Factor GC metadata table assembly generation out of Collector in preparation for splitting AsmPrinter into its own library.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54881 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 167 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/GCStrategy.h b/include/llvm/CodeGen/GCStrategy.h
new file mode 100644
index 0000000000..dea0785ef8
--- /dev/null
+++ b/include/llvm/CodeGen/GCStrategy.h
@@ -0,0 +1,167 @@
+//===-- llvm/CodeGen/Collector.h - Garbage collection -----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Collector records sufficient information about a machine function to enable
+// accurate garbage collectors. Specifically:
+// 
+// - Safe points
+//   Garbage collection is only possible at certain points in code. Code
+//   generators should record points:
+//
+//     - 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.
+//
+// This generic information should used by ABI-specific passes to emit support
+// tables for the runtime garbage collector.
+//
+// MachineCodeAnalysis identifies the GC safe points in the machine code. (Roots
+// are identified in SelectionDAGISel.)
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_COLLECTOR_H
+#define LLVM_CODEGEN_COLLECTOR_H
+
+#include "llvm/CodeGen/GCMetadata.h"
+#include <iosfwd>
+#include <string>
+
+namespace llvm {
+  
+  /// Collector describes a garbage collector's code generation requirements,
+  /// and provides overridable hooks for those needs which cannot be abstractly
+  /// described.
+  class Collector {
+  public:
+    typedef std::vector<CollectorMetadata*> list_type;
+    typedef list_type::iterator iterator;
+    
+  private:
+    friend class CollectorModuleMetadata;
+    const Module *M;
+    std::string Name;
+    
+    list_type Functions;
+    
+  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 InitRoots;            //< If set, roots are nulled during lowering.
+    bool UsesMetadata;         //< If set, backend must emit metadata tables.
+    
+  public:
+    Collector();
+    
+    virtual ~Collector();
+    
+    
+    /// getName - The name of the collector, for debugging.
+    /// 
+    const std::string &getName() const { return Name; }
+
+    /// getModule - The module upon which the collector is operating.
+    /// 
+    const Module &getModule() const { return *M; }
+
+    /// True if this collector requires safe points of any kind. By default,
+    /// none are recorded.
+    bool needsSafePoints() const { return NeededSafePoints != 0; }
+    
+    /// True if the collector requires the given kind of safe point. By default,
+    /// none are recorded.
+    bool needsSafePoint(GC::PointKind Kind) const {
+      return (NeededSafePoints & 1 << Kind) != 0;
+    }
+    
+    /// By default, write barriers are replaced with simple store instructions.
+    /// If true, then addPassesToCustomLowerIntrinsics must instead process
+    /// them.
+    bool customWriteBarrier() const { return CustomWriteBarriers; }
+    
+    /// By default, read barriers are replaced with simple load instructions.
+    /// If true, then addPassesToCustomLowerIntrinsics must instead process
+    /// them.
+    bool customReadBarrier() const { return CustomReadBarriers; }
+    
+    /// By default, roots are left for the code generator. If Custom, then 
+    /// addPassesToCustomLowerIntrinsics must add passes to delete them.
+    bool customRoots() const { return CustomRoots; }
+    
+    /// If set, gcroot intrinsics should initialize their allocas to null. This
+    /// is necessary for most collectors.
+    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; }
+    
+    /// begin/end - Iterators for function metadata.
+    /// 
+    iterator begin() { return Functions.begin(); }
+    iterator end()   { return Functions.end();   }
+
+    /// insertFunctionMetadata - Creates metadata for a function.
+    /// 
+    CollectorMetadata *insertFunctionMetadata(const Function &F);
+
+    /// initializeCustomLowering/performCustomLowering - If any of the actions
+    /// are set to custom, performCustomLowering must be overriden to create a
+    /// transform to lower those actions to LLVM IR. initializeCustomLowering
+    /// is optional to override. These are the only Collector methods through
+    /// which the LLVM IR can be modified.
+    virtual bool initializeCustomLowering(Module &F);
+    virtual bool performCustomLowering(Function &F);
+  };
+  
+  // GCMetadataPrinter - Emits GC metadata as assembly code.
+  class GCMetadataPrinter {
+  public:
+    typedef Collector::list_type list_type;
+    typedef Collector::iterator iterator;
+    
+  private:
+    Collector *Coll;
+    
+    friend class AsmPrinter;
+    
+  protected:
+    // May only be subclassed.
+    GCMetadataPrinter();
+    
+    // Do not implement.
+    GCMetadataPrinter(const GCMetadataPrinter &);
+    GCMetadataPrinter &operator=(const GCMetadataPrinter &);
+    
+  public:
+    Collector &getCollector() { return *Coll; }
+    const Module &getModule() const { return Coll->getModule(); }
+    
+    iterator begin() { return Coll->begin(); }
+    iterator end()   { return Coll->end();   }
+    
+    /// beginAssembly/finishAssembly - Emit module metadata as assembly code.
+    virtual void beginAssembly(std::ostream &OS, AsmPrinter &AP,
+                               const TargetAsmInfo &TAI);
+    
+    virtual void finishAssembly(std::ostream &OS, AsmPrinter &AP,
+                                const TargetAsmInfo &TAI);
+    
+    virtual ~GCMetadataPrinter();
+  };
+  
+}
+
+#endif