[Sema] Add option to skip non-inlinable functions without types

This frontend flag can be used as an alternative to
-experimental-skip-non-inlinable-function-bodies that doesn’t skip
functions defining nested types. We want to keep these types as they are
used by LLDB. Other functions ares safe to skip parsing and
type-checking.

rdar://71130519

Author: xymus

include/swift/AST/Decl.h

@@ -391,7 +391,7 @@ class alignas(1 << DeclAlignInBits) Decl {
   SWIFT_INLINE_BITFIELD(SubscriptDecl, VarDecl, 2,
     StaticSpelling : 2
   );
-  SWIFT_INLINE_BITFIELD(AbstractFunctionDecl, ValueDecl, 3+8+1+1+1+1+1+1,
+  SWIFT_INLINE_BITFIELD(AbstractFunctionDecl, ValueDecl, 3+8+1+1+1+1+1+1+1,
     /// \see AbstractFunctionDecl::BodyKind
     BodyKind : 3,
 
@@ -415,7 +415,11 @@ class alignas(1 << DeclAlignInBits) Decl {
     Synthesized : 1,
 
     /// Whether this member's body consists of a single expression.
-    HasSingleExpressionBody : 1
+    HasSingleExpressionBody : 1,
+
+    /// Whether peeking into this function detected nested type declarations.
+    /// This is set when skipping over the decl at parsing.
+    HasNestedTypeDeclarations : 1
   );
 
   SWIFT_INLINE_BITFIELD(FuncDecl, AbstractFunctionDecl, 1+1+2+1+1+2+1,
@@ -5544,6 +5548,7 @@ class AbstractFunctionDecl : public GenericContext, public ValueDecl {
     Bits.AbstractFunctionDecl.Throws = Throws;
     Bits.AbstractFunctionDecl.Synthesized = false;
     Bits.AbstractFunctionDecl.HasSingleExpressionBody = false;
+    Bits.AbstractFunctionDecl.HasNestedTypeDeclarations = false;
   }
 
   void setBodyKind(BodyKind K) {
@@ -5690,6 +5695,16 @@ class AbstractFunctionDecl : public GenericContext, public ValueDecl {
     setBody(S, BodyKind::Parsed);
   }
 
+  /// Was there a nested type declaration detected when parsing this
+  /// function was skipped?
+  bool hasNestedTypeDeclarations() const {
+    return Bits.AbstractFunctionDecl.HasNestedTypeDeclarations;
+  }
+
+  void setHasNestedTypeDeclarations(bool value) {
+    Bits.AbstractFunctionDecl.HasNestedTypeDeclarations = value;
+  }
+
   /// Note that parsing for the body was delayed.
   ///
   /// The function should return the body statement and a flag indicating

include/swift/Basic/FunctionBodySkipping.h

@@ -23,6 +23,9 @@ enum class FunctionBodySkipping : uint8_t {
   None,
   /// Only non-inlinable function bodies should be skipped.
   NonInlinable,
+  /// Only non-inlinable functions bodies without type definitions should
+  /// be skipped.
+  NonInlinableWithoutTypes,
   /// All function bodies should be skipped, where not otherwise required
   /// for type inference.
   All

include/swift/Option/Options.td

@@ -297,6 +297,10 @@ def experimental_skip_non_inlinable_function_bodies:
   Flag<["-"], "experimental-skip-non-inlinable-function-bodies">,
   Flags<[FrontendOption, HelpHidden]>,
   HelpText<"Skip type-checking and SIL generation for non-inlinable function bodies">;
+def experimental_skip_non_inlinable_function_bodies_without_types:
+  Flag<["-"], "experimental-skip-non-inlinable-function-bodies-without-types">,
+  Flags<[FrontendOption, HelpHidden]>,
+  HelpText<"Skip work on non-inlinable function bodies that do not declare nested types">;
 def profile_stats_events: Flag<["-"], "profile-stats-events">,
   Flags<[FrontendOption, HelpHidden]>,
   HelpText<"Profile changes to stats in -stats-output-dir">;

include/swift/Parse/Parser.h

@@ -687,7 +687,10 @@ class Parser {
 
   /// Skip a braced block (e.g. function body). The current token must be '{'.
   /// Returns \c true if the parser hit the eof before finding matched '}'.
-  bool skipBracedBlock();
+  ///
+  /// Set \c HasNestedTypeDeclarations to true if a token for a type
+  /// declaration is detected in the skipped block.
+  bool skipBracedBlock(bool &HasNestedTypeDeclarations);
 
