SILGen: Don't emit generator functions for caller-side default parameters

Some default parameter expressions like #file, #line, #function etc
are emitted into the caller directly by SILGen, instead of being
emitted as a call to a generator function.

In these cases, we don't need to emit the generator function at all.

Author: slavapestov

lib/SILGen/SILGen.cpp

@@ -916,7 +916,29 @@ void SILGenModule::emitDestructor(ClassDecl *cd, DestructorDecl *dd) {
   }
 }
 
-void SILGenModule::emitDefaultArgGenerator(SILDeclRef constant, Expr *arg) {
+void SILGenModule::emitDefaultArgGenerator(SILDeclRef constant, Expr *arg,
+                                           DefaultArgumentKind kind) {
+  switch (kind) {
+  case DefaultArgumentKind::None:
+    llvm_unreachable("No default argument here?");
+
+  case DefaultArgumentKind::Normal:
+    break;
+
+  case DefaultArgumentKind::Inherited:
+    return;
+
+  case DefaultArgumentKind::Column:
+  case DefaultArgumentKind::File:
+  case DefaultArgumentKind::Line:
+  case DefaultArgumentKind::Function:
+  case DefaultArgumentKind::DSOHandle:
+  case DefaultArgumentKind::Nil:
+  case DefaultArgumentKind::EmptyArray:
+  case DefaultArgumentKind::EmptyDictionary:
+    return;
+  }
+
   emitOrDelayFunction(*this, constant, [this,constant,arg](SILFunction *f) {
     preEmitFunction(constant, arg, f, arg);
     PrettyStackTraceSILFunction X("silgen emitDefaultArgGenerator ", f);
@@ -1004,7 +1026,7 @@ void SILGenModule::emitDefaultArgGenerators(SILDeclRef::Loc decl,
     for (auto param : *paramList) {
       if (auto defaultArg = param->getDefaultValue())
         emitDefaultArgGenerator(SILDeclRef::getDefaultArgGenerator(decl, index),
-                                defaultArg);
+                                defaultArg, param->getDefaultArgumentKind());
       ++index;
     }
   }

lib/SILGen/SILGen.h

@@ -264,7 +264,8 @@ class LLVM_LIBRARY_VISIBILITY SILGenModule : public ASTVisitor<SILGenModule> {
   void emitEnumConstructor(EnumElementDecl *decl);
 
   /// Emits the default argument generator with the given expression.
-  void emitDefaultArgGenerator(SILDeclRef constant, Expr *arg);
+  void emitDefaultArgGenerator(SILDeclRef constant, Expr *arg,
+                               DefaultArgumentKind kind);
 
   /// Emits the stored property initializer for the given pattern.
   void emitStoredPropertyInitialization(PatternBindingDecl *pd, unsigned i);

test/SILGen/default_arguments.swift

@@ -1,4 +1,5 @@
 // RUN: %target-swift-frontend -Xllvm -sil-full-demangle -emit-silgen %s | %FileCheck %s
+// RUN: %target-swift-frontend -Xllvm -sil-full-demangle -emit-silgen %s | %FileCheck %s --check-prefix=NEGATIVE
 
 // __FUNCTION__ used as top-level parameter produces the module name.
 // CHECK-LABEL: sil @main
@@ -74,17 +75,13 @@ func testMagicLiterals(file: String = #file,
 // Check that default argument generator functions don't leak information about
 // user's source.
 //
-// CHECK-LABEL: sil hidden @_T017default_arguments17testMagicLiteralsySS4file_SS8functionSi4lineSi6columntFfA_
-// CHECK: string_literal utf16 ""
+// NEGATIVE-NOT: sil hidden @_T017default_arguments17testMagicLiteralsySS4file_SS8functionSi4lineSi6columntFfA_
 //
-// CHECK-LABEL: sil hidden @_T017default_arguments17testMagicLiteralsySS4file_SS8functionSi4lineSi6columntFfA0_
-// CHECK: string_literal utf16 ""
+// NEGATIVE-NOT: sil hidden @_T017default_arguments17testMagicLiteralsySS4file_SS8functionSi4lineSi6columntFfA0_
 //
-// CHECK-LABEL: sil hidden @_T017default_arguments17testMagicLiteralsySS4file_SS8functionSi4lineSi6columntFfA1_
-// CHECK: integer_literal $Builtin.Int2048, 0
+// NEGATIVE-NOT: sil hidden @_T017default_arguments17testMagicLiteralsySS4file_SS8functionSi4lineSi6columntFfA1_
 //
-// CHECK-LABEL: sil hidden @_T017default_arguments17testMagicLiteralsySS4file_SS8functionSi4lineSi6columntFfA2_
-// CHECK: integer_literal $Builtin.Int2048, 0
+// NEGATIVE-NOT: sil hidden @_T017default_arguments17testMagicLiteralsySS4file_SS8functionSi4lineSi6columntFfA2_
 
 func closure(_: () -> ()) {}
 func autoclosure(_: @autoclosure () -> ()) {}

test/SILGen/dso_handle.swift

@@ -8,16 +8,9 @@
 // CHECK-NEXT: [[DSOPtr:%[0-9]+]] = address_to_pointer [[DSOAddr]] : $*Builtin.RawPointer to $Builtin.RawPointer
 // CHECK-NEXT: [[DSOPtrStruct:[0-9]+]] = struct $UnsafeRawPointer ([[DSOPtr]] : $Builtin.RawPointer)
 
-
-// CHECK-LABEL: sil hidden @_T010dso_handle14printDSOHandleS2V0A0_tFfA_
-// CHECK: [[DSOAddr:%[0-9]+]] = global_addr [[DSO]] : $*Builtin.RawPointer
-// CHECK-NEXT: [[DSOPtr:%[0-9]+]] = address_to_pointer [[DSOAddr]] : $*Builtin.RawPointer to $Builtin.RawPointer
-// CHECK-NEXT: [[DSOPtrStruct:%[0-9]+]] = struct $UnsafeRawPointer ([[DSOPtr]] : $Builtin.RawPointer)
-// CHECK-NEXT: return [[DSOPtrStruct]] : $UnsafeRawPointer
 func printDSOHandle(dso: UnsafeRawPointer = #dsohandle) -> UnsafeRawPointer {
   print(dso)
   return dso
 }
 
 _ = printDSOHandle()
-