Message ID | 20201127132622.GB78170@kam.mff.cuni.cz |
---|---|
State | New |
Headers | show |
Series | [C++] Re: Free more of CFG in release_function_body | expand |
On 11/27/20 6:26 AM, Jan Hubicka wrote: >>> On Wed, Nov 25, 2020 at 3:11 PM Jan Hubicka <hubicka@ucw.cz> wrote: >>>>> On Tue, 24 Nov 2020, Jan Hubicka wrote: >>>>> >>>>>> Hi, >>>>>> at the end of processing function body we loop over basic blocks and >>>>>> free all edges while we do not free the rest. I think this is leftover >>>>>> from time eges was not garbage collected and we was not using ggc_free. >>>>>> It makes more sense to free all associated structures (which is >>>>>> importnat for WPA memory footprint). >>>>>> >>>>>> Bootstrapped/regtested x86_64-linux, OK? >>>>> OK. >>>> Unforutnately the patch does not surive LTO bootstrap. The problem is >>>> that we keep DECL_INITIAL that points to blocks and blocks points to >>>> var_decls and these points to SSA_NAMES that points to statements and >>>> those points to basic blocks. >>> VAR_DECLs point to SSA_NAMEs? It's the other way around. We for sure >>> free SSA_NAMEs (well, maybe not explicitely with ggc_free). >> I am going to debug this more carefully now. I think it was VAR_DECL >> with variadic type pointing to SSA_NAME. Should be easy to reduct with >> gcac compiler. > Hi, > it turns out that the pointers to statements leaks through saved scopes > in C++ FE. Scopes seems to point to internal blocks of functions even > after we finish their compiling. > > This patch adds code to free pointers. I tried to clear saved_blocks > but it breaks since C++ finalization uses them, but it does not look > into previous class levels. > > Patch lto-bootstraps/regtestes x86_64-linux with all languages. OK? > > Honza > > * cfg.c (free_block): Call ggc_free on BB itself. I'll ACK this bit. The C++ team should own the rest, while it looks reasonable to me, there may be some reason I'm not aware of that they're keeping that stuff around. Jeff
On 11/27/20 8:26 AM, Jan Hubicka wrote: >>> On Wed, Nov 25, 2020 at 3:11 PM Jan Hubicka <hubicka@ucw.cz> wrote: >>>> >>>>> On Tue, 24 Nov 2020, Jan Hubicka wrote: >>>>> >>>>>> Hi, >>>>>> at the end of processing function body we loop over basic blocks and >>>>>> free all edges while we do not free the rest. I think this is leftover >>>>>> from time eges was not garbage collected and we was not using ggc_free. >>>>>> It makes more sense to free all associated structures (which is >>>>>> importnat for WPA memory footprint). >>>>>> >>>>>> Bootstrapped/regtested x86_64-linux, OK? >>>>> >>>>> OK. >>>> >>>> Unforutnately the patch does not surive LTO bootstrap. The problem is >>>> that we keep DECL_INITIAL that points to blocks and blocks points to >>>> var_decls and these points to SSA_NAMES that points to statements and >>>> those points to basic blocks. >>> >>> VAR_DECLs point to SSA_NAMEs? It's the other way around. We for sure >>> free SSA_NAMEs (well, maybe not explicitely with ggc_free). >> >> I am going to debug this more carefully now. I think it was VAR_DECL >> with variadic type pointing to SSA_NAME. Should be easy to reduct with >> gcac compiler. > > Hi, > it turns out that the pointers to statements leaks through saved scopes > in C++ FE. Scopes seems to point to internal blocks of functions even > after we finish their compiling. > > This patch adds code to free pointers. I tried to clear saved_blocks > but it breaks since C++ finalization uses them, but it does not look > into previous class levels. > > Patch lto-bootstraps/regtestes x86_64-linux with all languages. OK? > > Honza > > * cfg.c (free_block): Call ggc_free on BB itself. > > * cp-tre.eh (cp_tree_c_finish_parsing): Declare. > * semantics.c (finish_translation_unit): Call finish_parsing > * tree.c (cp_tree_c_finish_parsing): New function. > diff --git a/gcc/cfg.c b/gcc/cfg.c > index 529b6ed2105..e8bd1456c9f 100644 > --- a/gcc/cfg.c > +++ b/gcc/cfg.c > @@ -102,8 +102,7 @@ free_block (basic_block bb) > bb->succs = NULL; > vec_free (bb->preds); > bb->preds = NULL; > - /* Do not free BB itself yet since we leak pointers to dead statements > - that points to dead basic blocks. */ > + ggc_free (bb); > } > > /* Free the memory associated with the CFG in FN. */ > diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h > index 021de76e142..665d171d9b0 100644 > --- a/gcc/cp/cp-tree.h > +++ b/gcc/cp/cp-tree.h > @@ -7986,6 +7986,8 @@ struct uid_sensitive_constexpr_evaluation_checker > bool evaluation_restricted_p () const; > }; > > +void cp_tree_c_finish_parsing (); > + > /* In cp-ubsan.c */ > extern void cp_ubsan_maybe_instrument_member_call (tree); > extern void cp_ubsan_instrument_member_accesses (tree *); > diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c > index 5ff70ff4844..e9d17c21985 100644 > --- a/gcc/cp/semantics.c > +++ b/gcc/cp/semantics.c > @@ -3094,6 +3094,7 @@ finish_translation_unit (void) > "%<#pragma omp end declare target%>"); > scope_chain->omp_declare_target_attribute = 0; > } > + cp_tree_c_finish_parsing (); This is too soon for this call; it should be from c_parse_final_cleanups by the call to fini_constexpr, so that it follows template instantiation at EOF. > } > > /* Finish a template type parameter, specified as AGGR IDENTIFIER. > diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c > index 28e591086b3..e63d383c0a3 100644 > --- a/gcc/cp/tree.c > +++ b/gcc/cp/tree.c > @@ -5844,6 +5844,19 @@ maybe_warn_zero_as_null_pointer_constant (tree expr, location_t loc) > return false; > } > > +/* Release memory we no longer need after parsing. */ > +void > +cp_tree_c_finish_parsing () > +{ > + saved_scope *chain = scope_chain; > + while (chain) > + { > + chain->x_previous_class_level = NULL; > + chain = chain->prev; > + } This can just be invalidate_class_lookup_cache (). scope_chain->prev will always be NULL at this point. OK with those changes. > + deleted_copy_types = NULL; > +} > + > #if defined ENABLE_TREE_CHECKING && (GCC_VERSION >= 2007) > /* Complain that some language-specific thing hanging off a tree > node has been accessed improperly. */
diff --git a/gcc/cfg.c b/gcc/cfg.c index 529b6ed2105..e8bd1456c9f 100644 --- a/gcc/cfg.c +++ b/gcc/cfg.c @@ -102,8 +102,7 @@ free_block (basic_block bb) bb->succs = NULL; vec_free (bb->preds); bb->preds = NULL; - /* Do not free BB itself yet since we leak pointers to dead statements - that points to dead basic blocks. */ + ggc_free (bb); } /* Free the memory associated with the CFG in FN. */ diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 021de76e142..665d171d9b0 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -7986,6 +7986,8 @@ struct uid_sensitive_constexpr_evaluation_checker bool evaluation_restricted_p () const; }; +void cp_tree_c_finish_parsing (); + /* In cp-ubsan.c */ extern void cp_ubsan_maybe_instrument_member_call (tree); extern void cp_ubsan_instrument_member_accesses (tree *); diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c index 5ff70ff4844..e9d17c21985 100644 --- a/gcc/cp/semantics.c +++ b/gcc/cp/semantics.c @@ -3094,6 +3094,7 @@ finish_translation_unit (void) "%<#pragma omp end declare target%>"); scope_chain->omp_declare_target_attribute = 0; } + cp_tree_c_finish_parsing (); } /* Finish a template type parameter, specified as AGGR IDENTIFIER. diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c index 28e591086b3..e63d383c0a3 100644 --- a/gcc/cp/tree.c +++ b/gcc/cp/tree.c @@ -5844,6 +5844,19 @@ maybe_warn_zero_as_null_pointer_constant (tree expr, location_t loc) return false; } +/* Release memory we no longer need after parsing. */ +void +cp_tree_c_finish_parsing () +{ + saved_scope *chain = scope_chain; + while (chain) + { + chain->x_previous_class_level = NULL; + chain = chain->prev; + } + deleted_copy_types = NULL; +} + #if defined ENABLE_TREE_CHECKING && (GCC_VERSION >= 2007) /* Complain that some language-specific thing hanging off a tree node has been accessed improperly. */