[PATCH v2 7/9] compile: New 'compile print'

Jan Kratochvil
2015-04-06T17:27:26Z

It is planned the existing GDB command 'print' will be able to evaluate its
expressions using the compiler. There will be some option to choose between
the existing GDB evaluation and the compiler evaluation. But as an
intermediate step this patch provides the expression printing feature as a new
command.

I can imagine it could be also called 'maintenance compile print' as in the
future one should be able to use its functionality by the normal 'print'
command.

There was a discussion with Eli about the command name:
https://sourceware.org/ml/gdb-patches/2015-03/msg00880.html
As there were no other comments yet I haven't renamed it yet, before there is
some confirmation about settlement on the final name.

Support for the GDB '@' operator to create arrays has been submitted for GCC:
[gcc patch] libcc1: '@' GDB array operator
https://gcc.gnu.org/ml/gcc-patches/2015-03/msg01451.html

gdb/ChangeLog
2015-03-26 Jan Kratochvil <jan.kratochvil@redhat.com>
Phil Muldoon <pmuldoon@redhat.com>

* NEWS (Changes since GDB 7.9): Add compile print.
* compile/compile-c-support.c (add_code_header, add_code_footer)
(c_compute_program): Add COMPILE_I_PRINT_ADDRESS_SCOPE and
COMPILE_I_PRINT_VALUE_SCOPE.
* compile/compile-internal.h (COMPILE_I_PRINT_OUT_ARG_TYPE)
(COMPILE_I_PRINT_OUT_ARG, COMPILE_I_EXPR_VAL, COMPILE_I_EXPR_PTR_TYPE):
New.
* compile/compile-object-load.c: Include block.h.
(get_out_value_type): New function.
(compile_object_load): Handle COMPILE_I_PRINT_ADDRESS_SCOPE and
COMPILE_I_PRINT_VALUE_SCOPE. Set compile_module's OUT_VALUE_ADDR and
OUT_VALUE_TYPE.
* compile/compile-object-load.h (struct compile_module): Add fields
out_value_addr and out_value_type.
* compile/compile-object-run.c: Include valprint.h and compile.h.
(struct do_module_cleanup): Add fields out_value_addr and
out_value_type.
(do_module_cleanup): Handle COMPILE_I_PRINT_ADDRESS_SCOPE and
COMPILE_I_PRINT_VALUE_SCOPE.
(compile_object_run): Propagate out_value_addr and out_value_type.
Pass OUT_VALUE_ADDR.
* compile/compile.c: Include valprint.h.
(compile_print_value, compile_print_command): New functions.
(eval_compile_command): Handle failed COMPILE_I_PRINT_ADDRESS_SCOPE.
(_initialize_compile): Install compile_print_command.
* compile/compile.h (compile_print_value): New prototype.
* defs.h (enum compile_i_scope_types): Add
COMPILE_I_PRINT_ADDRESS_SCOPE and COMPILE_I_PRINT_VALUE_SCOPE.

gdb/doc/ChangeLog
2015-03-26 Jan Kratochvil <jan.kratochvil@redhat.com>

* gdb.texinfo (Compiling and Injecting Code): Add compile print.

gdb/testsuite/ChangeLog
2015-03-26 Jan Kratochvil <jan.kratochvil@redhat.com>

* gdb.compile/compile-print.c: New file.
* gdb.compile/compile-print.exp: New file.
---
gdb/NEWS | 3 +
gdb/compile/compile-c-support.c | 43 ++++++++
gdb/compile/compile-internal.h | 4 +
gdb/compile/compile-object-load.c | 141 ++++++++++++++++++++++++++-
gdb/compile/compile-object-load.h | 8 ++
gdb/compile/compile-object-run.c | 31 ++++++
gdb/compile/compile.c | 73 ++++++++++++++
gdb/compile/compile.h | 2
gdb/defs.h | 9 ++
gdb/doc/gdb.texinfo | 19 ++++
gdb/testsuite/gdb.compile/compile-print.c | 32 ++++++
gdb/testsuite/gdb.compile/compile-print.exp | 58 +++++++++++
12 files changed, 417 insertions(+), 6 deletions(-)
create mode 100644 gdb/testsuite/gdb.compile/compile-print.c
create mode 100644 gdb/testsuite/gdb.compile/compile-print.exp

diff --git a/gdb/NEWS b/gdb/NEWS
index 884c381..8dd3767 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -53,6 +53,9 @@ record btrace bts
record bts
Start branch trace recording using Branch Trace Store (BTS) format.

