compile: Add 'set compile-gcc'

As discussed in
	How to use compile & execute function in GDB
	https://sourceware.org/ml/gdb/2015-04/msg00026.html

GDB currently searches for compilers on /usr/bin/ARCH-OS-gcc and
chooses a match from there.  However, it is not currently possible for
the user to override which compiler to use.  This is what this patch
implements.

It is also a sync between GCC's and GDB's interfaces.

gdb/ChangeLog
2017-08-23  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* NEWS (Changes since GDB 7.9): Add set compile-gcc and show
	compile-gcc.
	* compile/compile.c (compile_gcc, show_compile_gcc): New.
	(compile_to_object): Implement compile_gcc.
	(_initialize_compile): Install "set compile-gcc".  Initialize
	compile_gcc.

gdb/doc/ChangeLog
2017-08-23  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.texinfo (Compiling and Injecting Code): Add to subsection
	"Compiler search for the compile command" descriptions of set
	compile-gcc and show compile-gcc.

include/ChangeLog
2017-08-23  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gcc-interface.h (enum gcc_base_api_version): Update comment for
	GCC_FE_VERSION_1.
	(struct gcc_base_vtable): Rename set_arguments to set_arguments_v0.
	Add set_arguments, set_triplet_regexp and set_driver_filename.

7 files changed, 155 insertions, 31 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index d7466d0..7eeab62 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,14 @@
 2017-08-23  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
+	* NEWS (Changes since GDB 8.0): Add set compile-gcc and show
+	compile-gcc.
+	* compile/compile.c (compile_gcc, show_compile_gcc): New.
+	(compile_to_object): Implement compile_gcc.
+	(_initialize_compile): Install "set compile-gcc".  Initialize
+	compile_gcc.
+
+2017-08-23  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
 	* compile/compile.c (compile_to_object): Conditionally call
 	set_verbose.  Conditionally call compile or compile_v0.
 
diff --git a/gdb/NEWS b/gdb/NEWS
index 4b0a956..7354154 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -27,6 +27,10 @@ QStartupWithShell
 
 * New commands
 
+set|show compile-gcc
+  Set and show compilation command used for compiling and injecting code
+  with the 'compile' commands.
+
 set debug separate-debug-file
 show debug separate-debug-file
   Control the display of debug output about separate debug file search.
diff --git a/gdb/compile/compile.c b/gdb/compile/compile.c
index 36baab3..bbb31f1 100644
--- a/gdb/compile/compile.c
+++ b/gdb/compile/compile.c
@@ -335,6 +335,19 @@ append_args (int *argcp, char ***argvp, int argc, char **argv)
   (*argvp)[(*argcp)] = NULL;
 }
 
+/* String for 'set compile-gcc' and 'show compile-gcc'.  */
+static char *compile_gcc;
+
+/* Implement 'show compile-gcc'.  */
+
+static void
+show_compile_gcc (struct ui_file *file, int from_tty,
+		  struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file, _("Compile command GCC driver filename is \"%s\".\n"),
+		    value);
+}
+
 /* Return DW_AT_producer parsed for get_selected_frame () (if any).
    Return NULL otherwise.
 
@@ -452,8 +465,6 @@ compile_to_object (struct command_line *cmd, const char *cmd_string,
   int ok;
   FILE *src;
   struct gdbarch *gdbarch = get_current_arch ();
-  const char *os_rx;
-  const char *arch_rx;
   char *triplet_rx;
   char *error_message;
 
@@ -505,22 +516,39 @@ compile_to_object (struct command_line *cmd, const char *cmd_string,
   if (compile_debug)
     fprintf_unfiltered (gdb_stdlog, "debug output:\n\n%s", code.c_str ());
 
-  os_rx = osabi_triplet_regexp (gdbarch_osabi (gdbarch));
-  arch_rx = gdbarch_gnu_triplet_regexp (gdbarch);
+  if (compiler->fe->ops->version >= GCC_FE_VERSION_1)
+    compiler->fe->ops->set_verbose (compiler->fe, compile_debug);
 
