Enable gcc-4.8 compilation (#1928)

Author: loganek

core/iwasm/libraries/libc-wasi/sandboxed-system-primitives/src/gnuc.h

@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) 2023 Amazon.com, Inc. or its affiliates. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ */
+
+#if !defined(__GNUC_PREREQ) && (defined(__GNUC__) || defined(__GNUG__)) \
+    && !defined(__clang__) && defined(__GNUC_MINOR__)
+/* Depending on the platform the macro is defined in sys/features.h or
+   features.h Given the macro is simple, we re-implement it here instead of
+   dealing with two different paths.
+ */
+#define __GNUC_PREREQ(maj, min) \
+    ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
+#endif

core/iwasm/libraries/libc-wasi/sandboxed-system-primitives/src/numeric_limits.h

@@ -15,7 +15,6 @@
 #include "bh_platform.h"
 #include "wasmtime_ssp.h"
 #include "locking.h"
-#include "numeric_limits.h"
 #include "posix.h"
 #include "random.h"
 #include "refcount.h"
@@ -2257,8 +2256,7 @@ convert_timestamp(__wasi_timestamp_t in, struct timespec *out)
     in /= 1000000000;
 
     // Clamp to the maximum in case it would overflow our system's time_t.
-    out->tv_sec =
-        (time_t)in < NUMERIC_MAX(time_t) ? (time_t)in : NUMERIC_MAX(time_t);
+    out->tv_sec = (time_t)in < BH_TIME_T_MAX ? (time_t)in : BH_TIME_T_MAX;
 }
 
 // Converts the provided timestamps and flags to a set of arguments for

core/iwasm/libraries/libc-wasi/sandboxed-system-primitives/src/posix.c

@@ -16,6 +16,7 @@
 
 #include "bh_platform.h"
 #include "locking.h"
+#include "gnuc.h"
 
 #define PRODUCES(...) LOCKS_SHARED(__VA_ARGS__) NO_LOCK_ANALYSIS
 #define CONSUMES(...) UNLOCKS(__VA_ARGS__) NO_LOCK_ANALYSIS
@@ -95,6 +96,42 @@ refcount_release(struct refcount *r)
     return old == 1;
 }
 
+#elif defined(__GNUC_PREREQ)
+
+#if __GNUC_PREREQ(4, 7)
+
+struct refcount {
+    unsigned int count;
+};
+
+/* Initialize the reference counter. */
+static inline void
+refcount_init(struct refcount *r, unsigned int count)
+{
+    __atomic_store_n(&r->count, count, __ATOMIC_SEQ_CST);
+}
+
+/* Increment the reference counter. */
+static inline void
+refcount_acquire(struct refcount *r)
+{
+    __atomic_fetch_add(&r->count, 1, __ATOMIC_ACQUIRE);
+}
+
+/* Decrement the reference counter, returning whether the reference
+   dropped to zero. */
+static inline bool
+refcount_release(struct refcount *r)
+{
+    int old = (int)__atomic_fetch_sub(&r->count, 1, __ATOMIC_RELEASE);
+    bh_assert(old != 0 && "Reference count becoming negative");
+    return old == 1;
+}
+
+#else /* else of __GNUC_PREREQ (4.7) */
+#error "Reference counter isn't implemented"
+#endif /* end of __GNUC_PREREQ (4.7) */
+
 #else /* else of CONFIG_HAS_STD_ATOMIC */
 #error "Reference counter isn't implemented"
 #endif /* end of CONFIG_HAS_STD_ATOMIC */

core/iwasm/libraries/libc-wasi/sandboxed-system-primitives/src/refcount.h

@@ -14,6 +14,7 @@
 #ifndef SSP_CONFIG_H
 #define SSP_CONFIG_H
 
+#include "gnuc.h"
 #include <stdlib.h>
 
 #if defined(__FreeBSD__) || defined(__APPLE__) \
@@ -107,10 +108,21 @@
 #endif
 
 #if !defined(BH_PLATFORM_LINUX_SGX)
+#if defined(__GNUC_PREREQ)
+/* Even though older versions of GCC support C11, atomics were
+not implemented until 4.9. See
+https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58016 */
+#if __GNUC_PREREQ(4, 9)
 #define CONFIG_HAS_STD_ATOMIC 1
-#else
+#else /* else of __GNUC_PREREQ(4, 9) */
 #define CONFIG_HAS_STD_ATOMIC 0
-#endif
+#endif /* end of __GNUC_PREREQ(4, 9) */
+#else  /* else of defined(__GNUC_PREREQ) */
+#define CONFIG_HAS_STD_ATOMIC 1
+#endif /* end of defined(__GNUC_PREREQ) */
+#else  /* else of !defined(BH_PLATFORM_LINUX_SGX) */
+#define CONFIG_HAS_STD_ATOMIC 0
+#endif /* end of !defined(BH_PLATFORM_LINUX_SGX) */
 
 #if !defined(__NuttX__)
 #define CONFIG_HAS_D_INO 1