compile: New 'compile print'

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
2015-05-16  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): Update compile code help text.  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
2015-05-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

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

gdb/testsuite/ChangeLog
2015-05-16  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.compile/compile-print.c: New file.
	* gdb.compile/compile-print.exp: New file.

1 files changed, 42 insertions, 2 deletions

diff --git a/gdb/compile/compile-c-support.c b/gdb/compile/compile-c-support.c
index 48a17e2..39f06c6 100644
--- a/gdb/compile/compile-c-support.c
+++ b/gdb/compile/compile-c-support.c
@@ -190,6 +190,24 @@ 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:
+      /* <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:
@@ -207,6 +225,8 @@ 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 +389,9 @@ 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 +405,25 @@ 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