-  /* Allow triplets with or without vendor set.  */
-  triplet_rx = concat (arch_rx, "(-[^-]*)?-", os_rx, (char *) NULL);
-  make_cleanup (xfree, triplet_rx);
+  if (compile_gcc[0] != 0)
+    {
+      if (compiler->fe->ops->version < GCC_FE_VERSION_1)
+	error (_("Command 'set compile-gcc' requires GCC version 6 or higher "
+		 "(libcc1 interface version 1 or higher)"));
+
+      compiler->fe->ops->set_driver_filename (compiler->fe, compile_gcc);
+    }
+  else
+    {
+      const char *os_rx = osabi_triplet_regexp (gdbarch_osabi (gdbarch));
+      const char *arch_rx = gdbarch_gnu_triplet_regexp (gdbarch);
+
+      /* Allow triplets with or without vendor set.  */
+      triplet_rx = concat (arch_rx, "(-[^-]*)?-", os_rx, (char *) NULL);
+      make_cleanup (xfree, triplet_rx);
+
+      if (compiler->fe->ops->version >= GCC_FE_VERSION_1)
+	compiler->fe->ops->set_triplet_regexp (compiler->fe, triplet_rx);
+    }
 
   /* Set compiler command-line arguments.  */
   get_args (compiler, gdbarch, &argc, &argv);
   gdb_argv argv_holder (argv);
 
   if (compiler->fe->ops->version >= GCC_FE_VERSION_1)
-    compiler->fe->ops->set_verbose (compiler->fe, compile_debug);
-
-  error_message = compiler->fe->ops->set_arguments (compiler->fe, triplet_rx,
-						    argc, argv);
+    error_message = compiler->fe->ops->set_arguments (compiler->fe, argc, argv);
+  else
+    error_message = compiler->fe->ops->set_arguments_v0 (compiler->fe, triplet_rx,
+							 argc, argv);
   if (error_message != NULL)
     {
       make_cleanup (xfree, error_message);
@@ -742,4 +770,17 @@ String quoting is parsed like in shell, for example:\n\
 			 " -fno-stack-protector"
   );
   set_compile_args (compile_args, 0, NULL);
+
+  add_setshow_optional_filename_cmd ("compile-gcc", class_support,
+				     &compile_gcc,
+				     _("Set compile command "
+				       "GCC driver filename"),
+				     _("Show compile command "
+				       "GCC driver filename"),
+				     _("\
+It should be absolute filename of the gcc executable.\n\
+If empty the default target triplet will be searched in $PATH."),
+				     NULL, show_compile_gcc, &setlist,
+				     &showlist);
+  compile_gcc = xstrdup ("");
 }
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 40b0e40..bf82730 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,9 @@
+2017-08-23  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* gdb.texinfo (Compiling and Injecting Code): Add to subsection
+	"Compiler search for the compile command" descriptions of set
+	compile-gcc and show compile-gcc.
+
 2017-08-07  Weimin Pan  <weimin.pan@oracle.com>
 
 	* gdb.texinfo (Architectures): Add new Sparc64 section to document
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index d0d5d96..d977b23 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -18154,13 +18154,15 @@ will print to the console.
 
 @subsection Compiler search for the @code{compile} command
 
-@value{GDBN} needs to find @value{NGCC} for the inferior being debugged which
-may not be obvious for remote targets of different architecture than where
-@value{GDBN} is running.  Environment variable @code{PATH} (@code{PATH} from
-shell that executed @value{GDBN}, not the one set by @value{GDBN}
-command @code{set environment}).  @xref{Environment}.  @code{PATH} on
+@value{GDBN} needs to find @value{NGCC} for the inferior being debugged
+which may not be obvious for remote targets of different architecture
+than where @value{GDBN} is running.  Environment variable @code{PATH} on
 @value{GDBN} host is searched for @value{NGCC} binary matching the
-target architecture and operating system.
+target architecture and operating system.  This search can be overriden
+by @code{set compile-gcc} @value{GDBN} command below.  @code{PATH} is
+taken from shell that executed @value{GDBN}, it is not the value set by
+@value{GDBN} command @code{set environment}).  @xref{Environment}.
+
 
 Specifically @code{PATH} is searched for binaries matching regular expression
 @code{@var{arch}(-[^-]*)?-@var{os}-gcc} according to the inferior target being
@@ -18170,6 +18172,28 @@ example both @code{i386} and @code{x86_64} targets look for pattern
 for pattern @code{s390x?}.  @var{os} is currently supported only for
 pattern @code{linux(-gnu)?}.
 
