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https://github.com/carbon-language/carbon-lang.git
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Jon Ross-Perkins
6feed2ae33
For parameters (and in the future, arguments too; generally comma-separated lists) track two node blocks: 1. param_ir: The complete IR. 2. param_refs: Nodes within the IR that are the "root" parameter. param_refs should allow quick counting of the # of parameters, and more efficient comparison of call args with function parameters. param_ir should be necessary to generate the actual signature. In order to construct this, this refactors the node_block_stack into its own class, which is reused in params_stack. These carry references to the underlying SmallVector for lazy modification in order to avoid a dependency cycle with SemanticsIR (also see notes on empty node blocks below). When finalized, the block pair is pushed onto finished_params_stack. That's because node_stack only has space for one thing, and this is two things -- so I'm essentially choosing a trade-off of adding another stack in order to avoid consuming more space in the expectation that most parse nodes have 0 or 1 things to return, and 2 will be very rare. As factored, this currently consolidates most empty node blocks into a single canonical empty node block. This is because I think empty blocks, i.e. `()`, will be very common. In order to achieve this, SemanticsNodeBlockStack does lazy creation. An alternative approach would have been to use 1 node block per parameter. We decided against this in order to reduce the number of vectors being created.
66 lines
2.3 KiB
C++
66 lines
2.3 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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#ifndef CARBON_TOOLCHAIN_SEMANTICS_SEMANTICS_NODE_BLOCK_STACK_H_
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#define CARBON_TOOLCHAIN_SEMANTICS_SEMANTICS_NODE_BLOCK_STACK_H_
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#include <type_traits>
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#include "common/check.h"
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#include "llvm/ADT/SmallVector.h"
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#include "toolchain/semantics/semantics_node.h"
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namespace Carbon {
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// Wraps the stack of node blocks for SemanticsParseTreeHandler.
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//
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// All pushes and pops will be vlogged.
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class SemanticsNodeBlockStack {
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public:
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explicit SemanticsNodeBlockStack(
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llvm::SmallVector<llvm::SmallVector<SemanticsNodeId>>& node_blocks,
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llvm::raw_ostream* vlog_stream)
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: node_blocks_(&node_blocks), vlog_stream_(vlog_stream) {}
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~SemanticsNodeBlockStack() { CARBON_CHECK(stack_.empty()) << stack_.size(); }
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// Pushes a new node block. It will be invalid unless PeekForAdd is called in
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// order to support lazy allocation.
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auto Push() -> void;
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// Pushes a new node block.
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// TODO: Try to remove this in favor of the lazy alloc in Push.
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auto PushWithUnconditionalAlloc() -> SemanticsNodeBlockId;
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// Peeks at the top node block. This does not trigger lazy allocation, so the
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// returned node block may be invalid.
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auto Peek() -> SemanticsNodeBlockId { return stack_.back(); }
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// Returns the top node block, allocating one if it's still invalid.
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auto PeekForAdd() -> SemanticsNodeBlockId;
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// Pops the top node block. This will always return a valid node block;
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// SemanticsNodeBlockId::Empty is returned if one wasn't allocated.
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auto Pop() -> SemanticsNodeBlockId;
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// Prints the stack for a stack dump.
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auto PrintForStackDump(llvm::raw_ostream& output) const -> void;
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private:
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// The underlying node block storage on SemanticsIR. Always non-null.
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llvm::SmallVector<llvm::SmallVector<SemanticsNodeId>>* const node_blocks_;
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// Whether to print verbose output.
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llvm::raw_ostream* vlog_stream_;
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// The actual stack.
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// PushEntry and PopEntry control modification in order to centralize
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// vlogging.
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llvm::SmallVector<SemanticsNodeBlockId> stack_;
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};
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} // namespace Carbon
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#endif // CARBON_TOOLCHAIN_SEMANTICS_SEMANTICS_NODE_BLOCK_STACK_H_
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