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//===- SPIRVConvergenceRegionAnalysis.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
//
//===----------------------------------------------------------------------===//
//
// The analysis determines the convergence region for each basic block of
// the module, and provides a tree-like structure describing the region
// hierarchy.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_SPIRV_SPIRVCONVERGENCEREGIONANALYSIS_H
#define LLVM_LIB_TARGET_SPIRV_SPIRVCONVERGENCEREGIONANALYSIS_H
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IntrinsicInst.h"
#include <iostream>
#include <optional>
#include <unordered_set>
namespace llvm {
class SPIRVSubtarget;
class MachineFunction;
class MachineModuleInfo;
namespace SPIRV {
// Returns the first convergence intrinsic found in |BB|, |nullopt| otherwise.
std::optional<IntrinsicInst *> getConvergenceToken(BasicBlock *BB);
std::optional<const IntrinsicInst *> getConvergenceToken(const BasicBlock *BB);
// Describes a hierarchy of convergence regions.
// A convergence region defines a CFG for which the execution flow can diverge
// starting from the entry block, but should reconverge back before the end of
// the exit blocks.
class ConvergenceRegion {
DominatorTree &DT;
LoopInfo &LI;
public:
// The parent region of this region, if any.
ConvergenceRegion *Parent = nullptr;
// The sub-regions contained in this region, if any.
SmallVector<ConvergenceRegion *> Children = {};
// The convergence instruction linked to this region, if any.
std::optional<IntrinsicInst *> ConvergenceToken = std::nullopt;
// The only block with a predecessor outside of this region.
BasicBlock *Entry = nullptr;
// All the blocks with an edge leaving this convergence region.
SmallPtrSet<BasicBlock *, 2> Exits = {};
// All the blocks that belongs to this region, including its subregions'.
SmallPtrSet<BasicBlock *, 8> Blocks = {};
// Creates a single convergence region encapsulating the whole function |F|.
ConvergenceRegion(DominatorTree &DT, LoopInfo &LI, Function &F);
// Creates a single convergence region defined by entry and exits nodes, a
// list of blocks, and possibly a convergence token.
ConvergenceRegion(DominatorTree &DT, LoopInfo &LI,
std::optional<IntrinsicInst *> ConvergenceToken,
BasicBlock *Entry, SmallPtrSet<BasicBlock *, 8> &&Blocks,
SmallPtrSet<BasicBlock *, 2> &&Exits);
ConvergenceRegion(ConvergenceRegion &&CR)
: DT(CR.DT), LI(CR.LI), Parent(std::move(CR.Parent)),
Children(std::move(CR.Children)),
ConvergenceToken(std::move(CR.ConvergenceToken)),
Entry(std::move(CR.Entry)), Exits(std::move(CR.Exits)),
Blocks(std::move(CR.Blocks)) {}
ConvergenceRegion(const ConvergenceRegion &other) = delete;
// Returns true if the given basic block belongs to this region, or to one of
// its subregion.
bool contains(const BasicBlock *BB) const { return Blocks.count(BB) != 0; }
void releaseMemory();
// Write to the debug output this region's hierarchy.
// |IndentSize| defines the number of tabs to print before any new line.
void dump(const unsigned IndentSize = 0) const;
};
// Holds a ConvergenceRegion hierarchy.
class ConvergenceRegionInfo {
// The convergence region this structure holds.
ConvergenceRegion *TopLevelRegion;
public:
ConvergenceRegionInfo() : TopLevelRegion(nullptr) {}
// Creates a new ConvergenceRegionInfo. Ownership of the TopLevelRegion is
// passed to this object.
ConvergenceRegionInfo(ConvergenceRegion *TopLevelRegion)
: TopLevelRegion(TopLevelRegion) {}
~ConvergenceRegionInfo() { releaseMemory(); }
ConvergenceRegionInfo(ConvergenceRegionInfo &&LHS)
: TopLevelRegion(LHS.TopLevelRegion) {
if (TopLevelRegion != LHS.TopLevelRegion) {
releaseMemory();
TopLevelRegion = LHS.TopLevelRegion;
}
LHS.TopLevelRegion = nullptr;
}
ConvergenceRegionInfo &operator=(ConvergenceRegionInfo &&LHS) {
if (TopLevelRegion != LHS.TopLevelRegion) {
releaseMemory();
TopLevelRegion = LHS.TopLevelRegion;
}
LHS.TopLevelRegion = nullptr;
return *this;
}
void releaseMemory() {
if (TopLevelRegion == nullptr)
return;
TopLevelRegion->releaseMemory();
delete TopLevelRegion;
TopLevelRegion = nullptr;
}
const ConvergenceRegion *getTopLevelRegion() const { return TopLevelRegion; }
};
} // namespace SPIRV
// Wrapper around the function above to use it with the legacy pass manager.
class SPIRVConvergenceRegionAnalysisWrapperPass : public FunctionPass {
SPIRV::ConvergenceRegionInfo CRI;
public:
static char ID;
SPIRVConvergenceRegionAnalysisWrapperPass();
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
AU.addRequired<LoopInfoWrapperPass>();
AU.addRequired<DominatorTreeWrapperPass>();
};
bool runOnFunction(Function &F) override;
SPIRV::ConvergenceRegionInfo &getRegionInfo() { return CRI; }
const SPIRV::ConvergenceRegionInfo &getRegionInfo() const { return CRI; }
};
// Wrapper around the function above to use it with the new pass manager.
class SPIRVConvergenceRegionAnalysis
: public AnalysisInfoMixin<SPIRVConvergenceRegionAnalysis> {
friend AnalysisInfoMixin<SPIRVConvergenceRegionAnalysis>;
static AnalysisKey Key;
public:
using Result = SPIRV::ConvergenceRegionInfo;
Result run(Function &F, FunctionAnalysisManager &AM);
};
namespace SPIRV {
ConvergenceRegionInfo getConvergenceRegions(Function &F, DominatorTree &DT,
LoopInfo &LI);
} // namespace SPIRV
} // namespace llvm
#endif // LLVM_LIB_TARGET_SPIRV_SPIRVCONVERGENCEREGIONANALYSIS_H
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