Re: [PATCH v3] Add configure flag to enable gnu hash style by default.

[Alan Modra <amodra at gmail dot com>]

On Wed, Jul 19, 2017 at 01:03:45PM +0000, Romain Geissler wrote:
> This is the third version of my hash style changes.
> 
> Changes since v2:
>  - Use by default "both" hash style for targets *-*-gnu*, *-*-linux*, and *-*-nacl*, and "sysv" otherwise.

This is what I'm about to check in.  mips is removed from targets
defaulting to hash-style=both since I believe mips must be
--hash-style=sysv.  The other thing I've changed is to not set
--hash-style=sysv globally for running the ld testsuite.

ld/
	* configure.ac: Add --enable-default-hash-style option.
	* ldmain.c (main): Set link_info.emit_hash to DEFAULT_EMIT_SYSV_HASH.
	Set link_info.emit_gnu_hash to DEFAULT_EMIT_GNU_HASH.
	* configure: Regenerate.
	* config.in: Regenerate.

gold/
	* configure.ac: Add --enable-default-hash-style option.
	* options.h (hash_style): Use DEFAULT_HASH_STYLE as default value.
	* configure: Regenerate.
	* config.in: Regenerate.

diff --git a/gold/configure.ac b/gold/configure.ac
index cbe3380..d7fa1f8 100644
--- a/gold/configure.ac
+++ b/gold/configure.ac
@@ -161,6 +161,26 @@ if test -n "$enable_targets"; then
   done
 fi
 
+# Decide which "--hash-style" to use by default
+# Provide a configure time option to override our default.
+AC_ARG_ENABLE([default-hash-style],
+AS_HELP_STRING([--enable-default-hash-style={sysv,gnu,both}],
+	       [use this default hash style]),
+[case "${enable_default_hash_style}" in
+  sysv | gnu | both) ;;
+  *) AC_MSG_ERROR([bad value ${enable_default_hash_style} for enable-default-hash-style option]) ;;
+esac],
+[case "${target}" in
+  # Enable gnu hash only on GNU targets, but not mips
+  mips*-*-*) enable_default_hash_style=sysv ;;
+  *-*-gnu* | *-*-linux* | *-*-nacl*) enable_default_hash_style=both ;;
+  *) enable_default_hash_style=sysv ;;
+esac])
+
+AC_DEFINE_UNQUOTED([DEFAULT_HASH_STYLE],
+  ["${enable_default_hash_style}"],
+  [Set the default --hash-style value])
+
 # See which specific instantiations we need.
 targetobjs=
 all_targets=
diff --git a/gold/options.h b/gold/options.h
index 6b45f64..970e76f 100644
--- a/gold/options.h
+++ b/gold/options.h
@@ -925,7 +925,7 @@ class General_options
 		N_("Min fraction of empty buckets in dynamic hash"),
 		N_("FRACTION"));
 
-  DEFINE_enum(hash_style, options::TWO_DASHES, '\0', "sysv",
+  DEFINE_enum(hash_style, options::TWO_DASHES, '\0', DEFAULT_HASH_STYLE,
 	      N_("Dynamic hash style"), N_("[sysv,gnu,both]"),
 	      {"sysv", "gnu", "both"});
 
diff --git a/ld/configure.ac b/ld/configure.ac
index ffe8018..99d127b 100644
--- a/ld/configure.ac
+++ b/ld/configure.ac
@@ -177,6 +177,32 @@ AC_ARG_ENABLE(relro,
   no)  ac_default_ld_z_relro=0 ;;
 esac])dnl
 
+# Decide which "--hash-style" to use by default
+# Provide a configure time option to override our default.
+AC_ARG_ENABLE([default-hash-style],
+AS_HELP_STRING([--enable-default-hash-style={sysv,gnu,both}],
+	       [use this default hash style]),
+[case "${enable_default_hash_style}" in
+  sysv | gnu | both) ;;
+  *) AC_MSG_ERROR([bad value ${enable_default_hash_style} for enable-default-hash-style option]) ;;
+esac],
+[case "${target}" in
+  # Enable gnu hash only on GNU targets, but not mips
+  mips*-*-*) enable_default_hash_style=sysv ;;
+  *-*-gnu* | *-*-linux* | *-*-nacl*) enable_default_hash_style=both ;;
+  *) enable_default_hash_style=sysv ;;
+esac])
+
+case "${enable_default_hash_style}" in
+  sysv | both) ac_default_emit_sysv_hash=1 ;;
+  *) ac_default_emit_sysv_hash=0 ;;
+esac
+
+case "${enable_default_hash_style}" in
+  gnu | both) ac_default_emit_gnu_hash=1 ;;
+  *) ac_default_emit_gnu_hash=0 ;;
+esac
+
 AM_BINUTILS_WARNINGS
 
 AM_LC_MESSAGES
@@ -408,6 +434,14 @@ AC_DEFINE_UNQUOTED(DEFAULT_LD_Z_RELRO,
   $ac_default_ld_z_relro,
   [Define to 1 if you want to enable -z relro in ELF linker by default.])
 
+AC_DEFINE_UNQUOTED([DEFAULT_EMIT_SYSV_HASH],
+  [$ac_default_emit_sysv_hash],
+  [Define to 1 if you want to emit sysv hash in the ELF linker by default.])
+
+AC_DEFINE_UNQUOTED([DEFAULT_EMIT_GNU_HASH],
+  [$ac_default_emit_gnu_hash],
+  [Define to 1 if you want to emit gnu hash in the ELF linker by default.])
+
 AC_SUBST(elf_list_options)
 AC_SUBST(elf_shlib_list_options)
 AC_SUBST(elf_plt_unwind_list_options)
diff --git a/ld/ldmain.c b/ld/ldmain.c
index cb1e2d1..2b09f20 100644
--- a/ld/ldmain.c
+++ b/ld/ldmain.c
@@ -273,7 +273,8 @@ main (int argc, char **argv)
   link_info.keep_memory = TRUE;
   link_info.combreloc = TRUE;
   link_info.strip_discarded = TRUE;
-  link_info.emit_hash = TRUE;
+  link_info.emit_hash = DEFAULT_EMIT_SYSV_HASH;
+  link_info.emit_gnu_hash = DEFAULT_EMIT_GNU_HASH;
   link_info.callbacks = &link_callbacks;
   link_info.input_bfds_tail = &link_info.input_bfds;
   /* SVR4 linkers seem to set DT_INIT and DT_FINI based on magic _init

-- 
Alan Modra
Australia Development Lab, IBM