Merge remote-tracking branch 'remotes/rth-gitlab/tags/pull-c11-20210615' into staging

Change to -std=gnu11.
Replace QEMU_GENERIC with _Generic.
Remove configure detect of _Static_assert.

# gpg: Signature made Wed 16 Jun 2021 02:32:32 BST
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
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* remotes/rth-gitlab/tags/pull-c11-20210615:
  configure: Remove probe for _Static_assert
  qemu/compiler: Remove QEMU_GENERIC
  include/qemu/lockable: Use _Generic instead of QEMU_GENERIC
  util: Use unique type for QemuRecMutex in thread-posix.h
  util: Pass file+line to qemu_rec_mutex_unlock_impl
  util: Use real functions for thread-posix QemuRecMutex
  softfloat: Use _Generic instead of QEMU_GENERIC
  configure: Use -std=gnu11

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

5 files changed, 61 insertions, 113 deletions

diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index 091c45248b..3baa5e3790 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -72,18 +72,7 @@
         int:(x) ? -1 : 1; \
     }
 
-/* QEMU_BUILD_BUG_MSG() emits the message given if _Static_assert is
- * supported; otherwise, it will be omitted from the compiler error
- * message (but as it remains present in the source code, it can still
- * be useful when debugging). */
-#if defined(CONFIG_STATIC_ASSERT)
 #define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg)
-#elif defined(__COUNTER__)
-#define QEMU_BUILD_BUG_MSG(x, msg) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \
-    glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused))
-#else
-#define QEMU_BUILD_BUG_MSG(x, msg)
-#endif
 
 #define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x)
 
@@ -173,46 +162,6 @@
 #define QEMU_ALWAYS_INLINE
 #endif
 
-/* Implement C11 _Generic via GCC builtins.  Example:
- *
- *    QEMU_GENERIC(x, (float, sinf), (long double, sinl), sin) (x)
- *
- * The first argument is the discriminator.  The last is the default value.
- * The middle ones are tuples in "(type, expansion)" format.
- */
-
-/* First, find out the number of generic cases.  */
-#define QEMU_GENERIC(x, ...) \
-    QEMU_GENERIC_(typeof(x), __VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
-
-/* There will be extra arguments, but they are not used.  */
-#define QEMU_GENERIC_(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, count, ...) \
-    QEMU_GENERIC##count(x, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9)
-
-/* Two more helper macros, this time to extract items from a parenthesized
- * list.
- */
-#define QEMU_FIRST_(a, b) a
-#define QEMU_SECOND_(a, b) b
-
-/* ... and a final one for the common part of the "recursion".  */
-#define QEMU_GENERIC_IF(x, type_then, else_)                                   \
-    __builtin_choose_expr(__builtin_types_compatible_p(x,                      \
-                                                       QEMU_FIRST_ type_then), \
-                          QEMU_SECOND_ type_then, else_)
-
-/* CPP poor man's "recursion".  */
-#define QEMU_GENERIC1(x, a0, ...) (a0)
-#define QEMU_GENERIC2(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC1(x, __VA_ARGS__))
-#define QEMU_GENERIC3(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC2(x, __VA_ARGS__))
-#define QEMU_GENERIC4(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC3(x, __VA_ARGS__))
-#define QEMU_GENERIC5(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC4(x, __VA_ARGS__))
-#define QEMU_GENERIC6(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC5(x, __VA_ARGS__))
-#define QEMU_GENERIC7(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC6(x, __VA_ARGS__))
-#define QEMU_GENERIC8(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC7(x, __VA_ARGS__))
-#define QEMU_GENERIC9(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC8(x, __VA_ARGS__))
-#define QEMU_GENERIC10(x, a0, ...) QEMU_GENERIC_IF(x, a0, QEMU_GENERIC9(x, __VA_ARGS__))
-
 /**
  * qemu_build_not_reached()
  *
diff --git a/include/qemu/lockable.h b/include/qemu/lockable.h
index b620023141..86db7cb04c 100644
--- a/include/qemu/lockable.h
+++ b/include/qemu/lockable.h
@@ -24,79 +24,71 @@ struct QemuLockable {
     QemuLockUnlockFunc *unlock;
 };
 
-/* This function gives an error if an invalid, non-NULL pointer type is passed
- * to QEMU_MAKE_LOCKABLE.  For optimized builds, we can rely on dead-code elimination
- * from the compiler, and give the errors already at link time.
- */
-#if defined(__OPTIMIZE__) && !defined(__SANITIZE_ADDRESS__)
-void unknown_lock_type(void *);
-#else
-static inline void unknown_lock_type(void *unused)
-{
-    abort();
-}
-#endif
-
 static inline __attribute__((__always_inline__)) QemuLockable *
 qemu_make_lockable(void *x, QemuLockable *lockable)
 {
-    /* We cannot test this in a macro, otherwise we get compiler
+    /*
+     * We cannot test this in a macro, otherwise we get compiler
      * warnings like "the address of 'm' will always evaluate as 'true'".
      */
     return x ? lockable : NULL;
 }
 
