Bug 1861291 - Move manual dependencies upon wasm2c to the backend. r=firefox-build-system-reviewers,ahochheiden

This change introduces the possibility for more interdependencies being
recorded automatically, but making this work reliably more generally
we'll probably need more work, so at the moment, just make it work for
wasm2c.

Differential Revision: https://phabricator.services.mozilla.com/D191925

config/recurse.mk

@@ -193,7 +193,6 @@ endif
 # Interdependencies that moz.build world don't know about yet for compilation.
 # Note some others are hardcoded or "guessed" in recursivemake.py and emitter.py
 ifdef MOZ_USING_WASM_SANDBOXING
-security/rlbox/pre-compile media/libsoundtouch/src/pre-compile: config/external/wasm2c_sandbox_compiler/host
 dom/media/ogg/target-objects extensions/spellcheck/hunspell/glue/target-objects gfx/thebes/target-objects parser/expat/target-objects parser/htmlparser/target-objects gfx/ots/src/target-objects: security/rlbox/pre-compile
 dom/media/target-objects dom/media/mediasink/target-objects: media/libsoundtouch/src/pre-compile
 endif

python/mozbuild/mozbuild/backend/recursivemake.py

@@ -369,6 +369,13 @@ class RecursiveMakeBackend(MakeBackend):
         self._gkrust_target = None
         self._pre_compile = set()
 
+        # For a given file produced by the build, gives the top-level target
+        # that will produce it.
+        self._target_per_file = {}
+        # A set of dependencies that need correlation after everything has
+        # been processed.
+        self._post_process_dependencies = []
+
         self._no_skip = {
             "pre-export": set(),
             "export": set(),
@@ -538,12 +545,20 @@ class RecursiveMakeBackend(MakeBackend):
             else:
                 self._no_skip[tier].add(relobjdir)
             backend_file.write_once("include $(topsrcdir)/config/AB_rCD.mk\n")
-            relobjdir = mozpath.relpath(obj.objdir, backend_file.objdir)
+            reldir = mozpath.relpath(obj.objdir, backend_file.objdir)
+            if not reldir:
+                for out in obj.outputs:
+                    out = mozpath.join(relobjdir, out)
+                    assert out not in self._target_per_file
+                    self._target_per_file[out] = (relobjdir, tier)
+                for input in obj.inputs:
+                    if isinstance(input, ObjDirPath):
+                        self._post_process_dependencies.append((relobjdir, tier, input))
             # For generated files that we handle in the top-level backend file,
             # we want to have a `directory/tier` target depending on the file.
             # For the others, we want a `tier` target.
-            if tier != "pre-compile" and relobjdir:
-                tier = "%s/%s" % (relobjdir, tier)
+            if tier != "pre-compile" and reldir:
+                tier = "%s/%s" % (reldir, tier)
             for stmt in self._format_statements_for_generated_file(
                 obj, tier, extra_dependencies="backend.mk" if obj.flags else ""
             ):
@@ -580,6 +595,10 @@ class RecursiveMakeBackend(MakeBackend):
         elif isinstance(obj, HostProgram):
             self._process_host_program(obj, backend_file)
             self._process_linked_libraries(obj, backend_file)
+            self._target_per_file[obj.output_path.full_path] = (
+                backend_file.relobjdir,
+                obj.KIND,
+            )
 
         elif isinstance(obj, SimpleProgram):
             self._process_simple_program(obj, backend_file)
@@ -824,6 +843,12 @@ class RecursiveMakeBackend(MakeBackend):
         for category, graph in sorted(six.iteritems(non_default_graphs)):
             add_category_rules(category, non_default_roots[category], graph)
 
+        for relobjdir, tier, input in self._post_process_dependencies:
+            dep = self._target_per_file.get(input.full_path)
+            if dep:
+                rule = root_deps_mk.create_rule([mozpath.join(relobjdir, tier)])
+                rule.add_dependencies([mozpath.join(*dep)])
+
         root_mk = Makefile()
 
         # Fill root.mk with the convenience variables.