modinfo: lookup compile_commands.json by object

Since modinfo support was added, Meson fixed several issues with
extract_objects and compile_commands.json lookups can be simplified.
If the lookup uses the object file as key, there is no need to use the
command line to distinguish among all entries for a given source.

Ninja 1.9 is required in order to produce the 'output' key in
compile_commands.json; it is available in CentOS Stream 9, Debian 11, SLES
15.2, Ubuntu 20.04 and in all recent BSD distros.  Samurai also has it.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

meson.build

@@ -3903,16 +3903,11 @@ foreach d, list : modules
                     install: true,
                     install_dir: qemu_moddir)
       if module_ss.sources() != []
-        # FIXME: Should use sl.extract_all_objects(recursive: true) as
-        # input. Sources can be used multiple times but objects are
-        # unique when it comes to lookup in compile_commands.json.
-        # Depnds on a mesion version with
-        # https://github.com/mesonbuild/meson/pull/8900
         modinfo_files += custom_target(d + '-' + m + '.modinfo',
                                        output: d + '-' + m + '.modinfo',
-                                       input: module_ss.sources() + genh,
+                                       input: sl.extract_all_objects(recursive: true),
                                        capture: true,
-                                       command: [modinfo_collect, module_ss.sources()])
+                                       command: [modinfo_collect, '@INPUT@'])
       endif
     else
       if d == 'block'
@@ -3951,12 +3946,11 @@ foreach d, list : target_modules
                     dependencies: target_module_ss.dependencies(),
                     install: true,
                     install_dir: qemu_moddir)
-            # FIXME: Should use sl.extract_all_objects(recursive: true) too.
             modinfo_files += custom_target(module_name + '.modinfo',
                                            output: module_name + '.modinfo',
-                                           input: target_module_ss.sources() + genh,
+                                           input: sl.extract_all_objects(recursive: true),
                                            capture: true,
-                                           command: [modinfo_collect, '--target', target, target_module_ss.sources()])
+                                           command: [modinfo_collect, '--target', target, '@INPUT@'])
           endif
         endif
       endforeach

scripts/modinfo-collect.py

@@ -7,15 +7,6 @@ import json
 import shlex
 import subprocess
 
-def find_command(src, target, compile_commands):
-    for command in compile_commands:
-        if command['file'] != src:
-            continue
-        if target != '' and command['command'].find(target) == -1:
-            continue
-        return command['command']
-    return 'false'
-
 def process_command(src, command):
     skip = False
     out = []
@@ -43,14 +34,22 @@ def main(args):
         print("MODINFO_DEBUG target %s" % target)
         arch = target[:-8] # cut '-softmmu'
         print("MODINFO_START arch \"%s\" MODINFO_END" % arch)
+
     with open('compile_commands.json') as f:
-        compile_commands = json.load(f)
+        compile_commands_json = json.load(f)
-    for src in args:
+    compile_commands = { x['output']: x for x in compile_commands_json }
+
+    for obj in args:
+        entry = compile_commands.get(obj, None)
+        if not entry:
+            sys.stderr.print('modinfo: Could not find object file', obj)
+            sys.exit(1)
+        src = entry['file']
         if not src.endswith('.c'):
             print("MODINFO_DEBUG skip %s" % src)
             continue
+        command = entry['command']
         print("MODINFO_DEBUG src %s" % src)
-        command = find_command(src, target, compile_commands)
         cmdline = process_command(src, command)
         print("MODINFO_DEBUG cmd", cmdline)
         result = subprocess.run(cmdline, stdout = subprocess.PIPE,