diff options
Diffstat (limited to 'contrib/llvm/include/llvm/CodeGen/GCStrategy.h')
-rw-r--r-- | contrib/llvm/include/llvm/CodeGen/GCStrategy.h | 173 |
1 files changed, 108 insertions, 65 deletions
diff --git a/contrib/llvm/include/llvm/CodeGen/GCStrategy.h b/contrib/llvm/include/llvm/CodeGen/GCStrategy.h index 81e1f85286e1..0b0c3124c537 100644 --- a/contrib/llvm/include/llvm/CodeGen/GCStrategy.h +++ b/contrib/llvm/include/llvm/CodeGen/GCStrategy.h @@ -12,9 +12,14 @@ // specified in a function's 'gc' attribute. Algorithms are enabled by setting // flags in a subclass's constructor, and some virtual methods can be // overridden. +// +// GCStrategy is relevant for implementations using either gc.root or +// gc.statepoint based lowering strategies, but is currently focused mostly on +// options for gc.root. This will change over time. // -// When requested, the GCStrategy will be populated with data about each -// function which uses it. Specifically: +// When requested by a subclass of GCStrategy, the gc.root implementation will +// populate GCModuleInfo and GCFunctionInfo with that about each Function in +// the Module that opts in to garbage collection. Specifically: // // - Safe points // Garbage collection is generally only possible at certain points in code. @@ -31,40 +36,42 @@ // This information can used to emit the metadata tables which are required by // the target garbage collector runtime. // +// When used with gc.statepoint, information about safepoint and roots can be +// found in the binary StackMap section after code generation. Safepoint +// placement is currently the responsibility of the frontend, though late +// insertion support is planned. gc.statepoint does not currently support +// custom stack map formats; such can be generated by parsing the standard +// stack map section if desired. +// +// The read and write barrier support can be used with either implementation. +// //===----------------------------------------------------------------------===// #ifndef LLVM_CODEGEN_GCSTRATEGY_H #define LLVM_CODEGEN_GCSTRATEGY_H +#include "llvm/ADT/Optional.h" #include "llvm/CodeGen/GCMetadata.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/Support/Registry.h" #include <string> namespace llvm { - - class GCStrategy; - - /// The GC strategy registry uses all the defaults from Registry. - /// - typedef Registry<GCStrategy> GCRegistry; - /// GCStrategy describes a garbage collector algorithm's code generation /// requirements, and provides overridable hooks for those needs which cannot - /// be abstractly described. + /// be abstractly described. GCStrategy objects currently must be looked up + /// through the GCModuleInfo analysis pass. They are owned by the analysis + /// pass and recreated every time that pass is invalidated. class GCStrategy { - public: - typedef std::vector<std::unique_ptr<GCFunctionInfo>> list_type; - typedef list_type::iterator iterator; - private: - friend class GCModuleInfo; - const Module *M; std::string Name; - - list_type Functions; + friend class GCModuleInfo; protected: + bool UseStatepoints; /// Uses gc.statepoints as opposed to gc.roots, + /// if set, none of the other options can be + /// anything but their default values. + unsigned NeededSafePoints; ///< Bitmask of required safe points. bool CustomReadBarriers; ///< Default is to insert loads. bool CustomWriteBarriers; ///< Default is to insert stores. @@ -76,78 +83,114 @@ namespace llvm { public: GCStrategy(); - virtual ~GCStrategy() {} - - /// getName - The name of the GC strategy, for debugging. - /// + /// Return the name of the GC strategy. This is the value of the collector + /// name string specified on functions which use this strategy. const std::string &getName() const { return Name; } - /// getModule - The module within which the GC strategy is operating. - /// - const Module &getModule() const { return *M; } + /// By default, write barriers are replaced with simple store + /// instructions. If true, then performCustomLowering must instead lower + /// them. + bool customWriteBarrier() const { return CustomWriteBarriers; } + + /// By default, read barriers are replaced with simple load + /// instructions. If true, then performCustomLowering must instead lower + /// them. + bool customReadBarrier() const { return CustomReadBarriers; } + + /// Returns true if this strategy is expecting the use of gc.statepoints, + /// and false otherwise. + bool useStatepoints() const { return UseStatepoints; } + + /** @name Statepoint Specific Properties */ + ///@{ - /// needsSafePoitns - True if safe points of any kind are required. By - // default, none are recorded. + /// If the value specified can be reliably distinguished, returns true for + /// pointers to GC managed locations and false for pointers to non-GC + /// managed locations. Note a GCStrategy can always return 'None' (i.e. an + /// empty optional indicating it can't reliably distinguish. + virtual Optional<bool> isGCManagedPointer(const