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Re: [PATCH, MPX, 2/X] Pointers Checker [15/25] IPA Propagation
- From: Ilya Enkovich <enkovich dot gnu at gmail dot com>
- To: Ilya Enkovich <enkovich dot gnu at gmail dot com>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 18 Nov 2013 22:38:49 +0400
- Subject: Re: [PATCH, MPX, 2/X] Pointers Checker [15/25] IPA Propagation
- Authentication-results: sourceware.org; auth=none
- References: <20131118102858 dot GI21297 at msticlxl57 dot ims dot intel dot com> <20131118182428 dot GD3403 at virgil dot suse>
2013/11/18 Martin Jambor <firstname.lastname@example.org>:
> On Mon, Nov 18, 2013 at 02:28:58PM +0400, Ilya Enkovich wrote:
>> 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.
>> 2013-11-13 Ilya Enkovich <email@example.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)