[clang] [C++20] [Modules] Offer -fmodules-embed-all-files option (PR #107194)
Chuanqi Xu via cfe-commits
cfe-commits at lists.llvm.org
Wed Sep 18 19:35:22 PDT 2024
https://github.com/ChuanqiXu9 updated https://github.com/llvm/llvm-project/pull/107194
>From f18b50fb6ae778ac9b4ddaee4029d54f859c50f9 Mon Sep 17 00:00:00 2001
From: Chuanqi Xu <yedeng.yd at linux.alibaba.com>
Date: Wed, 4 Sep 2024 16:02:53 +0800
Subject: [PATCH 1/2] [C++20] [Modules] Offer -fmodules-embed-all-files option
See
https://discourse.llvm.org/t/rfc-modules-should-we-embed-sources-to-the-bmi/81029
for details.
Close https://github.com/llvm/llvm-project/issues/72383
---
clang/docs/StandardCPlusPlusModules.rst | 34 +++++++++++++++++++
clang/include/clang/Driver/Options.td | 10 +++---
clang/lib/Driver/ToolChains/Clang.cpp | 3 ++
.../test/Driver/fmodules-embed-all-files.cpp | 2 ++
4 files changed, 45 insertions(+), 4 deletions(-)
create mode 100644 clang/test/Driver/fmodules-embed-all-files.cpp
diff --git a/clang/docs/StandardCPlusPlusModules.rst b/clang/docs/StandardCPlusPlusModules.rst
index 2b757a807a0e6e..02ca0db3f937b3 100644
--- a/clang/docs/StandardCPlusPlusModules.rst
+++ b/clang/docs/StandardCPlusPlusModules.rst
@@ -462,6 +462,33 @@ Currently, Clang accepts the above example, though it may produce surprising
results if the debugging code depends on consistent use of ``NDEBUG`` in other
translation units.
+Source Files Consistency
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+Clang may open the input files (*) of a BMI during the compilation. It implies that
+when we consume a BMI, all the input files need to be present with the same path
+and the same contents.
+
+To overcome the requirements and simplify cases like distributed builds and sandboxed
+builds, users can use ``-fmodules-embed-all-files`` flag to embed all input files
+into the BMI so that clang won't ask to open the corresponding file on disk.
+
+Input files (*): The source files that took part in the compilation of the BMI.
+For example,
+
+.. code-block:: c++
+
+ // M.cppm
+ module;
+ #include "foo.h"
+ export module M;
+
+ // foo.h
+ #pragma once
+ #include "bar.h"
+
+The ``M.cppm``, ``foo.h`` and ``bar.h`` are input files for the BMI of ``M.cppm``.
+
Object definition consistency
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -484,6 +511,13 @@ fragment is disabled by default. These checks can be enabled by specifying
and you encounter incorrect or missing diagnostics, please report them via the
`community issue tracker <https://github.com/llvm/llvm-project/issues/>`_.
+Privacy Issue
+-------------
+
+BMIs are not and should not be treated as an information hiding mechanism.
+They should always be assumed to contain all the information that was used to
+create them, in a recoverable form.
