Support glibc-back-compat on 64-bit POWER

Author: luke-jr

configure.ac

@@ -813,6 +813,11 @@ AX_GCC_FUNC_ATTRIBUTE([dllimport])
 if test x$use_glibc_compat != xno; then
   AX_CHECK_LINK_FLAG([[-Wl,--wrap=__divmoddi4]], [COMPAT_LDFLAGS="$COMPAT_LDFLAGS -Wl,--wrap=__divmoddi4"])
   AX_CHECK_LINK_FLAG([[-Wl,--wrap=log2f]], [COMPAT_LDFLAGS="$COMPAT_LDFLAGS -Wl,--wrap=log2f"])
+  case $host in
+    powerpc64* | ppc64*)
+      AX_CHECK_LINK_FLAG([[-Wl,--no-tls-get-addr-optimize]], [COMPAT_LDFLAGS="$COMPAT_LDFLAGS -Wl,--no-tls-get-addr-optimize"])
+    ;;
+  esac
 else
   AC_SEARCH_LIBS([clock_gettime],[rt])
 fi

src/compat/glibc_compat.cpp

@@ -54,6 +54,12 @@ __asm(".symver log2f_old,log2f@GLIBC_2.2.5");
 __asm(".symver log2f_old,log2f@GLIBC_2.4");
 #elif defined(__aarch64__)
 __asm(".symver log2f_old,log2f@GLIBC_2.17");
+#elif defined(__powerpc64__)
+#  ifdef WORDS_BIGENDIAN
+__asm(".symver log2f_old,log2f@GLIBC_2.3");
+#  else
+__asm(".symver log2f_old,log2f@GLIBC_2.17");
+#  endif
 #elif defined(__riscv)
 __asm(".symver log2f_old,log2f@GLIBC_2.27");
 #endif