libctf, elfcpp, gold: do not assume that <byteswap.h> contains bswap_*

At least one C library (uclibc-ng) defines some of these only when
the compiler is GCC.  We might as well test for all three cases and
handle any of them being missing.

Very similar code exists in libctf and split between elfcpp and gold:
fix both.

(Also sync up elfcpp with a change made to libctf swap.h a few months
ago: since there is no out-of-line definition of the bswap replacements,
they should be declared static inline, not just inline, to prevent the
linker generating out-of-line references to them.)

	PR libctf/25120
libctf/
	* configure.ac: Check for bswap_16, bswap_32, and bswap_64 decls.
	* swap.h (bswap_16): Do not assume that presence of <byteswap.h>
	means this is declared.
	(bswap_32): Likewise.
	(bswap_64): Likewise.
	(bswap_identity_64): Remove, unused.
	* configure: Regenerated.
	* config.h.in: Likewise.
gold/
	* configure.ac: Check for bswap_16, bswap_32, and bswap_64 decls.
	* configure: Regenerated.
	* config.h.in: Likewise.
elfcpp/
	* elfcpp_swap.h (bswap_16): Do not assume that presence of
	<byteswap.h> means this is declared.  Make static inline, matching
	recent change to libctf, since there is no non-inline definition
	of these functions.
	(bswap_32): Likewise.
	(bswap_64): Likewise.

11 files changed, 190 insertions, 59 deletions

diff --git a/elfcpp/ChangeLog b/elfcpp/ChangeLog
index dc37f65..ee6db3a 100644
--- a/elfcpp/ChangeLog
+++ b/elfcpp/ChangeLog
@@ -1,3 +1,12 @@
+2020-06-26  Nick Alcock  <nick.alcock@oracle.com>
+
+	* elfcpp_swap.h (bswap_16): Do not assume that presence of
+	<byteswap.h> means this is declared.  Make static inline, matching
+	recent change to libctf, since there is no non-inline definition
+	of these functions.
+	(bswap_32): Likewise.
+	(bswap_64): Likewise.
+
 2020-06-18  Fangrui Song  <i@maskray.me>
 
 	PR gold/26039
diff --git a/elfcpp/elfcpp_swap.h b/elfcpp/elfcpp_swap.h
index 3c9d259..61b3ba5 100644
--- a/elfcpp/elfcpp_swap.h
+++ b/elfcpp/elfcpp_swap.h
@@ -46,15 +46,19 @@
 
 #ifdef HAVE_BYTESWAP_H
 #include <byteswap.h>
-#else
+#endif // defined(HAVE_BYTESWAP_H)
+
 // Provide our own versions of the byteswap functions.
-inline uint16_t
+#if !HAVE_DECL_BSWAP_16
+static inline uint16_t
 bswap_16(uint16_t v)
 {
   return ((v >> 8) & 0xff) | ((v & 0xff) << 8);
 }
+#endif // !HAVE_DECL_BSWAP16
 
-inline uint32_t
+#if !HAVE_DECL_BSWAP_32
+static inline uint32_t
 bswap_32(uint32_t v)
 {
   return (  ((v & 0xff000000) >> 24)
@@ -62,8 +66,10 @@ bswap_32(uint32_t v)
 	  | ((v & 0x0000ff00) <<  8)
 	  | ((v & 0x000000ff) << 24));
 }
+#endif // !HAVE_DECL_BSWAP32
 
-inline uint64_t
+#if !HAVE_DECL_BSWAP_64
+static inline uint64_t
 bswap_64(uint64_t v)
 {
   return (  ((v & 0xff00000000000000ULL) >> 56)
@@ -75,7 +81,7 @@ bswap_64(uint64_t v)
 	  | ((v & 0x000000000000ff00ULL) << 40)
 	  | ((v & 0x00000000000000ffULL) << 56));
 }
-#endif // !defined(HAVE_BYTESWAP_H)
+#endif // !HAVE_DECL_BSWAP64
 
 // gcc 4.3 and later provides __builtin_bswap32 and __builtin_bswap64.
 
diff --git a/gold/ChangeLog b/gold/ChangeLog
index 78b5579..9e06ff8 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,9 @@
+2020-06-26  Nick Alcock  <nick.alcock@oracle.com>
+
+	* configure.ac: Check for bswap_16, bswap_32, and bswap_64 decls.
+	* configure: Regenerated.
+	* config.h.in: Likewise.
+
 2020-06-24  Nick Clifton  <nickc@redhat.com>
 
 	* target-reloc.h (issue_discarded_error): Initialise the
diff --git a/gold/config.in b/gold/config.in
index 7bac34a..aaad1be 100644
--- a/gold/config.in
+++ b/gold/config.in
@@ -52,6 +52,18 @@
    don't. */
 #undef HAVE_DECL_BASENAME
 
