[Patch ARM] Fix PR target/19599

[Richard Henderson]

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.

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

Missing %?.

> +      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.


r~