gdb/compile/compile-c-support.c - third_party/binutils-gdb - Git at Google

 /* C language support for compilation.

    Copyright (C) 2014-2016 Free Software Foundation, Inc.

    This file is part of GDB.

    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/>.  */

 #include "defs.h"
 #include "compile-internal.h"
 #include "compile.h"
 #include "gdb-dlfcn.h"
 #include "c-lang.h"
 #include "macrotab.h"
 #include "macroscope.h"
 #include "regcache.h"

 /* See compile-internal.h.  */

 const char *
 c_get_mode_for_size (int size)
 {
   const char *mode = NULL;

   switch (size)
     {
     case 1:
       mode = "QI";
       break;
     case 2:
       mode = "HI";
       break;
     case 4:
       mode = "SI";
       break;
     case 8:
       mode = "DI";
       break;
     default:
       internal_error (__FILE__, __LINE__, _("Invalid GCC mode size %d."), size);
     }

   return mode;
 }

 /* See compile-internal.h.  */

 char *
 c_get_range_decl_name (const struct dynamic_prop *prop)
 {
   return xstrprintf ("__gdb_prop_%s", host_address_to_string (prop));
 }


 #define STR(x) #x
 #define STRINGIFY(x) STR(x)

 /* Helper function for c_get_compile_context.  Open the GCC front-end
    shared library and return the symbol specified by the current
    GCC_C_FE_CONTEXT.  */

 static gcc_c_fe_context_function *
 load_libcc (void)
 {
   void *handle;
   gcc_c_fe_context_function *func;

    /* gdb_dlopen will call error () on an error, so no need to check
       value.  */
   handle = gdb_dlopen (STRINGIFY (GCC_C_FE_LIBCC));
   func = (gcc_c_fe_context_function *) gdb_dlsym (handle,
 						  STRINGIFY (GCC_C_FE_CONTEXT));

   if (func == NULL)
     error (_("could not find symbol %s in library %s"),
 	   STRINGIFY (GCC_C_FE_CONTEXT),
 	   STRINGIFY (GCC_C_FE_LIBCC));
   return func;
 }

 /* Return the compile instance associated with the current context.
    This function calls the symbol returned from the load_libcc
    function.  This will provide the gcc_c_context.  */

 struct compile_instance *
 c_get_compile_context (void)
 {
   static gcc_c_fe_context_function *func;

   struct gcc_c_context *context;

   if (func == NULL)
     {
       func = load_libcc ();
       gdb_assert (func != NULL);
     }

   context = (*func) (GCC_FE_VERSION_0, GCC_C_FE_VERSION_0);
   if (context == NULL)
     error (_("The loaded version of GCC does not support the required version "
 	     "of the API."));

   return new_compile_instance (context);
 }


 /* Write one macro definition.  */

 static void
 print_one_macro (const char *name, const struct macro_definition *macro,
 		 struct macro_source_file *source, int line,
 		 void *user_data)
 {
   struct ui_file *file = (struct ui_file *) user_data;

   /* Don't print command-line defines.  They will be supplied another
      way.  */
   if (line == 0)
     return;

   /* None of -Wno-builtin-macro-redefined, #undef first
      or plain #define of the same value would avoid a warning.  */
   fprintf_filtered (file, "#ifndef %s\n# define %s", name, name);

   if (macro->kind == macro_function_like)
     {
       int i;

       fputs_filtered ("(", file);
       for (i = 0; i < macro->argc; i++)
 	{
 	  fputs_filtered (macro->argv[i], file);
 	  if (i + 1 < macro->argc)
 	    fputs_filtered (", ", file);
 	}
       fputs_filtered (")", file);
     }

   fprintf_filtered (file, " %s\n#endif\n", macro->replacement);
 }

 /* Write macro definitions at PC to FILE.  */

 static void
 write_macro_definitions (const struct block *block, CORE_ADDR pc,
 			 struct ui_file *file)
 {
   struct macro_scope *scope;

   if (block != NULL)
     scope = sal_macro_scope (find_pc_line (pc, 0));
   else
     scope = default_macro_scope ();
   if (scope == NULL)
     scope = user_macro_scope ();

   if (scope != NULL && scope->file != NULL && scope->file->table != NULL)
     macro_for_each_in_scope (scope->file, scope->line, print_one_macro, file);
 }

