[Mesa-dev] [PATCH 06/10] nir: Make nir_[cf_node/instr]_[prev/next] return null if at the end

[Jason Ekstrand]

On Thu, Feb 5, 2015 at 3:40 PM, Connor Abbott <cwabbott0 at gmail.com> wrote:

> This should go before the previous patch, or else that patch won't
> work as intended, and also it confused me a little by using a behavior
> (the returning NULL) before introducing it.
>

The previous patch is a bug.  It uses a cast of a chunk of the block to an
instruction.  It just so happens that the ->type of what it gets is never a
phi.  This patch turns that bug into a segfault hence putting it after the
fix.


>
> On Thu, Feb 5, 2015 at 5:29 PM, Jason Ekstrand <jason at jlekstrand.net>
> wrote:
> > ---
> >  src/glsl/nir/nir.h | 28 ++++++++++++++++++++++------
> >  1 file changed, 22 insertions(+), 6 deletions(-)
> >
> > diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
> > index 4cb2e92..32c991a 100644
> > --- a/src/glsl/nir/nir.h
> > +++ b/src/glsl/nir/nir.h
> > @@ -416,15 +416,23 @@ typedef struct {
> >  } nir_instr;
> >
> >  static inline nir_instr *
> > -nir_instr_next(const nir_instr *instr)
> > +nir_instr_next(nir_instr *instr)
> >  {
> > -   return exec_node_data(nir_instr, (instr)->node.next, node);
> > +   struct exec_node *next = exec_node_get_next(&instr->node);
> > +   if (exec_node_is_tail_sentinel(next))
> > +      return NULL;
> > +   else
> > +      return exec_node_data(nir_instr, next, node);
> >  }
> >
> >  static inline nir_instr *
> > -nir_instr_prev(const nir_instr *instr)
> > +nir_instr_prev(nir_instr *instr)
> >  {
> > -   return exec_node_data(nir_instr, (instr)->node.prev, node);
> > +   struct exec_node *prev = exec_node_get_prev(&instr->node);
> > +   if (exec_node_is_head_sentinel(prev))
> > +      return NULL;
> > +   else
> > +      return exec_node_data(nir_instr, prev, node);
> >  }
> >
> >  typedef struct {
> > @@ -1264,13 +1272,21 @@ typedef struct {
> >  static inline nir_cf_node *
> >  nir_cf_node_next(nir_cf_node *node)
> >  {
> > -   return exec_node_data(nir_cf_node, exec_node_get_next(&node->node),
> node);
> > +   struct exec_node *next = exec_node_get_next(&node->node);
> > +   if (exec_node_is_tail_sentinel(next))
> > +      return NULL;
> > +   else
> > +      return exec_node_data(nir_cf_node, next, node);
> >  }
> >
> >  static inline nir_cf_node *
> >  nir_cf_node_prev(nir_cf_node *node)
> >  {
> > -   return exec_node_data(nir_cf_node, exec_node_get_prev(&node->node),
> node);
> > +   struct exec_node *prev = exec_node_get_prev(&node->node);
> > +   if (exec_node_is_head_sentinel(prev))
> > +      return NULL;
> > +   else
> > +      return exec_node_data(nir_cf_node, prev, node);
> >  }
> >
> >  static inline bool
> > --
> > 2.2.2
> >
> > _______________________________________________
> > mesa-dev mailing list
> > mesa-dev at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
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