8 files changed, 153 insertions, 7 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2d1488c..b2031ee 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2020-01-31  Sandra Loosemore  <sandra@codesourcery.com>
+
+	nios2: Support for GOT-relative DW_EH_PE_datarel encoding.
+
+	* configure.ac [nios2-*-*]: Check HAVE_AS_NIOS2_GOTOFF_RELOCATION.
+	* config.in: Regenerated.
+	* configure: Regenerated.
+	* config/nios2/nios2.h (ASM_PREFERRED_EH_DATA_FORMAT): Fix handling
+	for PIC when HAVE_AS_NIOS2_GOTOFF_RELOCATION.
+	(ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX): New.
+
 2020-02-01  Andrew Burgess  <andrew.burgess@embecosm.com>
 
 	* configure: Regenerate.
diff --git a/gcc/config.in b/gcc/config.in
index 1110492..4829286 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -571,6 +571,12 @@
 #endif
 
 
+/* Define if your assembler supports %gotoff relocation syntax. */
+#ifndef USED_FOR_TARGET
+#undef HAVE_AS_NIOS2_GOTOFF_RELOCATION
+#endif
+
+
 /* Define if your assembler supports the -no-mul-bug-abort option. */
 #ifndef USED_FOR_TARGET
 #undef HAVE_AS_NO_MUL_BUG_ABORT_OPTION
diff --git a/gcc/config/nios2/nios2.h b/gcc/config/nios2/nios2.h
index 78b538b..e81b928 100644
--- a/gcc/config/nios2/nios2.h
+++ b/gcc/config/nios2/nios2.h
@@ -494,14 +494,40 @@ do {                                                                    \
 #define EH_RETURN_DATA_REGNO(N) ((N) <= (LAST_ARG_REGNO - FIRST_ARG_REGNO) \
 				 ? (N) + FIRST_ARG_REGNO : INVALID_REGNUM)
 
-/* Nios II has no appropriate relocations for a 32-bit PC-relative or
-   section-relative pointer encoding.  This therefore always chooses an
-   absolute representation for pointers.  An unfortunate consequence of
-   this is that ld complains about the absolute fde encoding when linking
-   with -shared or -fpie, but the warning is harmless and there seems to
-   be no good way to suppress it.  */
+/* For PIC, use indirect for global references; it'll end up using a dynamic
+   relocation, which we want to keep out of read-only EH sections.
+   For local references, we want to use GOT-relative offsets provided
+   the assembler supports them.  For non-PIC, use an absolute encoding.  */
+#ifdef HAVE_AS_NIOS2_GOTOFF_RELOCATION
 #define ASM_PREFERRED_EH_DATA_FORMAT(CODE, GLOBAL)		\
-  (flag_pic ? DW_EH_PE_aligned : DW_EH_PE_sdata4)
+  (flag_pic							\
+   ? ((GLOBAL)							\
+      ? DW_EH_PE_indirect | DW_EH_PE_absptr			\
+      : DW_EH_PE_datarel | DW_EH_PE_sdata4)			\
+   : DW_EH_PE_absptr)
+
+#define ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX(FILE, ENCODING, SIZE, ADDR, DONE) \
+  do {									\
+      if (((ENCODING) & 0xf0) == DW_EH_PE_datarel)			\
+      {									\
+	fputs ("\t.4byte %gotoff(", FILE);				\
+	output_addr_const (FILE, ADDR);					\
+	fputs (")", FILE);						\
+	goto DONE;							\
+      }									\
+  } while (0)
+
+#else
+/* We don't have %gotoff support in the assembler.  Fall back to the encoding
+   it used to use instead before the assembler was fixed.  This has known
+   bugs but mostly works.  */
+#define ASM_PREFERRED_EH_DATA_FORMAT(CODE, GLOBAL)		\
+  (flag_pic							\
+   ? ((GLOBAL)							\
+      ? DW_EH_PE_indirect | DW_EH_PE_absptr			\
+      : DW_EH_PE_aligned)					\
+   : DW_EH_PE_absptr)
+#endif
 