 /* Helper function to construct a header scope for a block of code.
    Takes a scope argument which selects the correct header to
    insert into BUF.  */

 static void
 add_code_header (enum compile_i_scope_types type, struct ui_file *buf)
 {
   switch (type)
     {
     case COMPILE_I_SIMPLE_SCOPE:
       fputs_unfiltered ("void "
 			GCC_FE_WRAPPER_FUNCTION
 			" (struct "
 			COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG
 			" *"
 			COMPILE_I_SIMPLE_REGISTER_ARG_NAME
 			") {\n",
 			buf);
       break;
     case COMPILE_I_PRINT_ADDRESS_SCOPE:
     case COMPILE_I_PRINT_VALUE_SCOPE:
       /* <string.h> is needed for a memcpy call below.  */
       fputs_unfiltered ("#include <string.h>\n"
 			"void "
 			GCC_FE_WRAPPER_FUNCTION
 			" (struct "
 			COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG
 			" *"
 			COMPILE_I_SIMPLE_REGISTER_ARG_NAME
 			", "
 			COMPILE_I_PRINT_OUT_ARG_TYPE
 			" "
 			COMPILE_I_PRINT_OUT_ARG
 			") {\n",
 			buf);
       break;

     case COMPILE_I_RAW_SCOPE:
       break;
     default:
       gdb_assert_not_reached (_("Unknown compiler scope reached."));
     }
 }

 /* Helper function to construct a footer scope for a block of code.
    Takes a scope argument which selects the correct footer to
    insert into BUF.  */

 static void
 add_code_footer (enum compile_i_scope_types type, struct ui_file *buf)
 {
   switch (type)
     {
     case COMPILE_I_SIMPLE_SCOPE:
     case COMPILE_I_PRINT_ADDRESS_SCOPE:
     case COMPILE_I_PRINT_VALUE_SCOPE:
       fputs_unfiltered ("}\n", buf);
       break;
     case COMPILE_I_RAW_SCOPE:
       break;
     default:
       gdb_assert_not_reached (_("Unknown compiler scope reached."));
     }
 }

 /* Generate a structure holding all the registers used by the function
    we're generating.  */

 static void
 generate_register_struct (struct ui_file *stream, struct gdbarch *gdbarch,
 			  const unsigned char *registers_used)
 {
   int i;
   int seen = 0;

   fputs_unfiltered ("struct " COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG " {\n",
 		    stream);

   if (registers_used != NULL)
     for (i = 0; i < gdbarch_num_regs (gdbarch); ++i)
       {
 	if (registers_used[i])
 	  {
 	    struct type *regtype = check_typedef (register_type (gdbarch, i));
 	    char *regname = compile_register_name_mangled (gdbarch, i);
 	    struct cleanup *cleanups = make_cleanup (xfree, regname);

 	    seen = 1;

 	    /* You might think we could use type_print here.  However,
 	       target descriptions often use types with names like
 	       "int64_t", which may not be defined in the inferior
 	       (and in any case would not be looked up due to the
 	       #pragma business).  So, we take a much simpler
 	       approach: for pointer- or integer-typed registers, emit
 	       the field in the most direct way; and for other
 	       register types (typically flags or vectors), emit a
 	       maximally-aligned array of the correct size.  */

 	    fputs_unfiltered ("  ", stream);
 	    switch (TYPE_CODE (regtype))
 	      {
 	      case TYPE_CODE_PTR:
 		fprintf_filtered (stream, "__gdb_uintptr %s", regname);
 		break;

 	      case TYPE_CODE_INT:
 		{
 		  const char *mode
 		    = c_get_mode_for_size (TYPE_LENGTH (regtype));

 		  if (mode != NULL)
 		    {
 		      if (TYPE_UNSIGNED (regtype))
 			fputs_unfiltered ("unsigned ", stream);
 		      fprintf_unfiltered (stream,
 					  "int %s"
 					  " __attribute__ ((__mode__(__%s__)))",
 					  regname,
 					  mode);
 		      break;
 		    }
 		}

