Re: [PATCH] gcc.c: new macro POST_LINK_SPECS to be able to add additional steps after linking

[Andris Pavenis <andris dot pavenis at iki dot fi>]

On 11/10/2015 11:20 PM, Jeff Law wrote:
> On 11/10/2015 11:16 AM, Andris Pavenis wrote:
> > One may need to execute extra steps after linking program. This is required
> > for example for DJGPP to run stubify.exe on file generated by linker.
> >
> > The only way how to achieve was to use LINK_COMMAND_SPEC. It would be
> > much easier
> > and less error prone to use new macro POST_LINK_SPEC introduced in this
> > patch.
> >
> > Andris
> >
> > ChangeLog entry
> >
> > 2015 Nov 10 Andris Pavenis <andris.pavenis@iki.fi>
> >
> >      * gcc.c: new macro POST_LINK_SPEC
> >      * doc/tm.texi.in: document POST_LINK_SPEC
> >      * doc/tm.texi: regenerate
> Can you also include the changes to djgpp.h which exploit this capability?
>
> Jeff

OK. I'm only sending changes for djgpp.h. There are required changes to other files not included, 
so djgpp.h patch currently
to illustrate use of POST_LINK_SPEC only not committing.

In short:

- earlier entire LINK_COMMAND_SPEC was redefined in djgpp.h (copy/paste from trunk)

#undef LINK_COMMAND_SPEC
#define LINK_COMMAND_SPEC \
"%{!fsyntax-only: \
%{!c:%{!M:%{!MM:%{!E:%{!S:%(linker) %l " LINK_COMPRESS_DEBUG_SPEC \
"%X %{o*} %{e*} %{N} %{n} \
\t%{r} %{s} %{t} %{u*} %{z} %{Z}\
\t%{!nostdlib:%{!nostartfiles:%S}}\
\t%{static:} %{L*} %D %o\
\t%{!nostdlib:%{!nodefaultlibs:%G %L %G}}\
\t%{!nostdlib:%{!nostartfiles:%E}}\
\t-Tdjgpp.djl %{T*}}}}}}}\n\
%{!c:%{!M:%{!MM:%{!E:%{!S:stubify %{v} %{o*:%*} %{!o*:a.out} }}}}}"

One needed to update it each time when LINK_COMMAND_SPEC changes in gcc.c

- use of linker script djgpp.djl has actually done long ago (mentioned in comments for
LINK_COMMAND_SPEC override). The other reason: running stubify after linker has remain

- in new version I only need

#undef POST_LINK_SPEC
#define POST_LINK_SPEC "stubify %{v} %{o*:%*} %{!o*:a.out}"

instead, which is much simpler.

About DJGPP related changes accumulated in rather many years. There were changes to generic files 
which are highly
unlikely to be accepted (like use #ifdef __DJGPP__ in system independent files). I have to remove 
such ifdefs from
system independent files and re-implement it differently where possible. That will take some time 
and testing

Andris

diff --git a/gcc/config/i386/djgpp.h b/gcc/config/i386/djgpp.h
index f8b9031..f3033f7 100644
--- a/gcc/config/i386/djgpp.h
+++ b/gcc/config/i386/djgpp.h
@@ -17,12 +17,27 @@ You should have received a copy of the GNU General Public License
 along with GCC; see the file COPYING3.  If not see
 <http://www.gnu.org/licenses/>.  */
 
+#define DBX_DEBUGGING_INFO 1
+#define SDB_DEBUGGING_INFO 1
+
 /* Support generation of DWARF2 debugging info.  */
 #define DWARF2_DEBUGGING_INFO 1
 
+/* Use DWARF2 debugging info by default: comment out following  */
+/* 2 lines to default to COFF debugging info  */
+#undef PREFERRED_DEBUGGING_TYPE
+#define PREFERRED_DEBUGGING_TYPE DWARF2_DEBUG
+
 /* Don't assume anything about the header files.  */
 #define NO_IMPLICIT_EXTERN_C
 
