[Debug info] Dump macro expansion buffers to disk for debug info to reference

When emitting debug info that references into a macro expansion, dump
the macro expansion buffer into a file on disk (in the temporary
directory) so that one can see the macro expansion buffers in the
source files themselves.

The test here validates that the generated LLVM IR looks correct, but
I'm having a problem getting LLDB to actually locate the source code
correctly.

Author: DougGregor

include/swift/SIL/SILLocation.h

@@ -410,7 +410,12 @@ class SILLocation {
   }
 
   /// Extract the line, column, and filename from \p Loc.
-  static FilenameAndLocation decode(SourceLoc Loc, const SourceManager &SM);
+  ///
+  /// \p ForceGeneratedSourceToDisk can be set to true to create a temporary
+  /// file on-disk for buffers containing generated source code, returning the
+  /// name of that temporary file.
+  static FilenameAndLocation decode(SourceLoc Loc, const SourceManager &SM,
+                                    bool ForceGeneratedSourceToDisk = false);
 
   /// Return the decoded FilenameAndLocation.
   /// In case the location has a separate AST node for debugging, this node is

lib/IRGen/IRGenDebugInfo.cpp

@@ -2951,8 +2951,10 @@ void IRGenDebugInfoImpl::emitTypeMetadata(IRGenFunction &IGF,
 SILLocation::FilenameAndLocation
 IRGenDebugInfoImpl::decodeSourceLoc(SourceLoc SL) {
   auto &Cached = FilenameAndLocationCache[SL.getOpaquePointerValue()];
-  if (Cached.filename.empty())
-    Cached = sanitizeCodeViewFilenameAndLocation(SILLocation::decode(SL, SM));
+  if (Cached.filename.empty()) {
+    Cached = sanitizeCodeViewFilenameAndLocation(
+        SILLocation::decode(SL, SM, /*ForceGeneratedSourceToDisk=*/true));
+  }
   return Cached;
 }
 

lib/SIL/IR/SILLocation.cpp

@@ -137,10 +137,11 @@ DeclContext *SILLocation::getAsDeclContext() const {
 }
 
 SILLocation::FilenameAndLocation SILLocation::decode(SourceLoc Loc,
-                                              const SourceManager &SM) {
+                                              const SourceManager &SM,
+                                              bool ForceGeneratedSourceToDisk) {
   FilenameAndLocation DL;
   if (Loc.isValid()) {
-    DL.filename = SM.getDisplayNameForLoc(Loc);
+    DL.filename = SM.getDisplayNameForLoc(Loc, ForceGeneratedSourceToDisk);
     std::tie(DL.line, DL.column) = SM.getPresumedLineAndColumnForLoc(Loc);
   }
   return DL;

test/Macros/macro_expand.swift

@@ -8,8 +8,12 @@
 // RUN: not %target-swift-frontend -typecheck -enable-experimental-feature Macros -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir -module-name MacroUser -DTEST_DIAGNOSTICS -serialize-diagnostics-path %t/macro_expand.dia %s
 // RUN: c-index-test -read-diagnostics %t/macro_expand.dia 2>&1 | %FileCheck -check-prefix CHECK-DIAGS %s
 
+// Debug IR testing
+// RUN: %target-swift-frontend -emit-ir -enable-experimental-feature Macros -enable-experimental-feature Macros -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir %s -module-name MacroUser -o - -g | %FileCheck --check-prefix CHECK-IR %s
+
+
 // Execution testing
-// RUN: %target-build-swift -enable-experimental-feature Macros -enable-experimental-feature Macros -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir -L %swift-host-lib-dir %s -o %t/main -module-name MacroUser
+// RUN: %target-build-swift -g -enable-experimental-feature Macros -enable-experimental-feature Macros -load-plugin-library %t/%target-library-name(MacroDefinition) -I %swift-host-lib-dir -L %swift-host-lib-dir %s -o %t/main -module-name MacroUser
 // RUN: %target-run %t/main | %FileCheck %s
 // REQUIRES: executable_test
 
@@ -53,14 +57,24 @@ func testStringify(a: Int, b: Int) {
   _ = (b, b2, s2, s3)
 }
 
-struct Outer {
+// CHECK-IR-LABEL: define swiftcc void @"$s9MacroUser5OuterV4testyyF"
+// CHECK-IR: call {{.*}}@"$sSS21_builtinStringLiteral17utf8CodeUnitCount7isASCIISSBp_BwBi1_tcfC"{{.*}}!dbg ![[STRING_LITERAL_DI:[0-9]+]]
+// CHECK-IR: ![[STRING_LITERAL_DI]] = !DILocation(line: 1, column: 13, scope: ![[EXPANSION_FILE_SCOPE_DI:[0-9]+]])
+// CHECK-IR: ![[EXPANSION_FILE_SCOPE_DI]] = !DILexicalBlockFile(scope: ![[EXPANSION_FILE_SCOPE_SCOPE_DI:[0-9]+]], file: ![[EXPANSION_FILE_DI:[0-9]+]], discriminator: 0)
+// CHECK-IR: ![[EXPANSION_FILE_DI]] = !DIFile(filename: "{{.*}}swift-generated-sources{{.*}}.swift", directory: "")
+public struct Outer {
   var value: Int = 0
-  func test() {
-    _ = #stringify(1 + value)
+  public func test() {
+    let (a, b) = #stringify(1 + value)
 
-    _ = #stringify({ x in
+    let (c, d) = #stringify({ x in
       x + 1
     })
+
+    _ = a
+    _ = b
+    _ = c
+    _ = d
   }
 }
 
@@ -82,9 +96,9 @@ func testAddBlocker(a: Int, b: Int, c: Int, oa: OnlyAdds) {
   // expected-note@-1{{in expansion of macro 'addBlocker' here}}
   // expected-note@-2{{use '-'}}{{22-23=-}}
 
-  // CHECK-DIAGS: macro_expand.swift:81:7-81:27:1:4: error: binary operator '-' cannot be applied to two 'OnlyAdds' operands [] []
+  // CHECK-DIAGS: macro_expand.swift:[[@LINE-4]]:7-[[@LINE-4]]:27:1:4: error: binary operator '-' cannot be applied to two 'OnlyAdds' operands [] []
   // CHECK-DIAGS: CONTENTS OF FILE{{.*}}addBlocker
-  // CHECK-DIAGS-NEXT: Original source range: {{.*}}macro_expand.swift:81:7 - {{.*}}macro_expand.swift:81:27
+  // CHECK-DIAGS-NEXT: Original source range: {{.*}}macro_expand.swift:[[@LINE-6]]:7 - {{.*}}macro_expand.swift:[[@LINE-6]]:27
   // CHECK-DIAGS-NEXT: oa - oa
   // CHECK-DIAGS-NEXT: END CONTENTS OF FILE
   // Check recursion.