Re: enable sqrt insns for cdce3.c

[Alexandre Oliva <oliva@adacore.com>]

On Mar 10, 2021, Hans-Peter Nilsson <hp@bitrange.com> wrote:

> On Wed, 10 Mar 2021, Alexandre Oliva wrote:
>> 
>> The test expects shrink-wrapping of the fsqrt call, but that will only
>> occur when there is a usable sqrt insn.
>> 
>> Arrange for dejagnu to add the options that enable the sqrt insn, if
>> one is available, and to skip the test otherwise.
>> 
>> 
>> H-P, this *should* obviate the mmix-specific dg-skip-if.

> Unfortunately it doesn't.

Uhh :-(

>> Would it be
>> easy for you to confirm that this is the case and, if so, drop it?

> About as easy as for anyone (this is a compile-test),

I figured you'd have a recent toolchain around ;-)  Thanks!

> FAIL: gcc.dg/cdce3.c scan-tree-dump cdce "cdce3.c:12: [^\n\r]*
> function call is shrink-wrapped into error conditions."

How surprising!  My understanding was that dg-add-options <feature>
implicitly implies dg-require-effective-target <feature>.  That was how
I'd read et-dg-runtest.

Now I see the _runtime after the check_effective_target_${target} there,
and my understanding is updated, so some pending changes may need
revisiting.  Oh my...


> The dump files and assembly file show no obvious clues to me as
> to what is supposed to happen; attached.

The test just should keep on not running on mmix.  Without an insn for
sqrt, there's no point in shrink-wrapping, and the code that performs
the optimization is smart enough to realize that, so it just leaves the
code alone.


-- 
Alexandre Oliva, happy hacker  https://FSFLA.org/blogs/lxo/
   Free Software Activist         GNU Toolchain Engineer
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