[PATCH] D13490: [PlaceSafeopints] Extract out `callsGCLeafFunction`, NFC

[Sanjoy Das via llvm-commits]

sanjoy updated this revision to Diff 36694.
sanjoy added a comment.

- edit comment


http://reviews.llvm.org/D13490

Files:
  include/llvm/Transforms/Utils/Local.h
  lib/Transforms/Scalar/PlaceSafepoints.cpp
  lib/Transforms/Utils/Local.cpp

Index: lib/Transforms/Utils/Local.cpp
===================================================================
--- lib/Transforms/Utils/Local.cpp
+++ lib/Transforms/Utils/Local.cpp
@@ -1480,3 +1480,20 @@
   }
   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;
+}
Index: lib/Transforms/Scalar/PlaceSafepoints.cpp
===================================================================
--- lib/Transforms/Scalar/PlaceSafepoints.cpp
+++ lib/Transforms/Scalar/PlaceSafepoints.cpp
@@ -192,10 +192,8 @@
 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());
@@ -752,31 +750,6 @@
 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*/) {
Index: include/llvm/Transforms/Utils/Local.h
===================================================================
--- include/llvm/Transforms/Utils/Local.h
+++ include/llvm/Transforms/Utils/Local.h
@@ -304,6 +304,14 @@
 /// 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.
+bool callsGCLeafFunction(ImmutableCallSite CS);
+
 } // End llvm namespace
 
 #endif


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