lto-plugin: use locking only for selected targets

For now, support locking only for linux targets that are different from
riscv* where the target depends on libatomic (and fails during
bootstrap).

	PR lto/106170

lto-plugin/ChangeLog:

	* configure.ac: Configure HAVE_PTHREAD_LOCKING.
	* lto-plugin.c (LOCK_SECTION): New.
	(UNLOCK_SECTION): New.
	(claim_file_handler): Use the newly added macros.
	(onload): Likewise.
	* config.h.in: Regenerate.
	* configure: Regenerate.

4 files changed, 53 insertions, 18 deletions

diff --git a/lto-plugin/config.h.in b/lto-plugin/config.h.in
index 029e782..8eb9c8a 100644
--- a/lto-plugin/config.h.in
+++ b/lto-plugin/config.h.in
@@ -9,8 +9,8 @@
 /* Define to 1 if you have the <memory.h> header file. */
 #undef HAVE_MEMORY_H
 
-/* Define to 1 if pthread.h is present. */
-#undef HAVE_PTHREAD_H
+/* Define if the system provides pthread locking mechanism. */
+#undef HAVE_PTHREAD_LOCKING
 
 /* Define to 1 if you have the <stdint.h> header file. */
 #undef HAVE_STDINT_H
diff --git a/lto-plugin/configure b/lto-plugin/configure
index aaa91a6..870e49b 100755
--- a/lto-plugin/configure
+++ b/lto-plugin/configure
@@ -6011,14 +6011,27 @@ fi
 
 
 # Check for thread headers.
-ac_fn_c_check_header_mongrel "$LINENO" "pthread.h" "ac_cv_header_pthread_h" "$ac_includes_default"
+use_locking=no
+
+case $target in
+  riscv*)
+    # do not use locking as pthread depends on libatomic
+    ;;
+  *-linux*)
+    use_locking=yes
+    ;;
+esac
+
+if test x$use_locking = xyes; then
+  ac_fn_c_check_header_mongrel "$LINENO" "pthread.h" "ac_cv_header_pthread_h" "$ac_includes_default"
 if test "x$ac_cv_header_pthread_h" = xyes; then :
 
-$as_echo "#define HAVE_PTHREAD_H 1" >>confdefs.h
+$as_echo "#define HAVE_PTHREAD_LOCKING 1" >>confdefs.h
 
 fi
 
 
+fi
 
 case `pwd` in
   *\ * | *\	*)
@@ -12091,7 +12104,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12094 "configure"
+#line 12107 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12197,7 +12210,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12200 "configure"
+#line 12213 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/lto-plugin/configure.ac b/lto-plugin/configure.ac
index c2ec512..18eb4f6 100644
--- a/lto-plugin/configure.ac
+++ b/lto-plugin/configure.ac
@@ -88,8 +88,21 @@ AM_CONDITIONAL(LTO_PLUGIN_USE_SYMVER_GNU, [test "x$lto_plugin_use_symver" = xgnu
 AM_CONDITIONAL(LTO_PLUGIN_USE_SYMVER_SUN, [test "x$lto_plugin_use_symver" = xsun])
 
 # Check for thread headers.
-AC_CHECK_HEADER(pthread.h,
-  [AC_DEFINE(HAVE_PTHREAD_H, 1, [Define to 1 if pthread.h is present.])])
+use_locking=no
+
+case $target in
+  riscv*)
+    # do not use locking as pthread depends on libatomic
+    ;;
+  *-linux*)
+    use_locking=yes
+    ;;
+esac
+
+if test x$use_locking = xyes; then
+  AC_CHECK_HEADER(pthread.h,
+    [AC_DEFINE(HAVE_PTHREAD_LOCKING, 1, [Define if the system provides pthread locking mechanism.])])
+fi
 
 AM_PROG_LIBTOOL
 ACX_LT_HOST_FLAGS
diff --git a/lto-plugin/lto-plugin.c b/lto-plugin/lto-plugin.c
index 635e126..7927dca 100644
--- a/lto-plugin/lto-plugin.c
+++ b/lto-plugin/lto-plugin.c
@@ -40,11 +40,7 @@ along with this program; see the file COPYING3.  If not see
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
-#if !HAVE_PTHREAD_H
-#error POSIX threads are mandatory dependency
 #endif
-#endif
-
 #if HAVE_STDINT_H
 #include <stdint.h>
 #endif
@@ -59,7 +55,9 @@ along with this program; see the file COPYING3.  If not see
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/types.h>
+#if HAVE_PTHREAD_LOCKING
 #include <pthread.h>
+#endif
 #ifdef HAVE_SYS_WAIT_H
 #include <sys/wait.h>
 #endif
@@ -162,9 +160,17 @@ enum symbol_style
   ss_uscore,	/* Underscore prefix all symbols.  */
 };
 
+#if HAVE_PTHREAD_LOCKING
 /* Plug-in mutex.  */
 static pthread_mutex_t plugin_lock;
 
+#define LOCK_SECTION pthread_mutex_lock (&plugin_lock)
+#define UNLOCK_SECTION pthread_mutex_unlock (&plugin_lock)
+#else
+#define LOCK_SECTION
+#define UNLOCK_SECTION
+#endif
+
 static char *arguments_file_name;
 static ld_plugin_register_claim_file register_claim_file;
 static ld_plugin_register_all_symbols_read register_all_symbols_read;
@@ -1270,18 +1276,18 @@ claim_file_handler (const struct ld_plugin_input_file *file, int *claimed)
 			      lto_file.symtab.syms);
       check (status == LDPS_OK, LDPL_FATAL, "could not add symbols");
 
-      pthread_mutex_lock (&plugin_lock);
+      LOCK_SECTION;
       num_claimed_files++;
       claimed_files =
 	xrealloc (claimed_files,
 		  num_claimed_files * sizeof (struct plugin_file_info));
       claimed_files[num_claimed_files - 1] = lto_file;
-      pthread_mutex_unlock (&plugin_lock);
+      UNLOCK_SECTION;
 
       *claimed = 1;
     }
 
-  pthread_mutex_lock (&plugin_lock);
+  LOCK_SECTION;
   if (offload_files == NULL)
     {
       /* Add dummy item to the start of the list.  */
@@ -1344,14 +1350,15 @@ claim_file_handler (const struct ld_plugin_input_file *file, int *claimed)
 	offload_files_last_lto = ofld;
       num_offload_files++;
     }
-  pthread_mutex_unlock (&plugin_lock);
+
+  UNLOCK_SECTION;
 
   goto cleanup;
 
  err:
-  pthread_mutex_lock (&plugin_lock);
+  LOCK_SECTION;
   non_claimed_files++;
-  pthread_mutex_unlock (&plugin_lock);
+  UNLOCK_SECTION;
   free (lto_file.name);
 
  cleanup:
@@ -1429,11 +1436,13 @@ onload (struct ld_plugin_tv *tv)
   struct ld_plugin_tv *p;
   enum ld_plugin_status status;
 
+#if HAVE_PTHREAD_LOCKING
   if (pthread_mutex_init (&plugin_lock, NULL) != 0)
     {
       fprintf (stderr, "mutex init failed\n");
       abort ();
     }
+#endif
 
   p = tv;
   while (p->tv_tag)