graphs_n_codes.patch

commit ae5cc859d5e86867b2cc434c820d08957345793c
Author: Timo Paulssen <timonator@perpetuum-immobile.de>
Date:   Mon Jul 14 19:41:09 2014 +0200

    spesh graphs_s and codes_s into sp_get_i

diff --git a/src/spesh/optimize.c b/src/spesh/optimize.c
index 4eb1a67..1f89179 100644
--- a/src/spesh/optimize.c
+++ b/src/spesh/optimize.c
@@ -48,6 +48,26 @@ MVMint16 MVM_spesh_add_spesh_slot(MVMThreadContext *tc, MVMSpeshGraph *g, MVMCol
     return g->num_spesh_slots++;
 }
 
+/* Some ops are just lookups in a struct, so we emit sp_p6oget_* ops for those.
+ * This code assumes all our structs lengths fit into a 16 bit unsigned int. */
+static void optimize_simple_struct_lookup(MVMThreadContext *tc, MVMSpeshGraph *g, MVMSpeshIns *ins, MVMuint16 offset) 
+    switch(ins->info->opcode) {
+        case MVM_OP_graphs_s:
+        case MVM_OP_codes_s:
+            ins->info = MVM_op_get_op(MVM_OP_sp_get_i);
+            break;
+        default:
+            return;
+    }
+
+    {
+        MVMSpeshOperand *old_operands = ins->operands;
+        ins->operands = MVM_spesh_alloc(tc, g, 2 * sizeof(MVMSpeshOperand));
+        ins->operands[0] = old_operands[0];
+        ins->operands[1].lit_i16 = offset;
+    }
+}
+
 /* Performs optimization on a method lookup. If we know the type that we'll
  * be dispatching on, resolve it right off. If not, add a cache. */
 static void optimize_method_lookup(MVMThreadContext *tc, MVMSpeshGraph *g, MVMSpeshIns *ins) {
@@ -743,6 +763,12 @@ static void optimize_bb(MVMThreadContext *tc, MVMSpeshGraph *g, MVMSpeshBB *bb)
             if (specialized_on_invocant(tc, g))
                 optimize_getlex_known(tc, g, bb, ins);
             break;
+        case MVM_OP_graphs_s:
+            optimize_simple_struct_lookup(tc, g, ins, offsetof( MVMString, body.graphs ));
+            break;
+        case MVM_OP_codes_s:
+            optimize_simple_struct_lookup(tc, g, ins, offsetof( MVMString, body.codes ));
+            break;
         case MVM_OP_sp_log:
         case MVM_OP_sp_osrfinalize:
             /* Left-over log instruction that didn't become a guard, or OSR

This doesn't seem to be that big of an optimization (why would sp_p6oget_o be any faster than hard-compiled struct lookups), and as for JIT support, it'd seem to me that it'd be better to add a 'struct access node' to the JIT graph rather than to try and fix it on spesh level.