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Re: Question re missed CSEing at tree level


On Wed, 2004-07-28 at 22:23, Richard Kenner wrote:
> While looking at the miscompilation of back_end.adb, I noticed the following
> in the t56.tailc file, which makes it all the way out:
> 
> <L1>:;
>   saved_stack.134_91 = __builtin_stack_save ();
>   save_argv.54_96 = save_argv;
>   T.271_97 = FRAME.267.next_arg;
>   next_arg.51_98 = (types__TintB)T.271_97;
>   T.55_99 = (<unnamed type>)next_arg.51_98;
>   argv_ptr_100 = (*save_argv.54_96)[T.55_99];
>   save_argv.233_177 = save_argv;
>   T.236_176 = (*save_argv.233_177)[T.55_99];
>   T.240_320 = (*T.236_176)[1]{lb: 1 sz: 1};
>   if (T.240_320 == 0) goto <L3>; else goto <L5>;
> 
> The computations for argv_ptr_100 and t.240_320 are identical and the
> second dereference should have been suppressed.
> 
Is save_argv volatile?  It seems to be, as it's not renamed.  If so, we
can't prove that save_argv.233_177 == save_argv.54_96.  Show me the
output with -vops?


Diego.


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