[clang] 441f5b0 - [clang] Infer compilation directory in driver

[via cfe-commits]

Author: Steven Wu
Date: 2025-07-31T10:39:06-07:00
New Revision: 441f5b0e367ceee5b8b12d14c0d1ebb1c29fa414

URL: https://github.com/llvm/llvm-project/commit/441f5b0e367ceee5b8b12d14c0d1ebb1c29fa414
DIFF: https://github.com/llvm/llvm-project/commit/441f5b0e367ceee5b8b12d14c0d1ebb1c29fa414.diff

LOG: [clang] Infer compilation directory in driver

When building with -fdebug-compilation-dir/-fcoverige-compilation-dir,
infer the compilation directory in clang driver, rather than try to
fallback to VFS current working directory lookup during CodeGen. This
allows compilation directory to be used as it is passed via cc1 flag and
the value can be empty to remove dependency on CWD if needed.

Reviewers: adrian-prantl, dwblaikie

Reviewed By: adrian-prantl, dwblaikie

Pull Request: https://github.com/llvm/llvm-project/pull/150112

Added: 
    

Modified: 
    clang/lib/Driver/ToolChains/Clang.cpp
    clang/test/Driver/compilation-dir.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index f4674a5b71549..4e1b1d9e33621 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -226,17 +226,19 @@ static bool ShouldEnableAutolink(const ArgList &Args, const ToolChain &TC,
 static const char *addDebugCompDirArg(const ArgList &Args,
                                       ArgStringList &CmdArgs,
                                       const llvm::vfs::FileSystem &VFS) {
+  std::string DebugCompDir;
   if (Arg *A = Args.getLastArg(options::OPT_ffile_compilation_dir_EQ,
-                               options::OPT_fdebug_compilation_dir_EQ)) {
-    if (A->getOption().matches(options::OPT_ffile_compilation_dir_EQ))
-      CmdArgs.push_back(Args.MakeArgString(Twine("-fdebug-compilation-dir=") +
-                                           A->getValue()));
+                               options::OPT_fdebug_compilation_dir_EQ))
+    DebugCompDir = A->getValue();
+
+  if (DebugCompDir.empty()) {
+    if (llvm::ErrorOr<std::string> CWD = VFS.getCurrentWorkingDirectory())
+      DebugCompDir = std::move(*CWD);
     else
-      A->render(Args, CmdArgs);
-  } else if (llvm::ErrorOr<std::string> CWD =
-                 VFS.getCurrentWorkingDirectory()) {
-    CmdArgs.push_back(Args.MakeArgString("-fdebug-compilation-dir=" + *CWD));
+      return nullptr;
   }
+  CmdArgs.push_back(
+      Args.MakeArgString("-fdebug-compilation-dir=" + DebugCompDir));
   StringRef Path(CmdArgs.back());
   return Path.substr(Path.find('=') + 1).data();
 }
@@ -525,17 +527,17 @@ static void addPGOAndCoverageFlags(const ToolChain &TC, Compilation &C,
     CmdArgs.push_back("-fcoverage-mcdc");
   }
 
+  StringRef CoverageCompDir;
   if (Arg *A = Args.getLastArg(options::OPT_ffile_compilation_dir_EQ,
-                               options::OPT_fcoverage_compilation_dir_EQ)) {
-    if (A->getOption().matches(options::OPT_ffile_compilation_dir_EQ))
-      CmdArgs.push_back(Args.MakeArgString(
-          Twine("-fcoverage-compilation-dir=") + A->getValue()));
-    else
-      A->render(Args, CmdArgs);
-  } else if (llvm::ErrorOr<std::string> CWD =
-                 D.getVFS().getCurrentWorkingDirectory()) {
-    CmdArgs.push_back(Args.MakeArgString("-fcoverage-compilation-dir=" + *CWD));
-  }
+                               options::OPT_fcoverage_compilation_dir_EQ))
+    CoverageCompDir = A->getValue();
+  if (CoverageCompDir.empty()) {
+    if (auto CWD = D.getVFS().getCurrentWorkingDirectory())
+      CmdArgs.push_back(
+          Args.MakeArgString(Twine("-fcoverage-compilation-dir=") + *CWD));
+  } else
+    CmdArgs.push_back(Args.MakeArgString(Twine("-fcoverage-compilation-dir=") +
+                                         CoverageCompDir));
 
   if (Args.hasArg(options::OPT_fprofile_exclude_files_EQ)) {
     auto *Arg = Args.getLastArg(options::OPT_fprofile_exclude_files_EQ);

diff  --git a/clang/test/Driver/compilation-dir.c b/clang/test/Driver/compilation-dir.c
index dbe801c9f5fcb..70a117b064e66 100644
--- a/clang/test/Driver/compilation-dir.c
+++ b/clang/test/Driver/compilation-dir.c
@@ -8,3 +8,8 @@
 // RUN: %clang -### -integrated-as -ffile-compilation-dir=. -x assembler %s 2>&1 | FileCheck -check-prefixes=CHECK-DEBUG-COMPILATION-DIR %s
 // CHECK-DEBUG-COMPILATION-DIR: "-fdebug-compilation-dir=."
 // CHECK-DEBUG-COMPILATION-DIR-NOT: "-ffile-compilation-dir=."
+
+// RUN: %clang -### -S %s -working-directory %S 2>&1 | FileCheck -check-prefix=CHECK-CWD %s
+// RUN: cd %S
+// RUN: %clang -### -S %s 2>&1 | FileCheck -check-prefix=CHECK-CWD %s
+// CHECK-CWD: -fdebug-compilation-dir={{.*}}Driver