Hi there,
There is a common pattern on bare-metal code to refer to the value of
registers directly in a variable:
register unsigned long current_stack_pointer asm(sp);
But not only that depends on the register names (so you need to split
by arch with ifdefs), but it also uses a non-guaranteed
Renato Golin renato.go...@linaro.org writes:
Basically, introducing the builtin: __builtin_stack_pointer() which
will return the stack pointer register's value. There's no guarantee
that the register will contain the information you want (for example,
if the surrounding code uses it) and is
On 27 March 2014 10:12, Andreas Schwab sch...@suse.de wrote:
Can't you use __builtin_frame_address (0) instead?
That would give me the frame pointer, not the stack pointer, and the
user would have to calculate manually the offset to get the actual
stack pointer, which would be target-specific,
Renato Golin renato.go...@linaro.org writes:
On 27 March 2014 10:12, Andreas Schwab sch...@suse.de wrote:
Can't you use __builtin_frame_address (0) instead?
That would give me the frame pointer, not the stack pointer, and the
user would have to calculate manually the offset to get the actual
On 27 March 2014 10:29, Andreas Schwab sch...@suse.de wrote:
Depends on what you need the value for.
Mostly unwind code that uses both FP and SP, example:
http://git.linuxfoundation.org/?p=llvmlinux/kernel.git;a=commit;h=a875939682dc43bf244bd39a356bca76ac190d77
On Thu, Mar 27, 2014 at 09:38:11AM +, Renato Golin wrote:
There is a common pattern on bare-metal code to refer to the value of
registers directly in a variable:
register unsigned long current_stack_pointer asm(sp);
I don't see what is wrong with this, this isn't inline asm, it is
the
On Thu, Mar 27, 2014 at 3:25 AM, Renato Golin renato.go...@linaro.org wrote:
On 27 March 2014 10:12, Andreas Schwab sch...@suse.de wrote:
Can't you use __builtin_frame_address (0) instead?
That would give me the frame pointer, not the stack pointer, and the
user would have to calculate
.
-- Forwarded message --
From: llvmlinux-boun...@lists.linuxfoundation.org
Date: Thu, Mar 27, 2014 at 3:44 AM
Subject: Your message to LLVMLinux awaits moderator approval
To: pins...@gmail.com
Your mail to 'LLVMLinux' with the subject
Re: Builtin: stack pointer
Is being held until the list
On 27 March 2014 10:47, Andrew Pinski pins...@gmail.com wrote:
Please don't add a close list to the CC of GCC lists it is annoying.
I didn't realise this list was closed, sorry.
--renato
On Thu, Mar 27, 2014 at 03:44:39AM -0700, Andrew Pinski wrote:
(so you need to split by arch with ifdefs),
Except it is already in the kernel anyways; not even by ifdefs but by
different files so the reasoning adding a new builtin is not useful.
Not to mention that the kernel probably wants
Hi Jakub,
Just to make it clear, I'm not an official representative of Clang, or
LLVM, nor I was involved in all discussions about implementing
extensions either. I do not have an agenda to promote LLVM changes.
To me this sounds like clang proposing extensions because they aren't
willing to
On 27 March 2014 10:25, Renato Golin renato.go...@linaro.org wrote:
On 27 March 2014 10:12, Andreas Schwab sch...@suse.de wrote:
Can't you use __builtin_frame_address (0) instead?
That would give me the frame pointer, not the stack pointer, and the
user would have to calculate manually the
On Thu, Mar 27, 2014 at 11:20:09AM +, Renato Golin wrote:
On 27 March 2014 10:44, Jakub Jelinek ja...@redhat.com wrote:
I don't see what is wrong with this, this isn't inline asm, it is
the local register var GNU extension,
The argument I remember hearing of is the joint of:
1. The
On 27 March 2014 11:33, Jakub Jelinek ja...@redhat.com wrote:
Sure, normally register keyword is just a hint, that e.g. GCC I think
ignores whenever optimizing (for -O0 it means a variable doesn't have to
be allocated on the stack), but when it is part of the GNU global/local
register
On 03/27/14 04:20, Renato Golin wrote:
Hi Jakub,
Just to make it clear, I'm not an official representative of Clang, or
LLVM, nor I was involved in all discussions about implementing
extensions either. I do not have an agenda to promote LLVM changes.
I also don't speak for either clang nor the
On 03/27/14 03:44, Andrew Pinski wrote:
On Thu, Mar 27, 2014 at 3:25 AM, Renato Golin renato.go...@linaro.org wrote:
On 27 March 2014 10:12, Andreas Schwab sch...@suse.de wrote:
Can't you use __builtin_frame_address (0) instead?
That would give me the frame pointer, not the stack pointer, and
On 27 March 2014 14:44, Behan Webster beh...@converseincode.com wrote:
That is what led to this proposal.
I'm having a go at implementing named registers, and I also have
started a thread in the LLVM mailing list. Let's see how it goes...
For the existing cases this is true. However such a
On 27 March 2014 15:06, paul_kon...@dell.com wrote:
But unwind code is inherently platform-dependent. Your objection to the
inline asm that references SP by name is that it's platform dependent. The
builtin would reduce the amount of platform dependent code by one line, i.e.,
probably
On Mar 27, 2014, at 6:38 AM, Renato Golin renato.go...@linaro.org wrote:
On 27 March 2014 10:29, Andreas Schwab sch...@suse.de wrote:
Depends on what you need the value for.
Mostly unwind code that uses both FP and SP, example:
But unwind code is inherently platform-dependent. Your
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