Hi,
On Wed, 13 Feb 2008, H.J. Lu wrote:
> We need a callee-saved register for stack alignment.
Can you expand on why?
> In 64bit, our choices are rbx, and r12-r15. r12-r15 need the REX byte
> and r12 also needs the SIB byte. So I'd like to use rbx. x86-64 psABI
> says rbx is callee-saved and
On Feb 13, 2008 1:52 PM, Michael Matz <[EMAIL PROTECTED]> wrote:
> Hi,
>
> On Wed, 13 Feb 2008, H.J. Lu wrote:
>
> > We need a callee-saved register for stack alignment.
>
> Can you expand on why?
Our proposal is at
http://gcc.gnu.org/ml/gcc/2007-12/msg00567.html
For most cases, we can align sta
Hi,
On Wed, 13 Feb 2008, H.J. Lu wrote:
> Our proposal is at
>
> http://gcc.gnu.org/ml/gcc/2007-12/msg00567.html
>
> For most cases, we can align stack with RBP/RSP. But
> we need an extra register when there is dynamic stack
> allocation or nested functions. It has to be callee-saved
> to work
On Feb 13, 2008 2:49 PM, Michael Matz <[EMAIL PROTECTED]> wrote:
> Hi,
>
> On Wed, 13 Feb 2008, H.J. Lu wrote:
>
> > Our proposal is at
> >
> > http://gcc.gnu.org/ml/gcc/2007-12/msg00567.html
> >
> > For most cases, we can align stack with RBP/RSP. But
> > we need an extra register when there is dy
> Hi,
>
> On Wed, 13 Feb 2008, H.J. Lu wrote:
>
> > We need a callee-saved register for stack alignment.
>
> Can you expand on why?
>
> > In 64bit, our choices are rbx, and r12-r15. r12-r15 need the REX byte
> > and r12 also needs the SIB byte. So I'd like to use rbx. x86-64 psABI
> > says rb
> On Feb 13, 2008 2:49 PM, Michael Matz <[EMAIL PROTECTED]> wrote:
> > Hi,
> >
> > On Wed, 13 Feb 2008, H.J. Lu wrote:
> >
> > > Our proposal is at
> > >
> > > http://gcc.gnu.org/ml/gcc/2007-12/msg00567.html
> > >
> > > For most cases, we can align stack with RBP/RSP. But
> > > we need an extra reg
> > Hi,
> >
> > On Wed, 13 Feb 2008, H.J. Lu wrote:
> >
> > > We need a callee-saved register for stack alignment.
> >
> > Can you expand on why?
> >
> > > In 64bit, our choices are rbx, and r12-r15. r12-r15 need the REX byte
> > > and r12 also needs the SIB byte. So I'd like to use rbx. x
> > > Hi,
> > >
> > > On Wed, 13 Feb 2008, H.J. Lu wrote:
> > >
> > > > We need a callee-saved register for stack alignment.
> > >
> > > Can you expand on why?
> > >
> > > > In 64bit, our choices are rbx, and r12-r15. r12-r15 need the REX byte
> > > > and r12 also needs the SIB byte. So I'
On Wed, 13 Feb 2008, H.J. Lu wrote:
>> Recent i386 use arbitrary register as GOT pointer only for leaf
>> function. When you call something, the GOT entry uses EBX too.
>> We use RBX for large PIC model. But I am with Michael here that I
don't
>> see reason why choice of register needs to be
Hi,
> Michael, Jan,
>
> When aligning stack for those functions who have dynamic stack
> allocation, we must use an available callee-saved register in prologue.
> We named this hard register DRAP. It is worthwhile to emphasize that
> *free* here means "free in prologue". After prologue, a virtual
Honza,
> Honza said:
> I am bit confused here. If I wanted a free register in prologue only,
I
> would probably look at the caller saved ones. But I gues it is just
> typo.
> I don't see much value in making the register callee-saved especially
if
> you say that virtual reg (pseudo?) is used af
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