[interp] basic_blocks list improvements (#47505)

* [interp] Add basic blocks in reverse order, then reverse

g_list_append has to repeatedly traverse the list using g_list_last to
find the last element.

Instead use g_list_prepend to add the new bb to the front of the list
and then reverse at the end (g_list_reverse is inplace and doesn't allocate)

* [interp] Don't generate basic_blocks list if not generating seq points

Still fill in offset_to_bb, but don't make a list unless needed.

diff --git a/src/mono/mono/mini/interp/transform.c b/src/mono/mono/mini/interp/transform.c
index 3bb5239..df461de 100644 (file)
--- a/src/mono/mono/mini/interp/transform.c
+++ b/src/mono/mono/mini/interp/transform.c
@@ -3210,7 +3210,7 @@ interp_field_from_token (MonoMethod *method, guint32 token, MonoClass **klass, M
 }
 
 static InterpBasicBlock*
-get_bb (TransformData *td, unsigned char *ip)
+get_bb (TransformData *td, unsigned char *ip, gboolean make_list)
 {
        int offset = ip - td->il_code;
        InterpBasicBlock *bb = td->offset_to_bb [offset];
@@ -3223,7 +3223,9 @@ get_bb (TransformData *td, unsigned char *ip)
                bb->index = td->bb_count++;
                td->offset_to_bb [offset] = bb;
 
-               td->basic_blocks = g_list_append_mempool (td->mempool, td->basic_blocks, bb);
+                /* Add the blocks in reverse order */
+                if (make_list)
+                        td->basic_blocks = g_list_prepend_mempool (td->mempool, td->basic_blocks, bb);
        }
 
        return bb;
@@ -3235,7 +3237,7 @@ get_bb (TransformData *td, unsigned char *ip)
  *   Compute the set of IL level basic blocks.
  */
 static void
-get_basic_blocks (TransformData *td, MonoMethodHeader *header)
+get_basic_blocks (TransformData *td, MonoMethodHeader *header, gboolean make_list)
 {
        guint8 *start = (guint8*)td->il_code;
        guint8 *end = (guint8*)td->il_code + td->code_size;
@@ -3246,14 +3248,14 @@ get_basic_blocks (TransformData *td, MonoMethodHeader *header)
        const MonoOpcode *opcode;
 
        td->offset_to_bb = (InterpBasicBlock**)mono_mempool_alloc0 (td->mempool, sizeof (InterpBasicBlock*) * (end - start + 1));
-       get_bb (td, start);
+       get_bb (td, start, make_list);
 
        for (i = 0; i < header->num_clauses; i++) {
                MonoExceptionClause *c = header->clauses + i;
-               get_bb (td, start + c->try_offset);
-               get_bb (td, start + c->handler_offset);
+               get_bb (td, start + c->try_offset, make_list);
+               get_bb (td, start + c->handler_offset, make_list);
                if (c->flags == MONO_EXCEPTION_CLAUSE_FILTER)
-                       get_bb (td, start + c->data.filter_offset);
+                       get_bb (td, start + c->data.filter_offset, make_list);
        }
 
        while (ip < end) {
@@ -3283,15 +3285,15 @@ get_basic_blocks (TransformData *td, MonoMethodHeader *header)
                        break;
                case MonoShortInlineBrTarget:
                        target = start + cli_addr + 2 + (signed char)ip [1];
-                       get_bb (td, target);
+                       get_bb (td, target, make_list);
                        ip += 2;
-                       get_bb (td, ip);
+                       get_bb (td, ip, make_list);
                        break;
                case MonoInlineBrTarget:
                        target = start + cli_addr + 5 + (gint32)read32 (ip + 1);
-                       get_bb (td, target);
+                       get_bb (td, target, make_list);
                        ip += 5;
-                       get_bb (td, ip);
+                       get_bb (td, ip, make_list);
                        break;
                case MonoInlineSwitch: {
                        guint32 n = read32 (ip + 1);
@@ -3299,14 +3301,14 @@ get_basic_blocks (TransformData *td, MonoMethodHeader *header)
                        ip += 5;
                        cli_addr += 5 + 4 * n;
                        target = start + cli_addr;
-                       get_bb (td, target);
+                       get_bb (td, target, make_list);
 
                        for (j = 0; j < n; ++j) {
                                target = start + cli_addr + (gint32)read32 (ip);
-                               get_bb (td, target);
+                               get_bb (td, target, make_list);
                                ip += 4;
                        }
-                       get_bb (td, ip);
+                       get_bb (td, ip, make_list);
                        break;
                }
                case MonoInlineR:
@@ -3318,8 +3320,12 @@ get_basic_blocks (TransformData *td, MonoMethodHeader *header)
                }
 
                if (i == CEE_THROW || i == CEE_ENDFINALLY || i == CEE_RETHROW)
-                       get_bb (td, ip);
+                       get_bb (td, ip, make_list);
        }
+
+        /* get_bb added blocks in reverse order, unreverse now */
+        if (make_list)
+                td->basic_blocks = g_list_reverse (td->basic_blocks);
 }
 
 static void
@@ -4084,7 +4090,7 @@ generate_code (TransformData *td, MonoMethod *method, MonoMethodHeader *header,
                exit_bb->stack_height = -1;
        }
 
-       get_basic_blocks (td, header);
+       get_basic_blocks (td, header, td->gen_sdb_seq_points);
 
        if (!inlining)
                initialize_clause_bblocks (td);