mirror of
https://github.com/carbon-language/carbon-lang.git
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Richard Smith
a66f35e92c
`SemIR` now only stores complete blocks, and placeholders for blocks where we need a block ID before we know the block contents. This is a preparation step towards the new node block allocation design.
113 lines
3.7 KiB
C++
113 lines
3.7 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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#ifndef CARBON_TOOLCHAIN_CHECK_NODE_BLOCK_STACK_H_
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#define CARBON_TOOLCHAIN_CHECK_NODE_BLOCK_STACK_H_
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#include "llvm/ADT/SmallVector.h"
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#include "toolchain/sem_ir/file.h"
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#include "toolchain/sem_ir/node.h"
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namespace Carbon::Check {
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// Wraps the stack of node blocks for Context.
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//
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// All pushes and pops will be vlogged.
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class NodeBlockStack {
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public:
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explicit NodeBlockStack(llvm::StringLiteral name, SemIR::File& semantics_ir,
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llvm::raw_ostream* vlog_stream)
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: name_(name), semantics_ir_(&semantics_ir), vlog_stream_(vlog_stream) {}
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// Pushes an existing node block.
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auto Push(SemIR::NodeBlockId id) -> void;
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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 { Push(SemIR::NodeBlockId::Invalid); }
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// Pushes a new unreachable code block.
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auto PushUnreachable() -> void { Push(SemIR::NodeBlockId::Unreachable); }
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// Allocates and pushes a new node block.
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auto PushForAdd() -> SemIR::NodeBlockId {
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Push();
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return PeekForAdd();
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}
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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() -> SemIR::NodeBlockId {
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CARBON_CHECK(!empty()) << "no current block";
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return stack_[size() - 1].id;
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}
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// Returns the top node block, allocating one if it's still invalid. If
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// `depth` is specified, returns the node at `depth` levels from the top of
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// the stack, where the top block is at depth 0.
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auto PeekForAdd(int depth = 0) -> SemIR::NodeBlockId;
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// Pops the top node block. This will always return a valid node block;
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// SemIR::NodeBlockId::Empty is returned if one wasn't allocated.
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auto Pop() -> SemIR::NodeBlockId;
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// Adds the given node ID to the block at the top of the stack.
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auto AddNodeId(SemIR::NodeId node_id) -> void {
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CARBON_CHECK(!empty()) << "no current block";
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stack_[size_ - 1].content.push_back(node_id);
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}
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// Returns whether the current block is statically reachable.
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auto is_current_block_reachable() -> bool {
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return Peek() != SemIR::NodeBlockId::Unreachable;
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}
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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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auto empty() const -> bool { return size() == 0; }
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auto size() const -> int { return size_; }
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private:
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struct StackEntry {
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// Preallocate an arbitrary size for the stack entries.
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// TODO: Perform measurements to pick a good starting size to avoid
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// reallocation.
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StackEntry() { content.reserve(32); }
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auto Reset(SemIR::NodeBlockId new_id) {
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id = new_id;
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content.clear();
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}
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// The block ID, if one has been allocated, Invalid if no block has been
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// allocated, or Unreachable if this block is known to be unreachable.
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SemIR::NodeBlockId id = SemIR::NodeBlockId::Invalid;
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// The content of the block. Stored as a vector rather than as a SmallVector
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// to reduce the cost of resizing `stack_` and performing swaps.
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std::vector<SemIR::NodeId> content;
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};
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// A name for debugging.
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llvm::StringLiteral name_;
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// The underlying SemIR::File instance. Always non-null.
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SemIR::File* semantics_ir_;
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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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llvm::SmallVector<StackEntry> stack_;
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// The size of the stack. Entries after this in `stack_` are kept around so
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// that we can reuse the allocated buffer for their content.
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int size_ = 0;
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};
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} // namespace Carbon::Check
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#endif // CARBON_TOOLCHAIN_CHECK_NODE_BLOCK_STACK_H_
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