[clang] [clang] Delay normalization of `-fmodules-cache-path` (PR #150123)
Jan Svoboda via cfe-commits
cfe-commits at lists.llvm.org
Wed Sep 3 15:02:03 PDT 2025
https://github.com/jansvoboda11 updated https://github.com/llvm/llvm-project/pull/150123
>From a3221d4adcacb3cb53edf785a9b21028188797f5 Mon Sep 17 00:00:00 2001
From: Jan Svoboda <jan_svoboda at apple.com>
Date: Tue, 22 Jul 2025 14:46:09 -0700
Subject: [PATCH] [clang] Delay normalization of `-fmodules-cache-path`
---
clang/include/clang/Driver/Options.td | 3 +-
clang/lib/Frontend/CompilerInstance.cpp | 7 +-
clang/lib/Frontend/CompilerInvocation.cpp | 20 +----
clang/lib/Serialization/ASTWriter.cpp | 77 +++++++------------
...dules-cache-path-canonicalization-output.c | 18 +++++
5 files changed, 55 insertions(+), 70 deletions(-)
create mode 100644 clang/test/Modules/modules-cache-path-canonicalization-output.c
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 49e917a6a0786..40486e3b169aa 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3281,7 +3281,8 @@ defm declspec : BoolOption<"f", "declspec",
def fmodules_cache_path : Joined<["-"], "fmodules-cache-path=">, Group<i_Group>,
Flags<[]>, Visibility<[ClangOption, CC1Option]>,
MetaVarName<"<directory>">,
- HelpText<"Specify the module cache path">;
+ HelpText<"Specify the module cache path">,
+ MarshallingInfoString<HeaderSearchOpts<"ModuleCachePath">>;
def fmodules_user_build_path : Separate<["-"], "fmodules-user-build-path">, Group<i_Group>,
Flags<[]>, Visibility<[ClangOption, CC1Option]>,
MetaVarName<"<directory>">,
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index b2c566f44c27f..24222dfe70a8e 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -548,9 +548,14 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
}
std::string CompilerInstance::getSpecificModuleCachePath(StringRef ModuleHash) {
+ if (getHeaderSearchOpts().ModuleCachePath.empty())
+ return "";
+
// Set up the module path, including the hash for the module-creation options.
SmallString<256> SpecificModuleCache(getHeaderSearchOpts().ModuleCachePath);
- if (!SpecificModuleCache.empty() && !getHeaderSearchOpts().DisableModuleHash)
+ FileMgr->makeAbsolutePath(SpecificModuleCache);
+ llvm::sys::path::remove_dots(SpecificModuleCache);
+ if (!getHeaderSearchOpts().DisableModuleHash)
llvm::sys::path::append(SpecificModuleCache, ModuleHash);
return std::string(SpecificModuleCache);
}
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 8411d00cc7812..931766db4b0c8 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -3315,9 +3315,6 @@ static void GenerateHeaderSearchArgs(const HeaderSearchOptions &Opts,
if (Opts.UseLibcxx)
GenerateArg(Consumer, OPT_stdlib_EQ, "libc++");
- if (!Opts.ModuleCachePath.empty())
- GenerateArg(Consumer, OPT_fmodules_cache_path, Opts.ModuleCachePath);
-
for (const auto &File : Opts.PrebuiltModuleFiles)
GenerateArg(Consumer, OPT_fmodule_file, File.first + "=" + File.second);
@@ -3420,8 +3417,7 @@ static void GenerateHeaderSearchArgs(const HeaderSearchOptions &Opts,
}
static bool ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args,
- DiagnosticsEngine &Diags,
- const std::string &WorkingDir) {
+ DiagnosticsEngine &Diags) {
unsigned NumErrorsBefore = Diags.getNumErrors();
HeaderSearchOptions *HeaderSearchOpts = &Opts;
@@ -3434,17 +3430,6 @@ static bool ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args,
if (const Arg *A = Args.getLastArg(OPT_stdlib_EQ))
Opts.UseLibcxx = (strcmp(A->getValue(), "libc++") == 0);
- // Canonicalize -fmodules-cache-path before storing it.
- SmallString<128> P(Args.getLastArgValue(OPT_fmodules_cache_path));
- if (!(P.empty() || llvm::sys::path::is_absolute(P))) {
- if (WorkingDir.empty())
- llvm::sys::fs::make_absolute(P);
- else
- llvm::sys::fs::make_absolute(WorkingDir, P);
- }
- llvm::sys::path::remove_dots(P);
- Opts.ModuleCachePath = std::string(P);
-
// Only the -fmodule-file=<name>=<file> form.
for (const auto *A : Args.filtered(OPT_fmodule_file)) {
StringRef Val = A->getValue();
@@ -5021,8 +5006,7 @@ bool CompilerInvocation::CreateFromArgsImpl(
InputKind DashX = Res.getFrontendOpts().DashX;
ParseTargetArgs(Res.getTargetOpts(), Args, Diags);
llvm::Triple T(Res.getTargetOpts().Triple);
- ParseHeaderSearchArgs(Res.getHeaderSearchOpts(), Args, Diags,
- Res.getFileSystemOpts().WorkingDir);
+ ParseHeaderSearchArgs(Res.getHeaderSearchOpts(), Args, Diags);
if (Res.getFrontendOpts().GenReducedBMI ||
Res.getFrontendOpts().ProgramAction ==
frontend::GenerateReducedModuleInterface ||
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 293b67aac0219..29e42b20b16eb 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -1185,51 +1185,36 @@ static bool cleanPathForOutput(FileManager &FileMgr,
return Changed | llvm::sys::path::remove_dots(Path);
}
-/// Adjusts the given filename to only write out the portion of the
-/// filename that is not part of the system root directory.
