Prepare SMP code to support Pico

Allow smp platforms to define their own spinlock structures
Allow smp platforms to not provide stdatomic.h
Allow platforms to define MIN and MAX macros

Signed-off-by: Paul Guyot <[email protected]>

Author: pguyot

src/libAtomVM/CMakeLists.txt

@@ -130,8 +130,22 @@ if (AVM_DISABLE_SMP)
 else()
     include(CheckIncludeFile)
     CHECK_INCLUDE_FILE(stdatomic.h STDATOMIC_INCLUDE)
-    if(NOT STDATOMIC_INCLUDE)
-       message(FATAL_ERROR "stdatomic.h cannot be found, you need to disable SMP on this platform")
+    if(HAVE_PLATFORM_SMP_H)
+        target_compile_definitions(libAtomVM PUBLIC HAVE_PLATFORM_SMP_H)
+    endif()
+    include(CheckCSourceCompiles)
+    check_c_source_compiles("
+        #include <stdatomic.h>
+        int main() {
+            _Static_assert(ATOMIC_POINTER_LOCK_FREE == 2, \"Expected ATOMIC_POINTER_LOCK_FREE to be equal to 2\");
+        }
+    " ATOMIC_POINTER_LOCK_FREE_IS_TWO)
+    if (NOT ATOMIC_POINTER_LOCK_FREE_IS_TWO AND NOT HAVE_PLATFORM_SMP_H)
+        if (NOT STDATOMIC_INCLUDE)
+            message(FATAL_ERROR "stdatomic.h cannot be found, you need to disable SMP on this platform or provide platform_smp.h and define HAVE_PLATFORM_SMP_H")
+        else()
+            message(FATAL_ERROR "Platform doesn't support atomic pointers, you need to disable SMP or provide platform_smp.h and define HAVE_PLATFORM_SMP_H")
+        endif()
     endif()
 endif()
 

src/libAtomVM/context.c

@@ -181,7 +181,7 @@ void context_update_flags(Context *ctx, int mask, int value) CLANG_THREAD_SANITI
     enum ContextFlags desired;
     do {
         desired = (expected & mask) | value;
-    } while (!atomic_compare_exchange_weak(&ctx->flags, &expected, desired));
+    } while (!ATOMIC_COMPARE_EXCHANGE_WEAK(&ctx->flags, &expected, desired));
 #else
     ctx->flags = (ctx->flags & mask) | value;
 #endif

src/libAtomVM/context.h

@@ -35,16 +35,10 @@ extern "C" {
 #include "globalcontext.h"
 #include "linkedlist.h"
 #include "mailbox.h"
+#include "smp.h"
 #include "term.h"
 #include "timer_list.h"
 
-#if !defined(AVM_NO_SMP) && !defined(__cplusplus)
-#include <stdatomic.h>
-#define ATOMIC _Atomic
-#else
-#define ATOMIC
-#endif
-
 struct Module;
 
 #ifndef TYPEDEF_MODULE

src/libAtomVM/globalcontext.h

@@ -34,13 +34,6 @@ extern "C" {
 
 #include <stdint.h>
 
-#if !defined(AVM_NO_SMP) && !defined(__cplusplus)
-#include <stdatomic.h>
-#define ATOMIC _Atomic
-#else
-#define ATOMIC
-#endif
-
 #include "atom.h"
 #include "linkedlist.h"
 #include "smp.h"
@@ -102,7 +95,7 @@ struct GlobalContext
 #endif
 
 #if !defined(AVM_NO_SMP) && ATOMIC_LLONG_LOCK_FREE == 2
-    atomic_ullong ref_ticks;
+    unsigned long long ATOMIC ref_ticks;
 #else
     unsigned long long ref_ticks;
 #ifndef AVM_NO_SMP

src/libAtomVM/mailbox.c

@@ -142,7 +142,7 @@ static void mailbox_post_message(Context *c, MailboxMessage *m)
     MailboxMessage *current_first = NULL;
     do {
         m->next = current_first;
-    } while (!atomic_compare_exchange_weak(&c->mailbox.outer_first, &current_first, m));
+    } while (!ATOMIC_COMPARE_EXCHANGE_WEAK(&c->mailbox.outer_first, &current_first, m));
 #else
     m->next = c->mailbox.outer_first;
     c->mailbox.outer_first = m;
@@ -242,7 +242,7 @@ MailboxMessage *mailbox_process_outer_list(Mailbox *mbox)
     // Empty outer list using CAS
     MailboxMessage *current = mbox->outer_first;
 #ifndef AVM_NO_SMP
-    while (!atomic_compare_exchange_weak(&mbox->outer_first, &current, NULL)) {
+    while (!ATOMIC_COMPARE_EXCHANGE_WEAK(&mbox->outer_first, &current, NULL)) {
     };
 #else
     mbox->outer_first = NULL;

src/libAtomVM/mailbox.h

@@ -33,16 +33,10 @@
 extern "C" {
 #endif
 
-#if !defined(AVM_NO_SMP) && !defined(__cplusplus)
-#include <stdatomic.h>
-#define ATOMIC _Atomic
-#else
-#define ATOMIC
-#endif
-
 #include <stdbool.h>
 
