build: don't rely on the order of dependencies

It is impossible to sanely keep things tracked like that. All common
algorithms work on unordered graphs, and now we match that as well.

build

@@ -1,13 +1,13 @@
 #!/usr/bin/env python3
 
-import argparse
-import collections
 import platform
 import re
 import os
 
 import cli_function
+import collections
 import common
+import copy
 import shell_helpers
 from shell_helpers import LF
 
@@ -102,23 +102,73 @@ This is equivalent to:
                 'unzip',
             },
         )
+        buildroot_overlay_qemu_component = copy.copy(buildroot_component)
+        buildroot_overlay_qemu_component.dependencies = ['overlay', 'qemu']
+        buildroot_overlay_gem5_component = copy.copy(buildroot_component)
+        buildroot_overlay_gem5_component.dependencies = ['overlay-gem5']
+        gem5_deps = {
+            # TODO test it out on Docker and answer that question properly:
+            # https://askubuntu.com/questions/350475/how-can-i-install-gem5
+            'apt_get_pkgs': {
+                'device-tree-compiler',
+                'diod',
+                'libgoogle-perftools-dev',
+                'm4',
+                'protobuf-compiler',
+                'python-dev',
+                'python-pip',
+                # For prebuilt qcow2 unpack.
+                'qemu-utils',
+                'scons',
+                'zlib1g-dev',
+            },
+            'python2_pkgs': {
+                # Generate graphs of config.ini under m5out.
+                'pydot',
+            },
+            'submodules': {'gem5'},
+        }
 
         self.name_to_component_map = {
-            # Leaves without dependencies.
+            'all': _Component(dependencies=[
+                'all-linux',
+                'all-baremetal',
+            ]),
+            'all-baremetal': _Component(dependencies=[
+                    'qemu-baremetal',
+                    'gem5-baremetal',
+                    'baremetal-gem5-pbx',
+                ],
+                supported_archs=common.consts['crosstool_ng_supported_archs'],
+            ),
+            'all-linux': _Component(dependencies=[
+                'qemu-gem5-buildroot',
+                'gem5-debug',
+                'gem5-fast',
+                'qemu-user',
+            ]),
+            'baremetal': _Component(dependencies=[
+                'baremetal-gem5',
+                'baremetal-qemu',
+            ]),
             'baremetal-qemu': _Component(
                 self._build_file('build-baremetal', emulators=['qemu']),
                 supported_archs=common.consts['crosstool_ng_supported_archs'],
+                dependencies=['crosstool-ng'],
             ),
             'baremetal-gem5': _Component(
                 self._build_file('build-baremetal', emulators=['gem5']),
                 supported_archs=common.consts['crosstool_ng_supported_archs'],
+                dependencies=['crosstool-ng'],
             ),
             'baremetal-gem5-pbx': _Component(
                 self._build_file('build-baremetal', emulators=['gem5'], machine='RealViewPBX'),
                 supported_archs=common.consts['crosstool_ng_supported_archs'],
+                dependencies=['crosstool-ng'],
             ),
             'buildroot': buildroot_component,
-            'buildroot-gcc': buildroot_component,
+            'buildroot-overlay-qemu': buildroot_overlay_qemu_component,
+            'buildroot-overlay-gem5': buildroot_overlay_gem5_component,
             'copy-overlay': _Component(
                 self._build_file('copy-overlay'),
             ),
@@ -144,35 +194,28 @@ This is equivalent to:
             ),
             'gem5': _Component(
                 self._build_file('build-gem5'),
-                # TODO test it out on Docker and answer that question properly:
-                # https://askubuntu.com/questions/350475/how-can-i-install-gem5
-                apt_get_pkgs={
-                    'device-tree-compiler',
-                    'diod',
-                    'libgoogle-perftools-dev',
-                    'm4',
-                    'protobuf-compiler',
-                    'python-dev',
-                    'python-pip',
-                    # For prebuilt qcow2 unpack.
-                    'qemu-utils',
-                    'scons',
-                    'zlib1g-dev',
-                },
-                python2_pkgs={
-                    # Generate graphs of config.ini under m5out.
-                    'pydot',
-                },
-                submodules={'gem5'},
+                **gem5_deps
             ),
+            'gem5-baremetal': _Component(dependencies=[
+                'gem5',
+                'baremetal-gem5',
+            ]),
+            'gem5-buildroot': _Component(dependencies=[
+                'buildroot-overlay-gem5',
+                'linux',
+                'gem5',
+            ]),
             'gem5-debug': _Component(
                 self._build_file('build-gem5', gem5_build_type='debug'),
+                **gem5_deps
             ),
             'gem5-fast': _Component(
                 self._build_file('build-gem5', gem5_build_type='fast'),
+                **gem5_deps
             ),
             'linux': _Component(
                 self._build_file('build-linux', gem5_build_type='fast'),
+                dependencies={'buildroot'},
                 submodules_shallow={'linux'},
                 apt_get_pkgs={
                     'bison',
@@ -184,85 +227,50 @@ This is equivalent to:
             ),
             'modules': _Component(
                 self._build_file('build-modules'),
+                dependencies=['buildroot', 'linux'],
             ),
             'm5': _Component(
                 self._build_file('build-m5'),
+                dependencies=['buildroot'],
                 submodules={'gem5'},
             ),
+            'overlay': _Component(dependencies=[
+                'copy-overlay',
+                'modules',
+                'userland',
+            ]),
+            'overlay-gem5': _Component(dependencies=[
+                'm5',
+                'overlay',
+            ]),
+            'parsec-benchmark': _Component(
+                submodules={'parsec-benchmark'},
+                dependencies=['buildroot'],
+            ),
             'qemu': _Component(
                 self._build_file('build-qemu'),
                 apt_build_deps={'qemu'},
                 apt_get_pkgs={'libsdl2-dev'},
                 submodules={'qemu'},
             ),
-            'qemu-user': _Component(
-                self._build_file('build-qemu', user_mode=True),
-                apt_build_deps = {'qemu'},
-                apt_get_pkgs={'libsdl2-dev'},
-                submodules = {'qemu'},
-            ),
-            'parsec-benchmark': _Component(
-                submodules = {'parsec-benchmark'},
-            ),
-            'userland': _Component(
-                self._build_file('build-userland'),
-            ),
-
-            # Dependency only nodes.
-            'all': _Component(dependencies=[
-                'all-linux',
-                'all-baremetal',
-            ]),
-            'all-baremetal': _Component(dependencies=[
-                    'qemu-baremetal',
-                    'gem5-baremetal',
-                    'baremetal-gem5-pbx',
-                ],
-                supported_archs=common.consts['crosstool_ng_supported_archs'],
-            ),
-            'all-linux': _Component(dependencies=[
-                'qemu-gem5-buildroot',
-                'gem5-debug',
-                'gem5-fast',
-                'qemu-user',
-            ]),
-            'baremetal': _Component(dependencies=[
-                'baremetal-gem5',
-                'baremetal-qemu',
-            ]),
-            'gem5-buildroot': _Component(dependencies=[
-                'buildroot-gcc',
-                'linux',
-                'm5',
-                'overlay',
-                'gem5',
-            ]),
-            'gem5-baremetal': _Component(dependencies=[
-                'gem5',
-                'crosstool-ng',
-                'baremetal-gem5',
-            ]),
-            'overlay': _Component(dependencies=[
-                'copy-overlay',
-                'modules',
-                'userland',
-                'buildroot',
-            ]),
             'qemu-baremetal': _Component(dependencies=[
                 'qemu',
-                'crosstool-ng',
                 'baremetal-qemu',
             ]),
             'qemu-buildroot': _Component(dependencies=[
-                'qemu',
-                'buildroot-gcc',
-                'overlay',
+                'buildroot-overlay-qemu',
                 'linux',
             ]),
             'qemu-gem5-buildroot': _Component(dependencies=[
                 'qemu',
                 'gem5-buildroot',
             ]),
+            'qemu-user': _Component(
+                self._build_file('build-qemu', user_mode=True),
+                apt_build_deps = {'qemu'},
+                apt_get_pkgs={'libsdl2-dev'},
+                submodules={'qemu'},
+            ),
             'release': _Component(dependencies=[
                 'qemu-buildroot',
             ]),
@@ -271,7 +279,12 @@ This is equivalent to:
                 ],
                 supported_archs=common.consts['crosstool_ng_supported_archs'],
             ),
+            'userland': _Component(
+                self._build_file('build-userland'),
+                dependencies=['buildroot'],
+            ),
         }
+        self.component_to_name_map = {self.name_to_component_map[key]:key for key in self.name_to_component_map}
 
