add gcc/gdb interface files

The gcc plugin is split into two parts.  One part is an ordinary gcc
plugin.  The other part is a shared library that is loaded by gdb.

This patch adds some files that define the interface exported by this
shared library to gdb.  These files also define the internal API by
which the gdb- and gcc-sides communicate.

These files will be kept in sync between gcc and gdb like much of
include/.

The exported API has been intentionally kept very simple.  In
particular only a single function is exported from the gdb-side
library; symbol visibility is used to hide everything else.  This
exported symbol is a function which is called to return a structure
holding function pointers that gdb then uses.  This structure is
versioned so that changes can be made without necessarily requiring a
simultaneous gdb upgrade.

Note that the C compiler API is broken out separately.  This lets us
extend it to other GCC front ends as desired.  We plan to investigate
C++ in the future.

include/ChangeLog
2014-12-12  Phil Muldoon  <pmuldoon@redhat.com>
	    Jan Kratochvil  <jan.kratochvil@redhat.com>
	    Tom Tromey  <tromey@redhat.com>

	* gcc-c-fe.def: New file.
	* gcc-c-interface.h: New file.
	* gcc-interface.h: New file.

1 files changed, 220 insertions, 0 deletions

diff --git a/include/gcc-c-interface.h b/include/gcc-c-interface.h
new file mode 100644
index 0000000..25ef62f
--- /dev/null
+++ b/include/gcc-c-interface.h
@@ -0,0 +1,220 @@
+/* Interface between GCC C FE and GDB
+
+   Copyright (C) 2014 Free Software Foundation, Inc.
+
+   This file is part of GCC.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GCC_C_INTERFACE_H
+#define GCC_C_INTERFACE_H
+
+#include "gcc-interface.h"
+
+/* This header defines the interface to the GCC API.  It must be both
+   valid C and valid C++, because it is included by both programs.  */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Forward declaration.  */
+
+struct gcc_c_context;
+
+/*
+ * Definitions and declarations for the C front end.
+ */
+
+/* Defined versions of the C front-end API.  */
+
+enum gcc_c_api_version
+{
+  GCC_C_FE_VERSION_0 = 0
+};
+
+/* Qualifiers.  */
+
+enum gcc_qualifiers
+{
+  GCC_QUALIFIER_CONST = 1,
+  GCC_QUALIFIER_VOLATILE = 2,
+  GCC_QUALIFIER_RESTRICT = 4
+};
+
+/* This enumerates the kinds of decls that GDB can create.  */
+
+enum gcc_c_symbol_kind
+{
+  /* A function.  */
+
+  GCC_C_SYMBOL_FUNCTION,
+
+  /* A variable.  */
+
+  GCC_C_SYMBOL_VARIABLE,
+
+  /* A typedef.  */
+
+  GCC_C_SYMBOL_TYPEDEF,
+
+  /* A label.  */
+
+  GCC_C_SYMBOL_LABEL
+};
+
+/* This enumerates the types of symbols that GCC might request from
+   GDB.  */
+
+enum gcc_c_oracle_request
+{
+  /* An ordinary symbol -- a variable, function, typedef, or enum
+     constant.  */
+
+  GCC_C_ORACLE_SYMBOL,
+
+  /* A struct, union, or enum tag.  */
+
+  GCC_C_ORACLE_TAG,
+
+  /* A label.  */
+
+  GCC_C_ORACLE_LABEL
+};
+
+/* The type of the function called by GCC to ask GDB for a symbol's
+   definition.  DATUM is an arbitrary value supplied when the oracle
+   function is registered.  CONTEXT is the GCC context in which the
+   request is being made.  REQUEST specifies what sort of symbol is
+   being requested, and IDENTIFIER is the name of the symbol.  */
+
+typedef void gcc_c_oracle_function (void *datum,
+				    struct gcc_c_context *context,
+				    enum gcc_c_oracle_request request,
+				    const char *identifier);
+
+/* The type of the function called by GCC to ask GDB for a symbol's
+   address.  This should return 0 if the address is not known.  */
+
+typedef gcc_address gcc_c_symbol_address_function (void *datum,
+						   struct gcc_c_context *ctxt,
+						   const char *identifier);
+
+/* An array of types used for creating a function type.  */
+
+struct gcc_type_array
+{
+  /* Number of elements.  */
+
+  int n_elements;
+
+  /* The elements.  */
+
+  gcc_type *elements;
+};
+
+/* The vtable used by the C front end.  */
+
+struct gcc_c_fe_vtable
+{
+  /* The version of the C interface.  The value is one of the
+     gcc_c_api_version constants.  */
+
+  unsigned int c_version;
+
+  /* Set the callbacks for this context.
+
+     The binding oracle is called whenever the C parser needs to look
+     up a symbol.  This gives the caller a chance to lazily
+     instantiate symbols using other parts of the gcc_c_fe_interface
+     API.
+
+     The address oracle is called whenever the C parser needs to look
+     up a symbol.  This is only called for symbols not provided by the
+     symbol oracle -- that is, just built-in functions where GCC
+     provides the declaration.
+
+     DATUM is an arbitrary piece of data that is passed back verbatim
+     to the callbakcs in requests.  */
+
+  void (*set_callbacks) (struct gcc_c_context *self,
+			 gcc_c_oracle_function *binding_oracle,
+			 gcc_c_symbol_address_function *address_oracle,
+			 void *datum);
+
+#define GCC_METHOD0(R, N) \
+  R (*N) (struct gcc_c_context *);
+#define GCC_METHOD1(R, N, A) \
+  R (*N) (struct gcc_c_context *, A);
+#define GCC_METHOD2(R, N, A, B) \
+  R (*N) (struct gcc_c_context *, A, B);
+#define GCC_METHOD3(R, N, A, B, C) \
+  R (*N) (struct gcc_c_context *, A, B, C);
+#define GCC_METHOD4(R, N, A, B, C, D) \
+  R (*N) (struct gcc_c_context *, A, B, C, D);
+#define GCC_METHOD5(R, N, A, B, C, D, E) \
+  R (*N) (struct gcc_c_context *, A, B, C, D, E);
+#define GCC_METHOD7(R, N, A, B, C, D, E, F, G) \
+  R (*N) (struct gcc_c_context *, A, B, C, D, E, F, G);
+
+#include "gcc-c-fe.def"
+
+#undef GCC_METHOD0
+#undef GCC_METHOD1
+#undef GCC_METHOD2
+#undef GCC_METHOD3
+#undef GCC_METHOD4
+#undef GCC_METHOD5
+#undef GCC_METHOD7
+
+};
+
+/* The C front end object.  */
+
+struct gcc_c_context
+{
+  /* Base class.  */
+
+  struct gcc_base_context base;
+
+  /* Our vtable.  This is a separate field because this is simpler
+     than implementing a vtable inheritance scheme in C.  */
+
+  const struct gcc_c_fe_vtable *c_ops;
+};
+
+/* The name of the .so that the compiler builds.  We dlopen this
+   later.  */
+
+#define GCC_C_FE_LIBCC libcc1.so
+
+/* The compiler exports a single initialization function.  This macro
+   holds its name as a symbol.  */
+
+#define GCC_C_FE_CONTEXT gcc_c_fe_context
+
+/* The type of the initialization function.  The caller passes in the
+   desired base version and desired C-specific version.  If the
+   request can be satisfied, a compatible gcc_context object will be
+   returned.  Otherwise, the function returns NULL.  */
+
+typedef struct gcc_c_context *gcc_c_fe_context_function
+    (enum gcc_base_api_version,
+     enum gcc_c_api_version);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GCC_C_INTERFACE_H */