Support Debug Info path remapping

Add support for the `-fdebug-prefix-map=` option as in GCC.  The syntax is
`-fdebug-prefix-map=OLD=NEW`.  When compiling files from a path beginning with
OLD, change the debug info to indicate the path as start with NEW.  This is
particularly helpful if you are preprocessing in one path and compiling in
another (e.g. for a build cluster with distcc).

Note that the linearity of the implementation is not as terrible as it may seem.
This is normally done once per file with an expectation that the map will be
small (1-2) entries, making this roughly linear in the number of input paths.

Addresses PR24619.

llvm-svn: 250094

1 files changed, 20 insertions, 8 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 792b1b09a0f..09912493433 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -47,6 +47,8 @@ CGDebugInfo::CGDebugInfo(CodeGenModule &CGM)
     : CGM(CGM), DebugKind(CGM.getCodeGenOpts().getDebugInfo()),
       DebugTypeExtRefs(CGM.getCodeGenOpts().DebugTypeExtRefs),
       DBuilder(CGM.getModule()) {
+  for (const auto &KV : CGM.getCodeGenOpts().DebugPrefixMap)
+    DebugPrefixMap[KV.first] = KV.second;
   CreateCompileUnit();
 }
 
@@ -255,14 +257,16 @@ StringRef CGDebugInfo::getClassName(const RecordDecl *RD) {
 llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
   if (!Loc.isValid())
     // If Location is not valid then use main input file.
-    return DBuilder.createFile(TheCU->getFilename(), TheCU->getDirectory());
+    return DBuilder.createFile(remapDIPath(TheCU->getFilename()),
+                               remapDIPath(TheCU->getDirectory()));
 
   SourceManager &SM = CGM.getContext().getSourceManager();
   PresumedLoc PLoc = SM.getPresumedLoc(Loc);
 
   if (PLoc.isInvalid() || StringRef(PLoc.getFilename()).empty())
     // If the location is not valid then use main input file.
-    return DBuilder.createFile(TheCU->getFilename(), TheCU->getDirectory());
+    return DBuilder.createFile(remapDIPath(TheCU->getFilename()),
+                               remapDIPath(TheCU->getDirectory()));
 
   // Cache the results.
   const char *fname = PLoc.getFilename();
@@ -274,15 +278,23 @@ llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
       return cast<llvm::DIFile>(V);
   }
 
-  llvm::DIFile *F =
-      DBuilder.createFile(PLoc.getFilename(), getCurrentDirname());
+  llvm::DIFile *F = DBuilder.createFile(remapDIPath(PLoc.getFilename()),
+                                        remapDIPath(getCurrentDirname()));
 
   DIFileCache[fname].reset(F);
   return F;
 }
 
 llvm::DIFile *CGDebugInfo::getOrCreateMainFile() {
-  return DBuilder.createFile(TheCU->getFilename(), TheCU->getDirectory());
+  return DBuilder.createFile(remapDIPath(TheCU->getFilename()),
+                             remapDIPath(TheCU->getDirectory()));
+}
+
+std::string CGDebugInfo::remapDIPath(StringRef Path) const {
+  for (const auto &Entry : DebugPrefixMap)
+    if (Path.startswith(Entry.first))
+      return (Twine(Entry.second) + Path.substr(Entry.first.size())).str();
+  return Path.str();
 }
 
 unsigned CGDebugInfo::getLineNumber(SourceLocation Loc) {
@@ -338,7 +350,7 @@ void CGDebugInfo::CreateCompileUnit() {
   // file to determine the real absolute path for the file.
   std::string MainFileDir;
   if (const FileEntry *MainFile = SM.getFileEntryForID(SM.getMainFileID())) {
-    MainFileDir = MainFile->getDir()->getName();
+    MainFileDir = remapDIPath(MainFile->getDir()->getName());
     if (MainFileDir != ".") {
       llvm::SmallString<1024> MainFileDirSS(MainFileDir);
       llvm::sys::path::append(MainFileDirSS, MainFileName);
@@ -371,8 +383,8 @@ void CGDebugInfo::CreateCompileUnit() {
   // Create new compile unit.
   // FIXME - Eliminate TheCU.
   TheCU = DBuilder.createCompileUnit(
-      LangTag, MainFileName, getCurrentDirname(), Producer, LO.Optimize,
-      CGM.getCodeGenOpts().DwarfDebugFlags, RuntimeVers,
+      LangTag, remapDIPath(MainFileName), remapDIPath(getCurrentDirname()),
+      Producer, LO.Optimize, CGM.getCodeGenOpts().DwarfDebugFlags, RuntimeVers,
       CGM.getCodeGenOpts().SplitDwarfFile,
       DebugKind <= CodeGenOptions::DebugLineTablesOnly
           ? llvm::DIBuilder::LineTablesOnly