+On Posix hosts the compiler driver @value{GDBN} needs to find also
+shared library @file{libcc1.so} from the compiler.  It is searched in
+default shared library search path (overridable with usual environment
+variable @code{LD_LIBRARY_PATH}), unrelated to @code{PATH} or @code{set
+compile-gcc} settings.  Contrary to it @file{libcc1plugin.so} is found
+according to the installation of the found compiler --- as possibly
+specified by the @code{set compile-gcc} command.
+
+@table @code
+@item set compile-gcc
+@cindex compile command driver filename override
+Set compilation command used for compiling and injecting code with the
+@code{compile} commands.  If this option is not set (it is set to
+an empty string), the search described above will occur --- that is the
+default.
+
+@item show compile-gcc
+Displays the current compile command @value{NGCC} driver filename.
+If set, it is the main command @command{gcc}, found usually for example
+under name @file{x86_64-linux-gnu-gcc}.
+@end table
+
 @node GDB Files
 @chapter @value{GDBN} Files
 
diff --git a/include/ChangeLog b/include/ChangeLog
index 02ee554..3b89deb 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,5 +1,12 @@
 2017-08-23  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
+	* gcc-interface.h (enum gcc_base_api_version): Update comment for
+	GCC_FE_VERSION_1.
+	(struct gcc_base_vtable): Rename set_arguments to set_arguments_v0.
+	Add set_arguments, set_triplet_regexp and set_driver_filename.
+
+2017-08-23  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
 	* gcc-interface.h (enum gcc_base_api_version): Add
 	GCC_FE_VERSION_1.
 	(struct gcc_base_vtable): Rename compile to compile_v0.  Update
diff --git a/include/gcc-interface.h b/include/gcc-interface.h
index c98f078..e3ffd18 100644
--- a/include/gcc-interface.h
+++ b/include/gcc-interface.h
@@ -46,7 +46,9 @@ enum gcc_base_api_version
 {
   GCC_FE_VERSION_0 = 0,
 
-  /* Deprecated method compile_v0.  Added method set_verbose and compile.  */
+  /* Deprecated methods set_arguments_v0 and compile_v0.  Added methods
+     set_arguments, set_triplet_regexp, set_driver_filename, set_verbose and
+     compile.  */
   GCC_FE_VERSION_1 = 1,
 };
 
@@ -67,20 +69,12 @@ struct gcc_base_vtable
 
   unsigned int version;
 
-  /* Set the compiler's command-line options for the next compilation.
-     TRIPLET_REGEXP is a regular expression that is used to match the
-     configury triplet prefix to the compiler.
-     The arguments are copied by GCC.  ARGV need not be
-     NULL-terminated.  The arguments must be set separately for each
-     compilation; that is, after a compile is requested, the
-     previously-set arguments cannot be reused.
-
-     This returns NULL on success.  On failure, returns a malloc()d
-     error message.  The caller is responsible for freeing it.  */
+  /* Deprecated GCC_FE_VERSION_0 variant of the GCC_FE_VERSION_1
+     methods set_triplet_regexp and set_arguments.  */
 
-  char *(*set_arguments) (struct gcc_base_context *self,
-			  const char *triplet_regexp,
-			  int argc, char **argv);
+  char *(*set_arguments_v0) (struct gcc_base_context *self,
+			     const char *triplet_regexp,
+			     int argc, char **argv);
 
   /* Set the file name of the program to compile.  The string is
      copied by the method implementation, but the caller must
@@ -125,6 +119,45 @@ struct gcc_base_vtable
 
   int /* bool */ (*compile) (struct gcc_base_context *self,
 			     const char *filename);
+
+  /* Set the compiler's command-line options for the next compilation.
+     The arguments are copied by GCC.  ARGV need not be
+     NULL-terminated.  The arguments must be set separately for each
+     compilation; that is, after a compile is requested, the
+     previously-set arguments cannot be reused.
+
+     This returns NULL on success.  On failure, returns a malloc()d
+     error message.  The caller is responsible for freeing it.
+
+     This method is only available since GCC_FE_VERSION_1.  */
+
+  char *(*set_arguments) (struct gcc_base_context *self,
+			  int argc, char **argv);
+
+  /* Set TRIPLET_REGEXP as a regular expression that is used to match
+     the configury triplet prefix to the compiler.  Calling this method
+     overrides possible previous call of itself or set_driver_filename.
+
+     This returns NULL on success.  On failure, returns a malloc()d
+     error message.  The caller is responsible for freeing it.
+
+     This method is only available since GCC_FE_VERSION_1.  */
+
+  char *(*set_triplet_regexp) (struct gcc_base_context *self,
+			       const char *triplet_regexp);
+
+  /* DRIVER_FILENAME should be filename of the gcc compiler driver
+     program.  It will be searched in PATH components like
+     TRIPLET_REGEXP.  Calling this method overrides possible previous
+     call of itself or set_triplet_regexp.
+
+     This returns NULL on success.  On failure, returns a malloc()d
+     error message.  The caller is responsible for freeing it.
+
+     This method is only available since GCC_FE_VERSION_1.  */
+
+  char *(*set_driver_filename) (struct gcc_base_context *self,
+				const char *driver_filename);
 };
 
 /* The GCC object.  */