Move GC-related declarations to gc folder and add comments.

Author: rudi-c

src/core/types.h

@@ -29,6 +29,7 @@
 #include "core/common.h"
 #include "core/stats.h"
 #include "core/stringpool.h"
+#include "gc/gc.h"
 
 namespace llvm {
 class Function;
@@ -38,29 +39,6 @@ class Value;
 
 namespace pyston {
 
-namespace gc {
-
-class TraceStack;
-class GCVisitor {
-private:
-    bool isValid(void* p);
-
-public:
-    TraceStack* stack;
-    GCVisitor(TraceStack* stack) : stack(stack) {}
-
-    // These all work on *user* pointers, ie pointers to the user_data section of GCAllocations
-    void visitIf(void* p) {
-        if (p)
-            visit(p);
-    }
-    void visit(void* p);
-    void visitRange(void* const* start, void* const* end);
-    void visitPotential(void* p);
-    void visitPotentialRange(void* const* start, void* const* end);
-};
-
-} // namespace gc
 using gc::GCVisitor;
 
 enum class EffortLevel {
@@ -459,35 +437,7 @@ class BinopIC;
 
 class Box;
 
-namespace gc {
-
-enum class GCKind : uint8_t {
-    PYTHON = 1,
-    CONSERVATIVE = 2,
-    PRECISE = 3,
-    UNTRACKED = 4,
-    RUNTIME = 5,
-    CONSERVATIVE_PYTHON = 6,
-};
-
-extern "C" void* gc_alloc(size_t nbytes, GCKind kind);
-extern "C" void* gc_realloc(void* ptr, size_t bytes);
-extern "C" void gc_free(void* ptr);
-}
-
-class GCAllocatedRuntime {
-public:
-    virtual ~GCAllocatedRuntime() {}
-
-    void* operator new(size_t size) __attribute__((visibility("default"))) {
-        return gc::gc_alloc(size, gc::GCKind::RUNTIME);
-    }
-    void operator delete(void* ptr) __attribute__((visibility("default"))) { gc::gc_free(ptr); }
-
-    virtual void gc_visit(GCVisitor* visitor) = 0;
-};
-
-class BoxIteratorImpl : public GCAllocatedRuntime {
+class BoxIteratorImpl : public gc::GCAllocatedRuntime {
 public:
     virtual ~BoxIteratorImpl() = default;
     virtual void next() = 0;

src/gc/gc.h

@@ -0,0 +1,85 @@
+// Copyright (c) 2014-2015 Dropbox, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef PYSTON_GC_GC_H
+#define PYSTON_GC_GC_H
+
+namespace pyston {
+namespace gc {
+
+// GOAL: Eventually, move any declaration that needs to be visible outside the gc/ folder
+// to this file and only expose this header.
+
+class TraceStack;
+class GCVisitor {
+private:
+    bool isValid(void* p);
+
+public:
+    TraceStack* stack;
+    GCVisitor(TraceStack* stack) : stack(stack) {}
+
+    // These all work on *user* pointers, ie pointers to the user_data section of GCAllocations
+    void visitIf(void* p) {
+        if (p)
+            visit(p);
+    }
+    void visit(void* p);
+    void visitRange(void* const* start, void* const* end);
+    void visitPotential(void* p);
+    void visitPotentialRange(void* const* start, void* const* end);
+};
+
+enum class GCKind : uint8_t {
+    // Any Python object (e.g. any Box) that can be visited precisely, using
+    // a GC handler function.
+    PYTHON = 1,
+
+    // An arbitrary block of memory that may contain pointers.
+    CONSERVATIVE = 2,
+
+    // An arbitrary block of memory with contiguous pointers.
+    PRECISE = 3,
+
+    // An arbitrary block of memory that does not contain pointers.
+    UNTRACKED = 4,
+
+    // C++ objects that we need to manage with our own heap and GC, either
+    // because it contains pointers into our heap or our heap points to these
+    // objects. These objects inherit from GCAllocatedRuntime.
+    RUNTIME = 5,
+
+    // A Python object where we don't have a way to visit precisely with a GC
+    // handler function. These are usually Python objects allocated in C extensions.
+    CONSERVATIVE_PYTHON = 6,
+};
+
+extern "C" void* gc_alloc(size_t nbytes, GCKind kind);
+extern "C" void* gc_realloc(void* ptr, size_t bytes);
+extern "C" void gc_free(void* ptr);
+
+// Use this if a C++ object needs to be allocated in our heap.
+class GCAllocatedRuntime {
+public:
+    virtual ~GCAllocatedRuntime() {}
+
+    void* operator new(size_t size) __attribute__((visibility("default"))) { return gc_alloc(size, GCKind::RUNTIME); }
+    void operator delete(void* ptr) __attribute__((visibility("default"))) { gc_free(ptr); }
+
+    virtual void gc_visit(GCVisitor* visitor) = 0;
+};
+} // namespace gc
+}
+
+#endif

src/runtime/hiddenclass.h

@@ -25,7 +25,7 @@
 
 namespace pyston {
 
-class HiddenClass : public GCAllocatedRuntime {
+class HiddenClass : public gc::GCAllocatedRuntime {
 public:
     // We have a couple different storage strategies for attributes, which
     // are distinguished by having a different hidden class type.