The 08/28/2025 14:43, Jason Merrill wrote:
> On 8/28/25 5:49 AM, alfie.richa...@arm.com wrote:
> > From: Alfie Richards <alfie.richa...@arm.com>
> >
> > Adds the target_version and target_clones attributes to diagnostic messages
> > for target_version semantics.
> >
> > This is because the target_version/target_clones attributes affect the
> > identity
> > of the decls, so need to be represented in diagnostics for them.
> >
> > This also requires making maybe_print_whitespace available to c++ code so
>
> pp_c_maybe_whitespace
>
> But why do we need to call it in C++ when we don't in C?
(Resending as I forgot to reply all)
Because I use it to print the white space after the attribute which isn't needed
in the C diagnostic.
The difficulty is I want C++ to do:
'float foo [[target_version("sve")]] ()'
(with a space before and after)
and
'float foo()'
with no spaces (unchanged from current formatting)
But for C I want:
'foo [[target_version("sve")]]'
Notably, without a space after the attribute.
The slightly ugly way I achieved this is that pp_c_function_target_version
sets pp->set_padding (pp_before) if it prints the attribute, so then
pp_cpp_maybe_whitespace can be used only in the C++ code to add the extra
white space only if the attribute is added.
I'm not happy with this way of achieving this, if you know a simpler
way to achieve this I would be happy to change it.
>
> > we can control if whitespace is needed cosistantly between c and c++
>
> "consistently"
>
> > diagnostics.
> >
> > After this change diagnostics look like:
> >
> > c:
> > ```
> > test.c:6:8: error: redefinition of ‘foo [[target_version("sve")]]’
> > 6 | float foo () {return 1;}
> > | ^~~
> > test.c:3:8: note: previous definition of ‘foo [[target_version("sve")]]’
> > with type ‘float(void)’
> > 3 | float foo () {return 2;}
> > | ^~~
> > test.c:12:8: error: redefinition of ‘bar [[target_clones("sve")]]’
> > 12 | float bar () {return 1;}
> > | ^~~
> > test.c:9:8: note: previous definition of ‘bar [[target_clones("sve")]]’
> > with type ‘float(void)’
> > 9 | float bar () {return 2;}
> > | ^~~
> > ```
> >
> > c++:
> > ```
> > test.cpp:6:8: error: redefinition of ‘float foo [[target_version("sve")]]
> > ()’
> > 6 | float foo () {return 1;}
> > | ^~~
> > test.cpp:3:8: note: ‘float foo [[target_version("sve")]] ()’ previously
> > defined here
> > 3 | float foo () {return 2;}
> > | ^~~
> > test.cpp:12:8: error: redefinition of ‘float bar [[target_clones("sve")]]
> > ()’
> > 12 | float bar () {return 1;}
> > | ^~~
> > test.cpp:9:8: note: ‘float bar [[target_clones("sve")]] ()’ previously
> > defined here
> > 9 | float bar () {return 2;}
> > | ^~~
> > ```
> >
> > This only affects targets which use target_version (aarch64 and riscv).
> >
> > gcc/c-family/ChangeLog:
> >
> > * c-pretty-print.cc (pp_c_function_target_version): New function.
> > (pp_c_function_target_clones): New function.
> > (pp_c_maybe_whitespace): Move to c-pretty-print.h.
> > * c-pretty-print.h (pp_c_function_target_version): New function.
> > (pp_c_function_target_clones): New function.
> > (pp_c_maybe_whitespace): Moved here from c-pretty-print.cc.
> >
> > gcc/c/ChangeLog:
> >
> > * c-objc-common.cc (c_tree_printer): Add printing of target_clone and
> > target_version in decl diagnostics.
> >
> > gcc/cp/ChangeLog:
> >
> > * cxx-pretty-print.h (pp_cxx_function_target_version): New macro.
> > (pp_cxx_function_target_clones): Ditto.
> > (pp_cxx_maybe_whitespace): Ditto.
> > * error.cc (dump_function_decl): Add printing of target_clone and
> > target_version in decl diagnostics.