+compile print
+ Evaluate expression with the compiler and print result.
+
* New options

set max-completions
diff --git a/gdb/compile/compile-c-support.c b/gdb/compile/compile-c-support.c
index 48a17e2..86b02cf 100644
--- a/gdb/compile/compile-c-support.c
+++ b/gdb/compile/compile-c-support.c
@@ -190,6 +190,23 @@ add_code_header (enum compile_i_scope_types type, struct ui_file *buf)
") {\n",
buf);
break;
+ case COMPILE_I_PRINT_ADDRESS_SCOPE:
+ case COMPILE_I_PRINT_VALUE_SCOPE:
+ 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:
@@ -207,6 +224,8 @@ 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:
@@ -369,7 +388,9 @@ c_compute_program (struct compile_instance *inst,

add_code_header (inst->scope, buf);

- if (inst->scope == COMPILE_I_SIMPLE_SCOPE)
+ 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);
@@ -383,7 +404,25 @@ c_compute_program (struct compile_instance *inst,
fputs_unfiltered ("{\n", buf);

fputs_unfiltered ("#line 1 \"gdb command line\"\n", buf);
- fputs_unfiltered (input, 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
diff --git a/gdb/compile/compile-internal.h b/gdb/compile/compile-internal.h
index c369d46..b1a5a88 100644
--- a/gdb/compile/compile-internal.h
+++ b/gdb/compile/compile-internal.h
@@ -84,6 +84,10 @@ struct compile_c_instance
#define COMPILE_I_SIMPLE_REGISTER_STRUCT_TAG "__gdb_regs"
#define COMPILE_I_SIMPLE_REGISTER_ARG_NAME "__regs"
#define COMPILE_I_SIMPLE_REGISTER_DUMMY "_dummy"
+#define COMPILE_I_PRINT_OUT_ARG_TYPE "void *"
+#define COMPILE_I_PRINT_OUT_ARG "__gdb_out_param"
+#define COMPILE_I_EXPR_VAL "__gdb_expr_val"
+#define COMPILE_I_EXPR_PTR_TYPE "__gdb_expr_ptr_type"

/* Call gdbarch_register_name (GDBARCH, REGNUM) and convert its result
to a form suitable for the compiler source. The register names
diff --git a/gdb/compile/compile-object-load.c b/gdb/compile/compile-object-load.c
index 3c07840..e67e5ba 100644
--- a/gdb/compile/compile-object-load.c
+++ b/gdb/compile/compile-object-load.c
@@ -29,6 +29,7 @@
#include "regcache.h"
#include "inferior.h"
#include "compile.h"
+#include "block.h"
#include "arch-utils.h"

/* Helper data for setup_sections. */
@@ -354,6 +355,114 @@ copy_sections (bfd *abfd, asection *sect, void *data)
do_cleanups (cleanups);
}