+
ABI Impacts
-----------
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 1142416e227fc8..954cffc0f66950 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3162,6 +3162,12 @@ def modules_reduced_bmi : Flag<["-"], "fexperimental-modules-reduced-bmi">,
HelpText<"Generate the reduced BMI">,
MarshallingInfoFlag<FrontendOpts<"GenReducedBMI">>;
+def fmodules_embed_all_files : Joined<["-"], "fmodules-embed-all-files">,
+ Visibility<[ClangOption, CC1Option, CLOption]>,
+ HelpText<"Embed the contents of all files read by this compilation into "
+ "the produced module file.">,
+ MarshallingInfoFlag<FrontendOpts<"ModulesEmbedAllFiles">>;
+
def fmodules_prune_interval : Joined<["-"], "fmodules-prune-interval=">, Group<i_Group>,
Visibility<[ClangOption, CC1Option]>, MetaVarName<"<seconds>">,
HelpText<"Specify the interval (in seconds) between attempts to prune the module cache">,
@@ -7665,10 +7671,6 @@ def fmodules_embed_file_EQ : Joined<["-"], "fmodules-embed-file=">,
HelpText<"Embed the contents of the specified file into the module file "
"being compiled.">,
MarshallingInfoStringVector<FrontendOpts<"ModulesEmbedFiles">>;
-def fmodules_embed_all_files : Joined<["-"], "fmodules-embed-all-files">,
- HelpText<"Embed the contents of all files read by this compilation into "
- "the produced module file.">,
- MarshallingInfoFlag<FrontendOpts<"ModulesEmbedAllFiles">>;
defm fimplicit_modules_use_lock : BoolOption<"f", "implicit-modules-use-lock",
FrontendOpts<"BuildingImplicitModuleUsesLock">, DefaultTrue,
NegFlag<SetFalse>,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 3fe4ce5d893b8d..870575bb8a907c 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4214,6 +4214,9 @@ static bool RenderModulesOptions(Compilation &C, const Driver &D,
Args.ClaimAllArgs(options::OPT_fmodule_output_EQ);
}
+ if (Args.hasArg(options::OPT_fmodules_embed_all_files))
+ CmdArgs.push_back("-fmodules-embed-all-files");
+
return HaveModules;
}
diff --git a/clang/test/Driver/fmodules-embed-all-files.cpp b/clang/test/Driver/fmodules-embed-all-files.cpp
new file mode 100644
index 00000000000000..f8e232f792d540
--- /dev/null
+++ b/clang/test/Driver/fmodules-embed-all-files.cpp
@@ -0,0 +1,2 @@
+// RUN: %clang -std=c++20 %s -fmodules-embed-all-files -### 2>&1 | FileCheck %s
+// CHECK: -fmodules-embed-all-files
>From d539f51c09d76170fe93644f00451989fc90e86d Mon Sep 17 00:00:00 2001
From: Chuanqi Xu <yedeng.yd at linux.alibaba.com>
Date: Thu, 19 Sep 2024 10:31:34 +0800
Subject: [PATCH 2/2] update
---
clang/docs/StandardCPlusPlusModules.rst | 20 +++++++++++--------
.../test/Driver/fmodules-embed-all-files.cpp | 3 +++
2 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/clang/docs/StandardCPlusPlusModules.rst b/clang/docs/StandardCPlusPlusModules.rst
index 02ca0db3f937b3..f2ac3ee11ceb42 100644
--- a/clang/docs/StandardCPlusPlusModules.rst
+++ b/clang/docs/StandardCPlusPlusModules.rst
@@ -465,16 +465,20 @@ translation units.
Source Files Consistency
^^^^^^^^^^^^^^^^^^^^^^^^
-Clang may open the input files (*) of a BMI during the compilation. It implies that
-when we consume a BMI, all the input files need to be present with the same path
-and the same contents.
+Clang may open the input files\ :sup:`*` of a BMI during the compilation. This implies that
+when Clang consumes a BMI, all the input files need to be present in the original path
+and with the original contents.
-To overcome the requirements and simplify cases like distributed builds and sandboxed
-builds, users can use ``-fmodules-embed-all-files`` flag to embed all input files
-into the BMI so that clang won't ask to open the corresponding file on disk.
+To overcome these requirements and simplify cases like distributed builds and sandboxed
+builds, users can use the ``-fmodules-embed-all-files`` flag to embed all input files
+into the BMI so that Clang does not need to open the corresponding file on disk.
-Input files (*): The source files that took part in the compilation of the BMI.
-For example,
+When the ``-fmodules-embed-all-files`` flag are enabled, Clang explicitly emits the source
+code into the BMI file, the contents of the BMI file contain a sufficiently verbose
+representation to reproduce the original source file.
+
+:sup:`*`Input files: The source files which took part in the compilation of the BMI.
+For example:
.. code-block:: c++
diff --git a/clang/test/Driver/fmodules-embed-all-files.cpp b/clang/test/Driver/fmodules-embed-all-files.cpp
index f8e232f792d540..8da836a40446c4 100644
--- a/clang/test/Driver/fmodules-embed-all-files.cpp
+++ b/clang/test/Driver/fmodules-embed-all-files.cpp
@@ -1,2 +1,5 @@
// RUN: %clang -std=c++20 %s -fmodules-embed-all-files -### 2>&1 | FileCheck %s
// CHECK: -fmodules-embed-all-files
+
+// RUN: %clang -std=c++20 %s -### 2>&1 | FileCheck %s --check-prefix=NON-EMBED
+// NON-EMBED-NOT: -fmodules-embed-all-files
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