[Statepoints] Check for the "gc-leaf-function" attribute on call sites as well.

[reames]

LGTM

lib/Transforms/Utils/Local.cpp

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 (CS.hasFnAttr("gc-leaf-function"))
+    return true;
   if (const Function *F = CS.getCalledFunction())
     return F->hasFnAttribute("gc-leaf-function");
 
   return false;
 }

test/Transforms/PlaceSafepoints/leaf-function.ll

 ; RUN: opt %s -S -place-safepoints | FileCheck %s
 
 declare void @foo() "gc-leaf-function"
+declare void @bar()
 
 ; Calls of functions with the "gc-leaf-function" attribute shouldn't be turned
 ; into a safepoint.  An entry safepoint should get inserted, though.
 define void @test_leaf_function() gc "statepoint-example" {
 ; CHECK-LABEL: test_leaf_function
 ; CHECK: gc.statepoint.p0f_isVoidf
 ; CHECK-NOT: statepoint
 ; CHECK-NOT: gc.result
 entry:
   call void @foo()
   ret void
 }
 
+define void @test_leaf_function_call() gc "statepoint-example" {
+; CHECK-LABEL: test_leaf_function_call
+; CHECK: gc.statepoint.p0f_isVoidf
+; CHECK-NOT: statepoint
+; CHECK-NOT: gc.result
+entry:
+  call void @bar() "gc-leaf-function"
+  ret void
+}
+
 ; This function is inlined when inserting a poll.
 declare void @do_safepoint()
 define void @gc.safepoint_poll() {
 ; CHECK-LABEL: gc.safepoint_poll
 entry:
   call void @do_safepoint()
   ret void
 }