+/* Fetch the type of COMPILE_I_EXPR_PTR_TYPE and COMPILE_I_EXPR_VAL
+ symbols in OBJFILE so we can calculate how much memory to allocate
+ for the out parameter. This avoids needing a malloc in the generated
+ code. Throw an error if anything fails.
+ Set *OUT_VALUE_TAKE_ADDRESSP depending whether inferior code should
+ copy COMPILE_I_EXPR_VAL or its address - this depends on __auto_type
+ array-to-pointer type conversion of COMPILE_I_EXPR_VAL, as detected
+ by COMPILE_I_EXPR_PTR_TYPE preserving the array type. */
+
+static struct type *
+get_out_value_type (struct symbol *func_sym, struct objfile *objfile,
+ enum compile_i_scope_types scope)
+{
+ struct symbol *gdb_ptr_type_sym, *gdb_val_sym;
+ struct type *gdb_ptr_type, *gdb_type_from_ptr, *gdb_type, *retval;
+ const struct block *block;
+ const struct blockvector *bv;
+ int nblocks = 0;
+ int block_loop = 0;
+
+ bv = SYMTAB_BLOCKVECTOR (func_sym->owner.symtab);
+ nblocks = BLOCKVECTOR_NBLOCKS (bv);
+
+ gdb_ptr_type_sym = NULL;
+ for (block_loop = 0; block_loop < nblocks; block_loop++)
+ {
+ struct symbol *function;
+ const struct block *function_block;
+
+ block = BLOCKVECTOR_BLOCK (bv, block_loop);
+ if (BLOCK_FUNCTION (block) != NULL)
+ continue;
+ gdb_val_sym = block_lookup_symbol (block, COMPILE_I_EXPR_VAL, VAR_DOMAIN);
+ if (gdb_val_sym == NULL)
+ continue;
+
+ function_block = block;
+ while (function_block != BLOCKVECTOR_BLOCK (bv, STATIC_BLOCK)
+ && function_block != BLOCKVECTOR_BLOCK (bv, GLOBAL_BLOCK))
+ {
+ function_block = BLOCK_SUPERBLOCK (function_block);
+ function = BLOCK_FUNCTION (function_block);
+ if (function != NULL)
+ break;
+ }
+ if (function != NULL
+ && (BLOCK_SUPERBLOCK (function_block)
+ == BLOCKVECTOR_BLOCK (bv, STATIC_BLOCK))
+ && (strcmp (SYMBOL_LINKAGE_NAME (function), GCC_FE_WRAPPER_FUNCTION)
+ == 0))
+ break;
+ }
+ if (block_loop == nblocks)
+ error (_("No \"%s\" symbol found"), COMPILE_I_EXPR_PTR_TYPE);
+
+ gdb_type = SYMBOL_TYPE (gdb_val_sym);
+ CHECK_TYPEDEF (gdb_type);
+
+ gdb_ptr_type_sym = block_lookup_symbol (block, COMPILE_I_EXPR_PTR_TYPE,
+ VAR_DOMAIN);
+ if (gdb_ptr_type_sym == NULL)
+ error (_("No \"%s\" symbol found"), COMPILE_I_EXPR_PTR_TYPE);
+ gdb_ptr_type = SYMBOL_TYPE (gdb_ptr_type_sym);
+ CHECK_TYPEDEF (gdb_ptr_type);
+ if (TYPE_CODE (gdb_ptr_type) != TYPE_CODE_PTR)
+ error (_("Type of \"%s\" is not a pointer"), COMPILE_I_EXPR_PTR_TYPE);
+ gdb_type_from_ptr = TYPE_TARGET_TYPE (gdb_ptr_type);
+
+ if (types_deeply_equal (gdb_type, gdb_type_from_ptr))
+ {
+ if (scope != COMPILE_I_PRINT_ADDRESS_SCOPE)
+ error (_("Expected address scope in compiled module \"%s\"."),
+ objfile_name (objfile));
+ return gdb_type;
+ }
+
+ if (TYPE_CODE (gdb_type) != TYPE_CODE_PTR)
+ error (_("Invalid type code %d of symbol \"%s\" "
+ "in compiled module \"%s\"."),
+ TYPE_CODE (gdb_type_from_ptr), COMPILE_I_EXPR_VAL,
+ objfile_name (objfile));
+
+ switch (TYPE_CODE (gdb_type_from_ptr))
+ {
+ case TYPE_CODE_ARRAY:
+ retval = gdb_type_from_ptr;
+ gdb_type_from_ptr = TYPE_TARGET_TYPE (gdb_type_from_ptr);
+ break;
+ case TYPE_CODE_FUNC:
+ retval = gdb_type_from_ptr;
+ break;
+ default:
+ error (_("Invalid type code %d of symbol \"%s\" "
+ "in compiled module \"%s\"."),
+ TYPE_CODE (gdb_type_from_ptr), COMPILE_I_EXPR_PTR_TYPE,
+ objfile_name (objfile));
+ }
+ if (!types_deeply_equal (gdb_type_from_ptr,
+ TYPE_TARGET_TYPE (gdb_type)))
+ error (_("Referenced types do not match for symbols \"%s\" and \"%s\" "
+ "in compiled module \"%s\"."),
+ COMPILE_I_EXPR_PTR_TYPE, COMPILE_I_EXPR_VAL,
+ objfile_name (objfile));
+ if (scope == COMPILE_I_PRINT_ADDRESS_SCOPE)
+ return NULL;
+ return retval;
+}
+
/* Fetch the type of first parameter of FUNC_SYM.
Return NULL if FUNC_SYM has no parameters. Throw an error otherwise. */

