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Richard SmithandChandler Carruth
1013d1773c
Start treating function calls as initializing expressions instead of as value expressions. This required adding support for expression categories. Value bindings and temporary materialization conversions are created where necessary to transition between expression categories. For a function call with a return slot, we speculatively create a materialized temporary before the call and either commit to it or replace it with something else later, once we see how the function call expression is actually used. This change follows the direction suggested in #3133 for initializing expressions: depending on the return type of a function, the return value will either be initialized in-place or returned directly. This is visible in the semantics IR, which is a little unfortunate but is probably necessary as this is part of the semantics of the program. --------- Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
70 lines
2.7 KiB
C++
70 lines
2.7 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/semantics/semantics_context.h"
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namespace Carbon::Check {
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auto HandleIfExpressionIf(Context& context, ParseTree::Node if_node) -> bool {
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auto cond_value_id = context.node_stack().PopExpression();
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context.node_stack().Push(if_node);
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// Convert the condition to `bool`, and branch on it.
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cond_value_id = context.ConvertToBoolValue(if_node, cond_value_id);
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auto then_block_id =
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context.AddDominatedBlockAndBranchIf(if_node, cond_value_id);
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auto else_block_id = context.AddDominatedBlockAndBranch(if_node);
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// Push the `else` block and `then` block, and start emitting the `then`.
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context.node_block_stack().Pop();
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context.node_block_stack().Push(else_block_id);
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context.node_block_stack().Push(then_block_id);
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context.AddCurrentCodeBlockToFunction();
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return true;
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}
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auto HandleIfExpressionThen(Context& context, ParseTree::Node then_node)
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-> bool {
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// Convert the first operand to a value.
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auto [then_value_node, then_value_id] =
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context.node_stack().PopExpressionWithParseNode();
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context.node_stack().Push(then_value_node,
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context.ConvertToValueExpression(then_value_id));
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context.node_stack().Push(then_node, context.node_block_stack().Pop());
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context.AddCurrentCodeBlockToFunction();
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return true;
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}
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auto HandleIfExpressionElse(Context& context, ParseTree::Node else_node)
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-> bool {
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auto else_value_id = context.node_stack().PopExpression();
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auto [then_node, then_end_block_id] =
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context.node_stack().PopWithParseNode<ParseNodeKind::IfExpressionThen>();
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auto then_value_id = context.node_stack().PopExpression();
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auto if_node =
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context.node_stack().PopForSoloParseNode<ParseNodeKind::IfExpressionIf>();
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// Convert the `else` value to the `then` value's type, and finish the `else`
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// block.
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// TODO: Find a common type, and convert both operands to it instead.
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auto result_type_id = context.semantics_ir().GetNode(then_value_id).type_id();
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else_value_id =
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context.ConvertToValueOfType(else_node, else_value_id, result_type_id);
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auto else_end_block_id = context.node_block_stack().Pop();
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// Create a resumption block and branches to it.
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auto chosen_value_id = context.AddConvergenceBlockWithArgAndPush(
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if_node,
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{{then_end_block_id, then_value_id}, {else_end_block_id, else_value_id}});
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context.AddCurrentCodeBlockToFunction();
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// Push the result value.
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context.node_stack().Push(else_node, chosen_value_id);
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return true;
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}
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} // namespace Carbon::Check
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