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Tue, 25 Jun 2024 04:18:51 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGUYgt582YliqFKpeBZWupiJsH2UBhB4aGot8ki1bqX9rpdWG62R2BWUIZ5uCJYKRo/Zu6O+w== X-Received: by 2002:a17:907:c787:b0:a6f:b6c3:fb30 with SMTP id a640c23a62f3a-a7245b84f56mr710025266b.7.1719314331353; Tue, 25 Jun 2024 04:18:51 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: flwu@google.com, berrange@redhat.com, peter.maydell@linaro.org, rkir@google.com Subject: [PATCH] include: move typeof_strip_qual to compiler.h, use it in QAPI_LIST_LENGTH() Date: Tue, 25 Jun 2024 13:18:48 +0200 Message-ID: <20240625111848.709176-1-pbonzini@redhat.com> X-Mailer: git-send-email 2.45.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.151, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1719314375403100001 Content-Type: text/plain; charset="utf-8" The typeof_strip_qual() is most useful for the atomic fetch-and-modify operations in atomic.h, but it can be used elsewhere as well. For example, QAPI_LIST_LENGTH() assumes that the argument is not const, which is not a requirement. Move the macro to compiler.h and, while at it, move it under #ifndef __cplusplus to emphasize that it uses C-only constructs. A C++ version of typeof_strip_qual() using type traits is possible[1], but beyond the scope of this patch because the little C++ code that is in QEMU does not use QAPI. The patch was tested by changing the declaration of strv_from_str_list() in qapi/qapi-type-helpers.c to: char **strv_from_str_list(const strList *const list) This is valid C code, and it fails to compile without this change. [1] https://lore.kernel.org/qemu-devel/20240624205647.112034-1-flwu@google.= com/ Signed-off-by: Paolo Bonzini Reviewed-by: Manos Pitsidianakis Reviewed-by: Richard Henderson Tested-by: Manos Pitsidianakis --- include/qapi/util.h | 2 +- include/qemu/atomic.h | 42 ------------------------------------- include/qemu/compiler.h | 46 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 47 insertions(+), 43 deletions(-) diff --git a/include/qapi/util.h b/include/qapi/util.h index 20dfea8a545..b8254247b8d 100644 --- a/include/qapi/util.h +++ b/include/qapi/util.h @@ -62,7 +62,7 @@ int parse_qapi_name(const char *name, bool complete); #define QAPI_LIST_LENGTH(list) \ ({ \ size_t _len =3D 0; \ - typeof(list) _tail; \ + typeof_strip_qual(list) _tail; \ for (_tail =3D list; _tail !=3D NULL; _tail =3D _tail->next) { \ _len++; \ } \ diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h index 99110abefb3..dc4118ddd9e 100644 --- a/include/qemu/atomic.h +++ b/include/qemu/atomic.h @@ -20,48 +20,6 @@ /* Compiler barrier */ #define barrier() ({ asm volatile("" ::: "memory"); (void)0; }) =20 -/* The variable that receives the old value of an atomically-accessed - * variable must be non-qualified, because atomic builtins return values - * through a pointer-type argument as in __atomic_load(&var, &old, MODEL). - * - * This macro has to handle types smaller than int manually, because of - * implicit promotion. int and larger types, as well as pointers, can be - * converted to a non-qualified type just by applying a binary operator. - */ -#define typeof_strip_qual(expr) = \ - typeof( = \ - __builtin_choose_expr( = \ - __builtin_types_compatible_p(typeof(expr), bool) || = \ - __builtin_types_compatible_p(typeof(expr), const bool) || = \ - __builtin_types_compatible_p(typeof(expr), volatile bool) || = \ - __builtin_types_compatible_p(typeof(expr), const volatile bool), = \ - (bool)1, = \ - __builtin_choose_expr( = \ - __builtin_types_compatible_p(typeof(expr), signed char) || = \ - __builtin_types_compatible_p(typeof(expr), const signed char) || = \ - __builtin_types_compatible_p(typeof(expr), volatile signed char) |= | \ - __builtin_types_compatible_p(typeof(expr), const