 		/* Fall through.  */

 	      default:
 		fprintf_unfiltered (stream,
 				    "  unsigned char %s[%d]"
 				    " __attribute__((__aligned__("
 				    "__BIGGEST_ALIGNMENT__)))",
 				    regname,
 				    TYPE_LENGTH (regtype));
 	      }
 	    fputs_unfiltered (";\n", stream);

 	    do_cleanups (cleanups);
 	  }
       }

   if (!seen)
     fputs_unfiltered ("  char " COMPILE_I_SIMPLE_REGISTER_DUMMY ";\n",
 		      stream);

   fputs_unfiltered ("};\n\n", stream);
 }

 /* Take the source code provided by the user with the 'compile'
    command, and compute the additional wrapping, macro, variable and
    register operations needed.  INPUT is the source code derived from
    the 'compile' command, GDBARCH is the architecture to use when
    computing above, EXPR_BLOCK denotes the block relevant contextually
    to the inferior when the expression was created, and EXPR_PC
    indicates the value of $PC.  */

 char *
 c_compute_program (struct compile_instance *inst,
 		   const char *input,
 		   struct gdbarch *gdbarch,
 		   const struct block *expr_block,
 		   CORE_ADDR expr_pc)
 {
   struct ui_file *buf, *var_stream = NULL;
   char *code;
   struct cleanup *cleanup;
   struct compile_c_instance *context = (struct compile_c_instance *) inst;

   buf = mem_fileopen ();
   cleanup = make_cleanup_ui_file_delete (buf);

   write_macro_definitions (expr_block, expr_pc, buf);

   /* Do not generate local variable information for "raw"
      compilations.  In this case we aren't emitting our own function
      and the user's code may only refer to globals.  */
   if (inst->scope != COMPILE_I_RAW_SCOPE)
     {
       unsigned char *registers_used;
       int i;

       /* Generate the code to compute variable locations, but do it
 	 before generating the function header, so we can define the
 	 register struct before the function body.  This requires a
 	 temporary stream.  */
       var_stream = mem_fileopen ();
       make_cleanup_ui_file_delete (var_stream);
       registers_used = generate_c_for_variable_locations (context,
 							  var_stream, gdbarch,
 							  expr_block, expr_pc);
       make_cleanup (xfree, registers_used);

       fputs_unfiltered ("typedef unsigned int"
 			" __attribute__ ((__mode__(__pointer__)))"
 			" __gdb_uintptr;\n",
 			buf);
       fputs_unfiltered ("typedef int"
 			" __attribute__ ((__mode__(__pointer__)))"
 			" __gdb_intptr;\n",
 			buf);

       /* Iterate all log2 sizes in bytes supported by c_get_mode_for_size.  */
       for (i = 0; i < 4; ++i)
 	{
 	  const char *mode = c_get_mode_for_size (1 << i);

 	  gdb_assert (mode != NULL);
 	  fprintf_unfiltered (buf,
 			      "typedef int"
 			      " __attribute__ ((__mode__(__%s__)))"
 			      " __gdb_int_%s;\n",
 			      mode, mode);
 	}

       generate_register_struct (buf, gdbarch, registers_used);
     }

   add_code_header (inst->scope, buf);

   if (inst->scope == COMPILE_I_SIMPLE_SCOPE
       || inst->scope == COMPILE_I_PRINT_ADDRESS_SCOPE
       || inst->scope == COMPILE_I_PRINT_VALUE_SCOPE)
     {
       ui_file_put (var_stream, ui_file_write_for_put, buf);
       fputs_unfiltered ("#pragma GCC user_expression\n", buf);
     }

   /* The user expression has to be in its own scope, so that "extern"
      works properly.  Otherwise gcc thinks that the "extern"
      declaration is in the same scope as the declaration provided by
      gdb.  */
   if (inst->scope != COMPILE_I_RAW_SCOPE)
     fputs_unfiltered ("{\n", buf);

   fputs_unfiltered ("#line 1 \"gdb command line\"\n", buf);

   switch (inst->scope)
     {
     case COMPILE_I_PRINT_ADDRESS_SCOPE:
     case COMPILE_I_PRINT_VALUE_SCOPE:
       fprintf_unfiltered (buf,
 "__auto_type " COMPILE_I_EXPR_VAL " = %s;\n"
 "typeof (%s) *" COMPILE_I_EXPR_PTR_TYPE ";\n"
 "memcpy (" COMPILE_I_PRINT_OUT_ARG ", %s" COMPILE_I_EXPR_VAL ",\n"
 	 "sizeof (*" COMPILE_I_EXPR_PTR_TYPE "));\n"
 			  , input, input,
 			  (inst->scope == COMPILE_I_PRINT_ADDRESS_SCOPE
 			   ? "&" : ""));
       break;
     default:
       fputs_unfiltered (input, buf);
       break;
     }

   fputs_unfiltered ("\n", buf);

   /* For larger user expressions the automatic semicolons may be
      confusing.  */
   if (strchr (input, '\n') == NULL)
     fputs_unfiltered (";\n", buf);

   if (inst->scope != COMPILE_I_RAW_SCOPE)
     fputs_unfiltered ("}\n", buf);

   add_code_footer (inst->scope, buf);
   code = ui_file_xstrdup (buf, NULL);
   do_cleanups (cleanup);
   return code;
 }
	/* C language support for compilation.