+/* If defined, a C expression whose value is a string containing the
+   assembler operation to identify the following data as
+   uninitialized global data.  If not defined, and neither
+   `ASM_OUTPUT_BSS' nor `ASM_OUTPUT_ALIGNED_BSS' are defined,
+   uninitialized global data will be output in the data section if
+   `-fno-common' is passed, otherwise `ASM_OUTPUT_COMMON' will be
+   used.  */
 #undef BSS_SECTION_ASM_OP
 #define BSS_SECTION_ASM_OP "\t.section\t.bss"
 
@@ -30,6 +45,10 @@ along with GCC; see the file COPYING3.  If not see
 #undef DATA_SECTION_ASM_OP
 #define DATA_SECTION_ASM_OP "\t.section .data"
 
+/* Define the name of the .ident op.  */
+#undef TARGET_ASM_OUTPUT_IDENT
+#define TARGET_ASM_OUTPUT_IDENT default_asm_output_ident_directive
+
 /* Enable alias attribute support.  */
 #ifndef SET_ASM_OP
 #define SET_ASM_OP "\t.set\t"
@@ -39,56 +58,26 @@ along with GCC; see the file COPYING3.  If not see
 #undef TEXT_SECTION_ASM_OP
 #define TEXT_SECTION_ASM_OP "\t.section .text"
 
-/* Define standard DJGPP installation paths.  */
-/* We override default /usr or /usr/local part with /dev/env/DJDIR which */
-/* points to actual DJGPP installation directory.  */
-
-/* Search for as.exe and ld.exe in DJGPP's binary directory.  */ 
-#undef MD_EXEC_PREFIX
-#define MD_EXEC_PREFIX "/dev/env/DJDIR/bin/"
-
-/* Standard DJGPP library and startup files */
-#undef MD_STARTFILE_PREFIX
-#define MD_STARTFILE_PREFIX "/dev/env/DJDIR/lib/"
-
-/* Correctly handle absolute filename detection in cp/xref.c */
-#define FILE_NAME_ABSOLUTE_P(NAME) \
-        (((NAME)[0] == '/') || ((NAME)[0] == '\\') || \
-        (((NAME)[0] >= 'A') && ((NAME)[0] <= 'z') && ((NAME)[1] == ':')))
-
 #define TARGET_OS_CPP_BUILTINS()		\
   do						\
     {						\
+        if (!flag_iso)                          \
+	   builtin_define_with_int_value ("DJGPP",2);  \
+	builtin_define_with_int_value ("__DJGPP",2);   \
+	builtin_define_with_int_value ("__DJGPP__",2); \
 	builtin_define_std ("MSDOS");		\
 	builtin_define_std ("GO32");		\
+	builtin_define_std ("unix");		\
 	builtin_assert ("system=msdos");	\
     }						\
   while (0)
 
 /* Include <sys/version.h> so __DJGPP__ and __DJGPP_MINOR__ are defined.  */
 #undef CPP_SPEC
-#define CPP_SPEC "-remap %{posix:-D_POSIX_SOURCE} \
-  -imacros %s../include/sys/version.h"
-
-/* We need to override link_command_spec in gcc.c so support -Tdjgpp.djl.
-   This cannot be done in LINK_SPECS as that LINK_SPECS is processed
-   before library search directories are known by the linker.
-   This avoids problems when specs file is not available. An alternate way,
-   suggested by Robert Hoehne, is to use SUBTARGET_EXTRA_SPECS instead.
-*/ 
-
-#undef LINK_COMMAND_SPEC
-#define LINK_COMMAND_SPEC \
-"%{!fsyntax-only: \
-%{!c:%{!M:%{!MM:%{!E:%{!S:%(linker) %l " LINK_COMPRESS_DEBUG_SPEC \
-"%X %{o*} %{e*} %{N} %{n} \
-\t%{r} %{s} %{t} %{u*} %{z} %{Z}\
-\t%{!nostdlib:%{!nostartfiles:%S}}\
-\t%{static:} %{L*} %D %o\
-\t%{!nostdlib:%{!nodefaultlibs:%G %L %G}}\
-\t%{!nostdlib:%{!nostartfiles:%E}}\
-\t-Tdjgpp.djl %{T*}}}}}}}\n\
-%{!c:%{!M:%{!MM:%{!E:%{!S:stubify %{v} %{o*:%*} %{!o*:a.out} }}}}}"
+#define CPP_SPEC "-remap %{posix:-D_POSIX_SOURCE}"
+
+#undef POST_LINK_SPEC
+#define POST_LINK_SPEC "stubify %{v} %{o*:%*} %{!o*:a.out}"
 
