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refactor ir_gen_block to make different return paths more clear

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This commit is contained in:
Josh Wolfe 2017-04-23 09:04:15 -07:00
parent 14dfbd6ad3
commit 2ed47070ef
1 changed files with 19 additions and 14 deletions
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33
src/ir.cpp
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@ -3350,6 +3350,7 @@ static IrInstruction *ir_gen_block(IrBuilder *irb, Scope *parent_scope, AstNode
}
bool is_continuation_unreachable = false;
IrInstruction *noreturn_return_value = nullptr;
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);
@ -3383,16 +3384,15 @@ static IrInstruction *ir_gen_block(IrBuilder *irb, Scope *parent_scope, AstNode
// a label is an entry point
is_continuation_unreachable = false;
return_value = nullptr;
continue;
}
IrInstruction *statement_value = ir_gen_node(irb, statement_node, child_scope);
is_continuation_unreachable = instr_is_unreachable(statement_value);
if (is_continuation_unreachable)
return_value = statement_value;
else
return_value = nullptr;
if (is_continuation_unreachable) {
// keep the last noreturn statement value around in case we need to return it
noreturn_return_value = statement_value;
}
if (statement_node->type == NodeTypeDefer && statement_value != irb->codegen->invalid_instruction) {
// defer starts a new scope
child_scope = statement_node->data.defer.child_scope;
@ -3420,18 +3420,23 @@ static IrInstruction *ir_gen_block(IrBuilder *irb, Scope *parent_scope, AstNode
}
}
if (!is_continuation_unreachable) {
// control flow falls out of block
if (is_continuation_unreachable) {
assert(noreturn_return_value != nullptr);
return noreturn_return_value;
}
// control flow falls out of block
if (!block_node->data.block.last_statement_is_result_expression) {
assert(return_value == nullptr);
return_value = ir_mark_gen(ir_build_const_void(irb, child_scope, block_node));
}
ir_gen_defers_for_block(irb, child_scope, outer_block_scope, false);
if (block_node->data.block.last_statement_is_result_expression) {
// return value was determined by the last statement
assert(return_value != nullptr);
} else {
// return value is implicitly void
assert(return_value == nullptr);
return_value = ir_mark_gen(ir_build_const_void(irb, child_scope, block_node));
}
assert(return_value != nullptr);
ir_gen_defers_for_block(irb, child_scope, outer_block_scope, false);
return return_value;
}