Re: [PATCH] or1k: Add mcmodel option to handle large GOTs

[Jeff Law via Gcc-patches]

On 4/20/2021 6:12 PM, Stafford Horne wrote:

On Tue, Apr 20, 2021 at 05:20:39PM -0600, Jeff Law wrote:

On 4/18/2021 6:10 PM, Stafford Horne via Gcc-patches wrote:

When building libgeos we get an error with:

  linux-uclibc/9.3.0/crtbeginS.o: in function `__do_global_dtors_aux':
  crtstuff.c:(.text+0x118): relocation truncated to fit: R_OR1K_GOT16 
against symbol `__cxa_finalize' defined in .text section in
  
/home/shorne/work/openrisc/3eb9f9d0f6d8274b2d19753c006bd83f7d536e3c/output/host/or1k-buildroot-linux-uclibc/sysroot/lib/libc.so.

This is caused by GOT code having a limit of 64k.  In OpenRISC this
looks to be the only relocation code pattern to be limited to 64k.

This patch allows specifying a new option -mcmodel=large which can be
used to generate 2 more instructions to construct 32-bit addresses for
up to 4G GOTs.

gcc/ChangeLog:

PR 99783
* config/or1k/or1k-opts.h: New file.
* config/or1k/or1k.c (or1k_legitimize_address_1, print_reloc):
Support generating gotha relocations if -mcmodel=large is
specified.
* config/or1k/or1k.h (TARGET_CMODEL_SMALL, TARGET_CMODEL_LARGE):
New macros.
* config/or1k/or1k.opt (mcmodel=): New option.
* doc/invoke.text (OpenRISC Options): Document mcmodel.

Note you're the port maintainer, so you don't need approval to commit this
to GCC.

Thanks for confirming, I know that after Segher told me with some previous
patches. :)

For this series Giulio picked it up and tested it.  We found some issues and I
am going to fix with a V2.  I should commit that version, after the binutils
changes are in.


Sounds good.  Thanks.  Given we're making gcc-11 RCs you'll have to 
decide if its worth the risk of introducing those changes this late in 
the cycle is safe or not.


jeff

Re: [PATCH] or1k: Add mcmodel option to handle large GOTs

[Stafford Horne via Gcc-patches]

On Tue, Apr 20, 2021 at 05:20:39PM -0600, Jeff Law wrote:
> 
> On 4/18/2021 6:10 PM, Stafford Horne via Gcc-patches wrote:
> > When building libgeos we get an error with:
> > 
> >  linux-uclibc/9.3.0/crtbeginS.o: in function `__do_global_dtors_aux':
> >  crtstuff.c:(.text+0x118): relocation truncated to fit: R_OR1K_GOT16 
> > against symbol `__cxa_finalize' defined in .text section in
> >  
> > /home/shorne/work/openrisc/3eb9f9d0f6d8274b2d19753c006bd83f7d536e3c/output/host/or1k-buildroot-linux-uclibc/sysroot/lib/libc.so.
> > 
> > This is caused by GOT code having a limit of 64k.  In OpenRISC this
> > looks to be the only relocation code pattern to be limited to 64k.
> > 
> > This patch allows specifying a new option -mcmodel=large which can be
> > used to generate 2 more instructions to construct 32-bit addresses for
> > up to 4G GOTs.
> > 
> > gcc/ChangeLog:
> > 
> > PR 99783
> > * config/or1k/or1k-opts.h: New file.
> > * config/or1k/or1k.c (or1k_legitimize_address_1, print_reloc):
> > Support generating gotha relocations if -mcmodel=large is
> > specified.
> > * config/or1k/or1k.h (TARGET_CMODEL_SMALL, TARGET_CMODEL_LARGE):
> > New macros.
> > * config/or1k/or1k.opt (mcmodel=): New option.
> > * doc/invoke.text (OpenRISC Options): Document mcmodel.
> 
> Note you're the port maintainer, so you don't need approval to commit this
> to GCC.

Thanks for confirming, I know that after Segher told me with some previous
patches. :)

For this series Giulio picked it up and tested it.  We found some issues and I
am going to fix with a V2.  I should commit that version, after the binutils
changes are in.

-Stafford

Re: [PATCH] or1k: Add mcmodel option to handle large GOTs

[Jeff Law via Gcc-patches]

On 4/18/2021 6:10 PM, Stafford Horne via Gcc-patches wrote:

When building libgeos we get an error with:

 linux-uclibc/9.3.0/crtbeginS.o: in function `__do_global_dtors_aux':
 crtstuff.c:(.text+0x118): relocation truncated to fit: R_OR1K_GOT16 
against symbol `__cxa_finalize' defined in .text section in
 
/home/shorne/work/openrisc/3eb9f9d0f6d8274b2d19753c006bd83f7d536e3c/output/host/or1k-buildroot-linux-uclibc/sysroot/lib/libc.so.

This is caused by GOT code having a limit of 64k.  In OpenRISC this
looks to be the only relocation code pattern to be limited to 64k.

This patch allows specifying a new option -mcmodel=large which can be
used to generate 2 more instructions to construct 32-bit addresses for
up to 4G GOTs.

gcc/ChangeLog:

PR 99783
* config/or1k/or1k-opts.h: New file.
* config/or1k/or1k.c (or1k_legitimize_address_1, print_reloc):
Support generating gotha relocations if -mcmodel=large is
specified.
* config/or1k/or1k.h (TARGET_CMODEL_SMALL, TARGET_CMODEL_LARGE):
New macros.
* config/or1k/or1k.opt (mcmodel=): New option.
* doc/invoke.text (OpenRISC Options): Document mcmodel.


Note you're the port maintainer, so you don't need approval to commit 
this to GCC.


