Create and use first-versions.h with macros for function symbol versions.

This patch arranges for the glibc build to generate a header
first-versions.h that defines macros for the earliest symbol version
in which each public symbol (GLIBC_[0-9]* symbol version, name only
uses C identifier characters) is available.

This is used in sysdeps/ieee754/ldbl-opt/math-type-macros-double.h to
replace the manually defined LDOUBLE_*_libm_version macros for various
functions defined using type-generic templates, the purpose of which
is to use in LONG_DOUBLE_COMPAT tests "was this function originally
added before glibc supported long double != double on this platform?".
As discussed in
<https://sourceware.org/ml/libc-alpha/2016-12/msg00246.html>, I expect
this to be useful more generally in reducing the amount of
special-case code needed in ldbl-opt and ldbl-64-128.

Tested with build-many-glibcs.py that installed stripped shared
libraries are unchanged by this patch.

	* scripts/versions.awk: Generate first-versions.h.
	* sysdeps/ieee754/ldbl-opt/math-type-macros-double.h: Include
	<first-versions.h>.
	(LDOUBLE_cabsl_libm_version): Remove macro.
	(LDOUBLE_cargl_libm_version): Likewise.
	(LDOUBLE_cimagl_libm_version): Likewise.
	(LDOUBLE_conjl_libm_version): Likewise.
	(LDOUBLE_creall_libm_version): Likewise.
	(LDOUBLE_cacosl_libm_version): Likewise.
	(LDOUBLE_cacoshl_libm_version): Likewise.
	(LDOUBLE_ccosl_libm_version): Likewise.
	(LDOUBLE_ccoshl_libm_version): Likewise.
	(LDOUBLE_casinl_libm_version): Likewise.
	(LDOUBLE_csinl_libm_version): Likewise.
	(LDOUBLE_casinhl_libm_version): Likewise.
	(LDOUBLE_csinhl_libm_version): Likewise.
	(LDOUBLE_catanl_libm_version): Likewise.
	(LDOUBLE_catanhl_libm_version): Likewise.
	(LDOUBLE_ctanl_libm_version): Likewise.
	(LDOUBLE_ctanhl_libm_version): Likewise.
	(LDOUBLE_cexpl_libm_version): Likewise.
	(LDOUBLE_clogl_libm_version): Likewise.
	(LDOUBLE_cprojl_libm_version): Likewise.
	(LDOUBLE_csqrtl_libm_version): Likewise.
	(LDOUBLE_cpowl_libm_version): Likewise.
	(LDOUBLE_clog10l_libm_version): Likewise.
	(LDOUBLE___clog10l_libm_version): Likewise.
	(LDOUBLE_fdiml_libm_version): Likewise.
	(LDOUBLE_fmaxl_libm_version): Likewise.
	(LDOUBLE_fminl_libm_version): Likewise.
	(LDOUBLE_ilogbl_libm_version): Likewise.
	(LDOUBLE_nanl_libm_version): Likewise.
	[!M_LIBM_NEED_COMPAT] (M_LIBM_NEED_COMPAT): Use
	FIRST_VERSION_libm_* macros.
	[!declare_mgen_libm_compat] (declare_mgen_libm_compat): Likewise.
	* Makerules [$(build-shared) = yes && !avoid-generated]
	(before-compile): Add $(common-objpfx)first-versions.h.
	[$(build-shared) = yes && !avoid-generated]
	($(common-objpfx)first-versions.h): New target.
	($(common-objpfx)sysd-versions): Depend on and change to rule for
	building $(common-objpfx)versions.stmp.

1 files changed, 17 insertions, 0 deletions

diff --git a/scripts/versions.awk b/scripts/versions.awk
index df33529e59..df08d06816 100644
--- a/scripts/versions.awk
+++ b/scripts/versions.awk
@@ -101,6 +101,10 @@ END {
 
   oldlib = "";
   oldver = "";
+  real_first_ver_header = buildroot "first-versions.h"
+  first_ver_header = real_first_ver_header "T"
+  printf("#ifndef _FIRST_VERSIONS_H\n") > first_ver_header;
+  printf("#define _FIRST_VERSIONS_H\n") > first_ver_header;
   printf("version-maps =");
   while (getline < tmpfile) {
     if ($1 != oldlib) {
@@ -127,11 +131,24 @@ END {
     printf("   ") > outfile;
     for (n = 3; n <= NF; ++n) {
       printf(" %s", $n) > outfile;
+      sym = $n;
+      sub(";", "", sym);
+      first_ver_macro = "FIRST_VERSION_" oldlib "_" sym;
+      if (!(first_ver_macro in first_ver_seen) \
+	  && oldver ~ "^GLIBC_[0-9]" \
+	  && sym ~ "^[A-Za-z0-9_]*$") {
+	ver_val = oldver;
+	gsub("\\.", "_", ver_val);
+	printf("#define %s %s\n", first_ver_macro, ver_val) > first_ver_header;
+	first_ver_seen[first_ver_macro] = 1;
+      }
     }
     printf("\n") > outfile;
   }
   printf("\n");
+  printf("#endif /* first-versions.h */\n") > first_ver_header;
   closeversion(oldver, veryoldver);
   close_and_move(outfile, real_outfile);
+  close_and_move(first_ver_header, real_first_ver_header);
   #system("rm -f " tmpfile);
 }