X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FCodeGen%2FGCStrategy.h;h=2a4dabb01b9bb995a666f697f8816d5d221dd82e;hb=cf0db29df20d9c665da7e82bb261bdd7cf7f1b2b;hp=98c25e4a08de69555cdebf840af91a87c9bba752;hpb=b7dfa31ac8b8a83a4df5a947bb4fd83ec12657dd;p=oota-llvm.git diff --git a/include/llvm/CodeGen/GCStrategy.h b/include/llvm/CodeGen/GCStrategy.h index 98c25e4a08d..2a4dabb01b9 100644 --- a/include/llvm/CodeGen/GCStrategy.h +++ b/include/llvm/CodeGen/GCStrategy.h @@ -16,11 +16,11 @@ // 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 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. // GCStrategy can request that the collector insert such points: @@ -28,7 +28,7 @@ // - At and after any call to a subroutine // - Before returning from the current function // - Before backwards branches (loops) -// +// // - Roots // When a reference to a GC-allocated object exists on the stack, it must be // stored in an alloca registered with llvm.gcoot. @@ -42,132 +42,136 @@ // 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 +#ifndef LLVM_IR_GCSTRATEGY_H +#define LLVM_IR_GCSTRATEGY_H -#include "llvm/CodeGen/GCMetadata.h" -#include "llvm/CodeGen/MachineFunction.h" +#include "llvm/ADT/Optional.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/Value.h" +#include "llvm/Support/ErrorHandling.h" #include "llvm/Support/Registry.h" #include namespace llvm { - /// GCStrategy describes a garbage collector algorithm's code generation - /// requirements, and provides overridable hooks for those needs which cannot - /// 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 { - private: - std::string Name; - friend class GCModuleInfo; - - protected: - unsigned NeededSafePoints; ///< Bitmask of required safe points. - bool CustomReadBarriers; ///< Default is to insert loads. - bool CustomWriteBarriers; ///< Default is to insert stores. - bool CustomRoots; ///< Default is to pass through to backend. - bool CustomSafePoints; ///< Default is to use NeededSafePoints - ///< to find safe points. - bool InitRoots; ///< If set, roots are nulled during lowering. - bool UsesMetadata; ///< If set, backend must emit metadata tables. - - public: - GCStrategy(); - virtual ~GCStrategy() {} - - /// 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; } - - /// 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; } - - /** @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; - } - - /// 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; - } - - /// 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; } - - /// By default, the GC analysis will find safe points according to - /// NeededSafePoints. If true, then findCustomSafePoints must create them. - bool customSafePoints() const { return CustomSafePoints; } - - /// 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; } - - /// If set, appropriate metadata tables must be emitted by the back-end - /// (assembler, JIT, or otherwise). - bool usesMetadata() const { return UsesMetadata; } - - ///@} - - /// 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. 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 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 GCRegistry; +namespace GC { +/// PointKind - Used to indicate whether the address of the call instruction +/// or the address after the call instruction is listed in the stackmap. For +/// most runtimes, PostCall safepoints are appropriate. +/// +enum PointKind { + PreCall, ///< Instr is a call instruction. + PostCall ///< Instr is the return address of a call. +}; } +/// GCStrategy describes a garbage collector algorithm's code generation +/// requirements, and provides overridable hooks for those needs which cannot +/// be abstractly described. GCStrategy objects must be looked up through +/// the Function. The objects themselves are owned by the Context and must +/// be immutable. +class GCStrategy { +private: + std::string Name; + 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. + bool CustomRoots; ///< Default is to pass through to backend. + bool InitRoots; ///< If set, roots are nulled during lowering. + bool UsesMetadata; ///< If set, backend must emit metadata tables. + +public: + GCStrategy(); + virtual ~GCStrategy() {} + + /// 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; } + + /// By default, write barriers are replaced with simple store + /// instructions. If true, you must provide a custom pass to lower + /// calls to @llvm.gcwrite. + bool customWriteBarrier() const { return CustomWriteBarriers; } + + /// By default, read barriers are replaced with simple load + /// instructions. If true, you must provide a custom pass to lower + /// calls to @llvm.gcread. + 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 */ + ///@{ + + /// 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 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 NeededSafePoints != 0; } + + /// 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; + } + + /// By default, roots are left for the code generator so it can generate a + /// stack map. If true, you must provide a custom pass to lower + /// calls to @llvm.gcroot. + bool customRoots() const { return CustomRoots; } + + /// 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; } + + /// 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; } + + ///@} +}; + +/// 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 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 GCRegistry; +} // namespace llvm + #endif