mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 21:30:12 +01:00
Richard Smith
06ce3b0161
Lowering for `and` and `or` is not yet complete because `Branch` lowering isn't done yet.
76 lines
3.1 KiB
C++
76 lines
3.1 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 {
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auto SemanticsHandleIfExpressionIf(SemanticsContext& context,
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ParseTree::Node if_node) -> bool {
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auto cond_value_id = context.node_stack().Pop<SemanticsNodeId>();
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context.node_stack().Push(if_node);
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// Convert the condition to `bool`.
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cond_value_id = context.ImplicitAsBool(if_node, cond_value_id);
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// Stop emitting the current block. We'll add some branch instructions to it
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// later, but we don't want it on the stack any more.
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auto if_block_id = context.node_block_stack().PeekForAdd();
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context.node_block_stack().Pop();
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// Create the resumption block, `else` block, and `then` block, and branches
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// to them.
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context.node_block_stack().Push();
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auto else_block_id = context.node_block_stack().PushForAdd();
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auto then_block_id = context.node_block_stack().PushForAdd();
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context.AddNodeToBlock(
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if_block_id,
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SemanticsNode::BranchIf::Make(if_node, then_block_id, cond_value_id));
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context.AddNodeToBlock(if_block_id,
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SemanticsNode::Branch::Make(if_node, else_block_id));
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return true;
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}
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auto SemanticsHandleIfExpressionThen(SemanticsContext& context,
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ParseTree::Node then_node) -> bool {
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context.node_stack().Push(then_node, context.node_block_stack().Pop());
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return true;
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}
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auto SemanticsHandleIfExpressionElse(SemanticsContext& context,
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ParseTree::Node else_node) -> bool {
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auto else_value_id = context.node_stack().Pop<SemanticsNodeId>();
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auto [then_node, then_end_block_id] =
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context.node_stack().PopWithParseNode<SemanticsNodeBlockId>(
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ParseNodeKind::IfExpressionThen);
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auto then_value_id = context.node_stack().Pop<SemanticsNodeId>();
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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.ImplicitAsRequired(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 branches to the resumption block.
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auto resume_block_id = context.node_block_stack().PeekForAdd();
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context.AddNodeToBlock(then_end_block_id,
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SemanticsNode::BranchWithArg::Make(
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then_node, resume_block_id, then_value_id));
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context.AddNodeToBlock(else_end_block_id,
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SemanticsNode::BranchWithArg::Make(
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else_node, resume_block_id, else_value_id));
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// Obtain the value in the resumption block and push it.
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context.AddNodeAndPush(
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if_node, SemanticsNode::BlockArg::Make(if_node, result_type_id));
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return true;
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}
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} // namespace Carbon
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