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clean up analysis of {blocks}

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* Don't insert void statements all over the place. {} now stays as
  {} instead of {{}}, and {;} becomes {} instead of {{};{}}.
* Ensure final statement is always the return value statement, or
  the block is empty. This means {label:} becomes {label:{}}.
This commit is contained in:
Josh Wolfe 2017-03-31 08:41:00 -07:00
parent d5a6cdb03f
commit 36a015741d
3 changed files with 23 additions and 10 deletions
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3
src/all_types.hpp
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@ -403,6 +403,9 @@ struct AstNodeParamDecl {
};
struct AstNodeBlock {
// the final statement is the returned expression.
// if there are no statements, the returned expression is void.
// the final statement is never a label.
ZigList<AstNode *> statements;
};

12
src/ir.cpp
View File

@ -3269,6 +3269,11 @@ static IrInstruction *ir_gen_block(IrBuilder *irb, Scope *parent_scope, AstNode
fn_entry->def_scope = scope_block;
}
if (block_node->data.block.statements.length == 0) {
// {}
return ir_mark_gen(ir_build_const_void(irb, child_scope, block_node));
}
IrInstruction *return_value = nullptr;
for (size_t i = 0; i < block_node->data.block.statements.length; i += 1) {
AstNode *statement_node = block_node->data.block.statements.at(i);
@ -3292,7 +3297,8 @@ static IrInstruction *ir_gen_block(IrBuilder *irb, Scope *parent_scope, AstNode
scope_block->label_table.put(label_name, label);
}
if (!return_value || !instr_is_unreachable(return_value)) {
if (!(return_value && instr_is_unreachable(return_value))) {
// fall through into new labeled basic block
IrInstruction *is_comptime = ir_mark_gen(ir_build_const_bool(irb, child_scope, statement_node,
ir_should_inline(irb->exec, child_scope)));
ir_mark_gen(ir_build_br(irb, child_scope, statement_node, label_block, is_comptime));
@ -3321,8 +3327,8 @@ static IrInstruction *ir_gen_block(IrBuilder *irb, Scope *parent_scope, AstNode
}
}
if (!return_value)
return_value = ir_mark_gen(ir_build_const_void(irb, child_scope, block_node));
// labels are never the last statement
assert(return_value != nullptr);
if (!instr_is_unreachable(return_value))
ir_gen_defers_for_block(irb, child_scope, outer_block_scope, false, false);

18
src/parser.cpp
View File

@ -2094,16 +2094,14 @@ static AstNode *ast_parse_block(ParseContext *pc, size_t *token_index, bool mand
AstNode *node = ast_create_node(pc, NodeTypeBlock, last_token);
// {} -> {void}
// {;} -> {void;void}
// {2} -> {2}
// {2;} -> {2;void}
// {;2} -> {void;2}
for (;;) {
AstNode *statement_node = ast_parse_label(pc, token_index, false);
bool need_implicit_final_void_statement = false;
bool semicolon_expected;
if (statement_node) {
semicolon_expected = false;
// if a label is the last thing in a block, add a void statement.
need_implicit_final_void_statement = true;
} else {
statement_node = ast_parse_variable_declaration_expr(pc, token_index, false, VisibModPrivate);
if (!statement_node) {
@ -2117,17 +2115,23 @@ static AstNode *ast_parse_block(ParseContext *pc, size_t *token_index, bool mand
if (!statement_node) {
statement_node = ast_parse_non_block_expr(pc, token_index, false);
if (!statement_node) {
statement_node = ast_create_void_expr(pc, last_token);
// final semicolon means add a void statement.
need_implicit_final_void_statement = true;
}
}
}
}
node->data.block.statements.append(statement_node);
if (statement_node)
node->data.block.statements.append(statement_node);
last_token = &pc->tokens->at(*token_index);
if (last_token->id == TokenIdRBrace) {
*token_index += 1;
if (node->data.block.statements.length > 0 && need_implicit_final_void_statement) {
node->data.block.statements.append(ast_create_void_expr(pc, last_token));
}
return node;
} else if (!semicolon_expected) {
continue;