[llvm-branch-commits] [clang] release/22.x: [clang][CodeView] Prevent the input name from appearing in LF_BUILDINFO (#194140) (PR #194348)
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Mon Apr 27 04:33:09 PDT 2026
https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/194348
Backport 27ebc84
Requested by: @aganea
>From 057879be538bf5c0127bf6a3eccc36fae229b0ca Mon Sep 17 00:00:00 2001
From: Alexandre Ganea <aganea at havenstudios.com>
Date: Mon, 27 Apr 2026 07:21:49 -0400
Subject: [PATCH] [clang][CodeView] Prevent the input name from appearing in
LF_BUILDINFO (#194140)
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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.
(cherry picked from commit 27ebc844f542c93991675a22dcd813020963819f)
---
clang/lib/CodeGen/BackendUtil.cpp | 22 +++++++++++--
.../DebugInfo/Generic/codeview-buildinfo.c | 33 +++++++++++++++++++
2 files changed, 52 insertions(+), 3 deletions(-)
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index d411ef1bf8763..5f147c3754246 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -322,7 +322,8 @@ 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{};
@@ -341,7 +342,15 @@ 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;
diff --git a/clang/test/DebugInfo/Generic/codeview-buildinfo.c b/clang/test/DebugInfo/Generic/codeview-buildinfo.c
index ee6f772944d84..b930e3cc642c4 100644
--- a/clang/test/DebugInfo/Generic/codeview-buildinfo.c
+++ b/clang/test/DebugInfo/Generic/codeview-buildinfo.c
@@ -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: `
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