Swift SIL: improvements for Location

* make `var sourceLoc` return nil if the location doesn't have a valid line number
* add `var decl`

Author: eeckstein

SwiftCompilerSources/Sources/SIL/Location.swift

@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 import SILBridging
+import AST
 
 public struct Location: Equatable, CustomStringConvertible {
   let bridged: BridgedLocation
@@ -20,7 +21,10 @@ public struct Location: Equatable, CustomStringConvertible {
   }
 
   public var sourceLoc: SourceLoc? {
-    return SourceLoc(bridged: bridged.getSourceLocation())
+    if hasValidLineNumber {
+      return SourceLoc(bridged: bridged.getSourceLocation())
+    }
+    return nil
   }
 
   /// Keeps the debug scope but marks it as auto-generated.
@@ -34,6 +38,9 @@ public struct Location: Equatable, CustomStringConvertible {
 
   public var isDebugSteppable: Bool { hasValidLineNumber && !isAutoGenerated }
 
+  /// The `Decl` if the location refers to a declaration.
+  public var decl: Decl? { bridged.getDecl().decl }
+
   public static func ==(lhs: Location, rhs: Location) -> Bool {
     lhs.bridged.isEqualTo(rhs.bridged)
   }

include/swift/SIL/SILBridging.h

@@ -403,6 +403,7 @@ struct BridgedLocation {
   BRIDGED_INLINE bool isEqualTo(BridgedLocation rhs) const;
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedSourceLoc getSourceLocation() const;
   BRIDGED_INLINE bool hasSameSourceLocation(BridgedLocation rhs) const;
+  SWIFT_IMPORT_UNSAFE BRIDGED_INLINE OptionalBridgedDeclObj getDecl() const;
   static BRIDGED_INLINE BridgedLocation fromNominalTypeDecl(BridgedDeclObj decl);
   static BRIDGED_INLINE BridgedLocation getArtificialUnreachableLocation();
 };

include/swift/SIL/SILBridgingImpl.h

@@ -636,6 +636,9 @@ BridgedSourceLoc BridgedLocation::getSourceLocation() const {
 bool BridgedLocation::hasSameSourceLocation(BridgedLocation rhs) const {
   return getLoc().hasSameSourceLocation(rhs.getLoc());
 }
+OptionalBridgedDeclObj BridgedLocation::getDecl() const {
+  return {getLoc().getLocation().getAsASTNode<swift::Decl>()};
+}
 BridgedLocation BridgedLocation::fromNominalTypeDecl(BridgedDeclObj decl) {
   return swift::SILDebugLocation(decl.unbridged(), nullptr);
 }