bool FunctionAccessedStorage::summarizeFunction(SILFunction *F) {
assert(accessResult.isEmpty() && "expected uninitialized results.");
if (F->isDefinition())
return false;
// If the function definition is unavailable, set unidentifiedAccess to a
// conservative value, since analyzeInstruction will never be called.
//
// If FunctionSideEffects can be summarized, use that information.
FunctionSideEffects functionSideEffects;
if (!functionSideEffects.summarizeFunction(F)) {
setWorstEffects();
// May as well consider this a successful summary since there are no
// instructions to visit anyway.
return true;
}
bool mayRead = functionSideEffects.getGlobalEffects().mayRead();
bool mayWrite = functionSideEffects.getGlobalEffects().mayWrite();
for (auto ¶mEffects : functionSideEffects.getParameterEffects()) {
mayRead |= paramEffects.mayRead();
mayWrite |= paramEffects.mayWrite();
}
if (mayWrite)
accessResult.setUnidentifiedAccess(SILAccessKind::Modify);
else if (mayRead)
accessResult.setUnidentifiedAccess(SILAccessKind::Read);
// If function side effects is "readnone" then this result will have an empty
// storageAccessSet and unidentifiedAccess == None.
return true;
}
static bool isSafeReadOnlyApply(SideEffectAnalysis *SEA, ApplyInst *AI) {
FunctionSideEffects E;
SEA->getCalleeEffects(E, AI);
if (E.getGlobalEffects().mayRead()) {
// If we have Global effects,
// we don't know which memory is read in the callee.
// Therefore we bail for safety
return false;
}
auto MB = E.getMemBehavior(RetainObserveKind::ObserveRetains);
return (MB <= SILInstruction::MemoryBehavior::MayRead);
}
bool swift::isPureCall(FullApplySite AI, SideEffectAnalysis *SEA) {
// If a call has only constant arguments and the call is pure, i.e. has
// no side effects, then we should always inline it.
// This includes arguments which are objects initialized with constant values.
FunctionSideEffects ApplyEffects;
SEA->getCalleeEffects(ApplyEffects, AI);
auto GE = ApplyEffects.getGlobalEffects();
if (GE.mayRead() || GE.mayWrite() || GE.mayRetain() || GE.mayRelease())
return false;
// Check if all parameters are constant.
auto Args = AI.getArgumentOperands().slice(AI.getNumIndirectSILResults());
for (Operand &Arg : Args) {
if (!isConstantArg(&Arg)) {
return false;
}
}
return true;
}
