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Re: [PATCH, MPX, 2/X] Pointers Checker [15/25] IPA Propagation


2013/11/18 Martin Jambor <mjambor@suse.cz>:
> On Mon, Nov 18, 2013 at 02:28:58PM +0400, Ilya Enkovich wrote:
>> Hi,
>>
>> Here is a patch to disable propagation of bounded values.
>>
>
> Why do ypu need to do this?  If the problem is that IPA-CP can remove
> parameter it knows is a constant, which somehow confuses how you pass
> bounds, then it is much better to clear
> node->local.can_change_signature flag for such nodes and it will not
> happen while still propagating stuff.
>
> Or is there some other reason?

Thanks for pointing to this flag. I'll look into it.

There is another problem in propagation - value shoud never be
propagated into BUILT_IN_CHKP_ARG_BND calls.  Ideally bounds of
propagated value should also be analyzed and propagated (in the most
cases bounds for constant value are also constant).  I suppose
can_change_signature flag can be used for lightweight support, when
param is propagated but bounds are not (it would still require special
handling of BUILT_IN_CHKP_ARG_BND calls).

This patch is to avoid ICEs before some scheme is implemented.

Thanks,
Ilya
>
> Thanks,
>
> Martin
>
>
>> Thanks,
>> Ilya
>> --
>> 2013-11-13  Ilya Enkovich  <ilya.enkovich@intel.com>
>>
>>       * ipa-prop.c: Include tree-chkp.h.
>>       (ipa_compute_jump_functions_for_edge): Do not propagate bounded args.
>>
>>
>> diff --git a/gcc/ipa-prop.c b/gcc/ipa-prop.c
>> index eb464e4..81e1237 100644
>> --- a/gcc/ipa-prop.c
>> +++ b/gcc/ipa-prop.c
>> @@ -48,6 +48,7 @@ along with GCC; see the file COPYING3.  If not see
>>  #include "tree-streamer.h"
>>  #include "params.h"
>>  #include "ipa-utils.h"
>> +#include "tree-chkp.h"
>>
>>  /* Intermediate information about a parameter that is only useful during the
>>     run of ipa_analyze_node and is not kept afterwards.  */
>> @@ -1558,6 +1559,7 @@ ipa_compute_jump_functions_for_edge (struct param_analysis_info *parms_ainfo,
>>    struct ipa_node_params *info = IPA_NODE_REF (cs->caller);
>>    struct ipa_edge_args *args = IPA_EDGE_REF (cs);
>>    gimple call = cs->call_stmt;
>> +  tree fndecl = gimple_call_fndecl (call);
>>    int n, arg_num = gimple_call_num_args (call);
>>
>>    if (arg_num == 0 || args->jump_functions)
>> @@ -1575,7 +1577,13 @@ ipa_compute_jump_functions_for_edge (struct param_analysis_info *parms_ainfo,
>>        tree arg = gimple_call_arg (call, n);
>>        tree param_type = ipa_get_callee_param_type (cs, n);
>>
>> -      if (is_gimple_ip_invariant (arg))
>> +      /* No optimization for bounded types yet implemented.  */
>> +      if ((gimple_call_with_bounds_p (call)
>> +        || (fndecl && chkp_function_instrumented_p (fndecl)))
>> +       && ((param_type && chkp_type_has_pointer (param_type))
>> +           || (!param_type && chkp_type_has_pointer (TREE_TYPE (arg)))))
>> +     continue;
>> +      else if (is_gimple_ip_invariant (arg))
>>       ipa_set_jf_constant (jfunc, arg, cs);
>>        else if (!is_gimple_reg_type (TREE_TYPE (arg))
>>              && TREE_CODE (arg) == PARM_DECL)


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