| Message ID | alpine.LSU.2.11.1509021456160.5523@zhemvz.fhfr.qr |
|---|---|
| State | New |
| Headers | show |
> > I was naiively using ->get_constructor in IPA PTA without proper > checking on wheter that succeeds. Now I tried to use ctor_for_folding > but that isn't good as we want to analyze non-const globals in IPA > PTA and we need to analyze their initialiers as well. > > Thus I'm trying below with ctor_for_analysis, but I really "just" > need the initializer or a "not available" for conservative handling. > > Bootstrapped and tested on x86_64-unknown-linux-gnu. > > Honza - I suppose you should doble-check this and suggest sth > different (or implement sth more generic in the IPA infrastructure). Yep, you are correct that we don't currently have way to look into ctor without actually loading. But do you need something more than just walking references that you already have in ipa-ref lists? > > Thanks, > Richard. > > 2015-09-02 Richard Biener <rguenther@suse.de> > > PR ipa/66705 > * tree-ssa-structalias.c (ctor_for_analysis): New function. > (create_variable_info_for_1): Use ctor_for_analysis instead > of get_constructor. > (create_variable_info_for): Likewise. Otherwise I would go for making ctor_for_analysis a method of varpool_node and... > > * g++.dg/lto/pr66705_0.C: New testcase. > > Index: gcc/tree-ssa-structalias.c > =================================================================== > --- gcc/tree-ssa-structalias.c (revision 227207) > +++ gcc/tree-ssa-structalias.c (working copy) > @@ -5637,6 +5637,26 @@ check_for_overlaps (vec<fieldoff_s> fiel > return false; > } > > +/* We can't use ctor_for_folding as that only returns constant constructors. */ > + > +static tree > +ctor_for_analysis (tree decl) > +{ > + varpool_node *node = varpool_node::get (decl); > + if (!node) > + return error_mark_node; > + node = node->ultimate_alias_target (); > + if (DECL_INITIAL (node->decl) != error_mark_node > + || !in_lto_p) > + return (DECL_INITIAL (node->decl) > + ? DECL_INITIAL (node->decl) : error_mark_node); I think returning NULL here is just fine. error_mark_node means constructor is not really available. NULL is the usual way to say that the variable is not initialized.
On Wed, 2 Sep 2015, Jan Hubicka wrote: > > > > I was naiively using ->get_constructor in IPA PTA without proper > > checking on wheter that succeeds. Now I tried to use ctor_for_folding > > but that isn't good as we want to analyze non-const globals in IPA > > PTA and we need to analyze their initialiers as well. > > > > Thus I'm trying below with ctor_for_analysis, but I really "just" > > need the initializer or a "not available" for conservative handling. > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu. > > > > Honza - I suppose you should doble-check this and suggest sth > > different (or implement sth more generic in the IPA infrastructure). > > Yep, you are correct that we don't currently have way to look into ctor > without actually loading. But do you need something more than just walking > references that you already have in ipa-ref lists? Hmm, no, ipa-ref list should be enough (unless we start field-sensitive analysis or need NULL inits for correctness). Still have to figure out how to walk the list and how the reference would look like (what is ref->use? IPA_REF_ADDR? can those be speculative?) Richard. > > > > Thanks, > > Richard. > > > > 2015-09-02 Richard Biener <rguenther@suse.de> > > > > PR ipa/66705 > > * tree-ssa-structalias.c (ctor_for_analysis): New function. > > (create_variable_info_for_1): Use ctor_for_analysis instead > > of get_constructor. > > (create_variable_info_for): Likewise. > > Otherwise I would go for making ctor_for_analysis a method of varpool_node and... > > > > * g++.dg/lto/pr66705_0.C: New testcase. > > > > Index: gcc/tree-ssa-structalias.c > > =================================================================== > > --- gcc/tree-ssa-structalias.c (revision 227207) > > +++ gcc/tree-ssa-structalias.c (working copy) > > @@ -5637,6 +5637,26 @@ check_for_overlaps (vec<fieldoff_s> fiel > > return false; > > } > > > > +/* We can't use ctor_for_folding as that only returns constant constructors. */ > > + > > +static tree > > +ctor_for_analysis (tree decl) > > +{ > > + varpool_node *node = varpool_node::get (decl); > > + if (!node) > > + return error_mark_node; > > + node = node->ultimate_alias_target (); > > + if (DECL_INITIAL (node->decl) != error_mark_node > > + || !in_lto_p) > > + return (DECL_INITIAL (node->decl) > > + ? DECL_INITIAL (node->decl) : error_mark_node); > > I think returning NULL here is just fine. > error_mark_node means constructor is not really available. NULL is > the usual way to say that the variable is not initialized. > >