@@ -440,7 +549,9 @@ store_regs (struct type *regs_type, CORE_ADDR regs_base)
Caller must fully dispose the return value by calling compile_object_run.
SOURCE_FILE's copy is stored into the returned object.
Caller should free both OBJECT_FILE and SOURCE_FILE immediatelly after this
- function returns. */
+ function returns.
+ Function returns NULL only for COMPILE_I_PRINT_ADDRESS_SCOPE when
+ COMPILE_I_PRINT_VALUE_SCOPE should have been used instead. */

struct compile_module *
compile_object_load (const char *object_file, const char *source_file,
@@ -449,7 +560,7 @@ compile_object_load (const char *object_file, const char *source_file,
struct cleanup *cleanups, *cleanups_free_objfile;
bfd *abfd;
struct setup_sections_data setup_sections_data;
- CORE_ADDR addr, regs_addr;
+ CORE_ADDR addr, regs_addr, out_value_addr = 0;
struct symbol *func_sym;
struct type *func_type;
struct bound_minimal_symbol bmsym;
@@ -459,7 +570,7 @@ compile_object_load (const char *object_file, const char *source_file,
struct type *dptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
unsigned dptr_type_len = TYPE_LENGTH (dptr_type);
struct compile_module *retval;
- struct type *regs_type;
+ struct type *regs_type, *out_value_type = NULL;
char *filename, **matching;
struct objfile *objfile;
int expect_parameters;
@@ -521,6 +632,11 @@ compile_object_load (const char *object_file, const char *source_file,
expect_parameters = 0;
expect_return_type = builtin_type (target_gdbarch ())->builtin_void;
break;
+ case COMPILE_I_PRINT_ADDRESS_SCOPE:
+ case COMPILE_I_PRINT_VALUE_SCOPE:
+ expect_parameters = 2;
+ expect_return_type = builtin_type (target_gdbarch ())->builtin_void;
+ break;
default:
internal_error (__FILE__, __LINE__, _("invalid scope %d"), scope);
}
@@ -597,6 +713,23 @@ compile_object_load (const char *object_file, const char *source_file,
store_regs (regs_type, regs_addr);
}

+ if (scope == COMPILE_I_PRINT_ADDRESS_SCOPE
+ || scope == COMPILE_I_PRINT_VALUE_SCOPE)
+ {
+ out_value_type = get_out_value_type (func_sym, objfile, scope);
+ if (out_value_type == NULL)
+ {
+ do_cleanups (cleanups);
+ return NULL;
+ }
+ check_typedef (out_value_type);
+ out_value_addr = gdbarch_infcall_mmap (target_gdbarch (),
+ TYPE_LENGTH (out_value_type),
+ (GDB_MMAP_PROT_READ
+ | GDB_MMAP_PROT_WRITE));
+ gdb_assert (out_value_addr != 0);
+ }
+
discard_cleanups (cleanups_free_objfile);
do_cleanups (cleanups);

@@ -607,5 +740,7 @@ compile_object_load (const char *object_file, const char *source_file,
retval->regs_addr = regs_addr;
retval->scope = scope;
retval->scope_data = scope_data;
+ retval->out_value_addr = out_value_addr;
+ retval->out_value_type = out_value_type;
return retval;
}
diff --git a/gdb/compile/compile-object-load.h b/gdb/compile/compile-object-load.h
index 94f77be..ac72a6a 100644
--- a/gdb/compile/compile-object-load.h
+++ b/gdb/compile/compile-object-load.h
@@ -37,6 +37,14 @@ struct compile_module

