Replace message-building functions with message-building blocks

doc/grammar.txt

@@ -451,6 +451,7 @@ statement:
    <label>
    <palette-translation>
    <assert>
+   <buildmsg>
    <empty-statement>
    <expression-statement>
 
@@ -547,8 +548,9 @@ script-jump-statement:
    restart ;
 
 return-statement:
-   return <expression> ;
    return ;
+   return <expression> ;
+   return <buildmsg>
 
 goto-statement:
    goto <identifier> ;
@@ -586,6 +588,12 @@ assert:
    static assert ( <expression> ) ;
    static assert ( <expression> , <string> ) ;
 
+buildmsg-statement:
+   <buildmsg>
+
+buildmsg:
+   buildmsg ( <expression> ) <block-statement>
+
 inline-asm:
    > <id> <nl>
    > <id> <inline-asm-args> <nl>
@@ -692,14 +700,17 @@ suffix:
    <suffix> ++
    <suffix> --
    <suffix> [ <expression> ]
-   <suffix> ( )
-   <suffix> ( <expression-list> )
-   <suffix> ( const : <expression-list> )
-   <suffix> ( <format-item-list> )
-   <suffix> ( <format-item-list> ; <expression-list> )
+   <suffix> <call>
    <suffix> . <identifier>
    <suffix> ! !
 
+call:
+   ( )
+   ( <expression-list> )
+   ( const : <expression-list> )
+   ( <format-item-list> )
+   ( <format-item-list> ; <expression-list> )
+
 format-item-list:
    <format-item>
    <format-item-list> , <format-item>
@@ -852,6 +863,7 @@ keyword:
    auto
    bool
    break
+   buildmsg
    case
    const
    continue
@@ -925,4 +937,4 @@ context-sensitive-keyword:
    respawn
    unloading
    wadauthor
-   whitereturn
+   whitereturn

src/codegen/expr.c

@@ -1767,7 +1767,7 @@ void visit_format_item( struct codegen* codegen, struct format_item* item ) {
       if ( item->cast == FCAST_ARRAY ) {
          visit_array_format_item( codegen, item );
       }
-      else if ( item->cast == FCAST_MSGBUILD ) {
+      else if ( item->cast == FCAST_BUILDMSG ) {
          visit_msgbuild_format_item( codegen, item );
       }
       else {
@@ -1852,20 +1852,15 @@ void visit_array_format_item( struct codegen* codegen,
 
 void visit_msgbuild_format_item( struct codegen* codegen,
    struct format_item* item ) {
-   struct format_item_msgbuild* extra = item->extra;
-   if ( extra->call ) {
-      struct result result;
-      init_result( &result, true );
-      visit_user_call( codegen, &result, extra->call );
-   }
-   else if ( extra->func ) {
-      struct func_user* impl = extra->func->impl;
-      c_pcd( codegen, PCD_CALLDISCARD, impl->index );
+   struct format_item_buildmsg* extra = item->extra;
+   // Inline the message-building block if it only has a single user.
+   if ( list_size( &extra->usage->buildmsg->usages ) == 1 ) {
+      c_write_block( codegen, extra->usage->buildmsg->block );
    }
    else {
-      c_push_expr( codegen, item->value );
-      c_pcd( codegen, PCD_CALLSTACK );
-      c_pcd( codegen, PCD_DROP );
+      struct c_point* jump_point = c_create_point( codegen );
+      c_append_node( codegen, &jump_point->node );
+      extra->usage->point = jump_point;
    }
 }
 
@@ -3153,4 +3148,4 @@ void next_diminfo( struct codegen* codegen ) {
 void push_diminfo( struct codegen* codegen ) {
    c_push_dimtrack( codegen );
    c_pcd( codegen, PCD_PUSHMAPARRAY, codegen->shary.index );
-}
+}

src/codegen/stmt.c

@@ -53,6 +53,12 @@ static void write_palrange_tint( struct codegen* codegen,
 static void visit_script_jump( struct codegen* codegen, struct script_jump* );
 static void visit_label( struct codegen* codegen, struct label* );
 static void visit_goto( struct codegen* codegen, struct goto_stmt* );
+static void visit_buildmsg_stmt( struct codegen* codegen,
+   struct buildmsg_stmt* stmt );
+static void write_msgbuild_block( struct codegen* codegen,
+   struct buildmsg* buildmsg );
+static void write_multi_usage_msgbuild_block( struct codegen* codegen,
+   struct buildmsg* buildmsg );
 static void visit_expr_stmt( struct codegen* codegen, struct expr_stmt* stmt );
 
 void c_write_block( struct codegen* codegen, struct block* stmt ) {
@@ -213,6 +219,10 @@ void c_write_stmt( struct codegen* codegen, struct node* node ) {
    case NODE_PALTRANS:
       visit_paltrans( codegen, ( struct paltrans* ) node );
       break;
+   case NODE_BUILDMSG:
+      visit_buildmsg_stmt( codegen,
+         ( struct buildmsg_stmt* ) node );
+      break;
    case NODE_EXPR_STMT:
       visit_expr_stmt( codegen,
          ( struct expr_stmt* ) node );
@@ -1096,19 +1106,22 @@ void set_jumps_point( struct codegen* codegen, struct jump* jump,
 }
 
