compiler: improve `poset_from_mtypes` used for type coloring.

Instead of doing the full matrix mtypes X cast_types, a grouping is done by the base classes of the types so that we compare only types whose base classes are in inheritance.

For nitc/nitc/nitc the result is not that bad:

before:
0m6.584s
17.605 GIr
time passed in poset_from_mtypes: 26.01% (4.579 GIr)

now:
0m5.880s (-10%)
15.088 GIr (-14%)
time passed in poset_from_mtypes: 11.72% (1.768 GIr)

In the best condition, I can now expect to compile in less than 6s.

Note that coloring is still a MAJOR issue in term of compile time since 1/4 of the Ir are used to compute coloration.

 * type_coloring: 17.23%
 * property_coloring: 9.35%

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/compiler/separate_compiler.nit b/src/compiler/separate_compiler.nit
index f62d733..441abe1 100644 (file)
--- a/src/compiler/separate_compiler.nit
+++ b/src/compiler/separate_compiler.nit
@@ -478,13 +478,35 @@ class SeparateCompiler
 
        private fun poset_from_mtypes(mtypes, cast_types: Set[MType]): POSet[MType] do
                var poset = new POSet[MType]
+
+               # Instead of doing the full matrix mtypes X cast_types,
+               # a grouping is done by the base classes of the type so
+               # that we compare only types whose base classes are in inheritance.
+
+               var mtypes_by_class = new MultiHashMap[MClass, MType]
                for e in mtypes do
+                       var c = e.as_notnullable.as(MClassType).mclass
+                       mtypes_by_class[c].add(e)
+                       poset.add_node(e)
+               end
+
+               var casttypes_by_class = new MultiHashMap[MClass, MType]
+               for e in cast_types do
+                       var c = e.as_notnullable.as(MClassType).mclass
+                       casttypes_by_class[c].add(e)
                        poset.add_node(e)
-                       for o in cast_types do
-                               if e == o then continue
-                               poset.add_node(o)
-                               if e.is_subtype(mainmodule, null, o) then
-                                       poset.add_edge(e, o)
+               end
+
+               for c1, ts1 in mtypes_by_class do
+                       for c2 in c1.in_hierarchy(mainmodule).greaters do
+                               var ts2 = casttypes_by_class[c2]
+                               for e in ts1 do
+                                       for o in ts2 do
+                                               if e == o then continue
+                                               if e.is_subtype(mainmodule, null, o) then
+                                                       poset.add_edge(e, o)
+                                               end
+                                       end
                                end
                        end
                end