-/* Auxiliary macros to simplify QEMU_MAKE_LOCABLE.  */
-#define QEMU_LOCK_FUNC(x) ((QemuLockUnlockFunc *)    \
-    QEMU_GENERIC(x,                                  \
-                 (QemuMutex *, qemu_mutex_lock),     \
-                 (QemuRecMutex *, qemu_rec_mutex_lock), \
-                 (CoMutex *, qemu_co_mutex_lock),    \
-                 (QemuSpin *, qemu_spin_lock),       \
-                 unknown_lock_type))
-
-#define QEMU_UNLOCK_FUNC(x) ((QemuLockUnlockFunc *)  \
-    QEMU_GENERIC(x,                                  \
-                 (QemuMutex *, qemu_mutex_unlock),   \
-                 (QemuRecMutex *, qemu_rec_mutex_unlock), \
-                 (CoMutex *, qemu_co_mutex_unlock),  \
-                 (QemuSpin *, qemu_spin_unlock),     \
-                 unknown_lock_type))
-
-/* In C, compound literals have the lifetime of an automatic variable.
+static inline __attribute__((__always_inline__)) QemuLockable *
+qemu_null_lockable(void *x)
+{
+    if (x != NULL) {
+        qemu_build_not_reached();
+    }
+    return NULL;
+}
+
+/*
+ * In C, compound literals have the lifetime of an automatic variable.
  * In C++ it would be different, but then C++ wouldn't need QemuLockable
  * either...
  */
-#define QEMU_MAKE_LOCKABLE_(x) (&(QemuLockable) {     \
-        .object = (x),                               \
-        .lock = QEMU_LOCK_FUNC(x),                   \
-        .unlock = QEMU_UNLOCK_FUNC(x),               \
+#define QML_OBJ_(x, name) (&(QemuLockable) {                            \
+        .object = (x),                                                  \
+        .lock = (QemuLockUnlockFunc *) qemu_ ## name ## _lock,          \
+        .unlock = (QemuLockUnlockFunc *) qemu_ ## name ## _unlock       \
     })
 
-/* QEMU_MAKE_LOCKABLE - Make a polymorphic QemuLockable
+/**
+ * QEMU_MAKE_LOCKABLE - Make a polymorphic QemuLockable
  *
- * @x: a lock object (currently one of QemuMutex, QemuRecMutex, CoMutex, QemuSpin).
+ * @x: a lock object (currently one of QemuMutex, QemuRecMutex,
+ *     CoMutex, QemuSpin).
  *
  * Returns a QemuLockable object that can be passed around
  * to a function that can operate with locks of any kind, or
  * NULL if @x is %NULL.
+ *
+ * Note the special case for void *, so that we may pass "NULL".
  */
-#define QEMU_MAKE_LOCKABLE(x)                        \
-    QEMU_GENERIC(x,                                  \
-                 (QemuLockable *, (x)),              \
-                 qemu_make_lockable((x), QEMU_MAKE_LOCKABLE_(x)))
+#define QEMU_MAKE_LOCKABLE(x)                                           \
+    _Generic((x), QemuLockable *: (x),                                  \
+             void *: qemu_null_lockable(x),                             \
+             QemuMutex *: qemu_make_lockable(x, QML_OBJ_(x, mutex)),    \
+             QemuRecMutex *: qemu_make_lockable(x, QML_OBJ_(x, rec_mutex)), \
+             CoMutex *: qemu_make_lockable(x, QML_OBJ_(x, co_mutex)),   \
+             QemuSpin *: qemu_make_lockable(x, QML_OBJ_(x, spin)))
 
-/* QEMU_MAKE_LOCKABLE_NONNULL - Make a polymorphic QemuLockable
+/**
+ * QEMU_MAKE_LOCKABLE_NONNULL - Make a polymorphic QemuLockable
  *
- * @x: a lock object (currently one of QemuMutex, QemuRecMutex, CoMutex, QemuSpin).
+ * @x: a lock object (currently one of QemuMutex, QemuRecMutex,
+ *     CoMutex, QemuSpin).
  *
  * Returns a QemuLockable object that can be passed around
  * to a function that can operate with locks of any kind.
  */
-#define QEMU_MAKE_LOCKABLE_NONNULL(x)                \
-    QEMU_GENERIC(x,                                  \
-                 (QemuLockable *, (x)),              \
-                 QEMU_MAKE_LOCKABLE_(x))
+#define QEMU_MAKE_LOCKABLE_NONNULL(x)                           \
+    _Generic((x), QemuLockable *: (x),                          \
+                  QemuMutex *: QML_OBJ_(x, mutex),              \
+                  QemuRecMutex *: QML_OBJ_(x, rec_mutex),       \
+                  CoMutex *: QML_OBJ_(x, co_mutex),             \
+                  QemuSpin *: QML_OBJ_(x, spin))
 
 static inline void qemu_lockable_lock(QemuLockable *x)
 {
diff --git a/include/qemu/thread-posix.h b/include/qemu/thread-posix.h
index c903525062..b792e6ef37 100644
--- a/include/qemu/thread-posix.h
+++ b/include/qemu/thread-posix.h
@@ -4,12 +4,6 @@
 #include <pthread.h>
 #include <semaphore.h>
 