> > Hmm, no, ipa-ref list should be enough (unless we start field-sensitive > analysis or need NULL inits for correctness). Still have to figure out > how to walk the list and how the reference would look like (what > is ref->use? IPA_REF_ADDR? can those be speculative?) Yep, it should be IPA_REF_ADDR. If you do not check for that, you will probably also trip IPA_REF_ALIAS as dereference (which would lead to missed optimization). If we go field sensitive, we may want to extend ipa references anyway - that would be useful for ipa-reference and other stuff, too. Honza > > Richard. > > > > > > > Thanks, > > > Richard. > > > > > > 2015-09-02 Richard Biener <rguenther@suse.de> > > > > > > PR ipa/66705 > > > * tree-ssa-structalias.c (ctor_for_analysis): New function. > > > (create_variable_info_for_1): Use ctor_for_analysis instead > > > of get_constructor. > > > (create_variable_info_for): Likewise. > > > > Otherwise I would go for making ctor_for_analysis a method of varpool_node and... > > > > > > * g++.dg/lto/pr66705_0.C: New testcase. > > > > > > Index: gcc/tree-ssa-structalias.c > > > =================================================================== > > > --- gcc/tree-ssa-structalias.c (revision 227207) > > > +++ gcc/tree-ssa-structalias.c (working copy) > > > @@ -5637,6 +5637,26 @@ check_for_overlaps (vec<fieldoff_s> fiel > > > return false; > > > } > > > > > > +/* We can't use ctor_for_folding as that only returns constant constructors. */ > > > + > > > +static tree > > > +ctor_for_analysis (tree decl) > > > +{ > > > + varpool_node *node = varpool_node::get (decl); > > > + if (!node) > > > + return error_mark_node; > > > + node = node->ultimate_alias_target (); > > > + if (DECL_INITIAL (node->decl) != error_mark_node > > > + || !in_lto_p) > > > + return (DECL_INITIAL (node->decl) > > > + ? DECL_INITIAL (node->decl) : error_mark_node); > > > > I think returning NULL here is just fine. > > error_mark_node means constructor is not really available. NULL is > > the usual way to say that the variable is not initialized. > > > > > > -- > Richard Biener <rguenther@suse.de> > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)
Index: gcc/tree-ssa-structalias.c =================================================================== --- gcc/tree-ssa-structalias.c (revision 227207) +++ gcc/tree-ssa-structalias.c (working copy) @@ -5637,6 +5637,26 @@ check_for_overlaps (vec<fieldoff_s> fiel return false; } +/* We can't use ctor_for_folding as that only returns constant constructors. */ + +static tree +ctor_for_analysis (tree decl) +{ + varpool_node *node = varpool_node::get (decl); + if (!node) + return error_mark_node; + node = node->ultimate_alias_target (); + if (DECL_INITIAL (node->decl) != error_mark_node + || !in_lto_p) + return (DECL_INITIAL (node->decl) + ? DECL_INITIAL (node->decl) : error_mark_node); + if (in_lto_p + && node->lto_file_data + && !node->body_removed) + return node->get_constructor (); + return error_mark_node; +} + /* Create a varinfo structure for NAME and DECL, and add it to VARMAP. This will also create any varinfo structures necessary for fields of DECL. */ @@ -5650,7 +5670,6 @@ create_variable_info_for_1 (tree decl, c auto_vec<fieldoff_s> fieldstack; fieldoff_s *fo; unsigned int i; - varpool_node *vnode; if (!declsize || !tree_fits_uhwi_p (declsize)) @@ -5672,8 +5691,7 @@ create_variable_info_for_1 (tree decl, c in IPA mode. Else we'd have to parse arbitrary initializers. */ && !(in_ipa_mode && is_global_var (decl) - && (vnode = varpool_node::get (decl)) - && vnode->get_constructor ())) + && ctor_for_analysis (decl) != error_mark_node)) { fieldoff_s *fo = NULL; bool notokay = false; @@ -5805,13 +5823,13 @@ create_variable_info_for (tree decl, con /* If this is a global variable with an initializer and we are in IPA mode generate constraints for it. */ - if (vnode->get_constructor () - && vnode->definition) + tree ctor = ctor_for_analysis (decl); + if (ctor != error_mark_node) { auto_vec<ce_s> rhsc; struct constraint_expr lhs, *rhsp; unsigned i; - get_constraint_for_rhs (vnode->get_constructor (), &rhsc); + get_constraint_for_rhs (ctor, &rhsc); lhs.var = vi->id; lhs.offset = 0; lhs.type = SCALAR; Index: gcc/testsuite/g++.dg/lto/pr66705_0.C =================================================================== --- gcc/testsuite/g++.dg/lto/pr66705_0.C (revision 0) +++ gcc/testsuite/g++.dg/lto/pr66705_0.C (working copy) @@ -0,0 +1,15 @@ +// { dg-lto-do link } +// { dg-lto-options { { -O2 -flto -flto-partition=max -fipa-pta } } } +// { dg-extra-ld-options "-r -nostdlib" } + +class A { +public: + A(); +}; +int a = 0; +void foo() { + a = 0; + A b; + for (; a;) + ; +}