Mandatory Inlining: Look through convert_function recursively

Author: slavapestov

lib/SILOptimizer/Mandatory/MandatoryInlining.cpp

@@ -632,7 +632,7 @@ static SILValue stripFunctionConversions(SILValue CalleeValue) {
     // If the conversion only changes the substitution level of the function,
     // we can also look through it.
     if (ConvertFn->onlyConvertsSubstitutions())
-      return stripCopiesAndBorrows(ConvertFn->getOperand());
+      return stripFunctionConversions(ConvertFn->getOperand());
 
     auto FromCalleeTy =
         ConvertFn->getOperand()->getType().castTo<SILFunctionType>();

test/SILOptimizer/mandatory_inlining_generic_autoclosure.swift

@@ -0,0 +1,12 @@
+// RUN: %target-swift-frontend -emit-sil %s | %FileCheck %s
+
+@_transparent func takesGenericAutoclosure<T>(_ fn: @autoclosure () -> T) {
+  _ = fn()
+}
+
+// CHECK-LABEL: sil hidden @$s38mandatory_inlining_generic_autoclosure23callsGenericAutoclosureyyxlF : $@convention(thin) <T> (@in_guaranteed T) -> () {
+// CHECK-NOT: function_ref @$s38mandatory_inlining_generic_autoclosure23callsGenericAutoclosureyyxlFxyXEfu_
+
+func callsGenericAutoclosure<T>(_ t: T) {
+  takesGenericAutoclosure(t)
+}