+/// Adjusts the given filename to only write out the portion of the filename
+/// that is not part of the base directory.
///
/// \param Filename the file name to adjust.
///
-/// \param BaseDir When non-NULL, the PCH file is a relocatable AST file and
-/// the returned filename will be adjusted by this root directory.
+/// \param BasePath When not empty, the AST file is relocatable and the returned
+/// filename will be adjusted to be relative to this path.
///
-/// \returns either the original filename (if it needs no adjustment) or the
-/// adjusted filename (which points into the @p Filename parameter).
-static const char *
-adjustFilenameForRelocatableAST(const char *Filename, StringRef BaseDir) {
- assert(Filename && "No file name to adjust?");
-
- if (BaseDir.empty())
- return Filename;
-
- // Verify that the filename and the system root have the same prefix.
- unsigned Pos = 0;
- for (; Filename[Pos] && Pos < BaseDir.size(); ++Pos)
- if (Filename[Pos] != BaseDir[Pos])
- return Filename; // Prefixes don't match.
-
- // We hit the end of the filename before we hit the end of the system root.
- if (!Filename[Pos])
- return Filename;
-
- // If there's not a path separator at the end of the base directory nor
- // immediately after it, then this isn't within the base directory.
- if (!llvm::sys::path::is_separator(Filename[Pos])) {
- if (!llvm::sys::path::is_separator(BaseDir.back()))
- return Filename;
- } else {
- // If the file name has a '/' at the current position, skip over the '/'.
- // We distinguish relative paths from absolute paths by the
- // absence of '/' at the beginning of relative paths.
- //
- // FIXME: This is wrong. We distinguish them by asking if the path is
- // absolute, which isn't the same thing. And there might be multiple '/'s
- // in a row. Use a better mechanism to indicate whether we have emitted an
- // absolute or relative path.
- ++Pos;
- }
+/// \returns true when \c Filename was adjusted, false otherwise.
+static bool adjustFilenameForRelocatableAST(SmallVectorImpl<char> &Filename,
+ StringRef BasePath) {
+ auto FileIt = llvm::sys::path::begin({Filename.begin(), Filename.size()});
+ auto FileEnd = llvm::sys::path::end({Filename.begin(), Filename.size()});
+
+ auto BaseIt = llvm::sys::path::begin(BasePath);
+ auto BaseEnd = llvm::sys::path::end(BasePath);
+
+ for (; FileIt != FileEnd && BaseIt != BaseEnd; ++FileIt, ++BaseIt)
+ if (*FileIt != *BaseIt)
+ return false;
+
+ if (FileIt == FileEnd)
+ return false;
+
+ SmallString<128> Clean;
+ for (; FileIt != FileEnd; ++FileIt)
+ llvm::sys::path::append(Clean, *FileIt);
- return Filename + Pos;
+ Filename.assign(Clean.begin(), Clean.end());
+ return true;
}
std::pair<ASTFileSignature, ASTFileSignature>
@@ -1712,7 +1697,7 @@ void ASTWriter::WriteControlBlock(Preprocessor &PP, StringRef isysroot) {
AddString(HSOpts.Sysroot, Record);
AddString(HSOpts.ResourceDir, Record);
- AddString(HSOpts.ModuleCachePath, Record);
+ AddPath(HSOpts.ModuleCachePath, Record);
AddString(HSOpts.ModuleUserBuildPath, Record);
Record.push_back(HSOpts.DisableModuleHash);
Record.push_back(HSOpts.ImplicitModuleMaps);
@@ -5342,16 +5327,8 @@ bool ASTWriter::PreparePathForOutput(SmallVectorImpl<char> &Path) {
return false;
bool Changed = cleanPathForOutput(PP->getFileManager(), Path);
-
- // Remove a prefix to make the path relative, if relevant.
- const char *PathBegin = Path.data();
- const char *PathPtr =
- adjustFilenameForRelocatableAST(PathBegin, BaseDirectory);
- if (PathPtr != PathBegin) {
- Path.erase(Path.begin(), Path.begin() + (PathPtr - PathBegin));
+ if (adjustFilenameForRelocatableAST(Path, BaseDirectory))
Changed = true;
- }
-
return Changed;
}
diff --git a/clang/test/Modules/modules-cache-path-canonicalization-output.c b/clang/test/Modules/modules-cache-path-canonicalization-output.c
new file mode 100644
index 0000000000000..ad71b69e5299e
--- /dev/null
+++ b/clang/test/Modules/modules-cache-path-canonicalization-output.c
@@ -0,0 +1,18 @@
+// This checks that implicitly-built modules produce identical PCM
+// files regardless of the spelling of the same module cache path.
+
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fsyntax-only %t/tu.c \
+// RUN: -fmodules-cache-path=%t/cache -fdisable-module-hash
+// RUN: mv %t/cache/M.pcm %t/M.pcm
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fsyntax-only %t/tu.c \
+// RUN: -fmodules-cache-path=%t/./cache -fdisable-module-hash
+// RUN: diff %t/./cache/M.pcm %t/M.pcm
+
+//--- tu.c
+#include "M.h"
+//--- M.h
+//--- module.modulemap
+module M { header "M.h" }
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