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Jon Ross-Perkins
9751b4701d
I think there's more we can do here, but this seemed like a good checkpoint to make sure the path I'm going down is roughly what you expected. There's one actual edit in if expression structure to match the increased enforcement.
87 lines
3.2 KiB
C++
87 lines
3.2 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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#include "toolchain/semantics/semantics_node.h"
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namespace Carbon {
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auto SemanticsHandleIfConditionStart(SemanticsContext& /*context*/,
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ParseTree::Node /*parse_node*/) -> bool {
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return true;
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}
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auto SemanticsHandleIfCondition(SemanticsContext& context,
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ParseTree::Node parse_node) -> bool {
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// Convert the condition to `bool`.
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auto cond_value_id = context.node_stack().Pop<SemanticsNodeId>();
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cond_value_id = context.ImplicitAsBool(parse_node, cond_value_id);
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// Create the then block and the else block, and branch to the right one. If
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// there is no `else`, the then block will terminate with a branch to the
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// else block, which will be reused as the resumption block.
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auto then_block_id =
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context.AddDominatedBlockAndBranchIf(parse_node, cond_value_id);
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auto else_block_id = context.AddDominatedBlockAndBranch(parse_node);
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// Push the else and then blocks, and start emitting code in the then block.
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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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context.node_stack().Push(parse_node);
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return true;
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}
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auto SemanticsHandleIfStatementElse(SemanticsContext& context,
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ParseTree::Node parse_node) -> bool {
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context.node_stack().PopAndDiscardSoloParseNode<ParseNodeKind::IfCondition>();
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// Switch to emitting the else block.
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auto then_block_id = context.node_block_stack().PopForAdd();
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context.node_stack().Push(parse_node, then_block_id);
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context.AddCurrentCodeBlockToFunction();
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return true;
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}
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auto SemanticsHandleIfStatement(SemanticsContext& context,
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ParseTree::Node parse_node) -> bool {
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// Either the then or else block, depending on whether there's an `else` node
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// on the top of the node stack.
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auto sub_block_id = context.node_block_stack().PopForAdd();
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switch (auto kind = context.parse_tree().node_kind(
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context.node_stack().PeekParseNode())) {
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case ParseNodeKind::IfCondition: {
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// Branch from then block to else block.
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context.node_stack()
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.PopAndDiscardSoloParseNode<ParseNodeKind::IfCondition>();
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context.AddNodeToBlock(
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sub_block_id,
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SemanticsNode::Branch::Make(parse_node,
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context.node_block_stack().PeekForAdd()));
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break;
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}
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case ParseNodeKind::IfStatementElse: {
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// Branch from the then and else blocks to a new resumption block.
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SemanticsNodeBlockId then_block_id =
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context.node_stack().Pop<ParseNodeKind::IfStatementElse>();
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context.AddConvergenceBlockAndPush(parse_node,
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{then_block_id, sub_block_id});
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break;
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}
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default: {
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CARBON_FATAL() << "Unexpected parse node at start of `if`: " << kind;
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}
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}
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context.AddCurrentCodeBlockToFunction();
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return true;
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}
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} // namespace Carbon
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