         self.add_argument(
             '--all',
@@ -286,6 +299,14 @@ Build absolutely everything for all archs.
             help='''\
 Also download all dependencies required for a given build: Ubuntu packages,
 Python packages and git submodules.
+'''
+        )
+        self.add_argument(
+            '--print-components',
+            default=False,
+            help='''\
+Print the components that would be built, including dependencies, but don't
+build them, nor show the build commands.
 '''
         )
         self.add_argument(
@@ -326,16 +347,16 @@ Which components to build. Default: qemu-buildroot
         elif components == []:
             components = ['qemu-buildroot']
         selected_components = []
-        selected_component_name_set = set()
         for component_name in components:
             todo = [component_name]
             while todo:
                 current_name = todo.pop(0)
-                if current_name not in selected_component_name_set:
-                    selected_component_name_set.add(current_name)
-                    component = self.name_to_component_map[current_name]
-                    selected_components.append(component)
-                    todo.extend(component.dependencies)
+                component = self.name_to_component_map[current_name]
+                selected_components.insert(0, component)
+                todo.extend(component.dependencies)
+        # Remove duplicates, keep only the first one of each.
+        # https://stackoverflow.com/questions/7961363/removing-duplicates-in-lists/7961390#7961390
+        collections.OrderedDict.fromkeys(selected_components)
 
         if self.env['download_dependencies']:
             apt_get_pkgs = {
@@ -466,7 +487,10 @@ Which components to build. Default: qemu-buildroot
 
         # Do the build.
         for component in selected_components:
-            component.build(self.env['arch'])
+            if self.env['print_components']:
+                print(self.component_to_name_map[component])
+            else:
+                component.build(self.env['arch'])
 
 if __name__ == '__main__':
     Main().cli()