[Debug Info] Store the source code for macro expansions in the debug info

This patch stores the source code of macro in the source field of DIFile, which
can be used together with the DW_LLVM_LNCT_source extension to emit the source
code into DWARF debug info.

rdar://110926109

Author: adrian-prantl

lib/IRGen/IRGenDebugInfo.cpp

@@ -268,10 +268,36 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
   /// Decode (and cache) a SourceLoc.
   FileAndLocation decodeSourceLoc(SourceLoc SL) {
     auto &Cached = FileAndLocationCache[SL.getOpaquePointerValue()];
-    if (!Cached.File) {
-      Cached = getFileAndLocation(
-          SILLocation::decode(SL, SM, /*ForceGeneratedSourceToDisk=*/true));
+    if (Cached.File)
+      return Cached;
+
+    if (!SL.isValid()) {
+      Cached.File = CompilerGeneratedFile;
+      return Cached;
+    }
+
+    // If the source buffer is a macro, extract its full text.
+    llvm::Optional<StringRef> Source;
+    bool ForceGeneratedSourceToDisk = Opts.DWARFVersion < 5;
+    if (!ForceGeneratedSourceToDisk) {
+      auto BufferID = SM.findBufferContainingLoc(SL);
+      if (auto generatedInfo = SM.getGeneratedSourceInfo(BufferID)) {
+        // We only care about macros, so skip everything else.
+        if (generatedInfo->kind != GeneratedSourceInfo::ReplacedFunctionBody &&
+            generatedInfo->kind != GeneratedSourceInfo::PrettyPrinted)
+          if (auto *MemBuf = SM.getLLVMSourceMgr().getMemoryBuffer(BufferID))
+            Source = MemBuf->getBuffer();
+      }
     }
+    Cached.File = getOrCreateFile(
+        SM.getDisplayNameForLoc(SL, !ForceGeneratedSourceToDisk), Source);
+    std::tie(Cached.Line, Cached.Column) =
+        SM.getPresumedLineAndColumnForLoc(SL);
+    // When WinDbg finds two locations with the same line but different
+    // columns, the user must select an address when they break on that
+    // line. Also, clang does not emit column locations in CodeView for C++.
+    if (Opts.DebugInfoFormat == IRGenDebugInfoFormat::CodeView)
+      Cached.Column = 0;
     return Cached;
   }
 
@@ -295,7 +321,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
     const DeclContext *DC = D->getDeclContext()->getModuleScopeContext();
     StringRef Filename = getFilenameFromDC(DC);
     if (!Filename.empty())
-      L.File = getOrCreateFile(Filename);
+      L.File = getOrCreateFile(Filename, {});
     return L;
   }
 
@@ -306,7 +332,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
     // line. Also, clang does not emit column locations in CodeView for C++.
     bool CodeView = Opts.DebugInfoFormat == IRGenDebugInfoFormat::CodeView;
     return {FL.line, CodeView ? (uint16_t)0 : FL.column,
-            getOrCreateFile(FL.filename)};
+            getOrCreateFile(FL.filename, {})};
   }
 
   /// Use the Swift SM to figure out the actual line/column of a SourceLoc.
@@ -345,7 +371,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
         return L;
       L.Line = PresumedLoc.getLine();
       L.Column = PresumedLoc.getColumn();
-      L.File = getOrCreateFile(PresumedLoc.getFilename());
+      L.File = getOrCreateFile(PresumedLoc.getFilename(), {});
       return L;
     }
     return getSwiftFileAndLocation(D, End);
@@ -457,7 +483,8 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
 
 #endif
 
-  llvm::DIFile *getOrCreateFile(StringRef Filename) {
+  llvm::DIFile *getOrCreateFile(StringRef Filename,
+                                llvm::Optional<StringRef> Source) {
     if (Filename.empty())
       Filename = SILLocation::getCompilerGeneratedLoc()->filename;
 
@@ -486,7 +513,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
       }
     }
 
-    return createFile(Filename, llvm::None, llvm::None);
+    return createFile(Filename, llvm::None, Source);
   }
 
   /// This is effectively \p clang::CGDebugInfo::createFile().
@@ -2077,7 +2104,7 @@ IRGenDebugInfoImpl::IRGenDebugInfoImpl(const IRGenOptions &Opts,
   MainFile = (RelFile && RelDir)
                  ? createFile(SourcePath, {}, {})
                  : DBuilder.createFile(RemappedFile, RemappedDir);
-  CompilerGeneratedFile = getOrCreateFile("");
+  CompilerGeneratedFile = getOrCreateFile("", {});
 
   StringRef Sysroot = IGM.Context.SearchPathOpts.getSDKPath();
   StringRef SDK;
@@ -2287,7 +2314,7 @@ void IRGenDebugInfoImpl::addFailureMessageToCurrentLoc(IRBuilder &Builder,
   else {
     std::string FuncName = "Swift runtime failure: ";
     FuncName += failureMsg;
-    llvm::DIFile *File = getOrCreateFile({});
+    llvm::DIFile *File = getOrCreateFile({}, {});
     TrapSP = DBuilder.createFunction(
         File, FuncName, StringRef(), File, 0,
         DIFnTy, 0, llvm::DINode::FlagArtificial,

test/Macros/macro_expand.swift

@@ -24,7 +24,7 @@
 // RUN: %target-swift-frontend -swift-version 5 -emit-sil -load-plugin-library %t/%target-library-name(MacroDefinition) %s -module-name MacroUser -o - -g | %FileCheck --check-prefix CHECK-SIL %s
 
 // Debug info IR testing
-// RUN: %target-swift-frontend -swift-version 5 -emit-ir -load-plugin-library %t/%target-library-name(MacroDefinition) %s -module-name MacroUser -o - -g | %FileCheck --check-prefix CHECK-IR %s
+// RUN: %target-swift-frontend -swift-version 5 -dwarf-version 5 -emit-ir -load-plugin-library %t/%target-library-name(MacroDefinition) %s -module-name MacroUser -o - -g | %FileCheck --check-prefix CHECK-IR %s
 
 // Execution testing
 // RUN: %target-build-swift -swift-version 5 -g -load-plugin-library %t/%target-library-name(MacroDefinition) %s -o %t/main -module-name MacroUser -Xfrontend -emit-dependencies-path -Xfrontend %t/main.d -Xfrontend -emit-reference-dependencies-path -Xfrontend %t/main.swiftdeps
@@ -163,10 +163,11 @@ func testFileID(a: Int, b: Int) {
   // CHECK-AST: macro_expansion_expr type='String'{{.*}}name=line
   print("Builtin result is \(#fileID)")
   print(
-    /// CHECK-IR-DAG: ![[L1:[0-9]+]] = distinct !DILocation(line: [[@LINE+1]], column: 5
+    // CHECK-IR-DAG: ![[L1:[0-9]+]] = distinct !DILocation(line: [[@LINE+1]], column: 5
     #addBlocker(
-      /// CHECK-IR-DAG: ![[L2:[0-9]+]] = distinct !DILocation({{.*}}inlinedAt: ![[L1]])
-      /// CHECK-IR-DAG: ![[L3:[0-9]+]] = !DILocation({{.*}}inlinedAt: ![[L2]])
+      // CHECK-IR-DAG: ![[L2:[0-9]+]] = distinct !DILocation({{.*}}inlinedAt: ![[L1]])
+      // CHECK-IR-DAG: !DIFile(filename: "@__swiftmacro_9MacroUser10testFileID{{.*}}", {{.*}}source: "\22MacroUser/macro_expand.swift\22")
+
       #stringify(a - b)
       )
     )