 /* Misc. parameters.  */
 
diff --git a/gcc/configure b/gcc/configure
index 4c2c599..5fa565a 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -27973,6 +27973,43 @@ $as_echo "#define HAVE_NEWLIB_NANO_FORMATTED_IO 1" >>confdefs.h
 
       fi
     ;;
+    nios2-*-*)
+    # Versions 2.33 and earlier lacked support for the %gotoff relocation
+    # syntax that is documented in the ABI specification.
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for support for %gotoff relocations in constant data" >&5
+$as_echo_n "checking assembler for support for %gotoff relocations in constant data... " >&6; }
+if ${gcc_cv_as_nios2_gotoff_relocation+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  gcc_cv_as_nios2_gotoff_relocation=no
+  if test x$gcc_cv_as != x; then
+    $as_echo '	.extern foo
+	.data
+	.long %gotoff(foo)' > conftest.s
+    if { ac_try='$gcc_cv_as $gcc_cv_as_flags  -o conftest.o conftest.s >&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+    then
+	gcc_cv_as_nios2_gotoff_relocation=yes
+    else
+      echo "configure: failed program was" >&5
+      cat conftest.s >&5
+    fi
+    rm -f conftest.o conftest.s
+  fi
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_nios2_gotoff_relocation" >&5
+$as_echo "$gcc_cv_as_nios2_gotoff_relocation" >&6; }
+if test $gcc_cv_as_nios2_gotoff_relocation = yes; then
+
+$as_echo "#define HAVE_AS_NIOS2_GOTOFF_RELOCATION 1" >>confdefs.h
+
+fi
+
+    ;;
     riscv*-*-*)
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for .attribute support" >&5
 $as_echo_n "checking assembler for .attribute support... " >&6; }
diff --git a/gcc/configure.ac b/gcc/configure.ac
index a7521ee..671b9a6 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -5032,6 +5032,17 @@ pointers into PC-relative form.])
 configured with --enable-newlib-nano-formatted-io.])
       fi
     ;;
+    nios2-*-*)
+    # Versions 2.33 and earlier lacked support for the %gotoff relocation
+    # syntax that is documented in the ABI specification.
+    gcc_GAS_CHECK_FEATURE([support for %gotoff relocations in constant data],
+      gcc_cv_as_nios2_gotoff_relocation,,,
+[	.extern foo
+	.data
+	.long %gotoff(foo)],,
+      [AC_DEFINE(HAVE_AS_NIOS2_GOTOFF_RELOCATION, 1,
+          [Define if your assembler supports %gotoff relocation syntax.])])
+    ;;
     riscv*-*-*)
     gcc_GAS_CHECK_FEATURE([.attribute support],
       gcc_cv_as_riscv_attribute, [2,32,0],,
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e4213d1..5902ab6 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2020-01-31  Sandra Loosemore  <sandra@codesourcery.com>
+
+	nios2: Support for GOT-relative DW_EH_PE_datarel encoding.
+
+	* g++.target/nios2/hello-pie.C: New.
+	* g++.target/nios2/nios2.exp: New.
+
 2020-01-31  David Malcolm  <dmalcolm@redhat.com>
 
 	PR analyzer/93457
diff --git a/gcc/testsuite/g++.target/nios2/hello-pie.C b/gcc/testsuite/g++.target/nios2/hello-pie.C
new file mode 100644
index 0000000..ed016f3
--- /dev/null
+++ b/gcc/testsuite/g++.target/nios2/hello-pie.C
@@ -0,0 +1,14 @@
+// { dg-do run { target *-*-linux* } }
+// { dg-options "-pie -fpie" }
+// { dg-output "Hello, pie World" }
+
+// This test used to give an "FDE encoding" error from the linker due to
+// the ABI not having appropriate relocations for PIE.
+
+#include <iostream>
+
+int
+main ()
+{
+  std::cout << "Hello, pie World" << std::endl;
+}
diff --git a/gcc/testsuite/g++.target/nios2/nios2.exp b/gcc/testsuite/g++.target/nios2/nios2.exp
new file mode 100644
index 0000000..a4ff7d0
--- /dev/null
+++ b/gcc/testsuite/g++.target/nios2/nios2.exp
@@ -0,0 +1,34 @@
+# Copyright (C) 2019 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GCC; see the file COPYING3.  If not see
+# <http://www.gnu.org/licenses/>.
+
+# GCC testsuite that uses the `dg.exp' driver.
+
+# Exit immediately if this isn't a nios2 target.
+if ![istarget nios2*-*-*] then {
+  return
+}
+
+# Load support procs.
+load_lib g++-dg.exp
+
+# Initialize `dg'.
+dg-init
+
+# Main loop.
+dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/*.C]] "" ""
+
+# All done.
+dg-finish