[Utils] Consolidate LockstepReverseIterator into own header (NFC)
#116657
There are no files selected for viewing
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change | ||||||
|---|---|---|---|---|---|---|---|---|
| @@ -0,0 +1,155 @@ | ||||||||
| //===- 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 | ||||||||
| // | ||||||||
| //===----------------------------------------------------------------------===// | ||||||||
|
|
||||||||
| #ifndef LLVM_TRANSFORMS_UTILS_LOCKSTEPREVERSEITERATOR_H | ||||||||
| #define LLVM_TRANSFORMS_UTILS_LOCKSTEPREVERSEITERATOR_H | ||||||||
|
|
||||||||
| #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" | ||||||||
|
|
||||||||
| namespace llvm { | ||||||||
|
|
||||||||
| struct NoActiveBlocksOption {}; | ||||||||
|
|
||||||||
| struct ActiveBlocksOption { | ||||||||
| protected: | ||||||||
| SmallSetVector<BasicBlock *, 4> ActiveBlocks; | ||||||||
|
|
||||||||
| public: | ||||||||
| ActiveBlocksOption() = default; | ||||||||
| }; | ||||||||
|
|
||||||||
| /// 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> { | ||||||||
|
||||||||
| private: | ||||||||
| ArrayRef<BasicBlock *> Blocks; | ||||||||
| SmallVector<Instruction *, 4> Insts; | ||||||||
| bool Fail; | ||||||||
|
|
||||||||
| public: | ||||||||
| LockstepReverseIterator(ArrayRef<BasicBlock *> Blocks) : Blocks(Blocks) { | ||||||||
| reset(); | ||||||||
| } | ||||||||
|
|
||||||||
| void reset() { | ||||||||
| Fail = false; | ||||||||
| if constexpr (!EarlyFailure) { | ||||||||
| this->ActiveBlocks.clear(); | ||||||||
| for (BasicBlock *BB : Blocks) | ||||||||
| this->ActiveBlocks.insert(BB); | ||||||||
| } | ||||||||
| Insts.clear(); | ||||||||
| for (BasicBlock *BB : Blocks) { | ||||||||
| Instruction *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; | ||||||||
| } | ||||||||
|
|
||||||||
| bool isValid() const { return !Fail; } | ||||||||
| ArrayRef<Instruction *> operator*() const { return Insts; } | ||||||||
|
|
||||||||
| // 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. | ||||||||
| SmallSetVector<BasicBlock *, 4> &getActiveBlocks() { | ||||||||
| static_assert(!EarlyFailure, "Unknown method"); | ||||||||
| return this->ActiveBlocks; | ||||||||
| } | ||||||||
|
|
||||||||
|
Collaborator
There was a problem hiding this comment. Could this be a member of the active blocks base, so it's just totally not defined on the inactive version? (then there'd be no need for the static assert, and maybe it'd be better for compiler diagnostics?)
Contributor
Author
There was a problem hiding this comment. Makes sense, though we still need to expose getActiveBlocks in the derived as well, as the base one is now constrained by private inheritance. |
||||||||
| void restrictToBlocks(SmallSetVector<BasicBlock *, 4> &Blocks) { | ||||||||
| static_assert(!EarlyFailure, "Unknown method"); | ||||||||
| for (auto It = Insts.begin(); It != Insts.end();) { | ||||||||
| if (!Blocks.contains((*It)->getParent())) { | ||||||||
| this->ActiveBlocks.remove((*It)->getParent()); | ||||||||
| It = Insts.erase(It); | ||||||||
| } else { | ||||||||
| ++It; | ||||||||
| } | ||||||||
| } | ||||||||
| } | ||||||||
|
|
||||||||
| void operator--() { | ||||||||
|
||||||||
| if (Fail) | ||||||||
| return; | ||||||||
| SmallVector<Instruction *, 4> NewInsts; | ||||||||
| for (Instruction *Inst : Insts) { | ||||||||
| Instruction *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; | ||||||||
| } | ||||||||
|
|
||||||||
| void operator++() { | ||||||||
|
||||||||
| void operator++() { | |
| void operator++() { | |
| static_assert(!EarlyFailure, "Unknown method"); |
This method does not maintain the set of active blocks.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Use
class.Uh oh!
There was an error while loading. Please reload this page.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I'd rather favour
structfor consistency, as we keep the default constructor private forNoActiveBlocksOption, unless it's a strong concern.There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
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