llvm/llvm/include/llvm/CodeGen/GCMetadata.h

//===- GCMetadata.h - Garbage collector metadata ----------------*- 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
//
//===----------------------------------------------------------------------===//
//
// This file declares the GCFunctionInfo and GCModuleInfo classes, which are
// used as a communication channel from the target code generator to the target
// garbage collectors. This interface allows code generators and garbage
// collectors to be developed independently.
//
// The GCFunctionInfo class logs the data necessary to build a type accurate
// stack map. The code generator outputs:
//
//   - Safe points as specified by the GCStrategy's NeededSafePoints.
//   - Stack offsets for GC roots, as specified by calls to llvm.gcroot
//
// As a refinement, liveness analysis calculates the set of live roots at each
// safe point. Liveness analysis is not presently performed by the code
// generator, so all roots are assumed live.
//
// GCModuleInfo simply collects GCFunctionInfo instances for each Function as
// they are compiled. This accretion is necessary for collectors which must emit
// a stack map for the compilation unit as a whole. Therefore, GCFunctionInfo
// outlives the MachineFunction from which it is derived and must not refer to
// any code generator data structures.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CODEGEN_GCMETADATA_H
#define LLVM_CODEGEN_GCMETADATA_H

#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/GCStrategy.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <vector>

namespace llvm {

class Constant;
class Function;
class MCSymbol;

/// GCPoint - Metadata for a collector-safe point in machine code.
///
struct GCPoint { … };

/// GCRoot - Metadata for a pointer to an object managed by the garbage
/// collector.
struct GCRoot { … };

/// Garbage collection metadata for a single function.  Currently, this
/// information only applies to GCStrategies which use GCRoot.
class GCFunctionInfo { … };

struct GCStrategyMap { … };

/// An analysis pass which caches information about the entire Module.
/// Records a cache of the 'active' gc strategy objects for the current Module.
class CollectorMetadataAnalysis
    : public AnalysisInfoMixin<CollectorMetadataAnalysis> { … };

/// An analysis pass which caches information about the Function.
/// Records the function level information used by GCRoots.
/// This pass depends on `CollectorMetadataAnalysis`.
class GCFunctionAnalysis : public AnalysisInfoMixin<GCFunctionAnalysis> { … };

/// LowerIntrinsics - This pass rewrites calls to the llvm.gcread or
/// llvm.gcwrite intrinsics, replacing them with simple loads and stores as
/// directed by the GCStrategy. It also performs automatic root initialization
/// and custom intrinsic lowering.
///
/// This pass requires `CollectorMetadataAnalysis`.
class GCLoweringPass : public PassInfoMixin<GCLoweringPass> { … };

/// An analysis pass which caches information about the entire Module.
/// Records both the function level information used by GCRoots and a
/// cache of the 'active' gc strategy objects for the current Module.
class GCModuleInfo : public ImmutablePass { … };

} // end namespace llvm

#endif // LLVM_CODEGEN_GCMETADATA_H