[PATCH] Semihosting fix for AArch64 when heapinfo is not provided by debugger

[Tamar Christina]

> -----Original Message-----
> From: Richard Earnshaw (lists) [mailto:Richard.Earnshaw@arm.com]
> Sent: 24 October 2017 16:20
> To: Tamar Christina; Alexander Fedotov; newlib@sourceware.org
> Cc: nd
> Subject: Re: [PATCH] Semihosting fix for AArch64 when heapinfo is not
> provided by debugger
> 
> On 23/10/17 18:23, Tamar Christina wrote:
> > Hi Alex,
> >
> > In principle nothing against the patch. Just a comment
> >
> >> diff --git a/libgloss/aarch64/crt0.S b/libgloss/aarch64/crt0.S index
> >> f670e03..f831be1 100644
> >> --- a/libgloss/aarch64/crt0.S
> >> +++ b/libgloss/aarch64/crt0.S
> >> @@ -102,33 +102,44 @@
> >>  	ldr	x0, .LC0		/* point at returned values */
> >>  	ldr	x1, [x0, #8]		/* get heap_limit */
> >>
> >> +	/* Set __heap_limit.  */
> >> +#ifdef __ILP32__
> >> +	/* Sanity check on the __heap_limit.  */
> >> +	tst	x1, #0xffffffff00000000
> >> +	bne	.Linsanepar
> >> +#endif
> >
> > if x1 is 0 it won't pass the first test in ILP32 and takes the branch,
> > I assume you intended it to fall through in that case? So I think this
> > test should be re-ordered.
> 
> Huh?  zero & anything is zero, so the Z bit will be set and the branch will not
> be taken.
> 

Yes, sorry, I flipped the mask. Disregard my earlier comment.

> 
> >
> >> +	cmp     x1, xzr
> >> +	beq     .LC4
> >> +	adrp	x2, __heap_limit
> >> +	add	x2, x2, #:lo12:__heap_limit
> >> +	str     x1, [x2]
> >> +.LC4:
> >
> > Thanks,
> > Tamar
> >
> 
> Looks basically OK to me.
> 
> R.
> 
> >
> >
> >> -----Original Message-----
> >> From: newlib-owner@sourceware.org [mailto:newlib-
> >> owner@sourceware.org] On Behalf Of Alexander Fedotov
> >> Sent: 19 October 2017 22:41
> >> To: newlib@sourceware.org
> >> Subject: Re: [PATCH] Semihosting fix for AArch64 when heapinfo is not
> >> provided by debugger
> >>
> >> Any comments/thoughts on this patch ?
> >> It would be great to have this feature in newlib release version.
> >>
> >> Alex
> >>
> >> On Fri, 13 Oct 2017 at 12:16, Corinna Vinschen <vinschen@redhat.com>
> >> wrote:
> >>
> >>> On Oct 11 14:57, Alexander Fedotov wrote:
> >>>> Use the same approach as in ARM port for case when Debugger not
> >>>> providing necessary info for semihosting.
> >>>
> >>> I'd like to see an ACK from some arm folks.
> >>>
> >>>
> >>> Thanks,
> >>> Corinna
> >>>
> >>> --
> >>> Corinna Vinschen
> >>> Cygwin Maintainer
> >>> Red Hat
> >>>
> >> --
> >> Best regards,
> >> AF