> > ---
> > gcc/c-family/c-pretty-print.cc | 77 +++++++++++++++++++++++++++++++---
> > gcc/c-family/c-pretty-print.h | 8 ++++
> > gcc/c/c-objc-common.cc | 6 +++
> > gcc/cp/cxx-pretty-print.h | 5 +++
> > gcc/cp/error.cc | 8 ++++
> > 5 files changed, 98 insertions(+), 6 deletions(-)
> >
> > diff --git a/gcc/c-family/c-pretty-print.cc b/gcc/c-family/c-pretty-print.cc
> > index fad6b5eb9b0..5adb13b9784 100644
> > --- a/gcc/c-family/c-pretty-print.cc
> > +++ b/gcc/c-family/c-pretty-print.cc
> > @@ -36,6 +36,7 @@ along with GCC; see the file COPYING3. If not see
> > #include "function.h"
> > #include "basic-block.h"
> > #include "gimple.h"
> > +#include "tm.h"
> > /* The pretty-printer code is primarily designed to closely follow
> > (GNU) C and C++ grammars. That is to be contrasted with spaghetti
> > @@ -45,12 +46,6 @@ along with GCC; see the file COPYING3. If not see
> > takes expression or declaration contexts into account. */
> > -#define pp_c_maybe_whitespace(PP) \
> > - do { \
> > - if ((PP)->get_padding () == pp_before) \
> > - pp_c_whitespace (PP); \
> > - } while (0)
> > -
> > /* literal */
> > static void pp_c_char (c_pretty_printer *, int);
> > @@ -3054,6 +3049,76 @@ pp_c_tree_decl_identifier (c_pretty_printer *pp,
> > tree t)
> > pp_c_identifier (pp, name);
> > }
> > +/* Prints "[version: VERSION]" for a versioned function decl.
> > + This will only print for targets with target_version semantics. */
> > +void
> > +pp_c_function_target_version (c_pretty_printer *pp, tree t)
> > +{
> > + if (TARGET_HAS_FMV_TARGET_ATTRIBUTE)
> > + return;
> > +
> > + string_slice version = get_target_version (t);
> > + if (!version.is_valid ())
> > + return;
> > +
> > + pp_c_whitespace (pp);
> > +
> > + pp_c_left_bracket (pp);
> > + pp_c_left_bracket (pp);
> > + pp_string (pp, "target_version");
> > + pp_c_left_paren (pp);
> > + pp_doublequote (pp);
> > + pp_string_n (pp, version.begin (), version.size ());
> > + pp_doublequote (pp);
> > + pp_c_right_paren (pp);
> > + pp_c_right_bracket (pp);
> > + pp_c_right_bracket (pp);
> > +
> > + pp->set_padding (pp_before);
> > +}
> > +
> > +/* Prints "[clones: VERSION, +]" for a versioned function decl.
> > + This only works for targets with target_version semantics. */
> > +void
> > +pp_c_function_target_clones (c_pretty_printer *pp, tree t)
> > +{
> > + /* Only print for target_version semantics.
> > + This is because for target FMV semantics a target_clone always defines
> > + the entire FMV set. target_version semantics can mix target_clone and
> > + target_version decls in the definition of a FMV set and so the
> > + target_clone becomes a part of the identity of the declaration. */
> > + if (TARGET_HAS_FMV_TARGET_ATTRIBUTE)
> > + return;
> > +
> > + auto_vec<string_slice> versions = get_clone_versions (t, NULL, false);
> > + if (versions.is_empty ())
> > + return;
> > +
> > + pp_c_whitespace (pp);
> > +
> > + string_slice final_version = versions.pop ();
> > + pp_c_left_bracket (pp);
> > + pp_c_left_bracket (pp);
> > + pp_string (pp, "target_clones");
> > + pp_c_left_paren (pp);
> > + for (string_slice version : versions)
> > + {
> > + pp_doublequote (pp);
> > + pp_string_n (pp, version.begin (), version.size ());
> > + pp_doublequote (pp);
> > + pp_string (pp, ",");
> > + pp_c_whitespace (pp);
> > + }
> > + pp_doublequote (pp);
> > + pp_string_n (pp, final_version.begin (), final_version.size ());
> > + pp_doublequote (pp);
> > + pp_c_right_paren (pp);
> > + pp_c_right_bracket (pp);
> > + pp_c_right_bracket (pp);
> > +
> > + pp->set_padding (pp_before);
