();
AtomicOrdering Failure = cast<AtomicCmpXchgInst>(I)->getFailureOrdering();
// Only if both are relaxed, than it can be treated as relaxed.
// Otherwise it is non-relaxed.
if (Success != AtomicOrdering::Unordered &&
Success != AtomicOrdering::Monotonic)
return true;
if (Failure != AtomicOrdering::Unordered &&
Failure != AtomicOrdering::Monotonic)
return true;
return false;
}
default: default:
llvm_unreachable( llvm_unreachable(
"New atomic operations need to be known in the attributor."); "New atomic operations need to be known in the attributor.");
} }
// Relaxed. return (Ordering != AtomicOrdering::Unordered &&
if (Ordering == AtomicOrdering::Unordered || Ordering != AtomicOrdering::Monotonic);
Ordering == AtomicOrdering::Monotonic)
return false;
return true;
} }
/// Return true if this intrinsic is nosync. This is only used for intrinsics /// Return true if this intrinsic is nosync. This is only used for intrinsics