 /* Always just link in 'libc.a'.  */
 #undef LIB_SPEC
@@ -98,12 +87,8 @@ along with GCC; see the file COPYING3.  If not see
 #undef STARTFILE_SPEC
 #define STARTFILE_SPEC "%{pg:gcrt0.o%s}%{!pg:crt0.o%s}"
 
-/* Make sure that gcc will not look for .h files in /usr/local/include 
-   unless user explicitly requests it.  */
-#undef LOCAL_INCLUDE_DIR
-
 /* Switch into a generic section.  */
-#define TARGET_ASM_NAMED_SECTION  default_coff_asm_named_section
+#define TARGET_ASM_NAMED_SECTION  i386_djgpp_asm_named_section
 
 /* This is how to output an assembler line
    that says to advance the location counter
@@ -129,7 +114,7 @@ along with GCC; see the file COPYING3.  If not see
   while (0)
 #endif
 
-/* This is how to tell assembler that a symbol is weak  */ 
+/* This is how to tell assembler that a symbol is weak  */
 #undef ASM_WEAKEN_LABEL
 #define ASM_WEAKEN_LABEL(FILE,NAME) \
   do { fputs ("\t.weak\t", FILE); assemble_name (FILE, NAME); \
@@ -159,23 +144,38 @@ along with GCC; see the file COPYING3.  If not see
 #undef PTRDIFF_TYPE
 #define PTRDIFF_TYPE "int"
 
-/* Used to be defined in xm-djgpp.h, but moved here for cross-compilers.  */
-#define LIBSTDCXX "stdcxx"
-
-/* Warn that -mbnu210 is now obsolete.  */
-#undef  SUBTARGET_OVERRIDE_OPTIONS
-#define SUBTARGET_OVERRIDE_OPTIONS \
-do \
-  { \
-    if (TARGET_BNU210) \
-      {	\
-        warning (0, "-mbnu210 is ignored (option is obsolete)"); \
-      }	\
-  } \
-while (0)
-
 /* Support for C++ templates.  */
 #undef MAKE_DECL_ONE_ONLY
 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
 
-#define IX86_MAYBE_NO_LIBGCC_TFMODE
+#undef DBX_REGISTER_NUMBER
+#define DBX_REGISTER_NUMBER(n) svr4_dbx_register_map[n]
+
+/* Default to pcc-struct-return.  */
+#define DEFAULT_PCC_STRUCT_RETURN 1
+
+/* Ignore (with warning) -fPIC for DJGPP */
+#undef SUBTARGET_OVERRIDE_OPTIONS
+#define SUBTARGET_OVERRIDE_OPTIONS                                      \
+    do {                                                                \
+        if (flag_pic)                                                   \
+        {                                                               \
+            fnotice(stdout, "-f%s ignored (not supported for DJGPP)\n", \
+                (flag_pic > 1) ? "PIC" : "pic");                        \
+            flag_pic = 0;                                               \
+        }                                                               \
+                                                                        \
+        /* Don't emit DWARF3/4 unless specifically selected. */         \
+        /* DWARF3/4 currently does not work for DJGPP.  */              \
+        if (!global_options_set.x_dwarf_version)                        \
+            dwarf_version = 2;                                          \
+                                                                        \
+        }                                                               \
+    while (0)
+
+/* Function protypes for gcc/i486/djgpp.c */
+
+void
+i386_djgpp_asm_named_section(const char *name, unsigned int flags,
+			     tree decl);
+