	Copyright (C) 2014-2016 Free Software Foundation, Inc.

	This file is part of GDB.

	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/>. */

	#include "defs.h"
	#include "compile-internal.h"
	#include "compile.h"
	#include "gdb-dlfcn.h"
	#include "c-lang.h"
	#include "macrotab.h"
	#include "macroscope.h"
	#include "regcache.h"

	/* See compile-internal.h. */

	const char *
	c_get_mode_for_size (int size)
	{
	const char *mode = NULL;

	switch (size)
	{
	case 1:
	mode = "QI";
	break;
	case 2:
	mode = "HI";
	break;
	case 4:
	mode = "SI";
	break;
	case 8:
	mode = "DI";
	break;
	default:
	internal_error (__FILE__, __LINE__, _("Invalid GCC mode size %d."), size);
	}

	return mode;
	}

	/* See compile-internal.h. */

	char *
	c_get_range_decl_name (const struct dynamic_prop *prop)
	{
	return xstrprintf ("__gdb_prop_%s", host_address_to_string (prop));
	}



	#define STR(x) #x
	#define STRINGIFY(x) STR(x)

	/* Helper function for c_get_compile_context. Open the GCC front-end
	shared library and return the symbol specified by the current
	GCC_C_FE_CONTEXT. */

	static gcc_c_fe_context_function *
	load_libcc (void)
	{
	void *handle;
	gcc_c_fe_context_function *func;

	/* gdb_dlopen will call error () on an error, so no need to check
	value. */
	handle = gdb_dlopen (STRINGIFY (GCC_C_FE_LIBCC));
	func = (gcc_c_fe_context_function *) gdb_dlsym (handle,
	STRINGIFY (GCC_C_FE_CONTEXT));

	if (func == NULL)
	error (_("could not find symbol %s in library %s"),
	STRINGIFY (GCC_C_FE_CONTEXT),
	STRINGIFY (GCC_C_FE_LIBCC));
	return func;
	}

	/* Return the compile instance associated with the current context.
	This function calls the symbol returned from the load_libcc
	function. This will provide the gcc_c_context. */

	struct compile_instance *
	c_get_compile_context (void)
	{
	static gcc_c_fe_context_function *func;

	struct gcc_c_context *context;

	if (func == NULL)
	{
	func = load_libcc ();
	gdb_assert (func != NULL);
	}

	context = (*func) (GCC_FE_VERSION_0, GCC_C_FE_VERSION_0);
	if (context == NULL)
	error (_("The loaded version of GCC does not support the required version "
	"of the API."));

	return new_compile_instance (context);
	}



	/* Write one macro definition. */

	static void
	print_one_macro (const char name, const struct macro_definition macro,
	struct macro_source_file *source, int line,
	void *user_data)
	{
	struct ui_file file = (struct ui_file ) user_data;

	/* Don't print command-line defines. They will be supplied another
	way. */
	if (line == 0)
	return;

	/* None of -Wno-builtin-macro-redefined, #undef first
	or plain #define of the same value would avoid a warning. */
	fprintf_filtered (file, "#ifndef %s\n# define %s", name, name);

	if (macro->kind == macro_function_like)
	{
	int i;

	fputs_filtered ("(", file);
	for (i = 0; i < macro->argc; i++)
	{
	fputs_filtered (macro->argv[i], file);
	if (i + 1 < macro->argc)
	fputs_filtered (", ", file);
	}
	fputs_filtered (")", file);
	}

	fprintf_filtered (file, " %s\n#endif\n", macro->replacement);
	}

	/* Write macro definitions at PC to FILE. */

	static void
	write_macro_definitions (const struct block *block, CORE_ADDR pc,
	struct ui_file *file)
	{
	struct macro_scope *scope;

	if (block != NULL)
	scope = sal_macro_scope (find_pc_line (pc, 0));
	else
	scope = default_macro_scope ();
	if (scope == NULL)
	scope = user_macro_scope ();

	if (scope != NULL && scope->file != NULL && scope->file->table != NULL)
	macro_for_each_in_scope (scope->file, scope->line, print_one_macro, file);
	}

