On 12/28/23 12:35, Roger Sayle wrote:
Hi Jeff,
Thanks for the speedy review.
On 12/28/23 07:59, Roger Sayle wrote:
This patch fixes PR rtl-optmization/104914 by tweaking/improving the
way that fields are written into a pseudo register that needs to be
kept sign extended.
Well, I think "fi
On 12/30/23 21:34, YunQiang Su wrote:
Right. But that's the whole point behind avoiding the narrowing subreg
and forcing use of a truncate operation.
So basically the question becomes is there a way to modify those bits in
a way that GCC doesn't know that it needs to to truncate/extend?
I
> Right. But that's the whole point behind avoiding the narrowing subreg
> and forcing use of a truncate operation.
>
> So basically the question becomes is there a way to modify those bits in
> a way that GCC doesn't know that it needs to to truncate/extend?
>
I guess that this code may cause so
On 12/28/23 19:07, YunQiang Su wrote:
In general, I agree with this change.
When gcc12 on RV64, more than one `sext.w` will be produced with our test.
(Note, use -O1).
There are two things that help here. The first is that the most significant
bit never appears in the middle of a field, so
In general, I agree with this change.
When gcc12 on RV64, more than one `sext.w` will be produced with our test.
(Note, use -O1).
>
> There are two things that help here. The first is that the most significant
> bit never appears in the middle of a field, so we don't have to worry about
> overlap
Jeff Law 于2023年12月29日周五 02:23写道：
>
>
>
> On 12/28/23 07:59, Roger Sayle wrote:
> >
> > This patch fixes PR rtl-optmization/104914 by tweaking/improving the way
> > that fields are written into a pseudo register that needs to be kept sign
> > extended.
> Well, I think "fixes" is a bit of a stretch.
Hi Jeff,
Thanks for the speedy review.
> On 12/28/23 07:59, Roger Sayle wrote:
> > This patch fixes PR rtl-optmization/104914 by tweaking/improving the
> > way that fields are written into a pseudo register that needs to be
> > kept sign extended.
> Well, I think "fixes" is a bit of a stretch.
On 12/28/23 07:59, Roger Sayle wrote:
This patch fixes PR rtl-optmization/104914 by tweaking/improving the way
that fields are written into a pseudo register that needs to be kept sign
extended.
Well, I think "fixes" is a bit of a stretch. We're avoiding the issue
by changing the early RTL
This patch fixes PR rtl-optmization/104914 by tweaking/improving the way
that fields are written into a pseudo register that needs to be kept sign
extended.
The motivating example from the bugzilla PR is:
extern void ext(int);
void foo(const unsigned char *buf) {
int val;
((unsigned char*)&v