 #include "list.h"
+#include "smp.h"
 #include "term_typedef.h"
 
 struct Context;

src/libAtomVM/nifs.c

@@ -35,6 +35,7 @@
 #include "platform_nifs.h"
 #include "port.h"
 #include "scheduler.h"
+#include "smp.h"
 #include "sys.h"
 #include "term.h"
 #include "utils.h"
@@ -70,7 +71,10 @@
     ctx->x[1] = (b); \
     return term_invalid_term();
 
+#ifndef MAX
 #define MAX(x, y) (((x) > (y)) ? (x) : (y))
+#endif
+
 #define NOT_FOUND (0xFF)
 
 #ifdef ENABLE_ADVANCED_TRACE
@@ -2543,7 +2547,7 @@ static term nif_erlang_system_flag(Context *ctx, int argc, term argv[])
             argv[1] = BADARG_ATOM;
             return term_invalid_term();
         }
-        while (!atomic_compare_exchange_weak(&ctx->global->online_schedulers, &old_value, new_value)) {};
+        while (!ATOMIC_COMPARE_EXCHANGE_WEAK(&ctx->global->online_schedulers, &old_value, new_value)) {};
         return term_from_int32(old_value);
     }
 #else

src/libAtomVM/opcodesswitch.h

@@ -944,7 +944,9 @@ typedef union
     }
 
 
+#ifndef MIN
 #define MIN(X, Y) ((X) < (Y) ? (X) : (Y))
+#endif
 
 #ifdef IMPL_EXECUTE_LOOP
 struct Int24

src/libAtomVM/refc_binary.h

@@ -25,16 +25,11 @@
 extern "C" {
 #endif
 
-#include "list.h"
 #include <stdbool.h>
 #include <stdlib.h>
 
-#if !defined(AVM_NO_SMP) && !defined(__cplusplus)
-#include <stdatomic.h>
-#define ATOMIC _Atomic
-#else
-#define ATOMIC
-#endif
+#include "list.h"
+#include "smp.h"
 
 struct RefcBinary
 {

src/libAtomVM/smp.h

@@ -42,22 +42,18 @@ extern "C" {
 #define CLANG_THREAD_SANITIZE_SAFE
 #endif
 
-#ifndef AVM_NO_SMP
-
+#if defined(AVM_NO_SMP)
+#define ATOMIC
+#else
 #include <stdbool.h>
-
 #ifndef __cplusplus
+#ifdef HAVE_PLATFORM_SMP_H
+#include "platform_smp.h"
+#else
 #include <stdatomic.h>
+#define ATOMIC_COMPARE_EXCHANGE_WEAK atomic_compare_exchange_weak
 #define ATOMIC _Atomic
-
-#if ATOMIC_POINTER_LOCK_FREE != 2
-#error Current SMP implementation requires lock-free atomic pointers which this platform does not support, please disable SMP
 #endif
-
-#if ATOMIC_LONG_LOCK_FREE != 2
-#error Current SMP implementation requires lock-free atomic long (32 bits) words which this platform does not support, please disable SMP
-#endif
-
 #else
 #define ATOMIC
 #endif
@@ -87,10 +83,12 @@ typedef struct RWLock RWLock;
 typedef struct GlobalContext GlobalContext;
 #endif
 
+#if !defined(SMP_PLATFORM_SPINLOCK)
 struct SpinLock
 {
     int ATOMIC lock;
 };
+#endif
 
 /**
  * @brief Create a new mutex.
@@ -180,7 +178,7 @@ void smp_rwlock_wrlock(RWLock *lock);
  */
 void smp_rwlock_unlock(RWLock *lock);
 
-#ifndef __cplusplus
+#if !defined(__cplusplus) && !defined(SMP_PLATFORM_SPINLOCK)
 
 /**
  * @brief Initialize a spinlock based on atomics.
@@ -200,7 +198,7 @@ static inline void smp_spinlock_lock(SpinLock *lock)
     int current;
     do {
         current = 0;
-    } while (!atomic_compare_exchange_weak(&lock->lock, &current, 1));
+    } while (!ATOMIC_COMPARE_EXCHANGE_WEAK(&lock->lock, &current, 1));
 }
 
 /**