[aot] use hashtable for caching typespec of classes

I had a look in vtunes for

```
$ mono/mini/mono-sgen --stats -O=all --aot=threads=1,asmonly ~/work/benchmarker/tests/fsharp/lib/bootstrap/4.0/FSharp.Compiler.dll
```

and that method showed up as hot.

With this change I get an improvement from ~27.4s down to ~24.3s on my
machine.

diff --git a/mono/mini/aot-compiler.c b/mono/mini/aot-compiler.c
index 9c2ca7090e60162999c6bbf33bfbac7007254806..4ae5c894de5db2ba6175c0fa7e611c39767fd189 100644 (file)
--- a/mono/mini/aot-compiler.c
+++ b/mono/mini/aot-compiler.c
@@ -245,7 +245,7 @@ typedef struct MonoAotCompile {
        MonoAotFileFlags flags;
        MonoDynamicStream blob;
        gboolean blob_closed;
-       MonoClass **typespec_classes;
+       GHashTable *typespec_classes;
        GString *llc_args;
        GString *as_args;
        char *assembly_name_sym;
@@ -2719,22 +2719,16 @@ find_typespec_for_class (MonoAotCompile *acfg, MonoClass *klass)
 
        /* FIXME: Search referenced images as well */
        if (!acfg->typespec_classes) {
-               acfg->typespec_classes = (MonoClass **)mono_mempool_alloc0 (acfg->mempool, sizeof (MonoClass*) * len);
-               for (i = 0; i < len; ++i) {
+               acfg->typespec_classes = g_hash_table_new (NULL, NULL);
+               for (i = 0; i < len; i++) {
                        MonoError error;
-                       acfg->typespec_classes [i] = mono_class_get_and_inflate_typespec_checked (acfg->image, MONO_TOKEN_TYPE_SPEC | (i + 1), NULL, &error);
+                       int typespec = MONO_TOKEN_TYPE_SPEC | (i + 1);
+                       MonoClass *klass_key = mono_class_get_and_inflate_typespec_checked (acfg->image, typespec, NULL, &error);
                        g_assert (mono_error_ok (&error)); /* FIXME error handling */
+                       g_hash_table_insert (acfg->typespec_classes, klass_key, GINT_TO_POINTER (typespec));
                }
        }
-       for (i = 0; i < len; ++i) {
-               if (acfg->typespec_classes [i] == klass)
-                       break;
-       }
-
-       if (i < len)
-               return MONO_TOKEN_TYPE_SPEC | (i + 1);
-       else
-               return 0;
+       return GPOINTER_TO_INT (g_hash_table_lookup (acfg->typespec_classes, klass));
 }
 
 static void
@@ -10071,6 +10065,8 @@ acfg_free (MonoAotCompile *acfg)
        g_hash_table_destroy (acfg->image_hash);
        g_hash_table_destroy (acfg->unwind_info_offsets);
        g_hash_table_destroy (acfg->method_label_hash);
+       if (!acfg->typespec_classes)
+               g_hash_table_destroy (acfg->typespec_classes);
        g_hash_table_destroy (acfg->export_names);
        g_hash_table_destroy (acfg->plt_entry_debug_sym_cache);
        g_hash_table_destroy (acfg->klass_blob_hash);