[PATCH 7/9] Add RTL-error-handling to host

[David Malcolm <dmalcolm@redhat.com>]

Link to previous discussion:
  https://gcc.gnu.org/ml/gcc-patches/2016-10/msg00648.html

On Mon, 2016-10-10 at 19:53 +0100, Richard Sandiford wrote:
> David Malcolm <dmalcolm@redhat.com> writes:
> > On Wed, 2016-10-05 at 18:00 +0200, Bernd Schmidt wrote:
> > > On 10/05/2016 06:15 PM, David Malcolm wrote:
> > > > 	* errors.c: Use consistent pattern for bconfig.h vs
> > > > config.h
> > > > 	includes.
> > > > 	(progname): Wrap with #ifdef GENERATOR_FILE.
> > > > 	(error): Likewise.  Add "error: " to message.
> > > > 	(fatal): Likewise.
> > > > 	(internal_error): Likewise.
> > > > 	(trim_filename): Likewise.
> > > > 	(fancy_abort): Likewise.
> > > > 	* errors.h (struct file_location): Move here from read
> > > > -md.h.
> > > > 	(file_location::file_location): Likewise.
> > > > 	(error_at): New decl.
> > >
> > > Can you split these out into a separate patch as well? I'll
> > > require
> > > more
> > > explanation for them and they seem largely independent.
> >
> > [CCing Richard Sandiford]
> >
> > The gen* tools have their own diagnostics system, in errors.c:
> >
> > /* warning, error, and fatal.  These definitions are suitable for
> > use
> >    in the generator programs; the compiler has a more elaborate
> > suite
> >    of diagnostic printers, found in diagnostic.c.  */
> >
> > with file locations tracked using read-md.h's struct file_location,
> > rather than location_t (aka libcpp's source_location).
> >
> > Implementing an RTL frontend by using the RTL reader from read
> > -rtl.c
> > means that we now need a diagnostics subsystem on the *host* for
> > handling errors in RTL files, rather than just on the build
> > machine.
> >
> > There seem to be two ways to do this:
> >
> >   (A) build the "light" diagnostics system (errors.c) for the host
> > as
> > well as build machine, and link it with the RTL reader there, so
> > there
> > are two parallel diagnostics subsystems.
> >
> >   (B) build the "real" diagnostics system (diagnostics*) for the
> > *build* machine as well as the host, and use it from the gen*
> > tools,
> > eliminating the "light" system, and porting the gen* tools to use
> > libcpp for location tracking.
> >
> > Approach (A) seems to be simpler, which is what this part of the
> > patch
> > does.
> >
> > I've experimented with approach (B).  I think it's doable, but it's
> > much more invasive (perhaps needing a libdiagnostics.a and a
> > build/libdiagnostics.a in gcc/Makefile.in), so I hope this can be
> > followup work.
> >
> > I can split the relevant parts out into a separate patch, but I was
> > wondering if either of you had a strong opinion on (A) vs (B)
> > before I
> > do so?
>
> (A) sounds fine to me FWIW.  And sorry for the slow reply.
>
> Thanks,
> Richard

This patch implements approach (A).

It updates the error messages to contain "error: " so that they can
be handled by DejaGnu.

It also adds an "error_at" function to the "light" API.  Doing so requires
moving the decl of struct file_location to errors.h.

gcc/ChangeLog:
	* Makefile.in (OBJS): Add errors.o.
	* errors.c: Use consistent pattern for bconfig.h vs config.h
	includes.
	(progname): Wrap with #ifdef GENERATOR_FILE.
	(error): Likewise.  Add "error: " to message.
	(fatal): Likewise.
	(internal_error): Likewise.
	(trim_filename): Likewise.
	(fancy_abort): Likewise.
	* errors.h (struct file_location): Move here from read-md.h.
	(file_location::file_location): Likewise.
	(error_at): New decl.
	* read-md.h (struct file_location): Move to errors.h.
	(file_location::file_location): Likewise.
	Include errors.h.
---
 gcc/Makefile.in |  1 +
 gcc/errors.c    | 23 +++++++++++++++++------
 gcc/errors.h    | 14 ++++++++++++++
 gcc/read-md.h   | 14 +-------------
 4 files changed, 33 insertions(+), 19 deletions(-)

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index fa54215..c265893 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -1266,6 +1266,7 @@ OBJS = \
 	dwarf2cfi.o \
 	dwarf2out.o \
 	emit-rtl.o \
+	errors.o \
 	et-forest.o \
 	except.o \
 	explow.o \
diff --git a/gcc/errors.c b/gcc/errors.c
index 468384c..8df94ab 100644
--- a/gcc/errors.c
+++ b/gcc/errors.c
@@ -21,18 +21,21 @@ along with GCC; see the file COPYING3.  If not see
    in the generator programs; the compiler has a more elaborate suite
    of diagnostic printers, found in diagnostic.c.  */
 
