linux-kernel - [PATCH] gen_compile_commands: fix overlooked module files

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Message-ID: <20220615063315.279489-1-jhubbard@nvidia.com>
Date:   Tue, 14 Jun 2022 23:33:15 -0700
From:   John Hubbard <jhubbard@...dia.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
CC:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Tom Rix <trix@...hat.com>, Jason Gunthorpe <jgg@...dia.com>,
        LKML <linux-kernel@...r.kernel.org>, <llvm@...ts.linux.dev>,
        John Hubbard <jhubbard@...dia.com>
Subject: [PATCH] gen_compile_commands: fix overlooked module files

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: ecca4fea1ede4 ("gen_compile_commands: support *.o, *.a, modules.order in positional argument")
Cc: Masahiro Yamada <masahiroy@...nel.org>
Cc: Nick Desaulniers <ndesaulniers@...gle.com>
Signed-off-by: John Hubbard <jhubbard@...dia.com>
---
 scripts/clang-tools/gen_compile_commands.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/scripts/clang-tools/gen_compile_commands.py b/scripts/clang-tools/gen_compile_commands.py
index 1d1bde1fd45e..53590e886889 100755
--- a/scripts/clang-tools/gen_compile_commands.py
+++ b/scripts/clang-tools/gen_compile_commands.py
@@ -157,10 +157,11 @@ 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 line in m.readlines():
+                    for obj in line.split():
+                        yield to_cmdfile(obj)
 
 
 def process_line(root_directory, command_prefix, file_path):
-- 
2.36.1