From: Jakub Jelinek Date: Fri, 27 Jan 2023 09:51:35 +0000 (+0100) Subject: tree: Fix up tree_code_{length,type} X-Git-Tag: basepoints/gcc-14~1776 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b0241ce6e37031e1cbde73d5389ec7f1d063e099;p=thirdparty%2Fgcc.git tree: Fix up tree_code_{length,type} On Thu, Jan 26, 2023 at 09:45:35AM -0500, Patrick Palka via Gcc-patches wrote: > > +#define DEFTREECODE(SYM, NAME, TYPE, LENGTH) TYPE, > > +#define END_OF_BASE_TREE_CODES tcc_exceptional, > > + > > + > > /* Class of tree given its code. */ > > -extern const enum tree_code_class tree_code_type[]; > > +constexpr enum tree_code_class tree_code_type[] = { > > +#include "all-tree.def" > > +}; > > + > > +#undef DEFTREECODE > > +#undef END_OF_BASE_TREE_CODES > > > > /* Each tree code class has an associated string representation. > > These must correspond to the tree_code_class entries. */ > > extern const char *const tree_code_class_strings[]; > > > > /* Number of argument-words in each kind of tree-node. */ > > -extern const unsigned char tree_code_length[]; > > + > > +#define DEFTREECODE(SYM, NAME, TYPE, LENGTH) LENGTH, > > +#define END_OF_BASE_TREE_CODES 0, > > +constexpr unsigned char tree_code_length[] = { > > +#include "all-tree.def" > > +}; > > + > > +#undef DEFTREECODE > > +#undef END_OF_BASE_TREE_CODES > > IIUC defining these globals as non-inline constexpr gives them internal > linkage, and so each TU contains its own unique copy of these globals. > This bloats cc1plus by a tiny bit and is technically an ODR violation > because some inline functions such as tree_class_check also ODR-use > these variables and so each defn of tree_class_check will refer to a > "different" tree_code_class. Since inline variables are a C++17 > feature, I guess we could fix this by defining the globals the old way > before C++17 and as inline constexpr otherwise? And I'd argue with the tiny bit. In my x86_64-linux cc1plus from today, I see 193 _ZL16tree_code_length vars, 374 bytes each, and 324 _ZL14tree_code_type vars, 1496 bytes each. So, that means waste of 555016 .rodata bytes, plus being highly non-cache friendly. The following patch does that. Tested on x86_64-linux in my -O0 working tree (system gcc 12 compiler) where .rodata shrunk with the patch by 928896 bytes, in last stage of a bootstrapped tree (built by today's prev-gcc) where .rodata shrunk by 561728 bytes (in neither case .text or most other sections changed sizes) and on powerpc64le-linux --disable-bootstrap (system gcc 4.8.5) to test also the non-C++17 case plus with fully x86_64-linux, i686-linux and powerpc64le-linux bootstraps/regtests. BTW, wonder if tree_code_type couldn't be an array of unsigned char elements rather than enum tree_code_class and we'd then cast it to the enum in the macro, that would shrink that array from 1496 bytes to 374. Of course, that sounds like stage1 material. 2023-01-27 Patrick Palka Jakub Jelinek * tree-core.h (tree_code_type, tree_code_length): For C++17 and later, add inline keyword, otherwise don't define the arrays, but declare extern arrays. * tree.cc (tree_code_type, tree_code_length): Define these arrays for C++14 and older. --- diff --git a/gcc/tree-core.h b/gcc/tree-core.h index 8124a1328d46..acd8deea34ea 100644 --- a/gcc/tree-core.h +++ b/gcc/tree-core.h @@ -2284,17 +2284,20 @@ struct floatn_type_info { /* Matrix describing the structures contained in a given tree code. */ extern bool tree_contains_struct[MAX_TREE_CODES][64]; +/* Class of tree given its code. */ +#if __cpp_inline_variables >= 201606L #define DEFTREECODE(SYM, NAME, TYPE, LENGTH) TYPE, #define END_OF_BASE_TREE_CODES tcc_exceptional, - -/* Class of tree given its code. */ -constexpr enum tree_code_class tree_code_type[] = { +constexpr inline enum tree_code_class tree_code_type[] = { #include "all-tree.def" }; #undef DEFTREECODE #undef END_OF_BASE_TREE_CODES +#else +extern const enum tree_code_class tree_code_type[]; +#endif /* Each tree code class has an associated string representation. These must correspond to the tree_code_class entries. */ @@ -2302,14 +2305,18 @@ extern const char *const tree_code_class_strings[]; /* Number of argument-words in each kind of tree-node. */ +#if __cpp_inline_variables >= 201606L #define DEFTREECODE(SYM, NAME, TYPE, LENGTH) LENGTH, #define END_OF_BASE_TREE_CODES 0, -constexpr unsigned char tree_code_length[] = { +constexpr inline unsigned char tree_code_length[] = { #include "all-tree.def" }; #undef DEFTREECODE #undef END_OF_BASE_TREE_CODES +#else +extern const unsigned char tree_code_length[]; +#endif /* Vector of all alias pairs for global symbols. */ extern GTY(()) vec *alias_pairs; diff --git a/gcc/tree.cc b/gcc/tree.cc index 7473912a065f..952bbece8cdc 100644 --- a/gcc/tree.cc +++ b/gcc/tree.cc @@ -74,7 +74,33 @@ along with GCC; see the file COPYING3. If not see #include "asan.h" #include "ubsan.h" +#if __cpp_inline_variables < 201606L +/* Tree code classes. */ +#define DEFTREECODE(SYM, NAME, TYPE, LENGTH) TYPE, +#define END_OF_BASE_TREE_CODES tcc_exceptional, + +const enum tree_code_class tree_code_type[] = { +#include "all-tree.def" +}; + +#undef DEFTREECODE +#undef END_OF_BASE_TREE_CODES + +/* Table indexed by tree code giving number of expression + operands beyond the fixed part of the node structure. + Not used for types or decls. */ + +#define DEFTREECODE(SYM, NAME, TYPE, LENGTH) LENGTH, +#define END_OF_BASE_TREE_CODES 0, + +const unsigned char tree_code_length[] = { +#include "all-tree.def" +}; + +#undef DEFTREECODE +#undef END_OF_BASE_TREE_CODES +#endif /* Names of tree components. Used for printing out the tree and error messages. */