| Message ID | 1486509060.2866.57.camel@caviumnetworks.com |
|---|---|
| State | New |
| Headers | show |
On 07/02/17 23:11, Steve Ellcey wrote: > This patch was submitted last year by Andrew Pinski, this is a > resubmit/ping of that patch. > > https://gcc.gnu.org/ml/gcc-patches/2016-04/msg01726.html > > During the initial submittal James Greenhalgh asked if this was an ABI change. > I do not believe it is because while it is changing the size of the reg > structure in _Unwind_Context that structure is opaque to anything outside of > libunwind and so the change is not visible to user programs. It is not > changing the type or size of _Unwind_Word which remains as 64 bits but it > fixes some places where those 64 bits are being truncated to 32 bits. Any > ILP32 Aarch64 program that uses an unwind library without this change may > abort because of that truncation. > > The other thing that this patch does (by setting REG_VALUE_IN_UNWIND_CONTEXT) > is change the value of ASSUME_EXTENDED_UNWIND_CONTEXT to 1. That should not > matter because we are currently setting EXTENDED_CONTEXT_BIT in > uw_init_context_1 anyway and that basically does the same thing, saying that > we have the opaque extended unwind context structure which can be changed > without affecting the ABI. I believe that only pre-G++ 3.0 objects would not > have the extended opaque context structure and there is no ILP32 Aarch64 > support in a compiler that old. > > I am a little confused about why, when ASSUME_EXTENDED_UNWIND_CONTEXT > is set in unwind-dw2.c, we don't still set the EXTENDED_CONTEXT_BIT in > uw_init_context_1. I guess it doesn't matter because once we start assuming > the extended unwind context we will never go back and allowing a mix and match > with pre 3.0 unextended unwind contexts so it doesn't matter if the bit is set > or not. > > I actually tested this patch without changing ASSUME_EXTENDED_UNWIND_CONTEXT > and it worked as well as this patch where ASSUME_EXTENDED_UNWIND_CONTEXT is > changed so that change could be left out out by setting it to 0 in the new > aarch64 value-unwind.h header file if we thought there was a reason to do > that. > > Steve Ellcey > sellcey@cavium.com > > > 2017-02-07 Andrew Pinski <apinski@cavium.com> > > * config/aarch64/value-unwind.h: New file. > * config.host (aarch64*-*-*): Add aarch64/value-unwind.h > to tm_file. > OK. R. > > unwind.patch > > > diff --git a/libgcc/config.host b/libgcc/config.host > index 9472a60..8bab369 100644 > --- a/libgcc/config.host > +++ b/libgcc/config.host > @@ -1379,4 +1379,8 @@ i[34567]86-*-linux* | x86_64-*-linux*) > fi > tm_file="${tm_file} i386/value-unwind.h" > ;; > +aarch64*-*-*) > + # ILP32 needs an extra header for unwinding > + tm_file="${tm_file} aarch64/value-unwind.h" > + ;; > esac > diff --git a/libgcc/config/aarch64/value-unwind.h b/libgcc/config/aarch64/value-unwind.h > index e69de29..c79e832 100644 > --- a/libgcc/config/aarch64/value-unwind.h > +++ b/libgcc/config/aarch64/value-unwind.h > @@ -0,0 +1,25 @@ > +/* Store register values as _Unwind_Word type in DWARF2 EH unwind context. > + Copyright (C) 2017 Free Software Foundation, Inc. > + > + 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 and > + a copy of the GCC Runtime Library Exception along with this program; > + see the files COPYING3 and COPYING.RUNTIME respectively. If not, see > + <http://www.gnu.org/licenses/>. */ > + > +/* Define this macro if the target stores register values as _Unwind_Word > + type in unwind context. Only enable it for ilp32. */ > +#if defined __aarch64__ && !defined __LP64__ > +# define REG_VALUE_IN_UNWIND_CONTEXT > +#endif >
diff --git a/libgcc/config.host b/libgcc/config.host index 9472a60..8bab369 100644 --- a/libgcc/config.host +++ b/libgcc/config.host @@ -1379,4 +1379,8 @@ i[34567]86-*-linux* | x86_64-*-linux*) fi tm_file="${tm_file} i386/value-unwind.h" ;; +aarch64*-*-*) + # ILP32 needs an extra header for unwinding + tm_file="${tm_file} aarch64/value-unwind.h" + ;; esac diff --git a/libgcc/config/aarch64/value-unwind.h b/libgcc/config/aarch64/value-unwind.h index e69de29..c79e832 100644 --- a/libgcc/config/aarch64/value-unwind.h +++ b/libgcc/config/aarch64/value-unwind.h @@ -0,0 +1,25 @@ +/* Store register values as _Unwind_Word type in DWARF2 EH unwind context. + Copyright (C) 2017 Free Software Foundation, Inc. + + 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 and + a copy of the GCC Runtime Library Exception along with this program; + see the files COPYING3 and COPYING.RUNTIME respectively. If not, see + <http://www.gnu.org/licenses/>. */ + +/* Define this macro if the target stores register values as _Unwind_Word + type in unwind context. Only enable it for ilp32. */ +#if defined __aarch64__ && !defined __LP64__ +# define REG_VALUE_IN_UNWIND_CONTEXT +#endif