   /// Skip over SIL decls until we encounter the start of a Swift decl or eof.
   void skipSILUntilSwiftDecl();

lib/Frontend/ArgsToFrontendOptionsConverter.cpp

@@ -195,7 +195,9 @@ bool ArgsToFrontendOptionsConverter::convert(
 
   if (FrontendOptions::doesActionGenerateIR(Opts.RequestedAction) &&
       (Args.hasArg(OPT_experimental_skip_non_inlinable_function_bodies) ||
-       Args.hasArg(OPT_experimental_skip_all_function_bodies))) {
+       Args.hasArg(OPT_experimental_skip_all_function_bodies) ||
+       Args.hasArg(
+         OPT_experimental_skip_non_inlinable_function_bodies_without_types))) {
     Diags.diagnose(SourceLoc(), diag::cannot_emit_ir_skipping_function_bodies);
     return true;
   }

lib/Frontend/CompilerInvocation.cpp

@@ -716,6 +716,12 @@ static bool ParseTypeCheckerArgs(TypeCheckerOptions &Opts, ArgList &Args,
   Opts.DebugTimeExpressions |=
       Args.hasArg(OPT_debug_time_expression_type_checking);
 
+  // Check for SkipFunctionBodies arguments in order from skipping less to
+  // skipping more.
+  if (Args.hasArg(
+        OPT_experimental_skip_non_inlinable_function_bodies_without_types))
+    Opts.SkipFunctionBodies = FunctionBodySkipping::NonInlinableWithoutTypes;
+
   // If asked to perform InstallAPI, go ahead and enable non-inlinable function
   // body skipping.
   if (Args.hasArg(OPT_experimental_skip_non_inlinable_function_bodies) ||

lib/Parse/ParseDecl.cpp

@@ -3519,10 +3519,12 @@ static void diagnoseOperatorFixityAttributes(Parser &P,
 static unsigned skipUntilMatchingRBrace(Parser &P,
                                         bool &HasPoundDirective,
                                         bool &HasOperatorDeclarations,
-                                        bool &HasNestedClassDeclarations) {
+                                        bool &HasNestedClassDeclarations,
+                                        bool &HasNestedTypeDeclarations) {
   HasPoundDirective = false;
   HasOperatorDeclarations = false;
   HasNestedClassDeclarations = false;
+  HasNestedTypeDeclarations = false;
 
   unsigned OpenBraces = 1;
 
@@ -3541,6 +3543,10 @@ static unsigned skipUntilMatchingRBrace(Parser &P,
 
     HasPoundDirective |= P.Tok.isAny(tok::pound_sourceLocation, tok::pound_line,
       tok::pound_if, tok::pound_else, tok::pound_endif, tok::pound_elseif);
+
+    HasNestedTypeDeclarations |= P.Tok.isAny(tok::kw_class, tok::kw_struct,
+                                             tok::kw_enum);
+
     if (P.consumeIf(tok::l_brace)) {
       ++OpenBraces;
       continue;
@@ -4823,10 +4829,12 @@ bool Parser::canDelayMemberDeclParsing(bool &HasOperatorDeclarations,
   // we can't lazily parse.
   BacktrackingScope BackTrack(*this);
   bool HasPoundDirective;
+  bool HasNestedTypeDeclarations;
   skipUntilMatchingRBrace(*this,
                           HasPoundDirective,
                           HasOperatorDeclarations,
-                          HasNestedClassDeclarations);
+                          HasNestedClassDeclarations,
+                          HasNestedTypeDeclarations);
   if (!HasPoundDirective)
     BackTrack.cancelBacktrack();
   return !BackTrack.willBacktrack();
@@ -5514,7 +5522,7 @@ static ParameterList *parseOptionalAccessorArgument(SourceLoc SpecifierLoc,
   return ParameterList::create(P.Context, StartLoc, param, EndLoc);
 }
 
