Re: [tree-ssa] bootstrap problem on powerpc-apple-darwin6.6

[Daniel Berlin <dberlin at dberlin dot org>]

On Thursday, August 21, 2003, at 4:45 PM, law@redhat.com wrote:

> In message <622F711B-D416-11D7-B633-000393A6D2F2@physics.uc.edu>, 
> Andrew Pinski
>  writes:
> > Here is more reduced sources:
> > union tree_node;
> > typedef union tree_node *tree;
> > typedef enum fallback_t {
> >   fb_none = 0,
> >   fb_rvalue=1,
> >   fb_lvalue=2,
> >   fb_either=1|2
> > } fallback_t;
> >
> > int
> > gimplify_expr (tree *expr_p, fallback_t fallback)
> > {
> > if ((fallback & fb_rvalue) && *expr_p)
> >     {
> >         f_temp_2();
> >     }
> >   else
> >     {
> >         abort();
> >     }
> >   return 1;
> > }
> >
> >
> > The problem is gimplify_expr (which is weird as this is the function
> > which is causing this ICE)
> > These lines on 491-494:
> > 	  /* Strip away as many useless type conversions as possible
> > 	     at the toplevel.  */
> > 	  while (tree_ssa_useless_type_conversion (*expr_p))
> > 	    *expr_p = TREE_OPERAND (*expr_p, 0);
> > is removing the conversion to boolean_type:
> > From tree_ssa_useless_type_conversion:
> >       /* If both the inner and outer types are integral types, then
> >          we can enter the equivalence if they have the same mode
> >          and signedness.  */
> >       else if (INTEGRAL_TYPE_P (inner_type) && INTEGRAL_TYPE_P
> > (outer_type)
> > 	       && TYPE_MODE (inner_type) == TYPE_MODE (outer_type)
> > 	       && TREE_UNSIGNED (inner_type) == TREE_UNSIGNED (outer_type))
> > 	return true;
> > which is true in this case which cause it to remove the nop_expr which
> > converts to boolean_type.
> >
> > Jeff you added tree_ssa_useless_type_conversion can you say what is
> > going on and why is this happening?
> It's pretty self explanatory -- it's trying to remove type conversions 
> which
> are unnecessary.  I would ask, why do you think the conversion is 
> necessary
> in the first place?  It's possible y'all have summarized this already 
> and
> I simply missed it -- in which case just point me to the appropriate 
> point
> in the archives.

This stripping you do undoes what gimple_boolify_expr did to convert it 
to a boolean_type.
Then invert_truthop aborts when it tries to invert a non-boolean_type 
tree.
So either
1. The conversion isn't useless, but gimplify_boolify_expr is not 
generating the conversion in a way that makes it seem un-useless.
2. The conversion isn't useless, and the above is not working like it 
should.
3. The conversion really is useless, and invert_truthop_value should 
let us invert it even though it's not a BOOLEAN_TYPE.
> jeff