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From:   John Hubbard <jhubbard@nvidia.com>
To:     Masahiro Yamada <masahiroy@kernel.org>
CC:     Nick Desaulniers <ndesaulniers@google.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Tom Rix <trix@redhat.com>, Jason Gunthorpe <jgg@nvidia.com>,
        LKML <linux-kernel@vger.kernel.org>, <llvm@lists.linux.dev>,
        John Hubbard <jhubbard@nvidia.com>
Subject: [PATCH v2] gen_compile_commands: fix overlooked module files
Date:   Wed, 15 Jun 2022 19:11:49 -0700
Message-ID: <20220616021149.327587-1-jhubbard@nvidia.com>
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scripts/clang-tools/gen_compile_commands.py incorrectly assumes that
each .mod file only contains one line. In fact, such files contain one
entry per line, and for some subsystems, there can be many, many lines.
For example, Nouveau has 762 entries, but only the first entry was being
processed. This problem causes clangd to fail to provide references and
definitions for valid files that are part of the current kernel
configuration.

This problem only occurs when using Kbuild to generate, like this:

   make CC=clang compile_commands.json

It does not occur if you just run gen_compile_commands.py "bare", like
this (below):

   scripts/clang-tools/gen_compile_commands.py/gen_compile_commands.py .

Fix this by fully processing each .mod file. This fix causes the number
of build commands that clangd finds in my kernel build (these numbers
are heavily dependent upon .config), from 2848 to 5292, which is an 85%
increase.

Fixes: 9413e7640564 ("kbuild: split the second line of *.mod into *.usyms")
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---

Changes since v1:

Applied changes recommended by Masahiro Yamada (thanks!): corrected the
"Fixes" tag, and improved the python code for parsing .mod files.


 scripts/clang-tools/gen_compile_commands.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/scripts/clang-tools/gen_compile_commands.py b/scripts/clang-tools/gen_compile_commands.py
index 1d1bde1fd45e..acf4ec28aaf1 100755
--- a/scripts/clang-tools/gen_compile_commands.py
+++ b/scripts/clang-tools/gen_compile_commands.py
@@ -157,11 +157,10 @@ def cmdfiles_for_modorder(modorder):
             if ext != '.ko':
                 sys.exit('{}: module path must end with .ko'.format(ko))
             mod = base + '.mod'
-	    # The first line of *.mod lists the objects that compose the module.
+            # Read from *.mod, to get a list of objects that compose the module.
             with open(mod) as m:
-                for obj in m.readline().split():
-                    yield to_cmdfile(obj)
-
+                for mod_line in m:
+                    yield to_cmdfile(mod_line.rstrip())
 
 def process_line(root_directory, command_prefix, file_path):
     """Extracts information from a .cmd line and creates an entry from it.
-- 
2.36.1