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[PATCH 10/11] Make gcc::context be GC-managed


This patch makes gcc::context instances be allocated within the GC-heap,
and adds traversal hooks for GC/PCH so that a gcc::context can own refs
to other GC-allocated objects.

gcc/
	* Makefile.in (GTFILES): Add context.h.
	* context.c (gcc::context::operator new): New.
	(gcc::context::gt_ggc_mx): New.
	(gcc::context::gt_pch_nx): New.
	(gcc::context::gt_pch_nx): New.
	(gt_ggc_mx (gcc::context *)): New.
	(gt_pch_nx (gcc::context *)): New.
	(gt_pch_nx (gcc::context *ctxt, gt_pointer_operator op,
	void *cookie)): New.
	* context.h (gcc::context): Add GTY((user)) marking.
	(gcc::context::operator new): New.
	(gcc::context::gt_ggc_mx): New.
	(gcc::context::gt_pch_nx): New.
	(gcc::context::gt_pch_nx): New.
	(g): Add GTY marking.
	(gt_ggc_mx (gcc::context *)): New.
	(gt_pch_nx (gcc::context *)): New.
	(gt_pch_nx (gcc::context *ctxt, gt_pointer_operator op,
	void *cookie)): New.
	* gengtype.c (open_base_files) <ifiles>: Add context.h.
---
 gcc/Makefile.in |  1 +
 gcc/context.c   | 41 +++++++++++++++++++++++++++++++++++++++++
 gcc/context.h   | 46 ++++++++++++++++++++++++++++++++++++++++++++--
 gcc/gengtype.c  |  2 +-
 4 files changed, 87 insertions(+), 3 deletions(-)

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index c1fdb8a..e9d6247 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -3819,6 +3819,7 @@ GTFILES = $(CPP_ID_DATA_H) $(srcdir)/input.h $(srcdir)/coretypes.h \
   $(srcdir)/ipa-inline.h \
   $(srcdir)/asan.c \
   $(srcdir)/tsan.c \
+  $(srcdir)/context.h \
   @all_gtfiles@
 
 # Compute the list of GT header files from the corresponding C sources,
diff --git a/gcc/context.c b/gcc/context.c
index 8ec2e60..72135ed 100644
--- a/gcc/context.c
+++ b/gcc/context.c
@@ -27,7 +27,48 @@ along with GCC; see the file COPYING3.  If not see
 /* The singleton holder of global state: */
 gcc::context *g;
 
+void *
+gcc::context::operator new (std::size_t size)
+{
+  return ggc_internal_cleared_alloc_stat (size MEM_STAT_INFO);
+}
+
 gcc::context::context()
 {
   passes_ = new gcc::pipeline(this);
 }
+
+/* Functions relating to the garbage collector.  */
+void
+gcc::context::gt_ggc_mx ()
+{
+  /* Currently a no-op.  */
+}
+
+void
+gcc::context::gt_pch_nx ()
+{
+  /* Currently a no-op.  */
+}
+
+void
+gcc::context::gt_pch_nx (gt_pointer_operator op ATTRIBUTE_UNUSED,
+			 void *cookie ATTRIBUTE_UNUSED)
+{
+  /* Currently a no-op.  */
+}
+
+void gt_ggc_mx (gcc::context *ctxt)
+{
+  ctxt->gt_ggc_mx ();
+}
+
+void gt_pch_nx (gcc::context *ctxt)
+{
+  ctxt->gt_pch_nx ();
+}
+
+void gt_pch_nx (gcc::context *ctxt, gt_pointer_operator op, void *cookie)
+{
+  ctxt->gt_pch_nx (op, cookie);
+}
diff --git a/gcc/context.h b/gcc/context.h
index a83f7b2..a65e62b 100644
--- a/gcc/context.h
+++ b/gcc/context.h
@@ -27,11 +27,30 @@ class pipeline;
 /* GCC's internal state can be divided into zero or more
    "parallel universe" of state; an instance of this class is one such
    context of state.  */
-class context
+class GTY((user)) context
 {
 public:
+  /* Ensure that instances are allocated within the GC-heap.  */
+  void *operator new (std::size_t size);
+
   context();
 
+  /* Garbage-collector integration.
+
+     Each context assumes it has full control of the GC-heap that it
+     is associated with.  It acts as a root for that GC-heap, owning
+     references to within it.
+
+     Note that context instances are allocated within their own GC
+     heap.
+
+     The methods are called the *first time* that the context is reached
+     during a ggc/pch traversal, rather than every time.  */
+
+  void gt_ggc_mx ();
+  void gt_pch_nx ();
+  void gt_pch_nx (gt_pointer_operator op, void *cookie);
+
   /* Pass-management.  */
 
   pipeline &get_passes () { gcc_assert (passes_); return *passes_; }
@@ -46,6 +65,29 @@ private:
 
 /* The global singleton context aka "g".
    (the name is chosen to be easy to type in a debugger).  */
-extern gcc::context *g;
+extern GTY(()) gcc::context *g;
+
+/* Global hooks for ggc/pch.
+
+   The gcc::context class is marked with GTY((user)), which leads to
+   gengtype creating autogenerated functions for handling context within
+   gtype-desc.c:
+
+     void gt_ggc_mx_context (void *x_p);
+     void gt_pch_nx_context (void *x_p)
+     void gt_pch_p_7context (void *this_obj,
+			     void *x_p,
+			     gt_pointer_operator op,
+			     void *cookie);
+
+   Those functions call the following global functions the first time
+   that the context is reached during a traversal, and the following
+   global functions in turn simply call the corresponding  methods of the
+   context (so that they can access private fields of the context).  */
+
+void gt_ggc_mx (gcc::context *ctxt);
+void gt_pch_nx (gcc::context *ctxt);
+void gt_pch_nx (gcc::context *ctxt, gt_pointer_operator op, void *cookie);
+
 
 #endif /* ! GCC_CONTEXT_H */
diff --git a/gcc/gengtype.c b/gcc/gengtype.c
index 50efa9b..941c6e1 100644
--- a/gcc/gengtype.c
+++ b/gcc/gengtype.c
@@ -1733,7 +1733,7 @@ open_base_files (void)
       "tree-flow.h", "reload.h", "cpp-id-data.h", "tree-chrec.h",
       "except.h", "output.h", "gimple.h", "cfgloop.h",
       "target.h", "ipa-prop.h", "lto-streamer.h", "target-globals.h",
-      "ipa-inline.h", "dwarf2out.h", NULL
+      "ipa-inline.h", "dwarf2out.h", "context.h", NULL
     };
     const char *const *ifp;
     outf_p gtype_desc_c;
-- 
1.7.11.7


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