 void visit_return( struct codegen* codegen, struct return_stmt* stmt ) {
-   if ( codegen->func->nested_func ) {
-      if ( stmt->return_value ) {
-         c_push_initz_expr( codegen, codegen->func->func->ref,
-            stmt->return_value );
+   // Push return value.
+   if ( stmt->return_value ) {
+      c_push_initz_expr( codegen, codegen->func->func->ref,
+         stmt->return_value );
+      if ( stmt->buildmsg ) {
+         write_msgbuild_block( codegen, stmt->buildmsg );
       }
+   }
+   // Exit.
+   if ( codegen->func->nested_func ) {
       struct c_jump* epilogue_jump = c_create_jump( codegen, PCD_GOTO );
       c_append_node( codegen, &epilogue_jump->node );
       stmt->epilogue_jump = epilogue_jump;
    }
    else {
       if ( stmt->return_value ) {
-         c_push_initz_expr( codegen, codegen->func->func->ref,
-            stmt->return_value );
          c_pcd( codegen, PCD_RETURNVAL );
       }
       else {
@@ -1201,11 +1214,71 @@ void visit_goto( struct codegen* codegen, struct goto_stmt* stmt ) {
    jump->point = stmt->label->point;
 }
 
+static void visit_buildmsg_stmt( struct codegen* codegen,
+   struct buildmsg_stmt* stmt ) {
+   c_visit_expr( codegen, stmt->buildmsg->expr );
+   write_msgbuild_block( codegen, stmt->buildmsg );
+}
+
+static void write_msgbuild_block( struct codegen* codegen,
+   struct buildmsg* buildmsg ) {
+   // When a message-building block is used more than once in the same
+   // expression, instead of duplicating the block code, use a goto instruction
+   // to enter the block. Single-usage blocks are inlined at the call site.
+   if ( list_size( &buildmsg->usages ) > 1 ) {
+      write_multi_usage_msgbuild_block( codegen, buildmsg );
+   }
+}
+
+static void write_multi_usage_msgbuild_block( struct codegen* codegen,
+   struct buildmsg* buildmsg ) {
+   struct c_jump* exit_jump = c_create_jump( codegen, PCD_GOTO );
+   c_append_node( codegen, &exit_jump->node );
+   struct c_point* enter_point = c_create_point( codegen );
+   c_append_node( codegen, &enter_point->node );
+   c_write_block( codegen, buildmsg->block );
+   // Create jumps into the message-building block.
+   unsigned int entry_number = 0;
+   list_iter_t i;
+   list_iter_init( &i, &buildmsg->usages );
+   while ( ! list_end( &i ) ) {
+      struct buildmsg_usage* usage = list_data( &i );
+      c_seek_node( codegen, &usage->point->node );
+      c_pcd( codegen, PCD_PUSHNUMBER, entry_number );
+      struct c_jump* jump = c_create_jump( codegen, PCD_GOTO );
+      c_append_node( codegen, &jump->node );
+      jump->point = enter_point;
+      struct c_point* return_point = c_create_point( codegen );
+      c_append_node( codegen, &return_point->node );
+      usage->point = return_point;
+      ++entry_number;
+      list_next( &i );
+   }
+   c_seek_node( codegen, codegen->node_tail );
+   // Create return table.
+   struct c_sortedcasejump* return_table = c_create_sortedcasejump( codegen );
+   c_append_node( codegen, &return_table->node );
+   entry_number = 0;
+   list_iter_init( &i, &buildmsg->usages );
+   while ( ! list_end( &i ) ) {
+      struct buildmsg_usage* usage = list_data( &i );
+      struct c_casejump* entry = c_create_casejump( codegen, entry_number,
+         usage->point );
+      c_append_casejump( return_table, entry );
+      ++entry_number;
+      list_next( &i );
+   }
+   // Exit.
+   struct c_point* exit_point = c_create_point( codegen );
+   c_append_node( codegen, &exit_point->node );
+   exit_jump->point = exit_point;
+}
+
 void visit_expr_stmt( struct codegen* codegen, struct expr_stmt* stmt ) {
    list_iter_t i;
    list_iter_init( &i, &stmt->expr_list );
    while ( ! list_end( &i ) ) {
       c_visit_expr( codegen, list_data( &i ) );
       list_next( &i );
    }
-}
+}

src/parse/asm.c

@@ -79,4 +79,4 @@ struct inline_asm_arg* alloc_inline_asm_arg( struct pos* pos ) {
    arg->value.number = 0;
    arg->pos = *pos;
    return arg;
-}
+}

src/parse/dec.c

@@ -2711,4 +2711,4 @@ void read_special_return_type( struct parse* parse,
       p_bail( parse );
    }
    p_read_tk( parse );
-}
+}