-#ifdef HOST_GENERATOR_FILE
-#include "config.h"
-#define GENERATOR_FILE 1
-#else
+/* This file is compiled twice: once for the generator programs
+   once for the compiler.  */
+#ifdef GENERATOR_FILE
 #include "bconfig.h"
+#else
+#include "config.h"
 #endif
 #include "system.h"
 #include "errors.h"
 
 /* Set this to argv[0] at the beginning of main.  */
 
+#ifdef GENERATOR_FILE
 const char *progname;
+#endif /* #ifdef GENERATOR_FILE */
 
 /* Starts out 0, set to 1 if error is called.  */
 
@@ -55,13 +58,15 @@ warning (const char *format, ...)
 
 /* Print an error message - we keep going but the output is unusable.  */
 
+#ifdef GENERATOR_FILE
+
 void
 error (const char *format, ...)
 {
   va_list ap;
 
   va_start (ap, format);
-  fprintf (stderr, "%s: ", progname);
+  fprintf (stderr, "%s: error: ", progname);
   vfprintf (stderr, format, ap);
   va_end (ap);
   fputc ('\n', stderr);
@@ -69,6 +74,7 @@ error (const char *format, ...)
   have_error = 1;
 }
 
+#endif /* #ifdef GENERATOR_FILE */
 
 /* Fatal error - terminate execution immediately.  Does not return.  */
 
@@ -78,7 +84,7 @@ fatal (const char *format, ...)
   va_list ap;
 
   va_start (ap, format);
-  fprintf (stderr, "%s: ", progname);
+  fprintf (stderr, "%s: error: ", progname);
   vfprintf (stderr, format, ap);
   va_end (ap);
   fputc ('\n', stderr);
@@ -87,6 +93,8 @@ fatal (const char *format, ...)
 
 /* Similar, but say we got an internal error.  */
 
+#ifdef GENERATOR_FILE
+
 void
 internal_error (const char *format, ...)
 {
@@ -127,8 +135,11 @@ trim_filename (const char *name)
 /* "Fancy" abort.  Reports where in the compiler someone gave up.
    This file is used only by build programs, so we're not as polite as
    the version in diagnostic.c.  */
+
 void
 fancy_abort (const char *file, int line, const char *func)
 {
   internal_error ("abort in %s, at %s:%d", func, trim_filename (file), line);
 }
+
+#endif /* #ifdef GENERATOR_FILE */
diff --git a/gcc/errors.h b/gcc/errors.h
index a6973f3..ebafa77 100644
--- a/gcc/errors.h
+++ b/gcc/errors.h
@@ -28,8 +28,22 @@ along with GCC; see the file COPYING3.  If not see
 #ifndef GCC_ERRORS_H
 #define GCC_ERRORS_H
 
+/* Records a position in the file.  */
+struct file_location {
+  file_location () {}
+  file_location (const char *, int, int);
+
+  const char *filename;
+  int lineno;
+  int colno;
+};
+
+inline file_location::file_location (const char *filename_in, int lineno_in, int colno_in)
+: filename (filename_in), lineno (lineno_in), colno (colno_in) {}
+
 extern void warning (const char *, ...) ATTRIBUTE_PRINTF_1 ATTRIBUTE_COLD;
 extern void error (const char *, ...) ATTRIBUTE_PRINTF_1 ATTRIBUTE_COLD;
+extern void error_at (file_location, const char *, ...) ATTRIBUTE_PRINTF_2 ATTRIBUTE_COLD;
 extern void fatal (const char *, ...) ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF_1 ATTRIBUTE_COLD;
 extern void internal_error (const char *, ...) ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF_1 ATTRIBUTE_COLD;
 extern const char *trim_filename (const char *);
diff --git a/gcc/read-md.h b/gcc/read-md.h
index 27fc9c2..8910b75 100644
--- a/gcc/read-md.h
+++ b/gcc/read-md.h
@@ -21,19 +21,7 @@ along with GCC; see the file COPYING3.  If not see
 #define GCC_READ_MD_H
 
 #include "obstack.h"
-
-/* Records a position in the file.  */
-struct file_location {
-  file_location () {}
-  file_location (const char *, int, int);
-
-  const char *filename;
-  int lineno;
-  int colno;
-};
-
-inline file_location::file_location (const char *filename_in, int lineno_in, int colno_in)
-: filename (filename_in), lineno (lineno_in), colno (colno_in) {}
+#include "errors.h"
 
 /* Holds one symbol or number in the .md file.  */
 struct md_name {
-- 
1.8.5.3