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https://github.com/carbon-language/carbon-lang.git
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Richard Smith
4b69264cb1
Add validation that every code block in a function is terminated by a sequence of terminating instructions, and that terminators don't appear anywhere else in code blocks. This required tracking whether we're in a reachable code block. That's done on the fly when we create a new code block; the new `SemanticsNodeBlockId::Unreachable` is used to represent the case where we're not actually creating a code block because we're in unreachable code.
66 lines
2.6 KiB
C++
66 lines
2.6 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`, and branch on it.
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cond_value_id = context.ImplicitAsBool(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 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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context.AddCurrentCodeBlockToFunction();
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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 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(if_node, chosen_value_id);
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return true;
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}
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} // namespace Carbon
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