/* User data for SCOPE in use. */
void *scope_data;
+
+ /* Inferior parameter out value address or NULL if the inferior function does not
+ have one. */
+ CORE_ADDR out_value_addr;
+
+ /* Inferior parameter out value type or NULL if the inferior function does not
+ have one. */
+ struct type *out_value_type;
};

extern struct compile_module *compile_object_load (const char *object_file,
diff --git a/gdb/compile/compile-object-run.c b/gdb/compile/compile-object-run.c
index c454bd1..216cbf9 100644
--- a/gdb/compile/compile-object-run.c
+++ b/gdb/compile/compile-object-run.c
@@ -25,6 +25,8 @@
#include "compile-internal.h"
#include "dummy-frame.h"
#include "block.h"
+#include "valprint.h"
+#include "compile.h"

/* Helper for do_module_cleanup. */

@@ -41,6 +43,10 @@ struct do_module_cleanup
enum compile_i_scope_types scope;
void *scope_data;

+ /* Copy from struct compile_module. */
+ CORE_ADDR out_value_addr;
+ struct type *out_value_type;
+
/* objfile_name of our objfile. */
char objfile_name_string[1];
};
@@ -56,7 +62,21 @@ do_module_cleanup (void *arg)
struct objfile *objfile;

if (data->executedp != NULL)
- *data->executedp = 1;
+ {
+ *data->executedp = 1;
+
+ /* This code cannot be in compile_object_run as OUT_VALUE_TYPE
+ no longer exists there. */
+ if (data->scope == COMPILE_I_PRINT_ADDRESS_SCOPE
+ || data->scope == COMPILE_I_PRINT_VALUE_SCOPE)
+ {
+ struct value *addr_value;
+ struct type *ptr_type = lookup_pointer_type (data->out_value_type);
+
+ addr_value = value_from_pointer (ptr_type, data->out_value_addr);
+ compile_print_value (value_ind (addr_value), data->scope_data);
+ }
+ }

ALL_OBJFILES (objfile)
if ((objfile->flags & OBJF_USERLOADED) == 0
@@ -104,6 +124,8 @@ compile_object_run (struct compile_module *module)
strcpy (data->objfile_name_string, objfile_name_s);
data->scope = module->scope;
data->scope_data = module->scope_data;
+ data->out_value_addr = module->out_value_addr;
+ data->out_value_type = module->out_value_type;

xfree (module->source_file);
xfree (module);
@@ -133,6 +155,13 @@ compile_object_run (struct compile_module *module)
(TYPE_FIELD_TYPE (func_type, current_arg), regs_addr);
++current_arg;
}
+ if (TYPE_NFIELDS (func_type) >= 2)
+ {
+ gdb_assert (data->out_value_addr != 0);
+ vargs[current_arg] = value_from_pointer
+ (TYPE_FIELD_TYPE (func_type, current_arg), data->out_value_addr);
+ ++current_arg;
+ }
gdb_assert (current_arg == TYPE_NFIELDS (func_type));
call_function_by_hand_dummy (func_val, TYPE_NFIELDS (func_type), vargs,
do_module_cleanup, data);
diff --git a/gdb/compile/compile.c b/gdb/compile/compile.c
index ab19a5d..c4b8f2e 100644
--- a/gdb/compile/compile.c
+++ b/gdb/compile/compile.c
@@ -38,6 +38,7 @@
#include "target.h"
#include "osabi.h"
#include "gdb_wait.h"
+#include "valprint.h"

\f

@@ -163,6 +164,49 @@ compile_code_command (char *arg, int from_tty)
do_cleanups (cleanup);
}