	/* Helper function to construct a header scope for a block of code.
	Takes a scope argument which selects the correct header to
	insert into BUF. */

	static void
	add_code_header (enum compile_i_scope_types type, struct ui_file *buf)
	{
	switch (type)
	{
	case COMPILE_I_SIMPLE_SCOPE:
	fputs_unfiltered ("void "
	GCC_FE_WRAPPER_FUNCTION
	" (struct "
	COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG
	" *"
	COMPILE_I_SIMPLE_REGISTER_ARG_NAME
	") {\n",
	buf);
	break;
	case COMPILE_I_PRINT_ADDRESS_SCOPE:
	case COMPILE_I_PRINT_VALUE_SCOPE:
	/* <string.h> is needed for a memcpy call below. */
	fputs_unfiltered ("#include <string.h>\n"
	"void "
	GCC_FE_WRAPPER_FUNCTION
	" (struct "
	COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG
	" *"
	COMPILE_I_SIMPLE_REGISTER_ARG_NAME
	", "
	COMPILE_I_PRINT_OUT_ARG_TYPE
	" "
	COMPILE_I_PRINT_OUT_ARG
	") {\n",
	buf);
	break;

	case COMPILE_I_RAW_SCOPE:
	break;
	default:
	gdb_assert_not_reached (_("Unknown compiler scope reached."));
	}
	}

	/* Helper function to construct a footer scope for a block of code.
	Takes a scope argument which selects the correct footer to
	insert into BUF. */

	static void
	add_code_footer (enum compile_i_scope_types type, struct ui_file *buf)
	{
	switch (type)
	{
	case COMPILE_I_SIMPLE_SCOPE:
	case COMPILE_I_PRINT_ADDRESS_SCOPE:
	case COMPILE_I_PRINT_VALUE_SCOPE:
	fputs_unfiltered ("}\n", buf);
	break;
	case COMPILE_I_RAW_SCOPE:
	break;
	default:
	gdb_assert_not_reached (_("Unknown compiler scope reached."));
	}
	}

	/* Generate a structure holding all the registers used by the function
	we're generating. */

	static void
	generate_register_struct (struct ui_file stream, struct gdbarch gdbarch,
	const unsigned char *registers_used)
	{
	int i;
	int seen = 0;

	fputs_unfiltered ("struct " COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG " {\n",
	stream);

	if (registers_used != NULL)
	for (i = 0; i < gdbarch_num_regs (gdbarch); ++i)
	{
	if (registers_used[i])
	{
	struct type *regtype = check_typedef (register_type (gdbarch, i));
	char *regname = compile_register_name_mangled (gdbarch, i);
	struct cleanup *cleanups = make_cleanup (xfree, regname);

	seen = 1;

	/* You might think we could use type_print here. However,
	target descriptions often use types with names like
	"int64_t", which may not be defined in the inferior
	(and in any case would not be looked up due to the
	#pragma business). So, we take a much simpler
	approach: for pointer- or integer-typed registers, emit
	the field in the most direct way; and for other
	register types (typically flags or vectors), emit a
	maximally-aligned array of the correct size. */

	fputs_unfiltered (" ", stream);
	switch (TYPE_CODE (regtype))
	{
	case TYPE_CODE_PTR:
	fprintf_filtered (stream, "__gdb_uintptr %s", regname);
	break;

	case TYPE_CODE_INT:
	{
	const char *mode
	= c_get_mode_for_size (TYPE_LENGTH (regtype));

	if (mode != NULL)
	{
	if (TYPE_UNSIGNED (regtype))
	fputs_unfiltered ("unsigned ", stream);
	fprintf_unfiltered (stream,
	"int %s"
	" __attribute__ ((__mode__(__%s__)))",
	regname,
	mode);
	break;
	}
	}

	/* Fall through. */

	default:
	fprintf_unfiltered (stream,
	" unsigned char %s[%d]"
	" __attribute__((__aligned__("
	"__BIGGEST_ALIGNMENT__)))",
	regname,
	TYPE_LENGTH (regtype));
	}
	fputs_unfiltered (";\n", stream);

	do_cleanups (cleanups);
	}
	}

	if (!seen)
	fputs_unfiltered (" char " COMPILE_I_SIMPLE_REGISTER_DUMMY ";\n",
	stream);

