llvm · cachemeifyoucan · Jul 21, 2025 · Jul 21, 2025 · Jul 21, 2025 · qiongsiwu
diff --git a/clang/include/clang/Basic/CodeGenOptions.h b/clang/include/clang/Basic/CodeGenOptions.h
@@ -231,6 +231,9 @@ class CodeGenOptions : public CodeGenOptionsBase {
   /// The string to embed in coverage mapping as the current working directory.
   std::string CoverageCompilationDir;
 
+  /// No compilation directory, ignore debug/coverage compilation directory.
+  bool NoCompilationDir;
+
   /// The string to embed in the debug information for the compile unit, if
   /// non-empty.
   std::string DwarfDebugFlags;

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
@@ -1725,6 +1725,11 @@ def fcoverage_compilation_dir_EQ : Joined<["-"], "fcoverage-compilation-dir=">,
 def ffile_compilation_dir_EQ : Joined<["-"], "ffile-compilation-dir=">, Group<f_Group>,
     Visibility<[ClangOption, CLOption, DXCOption]>,
     HelpText<"The compilation directory to embed in the debug info and coverage mapping.">;
+def fno_compilation_dir: Flag<["-"], "fno-compilation-dir">,
+    Visibility<[ClangOption, CC1Option]>,
+    Group<f_Group>,
+    HelpText<"Ignore compilation directories">,
+    MarshallingInfoFlag<CodeGenOpts<"NoCompilationDir">>;
 defm debug_info_for_profiling : BoolFOption<"debug-info-for-profiling",
   CodeGenOpts<"DebugInfoForProfiling">, DefaultFalse,
   PosFlag<SetTrue, [], [ClangOption, CC1Option],

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -643,6 +643,9 @@ unsigned CGDebugInfo::getColumnNumber(SourceLocation Loc, bool Force) {
 }
 
 StringRef CGDebugInfo::getCurrentDirname() {
+  if (CGM.getCodeGenOpts().NoCompilationDir)
+    return StringRef();
+
   if (!CGM.getCodeGenOpts().DebugCompilationDir.empty())
     return CGM.getCodeGenOpts().DebugCompilationDir;
 
@@ -3246,6 +3249,9 @@ llvm::DIModule *CGDebugInfo::getOrCreateModuleRef(ASTSourceDescriptor Mod,
     std::string Remapped = remapDIPath(Path);
     StringRef Relative(Remapped);
     StringRef CompDir = TheCU->getDirectory();
+    if (CompDir.empty())
+      return Remapped;
+
     if (Relative.consume_front(CompDir))
       Relative.consume_front(llvm::sys::path::get_separator());
 

diff --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -2449,6 +2449,9 @@ CoverageMappingModuleGen::CoverageMappingModuleGen(
     : CGM(CGM), SourceInfo(SourceInfo) {}
 
 std::string CoverageMappingModuleGen::getCurrentDirname() {
+  if (CGM.getCodeGenOpts().NoCompilationDir)
+    return {};
+
   if (!CGM.getCodeGenOpts().CoverageCompilationDir.empty())
     return CGM.getCodeGenOpts().CoverageCompilationDir;
 

diff --git a/clang/lib/CodeGen/ObjectFilePCHContainerWriter.cpp b/clang/lib/CodeGen/ObjectFilePCHContainerWriter.cpp
@@ -164,6 +164,8 @@ class PCHContainerGenerator : public ASTConsumer {
     CodeGenOpts.DwarfVersion = CI.getCodeGenOpts().DwarfVersion;
     CodeGenOpts.DebugCompilationDir =
         CI.getInvocation().getCodeGenOpts().DebugCompilationDir;
+    CodeGenOpts.NoCompilationDir =
+        CI.getInvocation().getCodeGenOpts().NoCompilationDir;
     CodeGenOpts.DebugPrefixMap =
         CI.getInvocation().getCodeGenOpts().DebugPrefixMap;
     CodeGenOpts.DebugStrictDwarf = CI.getCodeGenOpts().DebugStrictDwarf;

diff --git a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
@@ -144,30 +144,9 @@ static void optimizeDiagnosticOpts(DiagnosticOptions &Opts,
 
