[Patch ARM] Fix PR target/19599

[Ramana Radhakrishnan]

On Fri, May 17, 2013 at 9:12 PM, Richard Henderson <rth@redhat.com> wrote:
> On 05/15/2013 04:50 AM, Ramana Radhakrishnan wrote:
>>    /* Cannot tail-call to long calls, since these are out of range of
>>       a branch instruction.  */
>> -  if (arm_is_long_call_p (decl))
>> +  if (decl && arm_is_long_call_p (decl))
>>      return false;
>
> You can tail call long calls via indirection now.  I.e. load the address first.

>
>>  (define_insn "*sibcall_insn"
>> - [(call (mem:SI (match_operand:SI 0 "" "X"))
>> + [(call (mem:SI (match_operand:SI 0 "call_insn_operand" "Cs,Ss"))
>
> FWIW, "i" or "s" would work just as well, given you've already constrained by
> call_insn_operand; Ss isn't really needed.

True - don't know what I was thinking there.

>
>> +      if (arm_arch5 || arm_arch4t)
>> +     return \" bx\\t%0\\t%@ indirect register sibling call\";
>
> Missing %?.

It's not marked predicable - if anything these %? markers ought to be
removed as well as I don't expect these to be conditionalized ever.

>
>> +      if (arm_arch5 || arm_arch4t)
>> +     return \"bx\\t%1\";
>
> Likewise.
>
>> diff --git a/gcc/testsuite/gcc.target/arm/pr40887.c b/gcc/testsuite/gcc.target/arm/pr40887.c
>> index 0b5e873..5cabe3a 100644
>> --- a/gcc/testsuite/gcc.target/arm/pr40887.c
>> +++ b/gcc/testsuite/gcc.target/arm/pr40887.c
>> @@ -2,9 +2,9 @@
>>  /* { dg-options "-O2 -march=armv5te" }  */
>>  /* { dg-final { scan-assembler "blx" } } */
>>
>> -int (*indirect_func)();
>> +int (*indirect_func)(int x);
>>
>>  int indirect_call()
>>  {
>> -    return indirect_func();
>> +  return indirect_func(20) + indirect_func (40);
>>  }
>>
>
> You've made this test case 100% useless.  Of course there will always be a blx
> insn, since you've two calls there, and one of them will never be tail called.
>  It should have been either removed or become your new test case.

If you haven't noticed it has effectively moved to pr19599.c as my
testcase . This is not 100% useless - this test was to make sure we
actually put out a blx for an indirect call as per PR40887 . So it
*actually* continues to test what we want as per PR40887 .

Thanks,
Ramana
>
> r~