+/* Callback for compile_print_command. */
+
+void
+compile_print_value (struct value *val, void *data_voidp)
+{
+ const struct format_data *fmtp = data_voidp;
+
+ print_value (val, fmtp);
+}
+
+/* Handle the input from the 'compile print' command. The "compile
+ print" command is used to evaluate and print an expression that may
+ contain calls to the GCC compiler. The language expected in this
+ compile command is the language currently set in GDB. */
+
+static void
+compile_print_command (char *arg_param, int from_tty)
+{
+ const char *arg = arg_param;
+ struct cleanup *cleanup;
+ enum compile_i_scope_types scope = COMPILE_I_PRINT_ADDRESS_SCOPE;
+ struct format_data *fmtp;
+
+ cleanup = make_cleanup_restore_integer (&interpreter_async);
+ interpreter_async = 0;
+
+ fmtp = print_command_parse_format (&arg, "compile print");
+
+ if (arg && *arg)
+ eval_compile_command (NULL, arg, scope, fmtp);
+ else
+ {
+ struct command_line *l = get_command_line (compile_control, "");
+
+ make_cleanup_free_command_lines (&l);
+ l->control_u.compile.scope = scope;
+ l->control_u.compile.scope_data = fmtp;
+ execute_control_command_untraced (l);
+ }
+
+ do_cleanups (cleanup);
+}
+
/* A cleanup function to remove a directory and all its contents. */

static void
@@ -576,6 +620,14 @@ eval_compile_command (struct command_line *cmd, const char *cmd_string,
make_cleanup (cleanup_unlink_file, source_file);
compile_module = compile_object_load (object_file, source_file,
scope, scope_data);
+ if (compile_module == NULL)
+ {
+ gdb_assert (scope == COMPILE_I_PRINT_ADDRESS_SCOPE);
+ do_cleanups (cleanup_xfree);
+ eval_compile_command (cmd, cmd_string,
+ COMPILE_I_PRINT_VALUE_SCOPE, scope_data);
+ return;
+ }
discard_cleanups (cleanup_unlink);
do_cleanups (cleanup_xfree);
compile_object_run (compile_module);
@@ -654,6 +706,27 @@ Usage: compile file [-r|-raw] [filename]\n\
&compile_command_list);
set_cmd_completer (c, filename_completer);

+ add_cmd ("print", class_obscure, compile_print_command,
+ _("\
+Evaluate EXPR with the compiler and print result.\n\
+\n\
+Usage: compile print[/FMT] [EXPR]\n\
+\n\
+The expression may be specified on the same line as the command, e.g.:\n\
+\n\
+ compile print i\n\
+\n\
+Alternatively, you can type the expression interactively.\n\
+You can invoke this mode when no argument is given to the command\n\
+(i.e., \"compile print\" is typed with nothing after it). An\n\
+interactive prompt will be shown allowing you to enter multiple\n\
+lines of source code. Type a line containing \"end\" to indicate\n\
+the end of the source code.\n\
+\n\
+EXPR may be preceded with /FMT, where FMT is a format letter\n\
+but no count or size letter (see \"x\" command)."),
+ &compile_command_list);
+
add_setshow_boolean_cmd ("compile", class_maintenance, &compile_debug, _("\
Set compile command debugging."), _("\
Show compile command debugging."), _("\
diff --git a/gdb/compile/compile.h b/gdb/compile/compile.h
index a973167..6e108c7 100644
--- a/gdb/compile/compile.h
+++ b/gdb/compile/compile.h
@@ -101,4 +101,6 @@ extern void compile_dwarf_bounds_to_c (struct ui_file *stream,
const gdb_byte *op_end,
struct dwarf2_per_cu_data *per_cu);

+extern void compile_print_value (struct value *val, void *data_voidp);
+
#endif /* GDB_COMPILE_H */
diff --git a/gdb/defs.h b/gdb/defs.h
index 6476f80..f6e010c 100644
--- a/gdb/defs.h
+++ b/gdb/defs.h
@@ -70,6 +70,15 @@ enum compile_i_scope_types
/* Do not wrap the expression,
it has to provide function "_gdb_expr" on its own. */
COMPILE_I_RAW_SCOPE,
+
+ /* A printable expression scope. Wrap an expression into a scope
+ suitable for the "compile print" command. It uses the generic
+ function name "_gdb_expr". COMPILE_I_PRINT_ADDRESS_SCOPE variant
+ is the usual one, taking address of the object.
+ COMPILE_I_PRINT_VALUE_SCOPE is needed for arrays where the array
+ name already specifies its address. */
+ COMPILE_I_PRINT_ADDRESS_SCOPE,
+ COMPILE_I_PRINT_VALUE_SCOPE,
};