+/* Define to 1 if you have the declaration of `bswap_16', and to 0 if you
+   don't. */
+#undef HAVE_DECL_BSWAP_16
+
+/* Define to 1 if you have the declaration of `bswap_32', and to 0 if you
+   don't. */
+#undef HAVE_DECL_BSWAP_32
+
+/* Define to 1 if you have the declaration of `bswap_64', and to 0 if you
+   don't. */
+#undef HAVE_DECL_BSWAP_64
+
 /* Define to 1 if you have the declaration of `ffs', and to 0 if you don't. */
 #undef HAVE_DECL_FFS
 
diff --git a/gold/configure b/gold/configure
index 474c69a..199a739 100755
--- a/gold/configure
+++ b/gold/configure
@@ -2167,6 +2167,52 @@ fi
 
 } # ac_fn_cxx_check_header_mongrel
 
+# ac_fn_cxx_check_decl LINENO SYMBOL VAR INCLUDES
+# -----------------------------------------------
+# Tests whether SYMBOL is declared in INCLUDES, setting cache variable VAR
+# accordingly.
+ac_fn_cxx_check_decl ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  as_decl_name=`echo $2|sed 's/ *(.*//'`
+  as_decl_use=`echo $2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $as_decl_name is declared" >&5
+$as_echo_n "checking whether $as_decl_name is declared... " >&6; }
+if eval \${$3+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+$4
+int
+main ()
+{
+#ifndef $as_decl_name
+#ifdef __cplusplus
+  (void) $as_decl_use;
+#else
+  (void) $as_decl_name;
+#endif
+#endif
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  eval "$3=yes"
+else
+  eval "$3=no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+eval ac_res=\$$3
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
+
+} # ac_fn_cxx_check_decl
+
 # ac_fn_cxx_try_link LINENO
 # -------------------------
 # Try to link conftest.$ac_ext, and return whether this succeeded.
@@ -2279,52 +2325,6 @@ $as_echo "$ac_res" >&6; }
   eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
 
 } # ac_fn_cxx_check_func
-
-# ac_fn_cxx_check_decl LINENO SYMBOL VAR INCLUDES
-# -----------------------------------------------
-# Tests whether SYMBOL is declared in INCLUDES, setting cache variable VAR
-# accordingly.
-ac_fn_cxx_check_decl ()
-{
-  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
-  as_decl_name=`echo $2|sed 's/ *(.*//'`
-  as_decl_use=`echo $2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $as_decl_name is declared" >&5
-$as_echo_n "checking whether $as_decl_name is declared... " >&6; }
-if eval \${$3+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-$4
-int
-main ()
-{
-#ifndef $as_decl_name
-#ifdef __cplusplus
-  (void) $as_decl_use;
-#else
-  (void) $as_decl_name;
-#endif
-#endif
-
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_cxx_try_compile "$LINENO"; then :
-  eval "$3=yes"
-else
-  eval "$3=no"
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-fi
-eval ac_res=\$$3
-	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-$as_echo "$ac_res" >&6; }
-  eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
-
-} # ac_fn_cxx_check_decl
 cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
@@ -9780,6 +9780,41 @@ fi
 done
 
 
+ac_fn_cxx_check_decl "$LINENO" "bswap_16" "ac_cv_have_decl_bswap_16" "#include <byteswap.h>
+"
+if test "x$ac_cv_have_decl_bswap_16" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_BSWAP_16 $ac_have_decl
+_ACEOF
+ac_fn_cxx_check_decl "$LINENO" "bswap_32" "ac_cv_have_decl_bswap_32" "#include <byteswap.h>
+"
+if test "x$ac_cv_have_decl_bswap_32" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_BSWAP_32 $ac_have_decl
+_ACEOF
+ac_fn_cxx_check_decl "$LINENO" "bswap_64" "ac_cv_have_decl_bswap_64" "#include <byteswap.h>
+"
+if test "x$ac_cv_have_decl_bswap_64" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_BSWAP_64 $ac_have_decl
+_ACEOF
+
+
 for ac_header in windows.h
 do :
   ac_fn_cxx_check_header_mongrel "$LINENO" "windows.h" "ac_cv_header_windows_h" "$ac_includes_default"
diff --git a/gold/configure.ac b/gold/configure.ac
index c4c93a0..eca4f01 100644
--- a/gold/configure.ac
+++ b/gold/configure.ac
@@ -602,6 +602,9 @@ AC_CHECK_HEADERS(tr1/unordered_set tr1/unordered_map)
 AC_CHECK_HEADERS(ext/hash_map ext/hash_set)
 AC_CHECK_HEADERS(byteswap.h)
 
+dnl Check for bswap_{16,32,64}
+AC_CHECK_DECLS([bswap_16, bswap_32, bswap_64], [], [], [[#include <byteswap.h>]])
+
 dnl When plugins enabled dynamic loader interface is required. Check headers
 dnl which may provide this interface. Add the necessary library to link.
 AC_CHECK_HEADERS(windows.h)
diff --git a/libctf/ChangeLog b/libctf/ChangeLog
index a8217fa..743237e 100644
--- a/libctf/ChangeLog
+++ b/libctf/ChangeLog
@@ -1,6 +1,18 @@
 2020-06-26  Nick Alcock  <nick.alcock@oracle.com>
 
