Unverified Commit 27ebc844 authored by Alexandre Ganea's avatar Alexandre Ganea Committed by GitHub
Browse files

[clang][CodeView] Prevent the input name from appearing in LF_BUILDINFO (#194140) 

The implicit contract of an `LF_BUILDINFO` record (represented in LLVM
by
[`BuildInfoRecord`](https://github.com/llvm/llvm-project/blob/6f0b55ec55f3e5e1ccc0d6b0d04a307479218768/llvm/include/llvm/DebugInfo/CodeView/TypeRecord.h#L667))
is that its `CommandLine` field should not contain the input source file
— a separate `SourceFile` field is reserved for that.

When the command-line flattening was moved from `llvm/` to `clang/` in
#106369, the comparison value used to identify and strip the source
positional was switched from `MainSourceFile->getFilename()` (the full
input path resolved by clang) to `CodeGenOpts.MainFileName` (just the
basename, set via `-main-file-name`). As a result, when the driver is
invoked with an absolute source path the cc1 positional is that absolute
path and no longer matches `MainFileName`, so the source filename leaks
into `CommandLine` as a trailing positional cc1 argument.

This is a regression in Clang 20. It breaks downstream tooling such as
Live++, whose unity-splitting feature relies on the embedded command
line being the cc1 invocation minus the source. Reported in #193900.

This PR restores the previous behavior by passing the resolved frontend
input path(s) to `flattenClangCommandLine` and including them in the
equality check that strips the source positional. The basename match
against `MainFileName` is kept for the relative-input case. A regression
test (and a symmetric relative-path test) is added to
`clang/test/DebugInfo/Generic/codeview-buildinfo.c`.

Should fix #193900.
parent bd7cd403

clang/lib/CodeGen/BackendUtil.cpp

+19 −3
Original line number Diff line number Diff line
@@ -323,7 +323,8 @@ static bool actionRequiresCodeGen(BackendAction Action) { 
}



static std::string flattenClangCommandLine(ArrayRef<std::string> Args,

                                           StringRef MainFilename) {

                                           StringRef MainFilename,

                                           ArrayRef<StringRef> InputFiles) {

  if (Args.empty())

    return std::string{};
@@ -342,7 +343,15 @@ static std::string flattenClangCommandLine(ArrayRef<std::string> Args, 
      i++; // Skip this argument and next one.

      continue;

    }

    if (Arg.starts_with("-object-file-name") || Arg == MainFilename)

    if (Arg.starts_with("-object-file-name"))

      continue;

    // Strip the source positional, matching either MainFilename (the

    // -main-file-name basename) or one of the resolved frontend input paths

    // (which is what the cc1 positional looks like for an absolute driver

    // input). Avoid a generic basename match: it would also strip values of

    // args like `-include <path>` whose trailing component happens to equal

    // the source basename.

    if (Arg == MainFilename || llvm::is_contained(InputFiles, Arg))

      continue;

    // Skip fmessage-length for reproducibility.

    if (Arg.starts_with("-fmessage-length"))
@@ -519,8 +528,15 @@ static bool initTargetOptions(const CompilerInstance &CI, 
      Options.MCOptions.IASSearchPaths.push_back(

          Entry.IgnoreSysRoot ? Entry.Path : HSOpts.Sysroot + Entry.Path);

  Options.MCOptions.Argv0 = CodeGenOpts.Argv0 ? CodeGenOpts.Argv0 : "";

  // Pass the resolved frontend inputs so flattenClangCommandLine can strip

  // the cc1 source positional even when the driver received an absolute path

  // (which won't match CodeGenOpts.MainFileName, that's just the basename).

  SmallVector<StringRef, 1> InputFiles;

  for (const auto &Input : CI.getFrontendOpts().Inputs)

    if (Input.isFile())

      InputFiles.push_back(Input.getFile());

  Options.MCOptions.CommandlineArgs = flattenClangCommandLine(

      CodeGenOpts.CommandLineArgs, CodeGenOpts.MainFileName);

      CodeGenOpts.CommandLineArgs, CodeGenOpts.MainFileName, InputFiles);

  Options.MCOptions.AsSecureLogFile = CodeGenOpts.AsSecureLogFile;

  Options.MCOptions.PPCUseFullRegisterNames =

      CodeGenOpts.PPCUseFullRegisterNames;

clang/test/DebugInfo/Generic/codeview-buildinfo.c

+33 −0
Original line number Diff line number Diff line
@@ -12,6 +12,18 @@ 
// RUN: %clang_cl -gcodeview-command-line --target=i686-windows-msvc -Xclang -fmessage-length=100 /c /Z7 /Fo%t.obj -- %s

// RUN: llvm-pdbutil dump --types %t.obj | FileCheck %s --check-prefix MESSAGELEN



// The source filename must be stripped from the embedded cc1 command line

// whether it's passed to the driver as an absolute or a relative path.

// See https://github.com/llvm/llvm-project/issues/193900.



// RUN: %clang_cl --target=i686-windows-msvc /c /Z7 /Fo%t.obj -- %s

// RUN: llvm-pdbutil dump --types %t.obj | FileCheck %s --check-prefix ABSPATH



// RUN: rm -rf %t.relpath && mkdir %t.relpath

// RUN: cp %s %t.relpath/hello.cpp

// RUN: cd %t.relpath && %clang_cl --target=i686-windows-msvc /c /Z7 /Fo:hello.obj -- hello.cpp

// RUN: llvm-pdbutil dump --types %t.relpath/hello.obj | FileCheck %s --check-prefix RELPATH



int main(void) { return 42; }



// CHECK:                       Types (.debug$T)
@@ -45,3 +57,24 @@ int main(void) { return 42; } 
// MESSAGELEN: ============================================================

// MESSAGELEN: 0x{{.+}} | LF_BUILDINFO [size = {{.+}}]

// MESSAGELEN-NOT: -fmessage-length



// The cmdline is the 5th argument of LF_BUILDINFO. The source filename must

// not appear inside its value (the SourceFile field, the 3rd argument, is

// reserved for that).

// ABSPATH:       0x{{.+}} | LF_BUILDINFO [size = {{.+}}]

// ABSPATH-NEXT:           0x{{.*}}: `{{.*}}`

// ABSPATH-NEXT:           0x{{.*}}: `{{.*}}`

// ABSPATH-NEXT:           0x{{.*}}: `{{.+[\\/]codeview-buildinfo\.c}}`

// ABSPATH-NEXT:           0x{{.*}}: ``

// ABSPATH-NEXT:           0x{{.*}}: `

// ABSPATH-NOT:   {{[^"]*[\\/]codeview-buildinfo\.c}}

// ABSPATH-SAME:  `



// RELPATH:       0x{{.+}} | LF_BUILDINFO [size = {{.+}}]

// RELPATH-NEXT:           0x{{.*}}: `{{.*}}`

// RELPATH-NEXT:           0x{{.*}}: `{{.*}}`

// RELPATH-NEXT:           0x{{.*}}: `{{.*hello\.cpp}}`

// RELPATH-NEXT:           0x{{.*}}: ``

// RELPATH-NEXT:           0x{{.*}}: `

// RELPATH-NOT:   {{hello\.cpp}}

// RELPATH-SAME:  `