Jeff

[PATCH] or1k: Add mcmodel option to handle large GOTs

[Stafford Horne via Gcc-patches]

When building libgeos we get an error with:

linux-uclibc/9.3.0/crtbeginS.o: in function `__do_global_dtors_aux':
crtstuff.c:(.text+0x118): relocation truncated to fit: R_OR1K_GOT16 against 
symbol `__cxa_finalize' defined in .text section in

/home/shorne/work/openrisc/3eb9f9d0f6d8274b2d19753c006bd83f7d536e3c/output/host/or1k-buildroot-linux-uclibc/sysroot/lib/libc.so.

This is caused by GOT code having a limit of 64k.  In OpenRISC this
looks to be the only relocation code pattern to be limited to 64k.

This patch allows specifying a new option -mcmodel=large which can be
used to generate 2 more instructions to construct 32-bit addresses for
up to 4G GOTs.

gcc/ChangeLog:

PR 99783
* config/or1k/or1k-opts.h: New file.
* config/or1k/or1k.c (or1k_legitimize_address_1, print_reloc):
Support generating gotha relocations if -mcmodel=large is
specified.
* config/or1k/or1k.h (TARGET_CMODEL_SMALL, TARGET_CMODEL_LARGE):
New macros.
* config/or1k/or1k.opt (mcmodel=): New option.
* doc/invoke.text (OpenRISC Options): Document mcmodel.
---

This depends on the binutils-gdb patch sent here:
 - https://sourceware.org/pipermail/binutils/2021-April/116155.html

 gcc/config/or1k/or1k-opts.h | 30 ++
 gcc/config/or1k/or1k.c  | 11 +--
 gcc/config/or1k/or1k.h  |  7 +++
 gcc/config/or1k/or1k.opt| 19 +++
 gcc/doc/invoke.texi | 12 +++-
 5 files changed, 76 insertions(+), 3 deletions(-)
 create mode 100644 gcc/config/or1k/or1k-opts.h

diff --git a/gcc/config/or1k/or1k-opts.h b/gcc/config/or1k/or1k-opts.h
new file mode 100644
index 000..f791b894fdd
--- /dev/null
+++ b/gcc/config/or1k/or1k-opts.h
@@ -0,0 +1,30 @@
+/* Definitions for option handling for OpenRISC.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   Contributed by Stafford Horne.
+
+   This file is part of GCC.
+
+   GCC 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, or (at your
+   option) any later version.
+
+   GCC 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
+   .  */
+
+#ifndef GCC_OR1K_OPTS_H
+#define GCC_OR1K_OPTS_H
+
+/* The OpenRISC code generation models available.  */
+enum or1k_cmodel_type {
+  CMODEL_SMALL,
+  CMODEL_LARGE
+};
+
+#endif /* GCC_OR1K_OPTS_H */
diff --git a/gcc/config/or1k/or1k.c b/gcc/config/or1k/or1k.c
index e772a7addea..27d3fa17995 100644
--- a/gcc/config/or1k/or1k.c
+++ b/gcc/config/or1k/or1k.c
@@ -750,7 +750,14 @@ or1k_legitimize_address_1 (rtx x, rtx scratch)
{
  base = gen_sym_unspec (base, UNSPEC_GOT);
  crtl->uses_pic_offset_table = 1;
- t2 = gen_rtx_LO_SUM (Pmode, pic_offset_table_rtx, base);
+ if (TARGET_CMODEL_LARGE)
+   {
+ emit_insn (gen_rtx_SET (t1, gen_rtx_HIGH (Pmode, base)));
+ emit_insn (gen_add3_insn (t1, t1, pic_offset_table_rtx));
+ t2 = gen_rtx_LO_SUM (Pmode, t1, base);
+   }
+ else
+   t2 = gen_rtx_LO_SUM (Pmode, pic_offset_table_rtx, base);
  t2 = gen_const_mem (Pmode, t2);
  emit_insn (gen_rtx_SET (t1, t2));
  base = t1;
@@ -1089,7 +1096,7 @@ print_reloc (FILE *stream, rtx x, HOST_WIDE_INT add, 
reloc_kind kind)
  no special markup.  */
   static const char * const relocs[RKIND_MAX][RTYPE_MAX] = {
 { "lo", "got", "gotofflo", "tpofflo", "gottpofflo", "tlsgdlo" },
-{ "ha", NULL,  "gotoffha", "tpoffha", "gottpoffha", "tlsgdhi" },
+{ "ha", "gotha", "gotoffha", "tpoffha", "gottpoffha", "tlsgdhi" },
   };
   reloc_type type = RTYPE_DIRECT;
 
diff --git a/gcc/config/or1k/or1k.h b/gcc/config/or1k/or1k.h
index fe01ab81ead..669907e7e74 100644
--- a/gcc/config/or1k/or1k.h
+++ b/gcc/config/or1k/or1k.h
@@ -21,6 +21,8 @@
 #ifndef GCC_OR1K_H
 #define GCC_OR1K_H
 
+#include "config/or1k/or1k-opts.h"
+
 /* Names to predefine in the preprocessor for this target machine.  */
 #define TARGET_CPU_CPP_BUILTINS()  \
   do   \
@@ -37,6 +39,11 @@
 }  \
   while (0)
 
+#define TARGET_CMODEL_SMALL \
+  (or1k_code_model == CMODEL_SMALL)
+#define TARGET_CMODEL_LARGE \
+  (or1k_code_model == CMODEL_LARGE)
+
 /* Storage layout.  */
 
 #define DEFAULT_SIGNED_CHAR 1
diff --git a/gcc/config/or1k/or1k.opt b/gcc/config/or1k/or1k.opt
index 6bd0f3eee6d..cc23e3b8856 100644
--- a/gcc/config/or1k/or1k.opt
+++