 static void optimizeCWD(CowCompilerInvocation &BuildInvocation, StringRef CWD) {
   BuildInvocation.getMutFileSystemOpts().WorkingDir.clear();
-  if (BuildInvocation.getCodeGenOpts().DwarfVersion) {
-    // It is necessary to explicitly set the DebugCompilationDir
-    // to a common directory (e.g. root) if IgnoreCWD is true.
-    // When IgnoreCWD is true, the module's content should not
-    // depend on the current working directory. However, if dwarf
-    // information is needed (when CGOpts.DwarfVersion is
-    // non-zero), then CGOpts.DebugCompilationDir must be
-    // populated, because otherwise the current working directory
-    // will be automatically embedded in the dwarf information in
-    // the pcm, contradicting the assumption that it is safe to
-    // ignore the CWD. Thus in such cases,
-    // CGOpts.DebugCompilationDir is explicitly set to a common
-    // directory.
-    // FIXME: It is still excessive to create a copy of
-    // CodeGenOpts for each module. Since we do not modify the
-    // CodeGenOpts otherwise per module, the following code
-    // ends up generating identical CodeGenOpts for each module
-    // with DebugCompilationDir pointing to the root directory.
-    // We can optimize this away by creating a _single_ copy of
-    // CodeGenOpts whose DebugCompilationDir points to the root
-    // directory and reuse it across modules.
-    BuildInvocation.getMutCodeGenOpts().DebugCompilationDir =
-        llvm::sys::path::root_path(CWD);
-  }
+  // To avoid clang inferring working directory from CWD, set to ignore
+  // compilation directory.
+  BuildInvocation.getMutCodeGenOpts().NoCompilationDir = true;
 }
 
 static std::vector<std::string> splitString(std::string S, char Separator) {
@@ -222,6 +201,9 @@ void dependencies::resetBenignCodeGenOptions(frontend::ActionKind ProgramAction,
     CGOpts.ProfileInstrumentUsePath.clear();
     CGOpts.SampleProfileFile.clear();
     CGOpts.ProfileRemappingFile.clear();
+    // To avoid clang inferring compilation directory from CWD, set
+    // -no-compilation-dir option.
+    CGOpts.NoCompilationDir = true;
   }
 }
 

diff --git a/clang/test/ClangScanDeps/modules-debug-dir.c b/clang/test/ClangScanDeps/modules-debug-dir.c
@@ -1,12 +1,16 @@
-// REQUIRES: shell
-
 // RUN: rm -rf %t
 // RUN: split-file %s %t
 // RUN: sed -e "s|DIR|%/t|g" %t/cdb.json.in > %t/cdb.json
 // RUN: clang-scan-deps -compilation-database %t/cdb.json -format \
 // RUN:   experimental-full -optimize-args=all > %t/result.json
 // RUN: cat %t/result.json | sed 's:\\\\\?:/:g' | FileCheck %s
 
+// RUN: %deps-to-rsp %t/result.json --module-name=mod > %t/mod.rsp
+// RUN: %clang @%t/mod.rsp -o %t/mod.pcm
+// RUN: llvm-dwarfdump --debug-info %t/mod.pcm | FileCheck %s --check-prefix=DWARF
+// DWARF: DW_TAG_compile_unit
+// DWARF-NOT: DW_AT_comp_dir
+
 //--- cdb.json.in
 [{
   "directory": "DIR",
@@ -28,5 +32,6 @@ module mod {
 // directory when current working directory optimization is in effect.
 // CHECK:  "modules": [
 // CHECK: "command-line": [
-// CHECK: "-fdebug-compilation-dir={{\/|.*:(\\)?}}",
+// CHECK: "-fno-compilation-dir"
+// CHECK-NOT: -fdebug-compilation-dir
 // CHECK:  "translation-units": [
diff --git a/clang/test/CodeGen/debug-info-compilation-dir.c b/clang/test/CodeGen/debug-info-compilation-dir.c
@@ -7,3 +7,10 @@
 // RUN: %clang_cc1 -emit-llvm -debug-info-kind=limited %s -o - | FileCheck -check-prefix=CHECK-DIR %s
 // CHECK-DIR: CodeGen
 
+/// Test path remapping.
+// RUN: %clang_cc1 -fdebug-compilation-dir %S -main-file-name %s -emit-llvm -debug-info-kind=limited %s -o - | FileCheck -check-prefix=CHECK-ABS %s
+// CHECK-ABS: DIFile(filename: "{{.*}}debug-info-compilation-dir.c", directory: "{{.*}}CodeGen")
+
+// RUN: %clang_cc1 -fno-compilation-dir -main-file-name %s -emit-llvm -debug-info-kind=limited %s -o - | FileCheck -check-prefix=CHECK-NOMAP %s
+// CHECK-NOMAP: DIFile(filename: "{{.*}}debug-info-compilation-dir.c", directory: "")
+