> > +}
> > +
> > #if CHECKING_P
> > namespace selftest {
> > diff --git a/gcc/c-family/c-pretty-print.h b/gcc/c-family/c-pretty-print.h
> > index c8fb6789991..5e00b952c81 100644
> > --- a/gcc/c-family/c-pretty-print.h
> > +++ b/gcc/c-family/c-pretty-print.h
> > @@ -102,6 +102,12 @@ public:
> > #define pp_ptr_operator(PP, D) (PP)->ptr_operator (PP, D)
> > #define pp_parameter_list(PP, T) (PP)->parameter_list (PP, T)
> > +#define pp_c_maybe_whitespace(PP) \
> > + do { \
> > + if ((PP)->get_padding () == pp_before) \
> > + pp_c_whitespace (PP); \
> > + } while (0)
> > +
> > void pp_c_whitespace (c_pretty_printer *);
> > void pp_c_left_paren (c_pretty_printer *);
> > void pp_c_right_paren (c_pretty_printer *);
> > @@ -138,6 +144,8 @@ void pp_c_ws_string (c_pretty_printer *, const char *);
> > void pp_c_identifier (c_pretty_printer *, const char *);
> > void pp_c_string_literal (c_pretty_printer *, tree);
> > void pp_c_integer_constant (c_pretty_printer *, tree);
> > +void pp_c_function_target_version (c_pretty_printer *, tree);
> > +void pp_c_function_target_clones (c_pretty_printer *, tree);
> > void print_c_tree (FILE *file, tree t, dump_flags_t);
> > diff --git a/gcc/c/c-objc-common.cc b/gcc/c/c-objc-common.cc
> > index 5c50983544d..109a8cb33ee 100644
> > --- a/gcc/c/c-objc-common.cc
> > +++ b/gcc/c/c-objc-common.cc
> > @@ -23,6 +23,7 @@ along with GCC; see the file COPYING3. If not see
> > #include "c-tree.h"
> > #include "intl.h"
> > #include "c-family/c-pretty-print.h"
> > +#include "tree-core.h"
> > #include "tree-pretty-print.h"
> > #include "tree-pretty-print-markup.h"
> > #include "gimple-pretty-print.h"
> > @@ -359,6 +360,11 @@ c_tree_printer (pretty_printer *pp, text_info *text,
> > const char *spec,
> > if (DECL_NAME (t))
> > {
> > pp_identifier (cpp, lang_hooks.decl_printable_name (t, 2));
> > + if (TREE_CODE (t) == FUNCTION_DECL)
> > + {
> > + pp_c_function_target_version (cpp, t);
> > + pp_c_function_target_clones (cpp, t);
> > + }
> > return true;
> > }
> > break;
> > diff --git a/gcc/cp/cxx-pretty-print.h b/gcc/cp/cxx-pretty-print.h
> > index 86e0ce7d85f..356fd6e4d23 100644
> > --- a/gcc/cp/cxx-pretty-print.h
> > +++ b/gcc/cp/cxx-pretty-print.h
> > @@ -81,8 +81,13 @@ public:
> > #define pp_cxx_ws_string(PP, I) pp_c_ws_string (PP, I)
> > #define pp_cxx_identifier(PP, I) pp_c_identifier (PP, I)
> > +#define pp_cxx_maybe_whitespace(PP) pp_c_maybe_whitespace (PP)
> > #define pp_cxx_tree_identifier(PP, T) \
> > pp_c_tree_identifier (PP, T)
> > +#define pp_cxx_function_target_version(PP, T) \
> > + pp_c_function_target_version (PP, T)
> > +#define pp_cxx_function_target_clones(PP, T) \
> > + pp_c_function_target_clones (PP, T)
> > void pp_cxx_begin_template_argument_list (cxx_pretty_printer *);
> > void pp_cxx_end_template_argument_list (cxx_pretty_printer *);
> > diff --git a/gcc/cp/error.cc b/gcc/cp/error.cc
> > index 8ef9f9ee458..16dfeafc07a 100644
> > --- a/gcc/cp/error.cc
> > +++ b/gcc/cp/error.cc
> > @@ -2008,6 +2008,14 @@ dump_function_decl (cxx_pretty_printer *pp, tree t,
> > int flags)
> > dump_function_name (pp, t, dump_function_name_flags);
> > + /* By default we need no padding here, but if we emit target_version or
> > + target_clones then we need some. */
> > + pp->set_padding (pp_none);
> > + pp_cxx_function_target_version (pp, t);
> > + pp_cxx_maybe_whitespace (pp);
> > + pp_cxx_function_target_clones (pp, t);
> > + pp_cxx_maybe_whitespace (pp);
> > +
> > if (!(flags & TFF_NO_FUNCTION_ARGUMENTS))
> > {
> > int const parm_flags
>
--
Alfie Richards