	fputs_unfiltered ("};\n\n", stream);
	}

	/* Take the source code provided by the user with the 'compile'
	command, and compute the additional wrapping, macro, variable and
	register operations needed. INPUT is the source code derived from
	the 'compile' command, GDBARCH is the architecture to use when
	computing above, EXPR_BLOCK denotes the block relevant contextually
	to the inferior when the expression was created, and EXPR_PC
	indicates the value of $PC. */

	char *
	c_compute_program (struct compile_instance *inst,
	const char *input,
	struct gdbarch *gdbarch,
	const struct block *expr_block,
	CORE_ADDR expr_pc)
	{
	struct ui_file buf, var_stream = NULL;
	char *code;
	struct cleanup *cleanup;
	struct compile_c_instance context = (struct compile_c_instance ) inst;

	buf = mem_fileopen ();
	cleanup = make_cleanup_ui_file_delete (buf);

	write_macro_definitions (expr_block, expr_pc, buf);

	/* Do not generate local variable information for "raw"
	compilations. In this case we aren't emitting our own function
	and the user's code may only refer to globals. */
	if (inst->scope != COMPILE_I_RAW_SCOPE)
	{
	unsigned char *registers_used;
	int i;

	/* Generate the code to compute variable locations, but do it
	before generating the function header, so we can define the
	register struct before the function body. This requires a
	temporary stream. */
	var_stream = mem_fileopen ();
	make_cleanup_ui_file_delete (var_stream);
	registers_used = generate_c_for_variable_locations (context,
	var_stream, gdbarch,
	expr_block, expr_pc);
	make_cleanup (xfree, registers_used);

	fputs_unfiltered ("typedef unsigned int"
	" __attribute__ ((__mode__(__pointer__)))"
	" __gdb_uintptr;\n",
	buf);
	fputs_unfiltered ("typedef int"
	" __attribute__ ((__mode__(__pointer__)))"
	" __gdb_intptr;\n",
	buf);

	/* Iterate all log2 sizes in bytes supported by c_get_mode_for_size. */
	for (i = 0; i < 4; ++i)
	{
	const char *mode = c_get_mode_for_size (1 << i);

	gdb_assert (mode != NULL);
	fprintf_unfiltered (buf,
	"typedef int"
	" __attribute__ ((__mode__(__%s__)))"
	" __gdb_int_%s;\n",
	mode, mode);
	}

	generate_register_struct (buf, gdbarch, registers_used);
	}

	add_code_header (inst->scope, buf);

	if (inst->scope == COMPILE_I_SIMPLE_SCOPE
	\|\| inst->scope == COMPILE_I_PRINT_ADDRESS_SCOPE
	\|\| inst->scope == COMPILE_I_PRINT_VALUE_SCOPE)
	{
	ui_file_put (var_stream, ui_file_write_for_put, buf);
	fputs_unfiltered ("#pragma GCC user_expression\n", buf);
	}

	/* The user expression has to be in its own scope, so that "extern"
	works properly. Otherwise gcc thinks that the "extern"
	declaration is in the same scope as the declaration provided by
	gdb. */
	if (inst->scope != COMPILE_I_RAW_SCOPE)
	fputs_unfiltered ("{\n", buf);

	fputs_unfiltered ("#line 1 \"gdb command line\"\n", buf);

	switch (inst->scope)
	{
	case COMPILE_I_PRINT_ADDRESS_SCOPE:
	case COMPILE_I_PRINT_VALUE_SCOPE:
	fprintf_unfiltered (buf,
	"__auto_type " COMPILE_I_EXPR_VAL " = %s;\n"
	"typeof (%s) *" COMPILE_I_EXPR_PTR_TYPE ";\n"
	"memcpy (" COMPILE_I_PRINT_OUT_ARG ", %s" COMPILE_I_EXPR_VAL ",\n"
	"sizeof (*" COMPILE_I_EXPR_PTR_TYPE "));\n"
	, input, input,
	(inst->scope == COMPILE_I_PRINT_ADDRESS_SCOPE
	? "&" : ""));
	break;
	default:
	fputs_unfiltered (input, buf);
	break;
	}

	fputs_unfiltered ("\n", buf);

	/* For larger user expressions the automatic semicolons may be
	confusing. */
	if (strchr (input, '\n') == NULL)
	fputs_unfiltered (";\n", buf);

	if (inst->scope != COMPILE_I_RAW_SCOPE)
	fputs_unfiltered ("}\n", buf);

	add_code_footer (inst->scope, buf);
	code = ui_file_xstrdup (buf, NULL);
	do_cleanups (cleanup);
	return code;
	}