/// the given BasicBlock. Returns the number of replacements made.
unsigned replaceDominatedUsesWith(Value *From, Value *To, DominatorTree &DT,
const BasicBlock *BB);
+
+
+/// \brief Return true if the CallSite CS calls a gc leaf function.
+///
+/// A leaf function is a function that does not safepoint the thread during its
+/// execution. During a call or invoke to such a function, the callers stack
+/// does not have to be made parseable.
+///
+/// Most passes can and should ignore this information, and it is only used
+/// during lowering by the GC infrastructure.
+bool callsGCLeafFunction(ImmutableCallSite CS);
+
} // End llvm namespace
#endif
InsertSafepointPoll(Instruction *InsertBefore,
std::vector<CallSite> &ParsePointsNeeded /*rval*/);
-static bool isGCLeafFunction(const CallSite &CS);
-
static bool needsStatepoint(const CallSite &CS) {
- if (isGCLeafFunction(CS))
+ if (callsGCLeafFunction(CS))
return false;
if (CS.isCall()) {
CallInst *call = cast<CallInst>(CS.getInstruction());
INITIALIZE_PASS_END(PlaceSafepoints, "place-safepoints", "Place Safepoints",
false, false)
-static bool isGCLeafFunction(const CallSite &CS) {
- Instruction *inst = CS.getInstruction();
- if (isa<IntrinsicInst>(inst)) {
- // Most LLVM intrinsics are things which can never take a safepoint.
- // As a result, we don't need to have the stack parsable at the
- // callsite. This is a highly useful optimization since intrinsic
- // calls are fairly prevalent, particularly in debug builds.
- return true;
- }
-
- // If this function is marked explicitly as a leaf call, we don't need to
- // place a safepoint of it. In fact, for correctness we *can't* in many
- // cases. Note: Indirect calls return Null for the called function,
- // these obviously aren't runtime functions with attributes
- // TODO: Support attributes on the call site as well.
- const Function *F = CS.getCalledFunction();
- bool isLeaf =
- F &&
- F->getFnAttribute("gc-leaf-function").getValueAsString().equals("true");
- if (isLeaf) {
- return true;
- }
- return false;
-}
-
static void
InsertSafepointPoll(Instruction *InsertBefore,
std::vector<CallSite> &ParsePointsNeeded /*rval*/) {
}
return Count;
}
+
+bool llvm::callsGCLeafFunction(ImmutableCallSite CS) {
+ if (isa<IntrinsicInst>(CS.getInstruction()))
+ // Most LLVM intrinsics are things which can never take a safepoint.
+ // As a result, we don't need to have the stack parsable at the
+ // callsite. This is a highly useful optimization since intrinsic
+ // calls are fairly prevalent, particularly in debug builds.
+ return true;
+
+ // Check if the function is specifically marked as a gc leaf function.
+ //
+ // TODO: we should be checking the attributes on the call site as well.
+ if (const Function *F = CS.getCalledFunction())
+ return F->hasFnAttribute("gc-leaf-function");
+
+ return false;
+}