-bool Parser::skipBracedBlock() {
+bool Parser::skipBracedBlock(bool &HasNestedTypeDeclarations) {
   SyntaxParsingContext disabled(SyntaxContext);
   SyntaxContext->disable();
   consumeToken(tok::l_brace);
@@ -5528,7 +5536,8 @@ bool Parser::skipBracedBlock() {
   unsigned OpenBraces = skipUntilMatchingRBrace(*this,
                                                 HasPoundDirectives,
                                                 HasOperatorDeclarations,
-                                                HasNestedClassDeclarations);
+                                                HasNestedClassDeclarations,
+                                                HasNestedTypeDeclarations);
   if (consumeIf(tok::r_brace))
     --OpenBraces;
   return OpenBraces != 0;
@@ -6424,11 +6433,13 @@ void Parser::consumeAbstractFunctionBody(AbstractFunctionDecl *AFD,
   BodyRange.Start = Tok.getLoc();
 
   // Advance the parser to the end of the block; '{' ... '}'.
-  skipBracedBlock();
+  bool HasNestedTypeDeclarations;
+  skipBracedBlock(HasNestedTypeDeclarations);
 
   BodyRange.End = PreviousLoc;
 
   AFD->setBodyDelayed(BodyRange);
+  AFD->setHasNestedTypeDeclarations(HasNestedTypeDeclarations);
 
   if (isCodeCompletionFirstPass() &&
       SourceMgr.rangeContainsCodeCompletionLoc(BodyRange)) {

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -2345,6 +2345,14 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
         FunctionBodySkipping::All)
       return true;
 
+    // If we want all types (for LLDB) we can't skip functions with nested
+    // types. We could probably improve upon this and type-check only the
+    // nested types instead for better performances.
+    if (AFD->hasNestedTypeDeclarations() &&
+        getASTContext().TypeCheckerOpts.SkipFunctionBodies ==
+          FunctionBodySkipping::NonInlinableWithoutTypes)
+      return false;
+
     // Only skip functions where their body won't be serialized
     return AFD->getResilienceExpansion() != ResilienceExpansion::Minimal;
   }

test/Frontend/skip-function-bodies.swift

@@ -3,6 +3,8 @@
 // Check -emit-ir and -c are invalid when skipping function bodies
 // RUN: not %target-swift-frontend -emit-ir %s -experimental-skip-non-inlinable-function-bodies %s 2>&1 | %FileCheck %s --check-prefix ERROR
 // RUN: not %target-swift-frontend -c %s -experimental-skip-non-inlinable-function-bodies %s 2>&1 | %FileCheck %s --check-prefix ERROR
+// RUN: not %target-swift-frontend -emit-ir %s -experimental-skip-non-inlinable-function-bodies-without-types %s 2>&1 | %FileCheck %s --check-prefix ERROR
+// RUN: not %target-swift-frontend -c %s -experimental-skip-non-inlinable-function-bodies-without-types %s 2>&1 | %FileCheck %s --check-prefix ERROR
 // RUN: not %target-swift-frontend -emit-ir %s -experimental-skip-all-function-bodies %s 2>&1 | %FileCheck %s --check-prefix ERROR
 // RUN: not %target-swift-frontend -c %s -experimental-skip-all-function-bodies %s 2>&1 | %FileCheck %s --check-prefix ERROR
 // ERROR: -experimental-skip-*-function-bodies do not support emitting IR
@@ -14,8 +16,10 @@
 
