[Utils] Consolidate LockstepReverseIterator into own header (NFC)
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| //===- LockstepReverseIterator.h ------------------------------*- C++ -*---===// | ||||||||
| // | ||||||||
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | ||||||||
| // See https://llvm.org/LICENSE.txt for license information. | ||||||||
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||||||||
| // | ||||||||
| //===----------------------------------------------------------------------===// | ||||||||
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| #ifndef LLVM_TRANSFORMS_UTILS_LOCKSTEPREVERSEITERATOR_H | ||||||||
| #define LLVM_TRANSFORMS_UTILS_LOCKSTEPREVERSEITERATOR_H | ||||||||
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| #include "llvm/ADT/ArrayRef.h" | ||||||||
| #include "llvm/ADT/SetVector.h" | ||||||||
| #include "llvm/ADT/SmallVector.h" | ||||||||
| #include "llvm/IR/BasicBlock.h" | ||||||||
| #include "llvm/IR/Instruction.h" | ||||||||
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| namespace llvm { | ||||||||
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| struct NoActiveBlocksOption { | ||||||||
| template <typename... Args> NoActiveBlocksOption(Args...) {} | ||||||||
| }; | ||||||||
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| struct ActiveBlocksOption { | ||||||||
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Contributor
Author
There was a problem hiding this comment. I'd rather favour
Collaborator
There was a problem hiding this comment. FWIW https://llvm.org/docs/CodingStandards.html#use-of-class-and-struct-keywords says to use struct when all members are public, which isn't the case here |
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| protected: | ||||||||
| SmallSetVector<BasicBlock *, 4> ActiveBlocks; | ||||||||
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| public: | ||||||||
| ActiveBlocksOption() = default; | ||||||||
| }; | ||||||||
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| /// Iterates through instructions in a set of blocks in reverse order from the | ||||||||
| /// first non-terminator. For example (assume all blocks have size n): | ||||||||
| /// LockstepReverseIterator I([B1, B2, B3]); | ||||||||
| /// *I-- = [B1[n], B2[n], B3[n]]; | ||||||||
| /// *I-- = [B1[n-1], B2[n-1], B3[n-1]]; | ||||||||
| /// *I-- = [B1[n-2], B2[n-2], B3[n-2]]; | ||||||||
| /// ... | ||||||||
| /// | ||||||||
| /// The iterator continues processing until all blocks have been exhausted if \p | ||||||||
| /// EarlyFailure is explicitly set to \c false. Use \c getActiveBlocks() to | ||||||||
| /// determine which blocks are still going and the order they appear in the list | ||||||||
| /// returned by operator*. | ||||||||
| template <bool EarlyFailure = true> | ||||||||
| class LockstepReverseIterator | ||||||||
| : public std::conditional_t<EarlyFailure, NoActiveBlocksOption, | ||||||||
| ActiveBlocksOption> { | ||||||||
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| private: | ||||||||
| using BasicBlockT = BasicBlock; | ||||||||
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| using InstructionT = Instruction; | ||||||||
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| ArrayRef<BasicBlockT *> Blocks; | ||||||||
| SmallVector<InstructionT *, 4> Insts; | ||||||||
| bool Fail; | ||||||||
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| public: | ||||||||
| LockstepReverseIterator(ArrayRef<BasicBlockT *> Blocks) : Blocks(Blocks) { | ||||||||
| reset(); | ||||||||
| } | ||||||||
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| void reset() { | ||||||||
| Fail = false; | ||||||||
| if constexpr (!EarlyFailure) { | ||||||||
| this->ActiveBlocks.clear(); | ||||||||
| for (BasicBlockT *BB : Blocks) | ||||||||
| this->ActiveBlocks.insert(BB); | ||||||||
| } | ||||||||
| Insts.clear(); | ||||||||
| for (BasicBlockT *BB : Blocks) { | ||||||||
| InstructionT *Prev = BB->getTerminator()->getPrevNonDebugInstruction(); | ||||||||
| if (!Prev) { | ||||||||
| // Block wasn't big enough - only contained a terminator. | ||||||||
| if constexpr (EarlyFailure) { | ||||||||
| Fail = true; | ||||||||
| return; | ||||||||
| } else { | ||||||||
| this->ActiveBlocks.remove(BB); | ||||||||
| continue; | ||||||||
| } | ||||||||
| } | ||||||||
| Insts.push_back(Prev); | ||||||||
| } | ||||||||
| if (Insts.empty()) | ||||||||
| Fail = true; | ||||||||
| } | ||||||||
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| bool isValid() const { return !Fail; } | ||||||||
| ArrayRef<InstructionT *> operator*() const { return Insts; } | ||||||||
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| // Note: This needs to return a SmallSetVector as the elements of | ||||||||
| // ActiveBlocks will be later copied to Blocks using std::copy. The | ||||||||
| // resultant order of elements in Blocks needs to be deterministic. | ||||||||
| // Using SmallPtrSet instead causes non-deterministic order while | ||||||||
| // copying. And we cannot simply sort Blocks as they need to match the | ||||||||
| // corresponding Values. | ||||||||
| template <bool C = EarlyFailure, std::enable_if_t<!C, int> = 0> | ||||||||
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| SmallSetVector<BasicBlockT *, 4> &getActiveBlocks() { | ||||||||
| return this->ActiveBlocks; | ||||||||
| } | ||||||||
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| template <bool C = EarlyFailure, std::enable_if_t<!C, int> = 0> | ||||||||
| void restrictToBlocks(SmallSetVector<BasicBlockT *, 4> &Blocks) { | ||||||||
| for (auto It = Insts.begin(); It != Insts.end();) { | ||||||||
| if (!Blocks.contains((*It)->getParent())) { | ||||||||
| this->ActiveBlocks.remove((*It)->getParent()); | ||||||||
| It = Insts.erase(It); | ||||||||
| } else { | ||||||||
| ++It; | ||||||||
| } | ||||||||
| } | ||||||||
| } | ||||||||
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| void operator--() { | ||||||||
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| if (Fail) | ||||||||
| return; | ||||||||
| SmallVector<InstructionT *, 4> NewInsts; | ||||||||
| for (InstructionT *Inst : Insts) { | ||||||||
| InstructionT *Prev = Inst->getPrevNonDebugInstruction(); | ||||||||
| if (!Prev) { | ||||||||
| if constexpr (!EarlyFailure) { | ||||||||
| this->ActiveBlocks.remove(Inst->getParent()); | ||||||||
| } else { | ||||||||
| Fail = true; | ||||||||
| return; | ||||||||
| } | ||||||||
| } else { | ||||||||
| NewInsts.push_back(Prev); | ||||||||
| } | ||||||||
| } | ||||||||
| if (NewInsts.empty()) { | ||||||||
| Fail = true; | ||||||||
| return; | ||||||||
| } | ||||||||
| Insts = NewInsts; | ||||||||
| } | ||||||||
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| void operator++() { | ||||||||
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| void operator++() { | |
| void operator++() { | |
| static_assert(!EarlyFailure, "Unknown method"); |
This method does not maintain the set of active blocks.
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