src/parse/expr.c

@@ -54,8 +54,6 @@ static void read_format_cast( struct parse* parse, struct format_cast* cast );
 static bool peek_format_cast( struct parse* parse );
 static void init_array_field( struct array_field* field );
 static void read_array_field( struct parse* parse, struct array_field* field );
-static void read_msgbuild_format_item( struct parse* parse,
-   struct format_item* item );
 static void read_id( struct parse* parse, struct expr_reading* reading );
 static void read_literal( struct parse* parse, struct expr_reading* reading );
 static void read_string( struct parse* parse, struct expr_reading* reading );
@@ -1041,12 +1039,8 @@ struct format_item* read_format_item_list( struct parse* parse ) {
 }
 
 struct format_item* read_format_item( struct parse* parse ) {
-   struct format_item* item = mem_alloc( sizeof( *item ) );
-   item->cast = FCAST_DECIMAL;
+   struct format_item* item = t_alloc_format_item();
    item->pos = parse->tk_pos;
-   item->next = NULL;
-   item->value = NULL;
-   item->extra = NULL;
    struct format_cast cast;
    init_format_cast( &cast );
    read_format_cast( parse, &cast );
@@ -1063,9 +1057,6 @@ struct format_item* read_format_item( struct parse* parse ) {
          item->extra = extra;
       }
    }
-   else if ( item->cast == FCAST_MSGBUILD ) {
-      read_msgbuild_format_item( parse, item );
-   }
    else {
       struct expr_reading value;
       p_init_expr_reading( &value, false, false, false, true );
@@ -1094,28 +1085,23 @@ void read_format_cast( struct parse* parse, struct format_cast* cast ) {
       }
       break;
    default:
-      if ( parse->tk == TK_MSGBUILD ) {
-         cast->type = FCAST_MSGBUILD;
+      switch ( parse->tk_text[ 0 ] ) {
+      case 'a': cast->type = FCAST_ARRAY; break;
+      case 'b': cast->type = FCAST_BINARY; break;
+      case 'c': cast->type = FCAST_CHAR; break;
+      case 'd': cast->type = FCAST_DECIMAL; break;
+      case 'f': cast->type = FCAST_FIXED; break;
+      case 'i': cast->type = FCAST_RAW; break;
+      case 'k': cast->type = FCAST_KEY; break;
+      case 'l': cast->type = FCAST_LOCAL_STRING; break;
+      case 'n': cast->type = FCAST_NAME; break;
+      case 's': cast->type = FCAST_STRING; break;
+      case 'x': cast->type = FCAST_HEX; break;
+      default:
+         cast->unknown = true;
       }
-      else {
-         switch ( parse->tk_text[ 0 ] ) {
-         case 'a': cast->type = FCAST_ARRAY; break;
-         case 'b': cast->type = FCAST_BINARY; break;
-         case 'c': cast->type = FCAST_CHAR; break;
-         case 'd': cast->type = FCAST_DECIMAL; break;
-         case 'f': cast->type = FCAST_FIXED; break;
-         case 'i': cast->type = FCAST_RAW; break;
-         case 'k': cast->type = FCAST_KEY; break;
-         case 'l': cast->type = FCAST_LOCAL_STRING; break;
-         case 'n': cast->type = FCAST_NAME; break;
-         case 's': cast->type = FCAST_STRING; break;
-         case 'x': cast->type = FCAST_HEX; break;
-         default:
-            cast->unknown = true;
-         }
-         if ( parse->tk_length != 1 ) {
-            cast->unknown = true;
-         }
+      if ( parse->tk_length != 1 ) {
+         cast->unknown = true;
       }
    }
    if ( cast->unknown ) {
@@ -1171,18 +1157,6 @@ void read_array_field( struct parse* parse, struct array_field* field ) {
    p_read_tk( parse );
 }
 
-void read_msgbuild_format_item( struct parse* parse,
-   struct format_item* item ) {
-   struct format_item_msgbuild* extra = mem_alloc( sizeof( *extra ) );
-   extra->func = NULL;
-   extra->call = NULL;
-   item->extra = extra;
-   struct expr_reading value;
-   p_init_expr_reading( &value, false, false, false, true );
-   p_read_expr( parse, &value );
-   item->value = value.output_node;
-}
-
 void read_sure( struct parse* parse, struct expr_reading* reading ) {
    p_test_tk( parse, TK_LOG_NOT );
    struct sure* sure = mem_alloc( sizeof( *sure ) );
@@ -1361,4 +1335,4 @@ void read_magic_id( struct parse* parse, struct expr_reading* reading ) {
    }
    p_read_tk( parse );
    reading->node = &magic_id->node;
-}
+}

src/parse/phase.h

@@ -177,6 +177,7 @@ enum tk {
    TK_FUNCTIONNAME,
    TK_SCRIPTNAME,
    TK_AT,
+   TK_BUILDMSG,
 
    TK_TOTAL,
 
@@ -560,4 +561,4 @@ void p_init_paren_reading( struct parse* parse,
 void p_read_paren_type( struct parse* parse, struct paren_reading* reading );
 void p_add_altern_file_name( struct parse* parse, const char* name, int line );
 
-#endif
+#endif