[patch] PR 48837

[Jeff Law]

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On 05/06/11 04:44, Zdenek Dvorak wrote:
> Hi,
> 
> when accumulator transformation is performed on a function like
> 
> foo(a)
> {
>   if (a > 0)
>     return 1 + foo (a - 1)
> 
>   return bla();
> }
> 
> this becomes
> 
> foo(a)
> {
>   int tmp = 0;
> 
>   while (a > 0)
>     tm = 1 + tmp;
> 
>   return tmp + bla();
> }
> 
> Before, bla was a tail-call, but after the optimization, it is not (since an addition
> has to be performed after the result of bla is known).  However, we used to mark bla
> as tail-call, leading to a misscompilation later.  Fixed by not marking tail-calls
> when the transformation is performed.  Bootstrapped and regtested on i686.
> 
> Zdenek
> 
> 	PR tree-optimization/48837
> 	* tree-tailcall.c (tree_optimize_tail_calls_1): Do not mark tailcalls
> 	when accumulator transformation is performed.
> 
> 	* gcc.dg/pr48837.c: New testcase.
OK.

Thanks,
jeff
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