/* Just in case they're not defined in stdio.h. */
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index d794893..3eaf9d3 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -17223,6 +17223,25 @@ compile file /home/user/example.c
@end smallexample
@end table

+@table @code
+@item compile print @var{expr}
+@itemx compile print /@var{f} @var{expr}
+Compile @var{expr} with the compiler language found as the current
+language in @value{GDBN} (@pxref{Languages}). By default the
+value of @var{expr} is printed in a format appropriate to its data type;
+you can choose a different format by specifying @samp{/@var{f}}, where
+@var{f} is a letter specifying the format; see @ref{Output Formats,,Output
+Formats}.
+
+@item compile print
+@itemx compile print /@var{f}
+@cindex reprint the last value
+Alternatively you can enter the expression (source code producing it) as
+multiple lines of text. To enter this mode, invoke the @samp{compile print}
+command without any text following the command. This will start the
+multiple-line editor.
+@end table
+
@subsection Caveats when using the @code{compile} command

There are a few caveats to keep in mind when using the @code{compile}
diff --git a/gdb/testsuite/gdb.compile/compile-print.c b/gdb/testsuite/gdb.compile/compile-print.c
new file mode 100644
index 0000000..e83b620
--- /dev/null
+++ b/gdb/testsuite/gdb.compile/compile-print.c
@@ -0,0 +1,32 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2015 Free Software Foundation, Inc.
+
+ 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 <stdlib.h>
+
+int varint = 10;
+int vararray[] = { 1, 2, 3, 4, 5 };
+int *vararrayp = vararray;
+struct object
+{
+ int field;
+} varobject = { 1 };
+
+int
+main (void)
+{
+ return 0;
+}
diff --git a/gdb/testsuite/gdb.compile/compile-print.exp b/gdb/testsuite/gdb.compile/compile-print.exp
new file mode 100644
index 0000000..92c6240
--- /dev/null
+++ b/gdb/testsuite/gdb.compile/compile-print.exp
@@ -0,0 +1,58 @@
+# Copyright 2015 Free Software Foundation, Inc.
+
+# 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/>.
+
+standard_testfile
+
+if { [prepare_for_testing ${testfile}.exp "$testfile"] } {
+ return -1
+}
+
+if ![runto_main] {
+ return -1
+}
+
+if {[skip_compile_feature_tests]} {
+ untested "compile command not supported (could not find libcc1 shared library?)"
+ return -1
+}
+
+gdb_test "compile print varint" " = 10"
+gdb_test "compile print vararray" " = \\{1, 2, 3, 4, 5\\}"
+gdb_test "compile print main" " = \\{int \\(void\\)\\} 0x\[0-9a-f\]+"
+
+set test "compile print *vararray@3"
+gdb_test_multiple $test $test {
+ -re " = \\{1, 2, 3\\}\r\n$gdb_prompt $" {
+ pass $test
+ }
+ -re ": error: stray '@' in program\r\n.*\r\n$gdb_prompt $" {
+ xfail "$test (gcc does not support '@')"
+ }
+}
+
+set test "compile print *vararrayp@3"
+gdb_test_multiple $test $test {
+ -re " = \\{1, 2, 3\\}\r\n$gdb_prompt $" {
+ pass $test
+ }
+ -re ": error: stray '@' in program\r\n.*\r\n$gdb_prompt $" {
+ xfail "$test (gcc does not support '@')"
+ }
+}
+
+gdb_test "compile print/x 256" " = 0x100"
+gdb_test {print $} " = 256"
+
+gdb_test "compile print varobject" { = {field = 1}}