[clang] Use File Location for debug info resolution.

[SergejSalnikov]

To improve debuggability, the macro arguments should be resolved to their original location rather than macro expansion location.

Macro.debug.webm

fixes #160667

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[llvmbot]

@llvm/pr-subscribers-debuginfo
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-codegen

Author: SKill (SergejSalnikov)

Changes

To improve deniability, the macro arguments should be resolved to their original location rather than macro expansion location.

Macro.debug.webm

fixes #160667

---

Full diff: https://github.com/llvm/llvm-project/pull/163982.diff

1 Files Affected:

• (modified) clang/lib/CodeGen/CGDebugInfo.cpp (+9-7)

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 12e2813ef2ec7..224a699784303 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -318,7 +318,7 @@ void CGDebugInfo::setLocation(SourceLocation Loc) {
   if (Loc.isInvalid())
     return;
 
-  CurLoc = CGM.getContext().getSourceManager().getExpansionLoc(Loc);
+  CurLoc = CGM.getContext().getSourceManager().getFileLoc(Loc);
 
   // If we've changed files in the middle of a lexical scope go ahead
   // and create a new lexical scope with file node if it's different
@@ -545,7 +545,7 @@ llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
     FileName = TheCU->getFile()->getFilename();
     CSInfo = TheCU->getFile()->getChecksum();
   } else {
-    PresumedLoc PLoc = SM.getPresumedLoc(Loc);
+    PresumedLoc PLoc = SM.getPresumedLoc(SM.getFileLoc(Loc));
     FileName = PLoc.getFilename();
 
     if (FileName.empty()) {
@@ -572,7 +572,8 @@ llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
     if (CSKind)
       CSInfo.emplace(*CSKind, Checksum);
   }
-  return createFile(FileName, CSInfo, getSource(SM, SM.getFileID(Loc)));
+  return createFile(FileName, CSInfo,
+                    getSource(SM, SM.getFileID(SM.getExpansionLoc(Loc))));
 }
 
 llvm::DIFile *CGDebugInfo::createFile(
@@ -627,7 +628,7 @@ unsigned CGDebugInfo::getLineNumber(SourceLocation Loc) {
   if (Loc.isInvalid())
     return 0;
   SourceManager &SM = CGM.getContext().getSourceManager();
-  return SM.getPresumedLoc(Loc).getLine();
+  return SM.getPresumedLoc(SM.getFileLoc(Loc)).getLine();
 }
 
 unsigned CGDebugInfo::getColumnNumber(SourceLocation Loc, bool Force) {
@@ -639,7 +640,7 @@ unsigned CGDebugInfo::getColumnNumber(SourceLocation Loc, bool Force) {
   if (Loc.isInvalid() && CurLoc.isInvalid())
     return 0;
   SourceManager &SM = CGM.getContext().getSourceManager();
-  PresumedLoc PLoc = SM.getPresumedLoc(Loc.isValid() ? Loc : CurLoc);
+  PresumedLoc PLoc = SM.getPresumedLoc(Loc.isValid() ? SM.getFileLoc(Loc) : CurLoc);
   return PLoc.isValid() ? PLoc.getColumn() : 0;
 }
 
@@ -4973,7 +4974,7 @@ void CGDebugInfo::EmitLocation(CGBuilderTy &Builder, SourceLocation Loc) {
   // Update our current location
   setLocation(Loc);
 
-  if (CurLoc.isInvalid() || CurLoc.isMacroID() || LexicalBlockStack.empty())
+  if (CurLoc.isInvalid() || LexicalBlockStack.empty())
     return;
 
   llvm::MDNode *Scope = LexicalBlockStack.back();
@@ -6244,7 +6245,8 @@ void CGDebugInfo::EmitGlobalAlias(const llvm::GlobalValue *GV,
 void CGDebugInfo::AddStringLiteralDebugInfo(llvm::GlobalVariable *GV,
                                             const StringLiteral *S) {
   SourceLocation Loc = S->getStrTokenLoc(0);
-  PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
+  SourceManager &SM = CGM.getContext().getSourceManager();
+  PresumedLoc PLoc = SM.getPresumedLoc(SM.getFileLoc(Loc));
   if (!PLoc.isValid())
     return;
 

[github-actions]

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff origin/main HEAD --extensions c,cpp -- clang/test/DebugInfo/Generic/macro-info.c clang/lib/CodeGen/CGDebugInfo.cpp --diff_from_common_commit

⚠️
The reproduction instructions above might return results for more than one PR
in a stack if you are using a stacked PR workflow. You can limit the results by
changing origin/main to the base branch/commit you want to compare against.
⚠️

View the diff from clang-format here.

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 224a69978..60ed0facf 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -640,7 +640,8 @@ unsigned CGDebugInfo::getColumnNumber(SourceLocation Loc, bool Force) {
   if (Loc.isInvalid() && CurLoc.isInvalid())
     return 0;
   SourceManager &SM = CGM.getContext().getSourceManager();
-  PresumedLoc PLoc = SM.getPresumedLoc(Loc.isValid() ? SM.getFileLoc(Loc) : CurLoc);
+  PresumedLoc PLoc =
+      SM.getPresumedLoc(Loc.isValid() ? SM.getFileLoc(Loc) : CurLoc);
   return PLoc.isValid() ? PLoc.getColumn() : 0;
 }
 

[dwblaikie]

Seems worth a go - @adrian-prantl @JDevlieghere @jmorse you folks on board with this, or want some more time to experiment (maybe have it behind a flag, etc)?