 // Check skipped bodies are neither typechecked nor SILgen'd
 // RUN: %target-swift-frontend -emit-sil -emit-sorted-sil -experimental-skip-non-inlinable-function-bodies -debug-forbid-typecheck-prefix NEVERTYPECHECK -debug-forbid-typecheck-prefix INLINENOTYPECHECK %s -o %t/Skip.noninlinable.sil
+// RUN: %target-swift-frontend -emit-sil -emit-sorted-sil -experimental-skip-non-inlinable-function-bodies-without-types -debug-forbid-typecheck-prefix NEVERTYPECHECK -debug-forbid-typecheck-prefix TYPESNOTYPECHECK %s -o %t/Skip.withouttypes.sil
 // RUN: %target-swift-frontend -emit-sil -emit-sorted-sil -experimental-skip-all-function-bodies -debug-forbid-typecheck-prefix NEVERTYPECHECK -debug-forbid-typecheck-prefix ALLNOTYPECHECK %s -o %t/Skip.all.sil
 // RUN: %FileCheck %s --check-prefixes CHECK,CHECK-NONINLINE-ONLY,CHECK-NONINLINE-SIL < %t/Skip.noninlinable.sil
+// RUN: %FileCheck %s --check-prefixes CHECK,CHECK-WITHOUTTYPES-ONLY,CHECK-NONINLINE-SIL < %t/Skip.withouttypes.sil
 // RUN: %FileCheck %s --check-prefixes CHECK,CHECK-ALL-ONLY < %t/Skip.all.sil
 
 // Emit the module interface and check it against the same set of strings.
@@ -178,6 +182,57 @@ public func inlinableNestedLocalTypeFunc() {
   nestedFunc()
 }
 
+public func funcWithEnum() {
+  let INLINENOTYPECHECK_local = 1
+  let ALLNOTYPECHECK_local = 1
+  _blackHole("func with enum body")
+  // CHECK-WITHOUTTYPES-ONLY: "func with enum body"
+  // CHECK-NONINLINE-ONLY-NOT: "func with enum body"
+  // CHECK-ALL-ONLY-NOT: "func with enum body"
+  enum E {}
+}
+
+public func funcWithClass() {
+  let INLINENOTYPECHECK_local = 1
+  let ALLNOTYPECHECK_local = 1
+  _blackHole("func with class body")
+  // CHECK-WITHOUTTYPES-ONLY: "func with class body"
+  // CHECK-NONINLINE-ONLY-NOT: "func with class body"
+  // CHECK-ALL-ONLY-NOT: "func with class body"
+  class C {}
+}
+
+public func funcWithStruct() {
+  let INLINENOTYPECHECK_local = 1
+  let ALLNOTYPECHECK_local = 1
+  _blackHole("func with struct body")
+  // CHECK-WITHOUTTYPES-ONLY: "func with struct body"
+  // CHECK-NONINLINE-ONLY-NOT: "func with struct body"
+  // CHECK-ALL-ONLY-NOT: "func with struct body"
+  struct S {}
+}
+
+public func funcWithNestedFuncs() {
+  let INLINENOTYPECHECK_local = 1
+  let ALLNOTYPECHECK_local = 1
+  _blackHole("func with nested funcs body")
+  // CHECK-WITHOUTTYPES-ONLY: "func with nested funcs body"
+  // CHECK-NONINLINE-ONLY-NOT: "func with nested funcs body"
+  // CHECK-ALL-ONLY-NOT: "func with nested funcs body"
+
+  func bar() {
+    _blackHole("nested func body")
+    // CHECK-WITHOUTTYPES-ONLY: "nested func body"
+    // FIXME: We could skip this nested function.
+  }
+
+  func foo() {
+    _blackHole("nested func with type body")
+    // CHECK-WITHOUTTYPES-ONLY: "nested func with type body"
+    struct S {}
+  }
+}
+
 public struct Struct {
   @inlinable public var inlinableVar: Int {
     let ALLNOTYPECHECK_local = 1