 	PR libctf/25120
+	* configure.ac: Check for bswap_16, bswap_32, and bswap_64 decls.
+	* swap.h (bswap_16): Do not assume that presence of <byteswap.h>
+	means this is declared.
+	(bswap_32): Likewise.
+	(bswap_64): Likewise.
+	(bswap_identity_64): Remove, unused.
+	* configure: Regenerated.
+	* config.h.in: Likewise.
+
+2020-06-26  Nick Alcock  <nick.alcock@oracle.com>
+
+	PR libctf/25120
 	* ctf-impl.h (_libctf_printflike_): Add non-GNU-C fallback.
 	(_libctf_unlikely_): Likewise.
 	(_libctf_unused): Likewise.
diff --git a/libctf/config.h.in b/libctf/config.h.in
index 264cbc3..ac0eb3e 100644
--- a/libctf/config.h.in
+++ b/libctf/config.h.in
@@ -13,6 +13,18 @@
    don't. */
 #undef HAVE_DECL_ASPRINTF
 
+/* Define to 1 if you have the declaration of `bswap_16', and to 0 if you
+   don't. */
+#undef HAVE_DECL_BSWAP_16
+
+/* Define to 1 if you have the declaration of `bswap_32', and to 0 if you
+   don't. */
+#undef HAVE_DECL_BSWAP_32
+
+/* Define to 1 if you have the declaration of `bswap_64', and to 0 if you
+   don't. */
+#undef HAVE_DECL_BSWAP_64
+
 /* Define to 1 if you have the <dlfcn.h> header file. */
 #undef HAVE_DLFCN_H
 
diff --git a/libctf/configure b/libctf/configure
index e5493b3..58263e5 100755
--- a/libctf/configure
+++ b/libctf/configure
@@ -13028,6 +13028,40 @@ cat >>confdefs.h <<_ACEOF
 #define HAVE_DECL_ASPRINTF $ac_have_decl
 _ACEOF
 
+ac_fn_c_check_decl "$LINENO" "bswap_16" "ac_cv_have_decl_bswap_16" "#include <byteswap.h>
+"
+if test "x$ac_cv_have_decl_bswap_16" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_BSWAP_16 $ac_have_decl
+_ACEOF
+ac_fn_c_check_decl "$LINENO" "bswap_32" "ac_cv_have_decl_bswap_32" "#include <byteswap.h>
+"
+if test "x$ac_cv_have_decl_bswap_32" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_BSWAP_32 $ac_have_decl
+_ACEOF
+ac_fn_c_check_decl "$LINENO" "bswap_64" "ac_cv_have_decl_bswap_64" "#include <byteswap.h>
+"
+if test "x$ac_cv_have_decl_bswap_64" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_BSWAP_64 $ac_have_decl
+_ACEOF
+
 
 
 
diff --git a/libctf/configure.ac b/libctf/configure.ac
index 7f2a713..f7e0cac 100644
--- a/libctf/configure.ac
+++ b/libctf/configure.ac
@@ -100,6 +100,8 @@ AC_CHECK_HEADERS(byteswap.h endian.h)
 AC_CHECK_FUNCS(pread)
 
 AC_CHECK_DECLS([asprintf])
+dnl Check for bswap_{16,32,64}
+AC_CHECK_DECLS([bswap_16, bswap_32, bswap_64], [], [], [[#include <byteswap.h>]])
 
 dnl Check for qsort_r.  (Taken from gnulib.)
 AC_CHECK_FUNCS_ONCE([qsort_r])
diff --git a/libctf/swap.h b/libctf/swap.h
index d526f7e..c8962a2 100644
--- a/libctf/swap.h
+++ b/libctf/swap.h
@@ -25,15 +25,19 @@
 
 #ifdef HAVE_BYTESWAP_H
 #include <byteswap.h>
-#else
+#endif /* defined(HAVE_BYTESWAP_H) */
 
 /* Provide our own versions of the byteswap functions.  */
+
+#if !HAVE_DECL_BSWAP_16
 static inline uint16_t
 bswap_16 (uint16_t v)
 {
   return ((v >> 8) & 0xff) | ((v & 0xff) << 8);
 }
+#endif /* !HAVE_DECL_BSWAP16 */
 
+#if !HAVE_DECL_BSWAP_32
 static inline uint32_t
 bswap_32 (uint32_t v)
 {
@@ -42,13 +46,9 @@ bswap_32 (uint32_t v)
 	  | ((v & 0x0000ff00) <<  8)
 	  | ((v & 0x000000ff) << 24));
 }
+#endif /* !HAVE_DECL_BSWAP32 */
 
-static inline uint64_t
-bswap_identity_64 (uint64_t v)
-{
-  return v;
-}
-
+#if !HAVE_DECL_BSWAP_64
 static inline uint64_t
 bswap_64 (uint64_t v)
 {
@@ -61,6 +61,6 @@ bswap_64 (uint64_t v)
 	  | ((v & 0x000000000000ff00ULL) << 40)
 	  | ((v & 0x00000000000000ffULL) << 56));
 }
-#endif /* !defined(HAVE_BYTESWAP_H) */
+#endif /* !HAVE_DECL_BSWAP64 */
 
 #endif /* !defined(_CTF_SWAP_H) */