-typedef QemuMutex QemuRecMutex;
-#define qemu_rec_mutex_destroy qemu_mutex_destroy
-#define qemu_rec_mutex_lock_impl    qemu_mutex_lock_impl
-#define qemu_rec_mutex_trylock_impl qemu_mutex_trylock_impl
-#define qemu_rec_mutex_unlock qemu_mutex_unlock
-
 struct QemuMutex {
     pthread_mutex_t lock;
 #ifdef CONFIG_DEBUG_MUTEX
@@ -19,6 +13,14 @@ struct QemuMutex {
     bool initialized;
 };
 
+/*
+ * QemuRecMutex cannot be a typedef of QemuMutex lest we have two
+ * compatible cases in _Generic.  See qemu/lockable.h.
+ */
+typedef struct QemuRecMutex {
+    QemuMutex m;
+} QemuRecMutex;
+
 struct QemuCond {
     pthread_cond_t cond;
     bool initialized;
diff --git a/include/qemu/thread-win32.h b/include/qemu/thread-win32.h
index d0a1a9597e..d95af4498f 100644
--- a/include/qemu/thread-win32.h
+++ b/include/qemu/thread-win32.h
@@ -18,12 +18,6 @@ struct QemuRecMutex {
     bool initialized;
 };
 
-void qemu_rec_mutex_destroy(QemuRecMutex *mutex);
-void qemu_rec_mutex_lock_impl(QemuRecMutex *mutex, const char *file, int line);
-int qemu_rec_mutex_trylock_impl(QemuRecMutex *mutex, const char *file,
-                                int line);
-void qemu_rec_mutex_unlock(QemuRecMutex *mutex);
-
 struct QemuCond {
     CONDITION_VARIABLE var;
     bool initialized;
diff --git a/include/qemu/thread.h b/include/qemu/thread.h
index 5435763184..460568d67d 100644
--- a/include/qemu/thread.h
+++ b/include/qemu/thread.h
@@ -28,6 +28,12 @@ int qemu_mutex_trylock_impl(QemuMutex *mutex, const char *file, const int line);
 void qemu_mutex_lock_impl(QemuMutex *mutex, const char *file, const int line);
 void qemu_mutex_unlock_impl(QemuMutex *mutex, const char *file, const int line);
 
+void qemu_rec_mutex_init(QemuRecMutex *mutex);
+void qemu_rec_mutex_destroy(QemuRecMutex *mutex);
+void qemu_rec_mutex_lock_impl(QemuRecMutex *mutex, const char *file, int line);
+int qemu_rec_mutex_trylock_impl(QemuRecMutex *mutex, const char *file, int line);
+void qemu_rec_mutex_unlock_impl(QemuRecMutex *mutex, const char *file, int line);
+
 typedef void (*QemuMutexLockFunc)(QemuMutex *m, const char *f, int l);
 typedef int (*QemuMutexTrylockFunc)(QemuMutex *m, const char *f, int l);
 typedef void (*QemuRecMutexLockFunc)(QemuRecMutex *m, const char *f, int l);
@@ -104,6 +110,9 @@ extern QemuCondTimedWaitFunc qemu_cond_timedwait_func;
 #define qemu_mutex_unlock(mutex) \
         qemu_mutex_unlock_impl(mutex, __FILE__, __LINE__)
 
+#define qemu_rec_mutex_unlock(mutex) \
+        qemu_rec_mutex_unlock_impl(mutex, __FILE__, __LINE__)
+
 static inline void (qemu_mutex_lock)(QemuMutex *mutex)
 {
     qemu_mutex_lock(mutex);
@@ -129,8 +138,10 @@ static inline int (qemu_rec_mutex_trylock)(QemuRecMutex *mutex)
     return qemu_rec_mutex_trylock(mutex);
 }
 
-/* Prototypes for other functions are in thread-posix.h/thread-win32.h.  */
-void qemu_rec_mutex_init(QemuRecMutex *mutex);
+static inline void (qemu_rec_mutex_unlock)(QemuRecMutex *mutex)
+{
+    qemu_rec_mutex_unlock(mutex);
+}
 
 void qemu_cond_init(QemuCond *cond);
 void qemu_cond_destroy(QemuCond *cond);