Remove unnecessary computed gotos

The computed goto is a GCC extension that isn't implemented by clang when
targeting wasm. Recent versions of emscripten failed to optimize it.

In fact, the emulator didn't need it and it can be replaced with a simple
boolean when waiting with timeout.

Signed-off-by: Paul Guyot <pguyot@kallisys.net>

Author: pguyot

src/libAtomVM/context.h

@@ -139,6 +139,9 @@ struct Context
     unsigned int has_max_heap_size : 1;
 
     bool trap_exit : 1;
+#ifndef AVM_NO_EMU
+    bool waiting_with_timeout : 1;
+#endif
 #ifdef ENABLE_ADVANCED_TRACE
     unsigned int trace_calls : 1;
     unsigned int trace_call_args : 1;

src/libAtomVM/opcodesswitch.h

@@ -1232,7 +1232,7 @@ static void destroy_extended_registers(Context *ctx, unsigned int live)
             goto terminate_context;                                                             \
         }                                                                                       \
         if (handle_error) {                                                                     \
-            goto handle_error;                                                                   \
+            goto handle_error;                                                                  \
         }                                                                                       \
         if (context_get_flags(ctx, Trap)) {                                                     \
             SCHEDULE_WAIT_ANY(mod);                                                             \
@@ -1920,26 +1920,16 @@ HOT_FUNC int scheduler_entry_point(GlobalContext *glb)
     }
 #endif
 
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpedantic"
-    // Handle traps.
-    if (ctx->restore_trap_handler) {
-#if AVM_NO_JIT
-        goto *ctx->restore_trap_handler;
-#elif AVM_NO_EMU
-        native_pc = ctx->restore_trap_handler;
-#else
-        if (mod->native_code == NULL) {
-            goto *ctx->restore_trap_handler;
-        } else {
-            native_pc = ctx->restore_trap_handler;
-        }
-#endif
+    // Handle waiting timeout
+#ifndef AVM_NO_EMU
+    if (ctx->waiting_with_timeout) {
+        goto wait_timeout_trap_handler;
     } else {
+#endif
         // Handle signals
         PROCESS_SIGNAL_MESSAGES();
+#ifndef AVM_NO_EMU
     }
-#pragma GCC diagnostic pop
 #endif
 
 #ifdef IMPL_CODE_LOADER
@@ -1989,7 +1979,7 @@ HOT_FUNC int scheduler_entry_point(GlobalContext *glb)
             if (mod->native_code == NULL) {
                 // set PC
                 native_pc = NULL;
-                JUMP_TO_ADDRESS(jit_state.continuation_pc);
+                JUMP_TO_ADDRESS(jit_state.continuation);
             } else {
 #endif
                 native_pc = jit_state.continuation;
@@ -2728,10 +2718,7 @@ HOT_FUNC int scheduler_entry_point(GlobalContext *glb)
                     if (context_get_flags(ctx, WaitingTimeout | WaitingTimeoutExpired)) {
                         scheduler_cancel_timeout(ctx);
                     }
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpedantic"
                     PROCESS_SIGNAL_MESSAGES();
-#pragma GCC diagnostic pop
                     mailbox_remove_message(&ctx->mailbox, &ctx->heap);
                     // Cannot GC now as remove_message is GC neutral
                 #endif
@@ -2759,10 +2746,7 @@ HOT_FUNC int scheduler_entry_point(GlobalContext *glb)
 
                 #ifdef IMPL_EXECUTE_LOOP
                     term ret;
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpedantic"
                     PROCESS_SIGNAL_MESSAGES();
-#pragma GCC diagnostic pop
                     if (mailbox_peek(ctx, &ret)) {
                         TRACE_RECEIVE(ctx, ret);
 
@@ -2782,10 +2766,7 @@ HOT_FUNC int scheduler_entry_point(GlobalContext *glb)
                 USED_BY_TRACE(label);
 
 #ifdef IMPL_EXECUTE_LOOP
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpedantic"
                 PROCESS_SIGNAL_MESSAGES();
-#pragma GCC diagnostic pop
                 mailbox_next(&ctx->mailbox);
                 pc = mod->labels[label];
 #endif
@@ -2830,10 +2811,7 @@ HOT_FUNC int scheduler_entry_point(GlobalContext *glb)
                     }
                     TRACE("wait_timeout/2, label: %i, timeout: %li\n", label, (long int) t);
 
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpedantic"
                     PROCESS_SIGNAL_MESSAGES();
-#pragma GCC diagnostic pop
                     int needs_to_wait = 0;
                     if (context_get_flags(ctx, WaitingTimeout | WaitingTimeoutExpired) == 0) {
                         if (timeout != INFINITY_ATOM) {
@@ -2847,10 +2825,7 @@ HOT_FUNC int scheduler_entry_point(GlobalContext *glb)
                     }
 
                     if (needs_to_wait) {
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpedantic"
-                        ctx->restore_trap_handler = &&wait_timeout_trap_handler;
-#pragma GCC diagnostic pop
+                        ctx->waiting_with_timeout = true;
                         SCHEDULE_WAIT(mod, saved_pc);
                     } else {
                         JUMP_TO_ADDRESS(mod->labels[label]);
@@ -2877,20 +2852,17 @@ HOT_FUNC int scheduler_entry_point(GlobalContext *glb)
                 int timeout;
                 DECODE_COMPACT_TERM(timeout, pc)
                 TRACE("wait_timeout_trap_handler, label: %i\n", label);
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wpedantic"
                 PROCESS_SIGNAL_MESSAGES();
-#pragma GCC diagnostic pop
                 if (context_get_flags(ctx, WaitingTimeoutExpired)) {
-                    ctx->restore_trap_handler = NULL;
+                    ctx->waiting_with_timeout = false;
                 } else {
                     if (UNLIKELY(!mailbox_has_next(&ctx->mailbox))) {
                         // No message is here.
                         // We were signaled for another reason.
                         ctx = scheduler_wait(ctx);
                         goto schedule_in;
                     } else {
-                        ctx->restore_trap_handler = NULL;
+                        ctx->waiting_with_timeout = false;
                         JUMP_TO_ADDRESS(mod->labels[label]);
                     }
                 }