ORDERED_EXPR in invert_tree_comparison
Richard Guenther
richard.guenther@gmail.com
Thu Aug 2 08:51:00 GMT 2012
On Wed, Aug 1, 2012 at 9:21 PM, Marc Glisse <marc.glisse@inria.fr> wrote:
> Hello,
>
> an opinion on this?
>
> (I just noticed: I'll update the list in the comment visible at the top of
> the patch if this gets in).
It looks ok to me but I am no floating-point expert. Can you add a testcase?
Ok with that change.
Thanks,
Richard.
>
> On Thu, 19 Jul 2012, Marc Glisse wrote:
>
>> Hello,
>>
>> the simple patch below passes the testsuite after a c,c++ bootstrap
>> without new regressions. Note however that
>>
>> #include <math.h>
>> int f(double a, double b){
>> return (!isunordered(a,b))&&(a<b);
>> }
>>
>> is then optimized by ifcombine to "return (a<b);", which seems wrong in
>> the absence of -fno-trapping-math. I don't know if there are ways to trigger
>> this latent bug without the patch.
>>
>>
>>
>> 2012-06-15 Marc Glisse <marc.glisse@inria.fr>
>>
>> PR tree-optimization/53805
>> * fold-const.c (invert_tree_comparison): Do invert ORDERED_EXPR and
>> UNORDERED_EXPR for floating point.
>>
>> --- fold-const.c (revision 189622)
>> +++ fold-const.c (working copy)
>> @@ -2096,13 +2096,14 @@ pedantic_non_lvalue_loc (location_t loc,
>> It is generally not safe to do this for floating-point comparisons,
>> except
>> for EQ_EXPR and NE_EXPR, so we return ERROR_MARK in this case. */
>>
>> enum tree_code
>> invert_tree_comparison (enum tree_code code, bool honor_nans)
>> {
>> - if (honor_nans && flag_trapping_math && code != EQ_EXPR && code !=
>> NE_EXPR)
>> + if (honor_nans && flag_trapping_math && code != EQ_EXPR && code !=
>> NE_EXPR
>> + && code != ORDERED_EXPR && code != UNORDERED_EXPR)
>> return ERROR_MARK;
>>
>> switch (code)
>> {
>> case EQ_EXPR:
>> return NE_EXPR;
>
>
> --
> Marc Glisse
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