Value *V) const { + return None; + } + ///@} + + /** @name GCRoot Specific Properties + * These properties and overrides only apply to collector strategies using + * GCRoot. + */ + ///@{ + + /// True if safe points of any kind are required. By default, none are + /// recorded. bool needsSafePoints() const { return CustomSafePoints || NeededSafePoints != 0; } - /// needsSafePoint(Kind) - True if the given kind of safe point is - // required. By default, none are recorded. + /// True if the given kind of safe point is required. By default, none are + /// recorded. bool needsSafePoint(GC::PointKind Kind) const { return (NeededSafePoints & 1 << Kind) != 0; } - - /// customWriteBarrier - By default, write barriers are replaced with simple - /// store instructions. If true, then - /// performCustomLowering must instead lower them. - bool customWriteBarrier() const { return CustomWriteBarriers; } - - /// customReadBarrier - By default, read barriers are replaced with simple - /// load instructions. If true, then - /// performCustomLowering must instead lower them. - bool customReadBarrier() const { return CustomReadBarriers; } - - /// customRoots - By default, roots are left for the code generator so it - /// can generate a stack map. If true, then - // performCustomLowering must delete them. + + /// By default, roots are left for the code generator so it can generate a + /// stack map. If true, then performCustomLowering must delete them. bool customRoots() const { return CustomRoots; } - /// customSafePoints - By default, the GC analysis will find safe - /// points according to NeededSafePoints. If true, - /// then findCustomSafePoints must create them. + /// By default, the GC analysis will find safe points according to + /// NeededSafePoints. If true, then findCustomSafePoints must create them. bool customSafePoints() const { return CustomSafePoints; } - /// initializeRoots - If set, gcroot intrinsics should initialize their - // allocas to null before the first use. This is - // necessary for most GCs and is enabled by default. + /// If set, gcroot intrinsics should initialize their allocas to null + /// before the first use. This is necessary for most GCs and is enabled by + /// default. bool initializeRoots() const { return InitRoots; } - /// usesMetadata - If set, appropriate metadata tables must be emitted by - /// the back-end (assembler, JIT, or otherwise). + /// If set, appropriate metadata tables must be emitted by the back-end + /// (assembler, JIT, or otherwise). For statepoint, this method is + /// currently unsupported. The stackmap information can be found in the + /// StackMap section as described in the documentation. bool usesMetadata() const { return UsesMetadata; } - - /// begin/end - Iterators for function metadata. - /// - iterator begin() { return Functions.begin(); } - iterator end() { return Functions.end(); } - - /// insertFunctionMetadata - Creates metadata for a function. - /// - GCFunctionInfo *insertFunctionInfo(const Function &F); + ///@} + /// initializeCustomLowering/performCustomLowering - If any of the actions /// are set to custom, performCustomLowering must be overriden to transform /// the corresponding actions to LLVM IR. initializeCustomLowering is /// optional to override. These are the only GCStrategy methods through - /// which the LLVM IR can be modified. - virtual bool initializeCustomLowering(Module &F); - virtual bool performCustomLowering(Function &F); - virtual bool findCustomSafePoints(GCFunctionInfo& FI, MachineFunction& MF); + /// which the LLVM IR can be modified. These methods apply mostly to + /// gc.root based implementations, but can be overriden to provide custom + /// barrier lowerings with gc.statepoint as well. + ///@{ + virtual bool initializeCustomLowering(Module &F) { + // No changes made + return false; + } + virtual bool performCustomLowering(Function &F) { + llvm_unreachable("GCStrategy subclass specified a configuration which" + "requires a custom lowering without providing one"); + } + ///@} + /// Called if customSafepoints returns true, used only by gc.root + /// implementations. + virtual bool findCustomSafePoints(GCFunctionInfo& FI, MachineFunction& MF) { + llvm_unreachable("GCStrategy subclass specified a configuration which" + "requests custom safepoint identification without" + "providing an implementation for such"); + } }; - + + /// Subclasses of GCStrategy are made available for use during compilation by + /// adding them to the global GCRegistry. This can done either within the + /// LLVM source tree or via a loadable plugin. An example registeration + /// would be: + /// static GCRegistry::Add<CustomGC> X("custom-name", + /// "my custom supper fancy gc strategy"); + /// + /// Note that to use a custom GCMetadataPrinter w/gc.roots, you must also + /// register your GCMetadataPrinter subclass with the + /// GCMetadataPrinterRegistery as well. + typedef Registry<GCStrategy> GCRegistry; } #endif |