volatile signed c= har), \ - (signed char)1, = \ - __builtin_choose_expr( = \ - __builtin_types_compatible_p(typeof(expr), unsigned char) || = \ - __builtin_types_compatible_p(typeof(expr), const unsigned char) ||= \ - __builtin_types_compatible_p(typeof(expr), volatile unsigned char)= || \ - __builtin_types_compatible_p(typeof(expr), const volatile unsigned= char), \ - (unsigned char)1, = \ - __builtin_choose_expr( = \ - __builtin_types_compatible_p(typeof(expr), signed short) || = \ - __builtin_types_compatible_p(typeof(expr), const signed short) || = \ - __builtin_types_compatible_p(typeof(expr), volatile signed short) = || \ - __builtin_types_compatible_p(typeof(expr), const volatile signed s= hort), \ - (signed short)1, = \ - __builtin_choose_expr( = \ - __builtin_types_compatible_p(typeof(expr), unsigned short) || = \ - __builtin_types_compatible_p(typeof(expr), const unsigned short) |= | \ - __builtin_types_compatible_p(typeof(expr), volatile unsigned short= ) || \ - __builtin_types_compatible_p(typeof(expr), const volatile unsigned= short), \ - (unsigned short)1, = \ - (expr)+0)))))) - #ifndef __ATOMIC_RELAXED #error "Expecting C11 atomic ops" #endif diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h index c797f0d4572..554c5ce7df7 100644 --- a/include/qemu/compiler.h +++ b/include/qemu/compiler.h @@ -227,4 +227,50 @@ #define SECOND_ARG(first, second, ...) second #define IS_EMPTY_(junk_maybecomma) SECOND_ARG(junk_maybecomma 1, 0) =20 +#ifndef __cplusplus +/* + * Useful in macros that need to declare temporary variables. For example, + * the variable that receives the old value of an atomically-accessed + * variable must be non-qualified, because atomic builtins return values + * through a pointer-type argument as in __atomic_load(&var, &old, MODEL). + * + * This macro has to handle types smaller than int manually, because of + * implicit promotion. int and larger types, as well as pointers, can be + * converted to a non-qualified type just by applying a binary operator. + */ +#define typeof_strip_qual(expr) = \ + typeof( = \ + __builtin_choose_expr( = \ + __builtin_types_compatible_p(typeof(expr), bool) || = \ + __builtin_types_compatible_p(typeof(expr), const bool) || = \ + __builtin_types_compatible_p(typeof(expr), volatile bool) || = \ + __builtin_types_compatible_p(typeof(expr), const volatile bool), = \ + (bool)1, = \ + __builtin_choose_expr( = \ + __builtin_types_compatible_p(typeof(expr), signed char) || = \ + __builtin_types_compatible_p(typeof(expr), const signed char) || = \ + __builtin_types_compatible_p(typeof(expr), volatile signed char) |= | \ + __builtin_types_compatible_p(typeof(expr), const volatile signed c= har), \ + (signed char)1, = \ + __builtin_choose_expr( = \ + __builtin_types_compatible_p(typeof(expr), unsigned char) || = \ + __builtin_types_compatible_p(typeof(expr), const unsigned char) ||= \ + __builtin_types_compatible_p(typeof(expr), volatile unsigned char)= || \ + __builtin_types_compatible_p(typeof(expr), const volatile unsigned= char), \ + (unsigned char)1, = \ + __builtin_choose_expr( = \ + __builtin_types_compatible_p(typeof(expr), signed short) || = \ + __builtin_types_compatible_p(typeof(expr), const signed short) || = \ + __builtin_types_compatible_p(typeof(expr), volatile signed short) = || \ + __builtin_types_compatible_p(typeof(expr), const volatile signed s= hort), \ + (signed short)1, = \ + __builtin_choose_expr( = \ + __builtin_types_compatible_p(typeof(expr), unsigned short) || = \ + __builtin_types_compatible_p(typeof(expr), const unsigned short) |= | \ + __builtin_types_compatible_p(typeof(expr), volatile unsigned short= ) || \ + __builtin_types_compatible_p(typeof(expr), const volatile unsigned= short), \ + (unsigned short)1, = \ + (expr)+0)))))) +#endif + #endif /* COMPILER_H */ --=20 2.45.2