2013/11/5 Richard Biener <[email protected]>:
> On Tue, Nov 5, 2013 at 1:52 PM, Ilya Enkovich <[email protected]> wrote:
>>
>> For input parameter P I need to have
>> BOUNDS = __builtin_arg_bnd (P)
>> to somehow refer to bounds of P in GIMPLE. Optimizations may modify
>> __builtin_arg_bnd (P) replacing P with its copy or some value. It
>> makes call useless because removes information about parameter whose
>> bounds we refer to. I want such optimization to ignore
>> __builtin_arg_bnd calls and always leave default SSA_NAME of PARM_DECL
>> there as arg.
>
> How does a compilable testcase look like that shows how the default def
> is used? And what transforms break that use? I really cannot see
> how this would happen (and you didn't add a testcase).
Here is a test source:
extern int bar1 (int *p);
extern int bar2 (int);
int foo (int *p)
{
if (!p)
return bar1 (p);
return bar2 (10);
}
After instrumentation GIMPLE looks like:
foo (int * p)
{
<unnamed type> __bound_tmp.0;
int _1;
int _6;
int _8;
<bb 6>:
__bound_tmp.0_9 = __builtin_ia32_arg_bnd (p_3(D));
<bb 2>:
if (p_3(D) == 0B)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
_6 = bar1 (p_3(D), __bound_tmp.0_9);
goto <bb 5>;
<bb 4>:
_8 = bar2 (10);
<bb 5>:
# _1 = PHI <_6(3), _8(4)>
return _1;
}
Here is optimized GIMPLE (if I do not apply my changes in tree-ssa-dom.c):
foo (int * p)
{
<unnamed type> __bound_tmp.0;
int _1;
int _6;
int _8;
<bb 2>:
if (p_3(D) == 0B)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
__bound_tmp.0_9 = __builtin_ia32_arg_bnd (0B); [return slot optimization]
_6 = bar1 (0B, __bound_tmp.0_9); [tail call]
goto <bb 5>;
<bb 4>:
_8 = bar2 (10); [tail call]
<bb 5>:
# _1 = PHI <_6(3), _8(4)>
return _1;
}
Now during expand or inline of foo I cannot determine the value for
__bound_tmp.0_9.
Ilya
>
> Richard.
>
