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https://github.com/carbon-language/carbon-lang.git
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Jon Ross-Perkins
311b4ff03d
This in particular uses free functions because it's likely to end up more consistent with types (versus a wrapper object for InstStore). Note, this is unlikely to have a performance impact, but if it does, we can look into related approaches (and we've already discussed using LTO). Renames `PendingBlock::AddInst` to `PendingBlock::Add` because `MakeElementAccessInst` expects the matching name to exist.
103 lines
3.5 KiB
C++
103 lines
3.5 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_PENDING_BLOCK_H_
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#define CARBON_TOOLCHAIN_CHECK_PENDING_BLOCK_H_
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#include "llvm/ADT/SmallVector.h"
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#include "toolchain/check/context.h"
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#include "toolchain/check/inst.h"
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#include "toolchain/sem_ir/inst.h"
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namespace Carbon::Check {
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// A block of code that contains pending instructions that might be needed but
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// that haven't been inserted yet.
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class PendingBlock {
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public:
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explicit PendingBlock(Context& context) : context_(context) {}
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PendingBlock(const PendingBlock&) = delete;
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auto operator=(const PendingBlock&) -> PendingBlock& = delete;
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// A scope in which we will tentatively add instructions to a pending block.
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// If we leave the scope without inserting or merging the block, instructions
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// added after this point will be removed again.
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class DiscardUnusedInstsScope {
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public:
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// If `block` is not null, enters the scope. If `block` is null, this object
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// has no effect.
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explicit DiscardUnusedInstsScope(PendingBlock* block)
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: block_(block), size_(block ? block->insts_.size() : 0) {}
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~DiscardUnusedInstsScope() {
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if (block_ && block_->insts_.size() > size_) {
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block_->insts_.truncate(size_);
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}
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}
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private:
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PendingBlock* block_;
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size_t size_;
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};
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template <typename InstT, typename LocT>
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auto AddInst(LocT loc_id, InstT inst) -> SemIR::InstId {
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auto inst_id = AddInstInNoBlock(context_, loc_id, inst);
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insts_.push_back(inst_id);
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return inst_id;
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}
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// Insert the pending block of code at the current position.
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auto InsertHere() -> void {
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for (auto id : insts_) {
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context_.inst_block_stack().AddInstId(id);
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}
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insts_.clear();
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}
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// Replace the instruction at target_id with the instructions in this block.
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// The new value for target_id should be value_id.
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auto MergeReplacing(SemIR::InstId target_id, SemIR::InstId value_id) -> void {
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auto value = context_.insts().GetWithLocId(value_id);
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// There are three cases here:
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if (insts_.empty()) {
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// 1) The block is empty. Replace `target_id` with an empty splice
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// pointing at `value_id`.
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ReplaceLocIdAndInstBeforeConstantUse(
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context_, target_id,
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SemIR::LocIdAndInst(
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value.loc_id,
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SemIR::SpliceBlock{.type_id = value.inst.type_id(),
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.block_id = SemIR::InstBlockId::Empty,
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.result_id = value_id}));
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} else if (insts_.size() == 1 && insts_[0] == value_id) {
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// 2) The block is {value_id}. Replace `target_id` with the instruction
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// referred to by `value_id`. This is intended to be the common case.
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ReplaceLocIdAndInstBeforeConstantUse(context_, target_id, value);
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} else {
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// 3) Anything else: splice it into the IR, replacing `target_id`.
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ReplaceLocIdAndInstBeforeConstantUse(
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context_, target_id,
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SemIR::LocIdAndInst(
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value.loc_id,
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SemIR::SpliceBlock{.type_id = value.inst.type_id(),
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.block_id = context_.inst_blocks().Add(insts_),
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.result_id = value_id}));
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}
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// Prepare to stash more pending instructions.
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insts_.clear();
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}
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private:
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Context& context_;
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llvm::SmallVector<SemIR::InstId> insts_;
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};
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} // namespace Carbon::Check
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#endif // CARBON_TOOLCHAIN_CHECK_PENDING_BLOCK_H_
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