Generic specializer: don't use pre-specialization for Array._endMutation

Pre-specialization of `Array._endMutation` (for AnyObject) prevents inlining this function and that results in sub-optimal code.
This function is basically a no-op. So it should be inlined.

Unfortunately we cannot remove the specialize-attributes anymore because the pre-specialized function(s) are now part of the stdlib's ABI.
Therefore make an exception for `Array._endMutation` in the generic specializer.

Author: eeckstein

lib/SILOptimizer/Utils/Generics.cpp

@@ -2982,6 +2982,13 @@ static bool usePrespecialized(
   if (refF->getSpecializeAttrs().empty())
     return false;
 
+  // `Array._endMutation` was added for pre-specialization by mistake. But we
+  // cannot remove the specialize-attributes anymore because the pre-specialized
+  // functions are now part of the stdlib's ABI.
+  // Therefore make an exception for `Array._endMutation` here.
+  if (refF->getName() == "$sSa12_endMutationyyF")
+    return false;
+
   SmallVector<std::tuple<unsigned, ReabstractionInfo, AvailabilityRange>, 4>
       layoutMatches;
 

test/SILOptimizer/static_arrays.swift

@@ -267,12 +267,12 @@ func takeUnsafePointer(ptr : UnsafePointer<SwiftClass>, len: Int) {
 // This should be a single basic block, and the array should end up being stack
 // allocated.
 //
-// CHECK-LABEL: sil [noinline] @{{.*passArrayOfClasses.*}} : $@convention(thin) (@guaranteed SwiftClass, @guaranteed SwiftClass, @guaranteed SwiftClass) -> () {
+// CHECK-LABEL: sil [noinline] @$s4test18passArrayOfClasses1a1b1cyAA10SwiftClassC_A2GtF : $@convention(thin) (@guaranteed SwiftClass, @guaranteed SwiftClass, @guaranteed SwiftClass) -> () {
 // CHECK:       bb0(%0 : $SwiftClass, %1 : $SwiftClass, %2 : $SwiftClass):
-// CHECK-NOT:   bb1(
-// CHECK:         alloc_ref{{(_dynamic)?}} {{.*}}[tail_elems $SwiftClass *
-// CHECK-NOT:   bb1(
-// CHECK:       } // end sil function '{{.*passArrayOfClasses.*}}'
+// CHECK-NOT:   bb1
+// CHECK:         alloc_ref{{.*}}[stack] [tail_elems $SwiftClass *
+// CHECK-NOT:   bb1
+// CHECK:       } // end sil function '$s4test18passArrayOfClasses1a1b1cyAA10SwiftClassC_A2GtF'
 @inline(never)
 public func passArrayOfClasses(a: SwiftClass, b: SwiftClass, c: SwiftClass) {
   let arr = [a, b, c]