Merge pull request swiftlang#1638 from gottesmm/guaranteed-arg-always…

…-known-safe-bu [arc] guaranteed parameters are always known safe BU.
jnjosh · Mar 11, 2016 · e9a1214 · e9a1214
2 parents bcb12a5 + 0c5d457
commit e9a1214
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diff --git a/lib/SILOptimizer/ARC/RCStateTransitionVisitors.cpp b/lib/SILOptimizer/ARC/RCStateTransitionVisitors.cpp
@@ -80,6 +80,15 @@ BottomUpDataflowRCStateVisitor<ARCState>::visitStrongDecrement(ValueBase *V) {
     }
   }
 
+  // A guaranteed function argument is guaranteed to outlive the function we are
+  // processing. So bottom up for such a parameter, we are always known safe.
+  if (auto *Arg = dyn_cast<SILArgument>(Op)) {
+    if (Arg->isFunctionArg() &&
+        Arg->hasConvention(SILArgumentConvention::Direct_Guaranteed)) {
+      State.updateKnownSafe(true);
+    }
+  }
+
   DEBUG(llvm::dbgs() << "    REF COUNT DECREMENT! Known Safe: "
                      << (State.isKnownSafe() ? "yes" : "no") << "\n");
 

diff --git a/test/SILOptimizer/arcsequenceopts.sil b/test/SILOptimizer/arcsequenceopts.sil
@@ -2116,3 +2116,18 @@ bb2:
   %5 = tuple()
   return %5 : $()
 }
+
+// CHECK-LABEL: sil @guaranteed_always_known_safe_bu : $@convention(thin) (@guaranteed Builtin.NativeObject) -> () {
+// CHECK: strong_retain
+// CHECK-NOT: strong_retain
+// CHECK-NOT: strong_release
+sil @guaranteed_always_known_safe_bu : $@convention(thin) (@guaranteed Builtin.NativeObject) -> () {
+bb0(%0 : $Builtin.NativeObject):
+  strong_retain %0 : $Builtin.NativeObject
+  strong_retain %0 : $Builtin.NativeObject
+  %1 = function_ref @use : $@convention(thin) (Builtin.NativeObject) -> ()
+  apply %1(%0) : $@convention(thin) (Builtin.NativeObject) -> ()
+  apply %1(%0) : $@convention(thin) (Builtin.NativeObject) -> ()
+  strong_release %0 : $Builtin.NativeObject
+  return undef : $()
+}