Move nmethod entry barrier code up in the signal handler.

Author: TheRealMDoerr

src/hotspot/os_cpu/aix_ppc/os_aix_ppc.cpp

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2024 SAP SE. All rights reserved.
+ * Copyright (c) 2012, 2025 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -254,6 +254,18 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
         goto run_stub;
       }
 
+      // SIGTRAP-based nmethod entry barriers.
+      else if (sig == SIGTRAP && TrapBasedNMethodEntryBarriers &&
+               nativeInstruction_at(pc)->is_sigtrap_nmethod_entry_barrier() &&
+               CodeCache::contains((void*) pc)) {
+        if (TraceTraps) {
+          tty->print_cr("trap: nmethod entry barrier at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));
+        }
+        stub = StubRoutines::method_entry_barrier();
+        uc->uc_mcontext.jmp_context.lr = (uintptr_t)(pc + BytesPerInstWord); // emulate call by setting LR
+        goto run_stub;
+      }
+
       // SIGTRAP-based ic miss check in compiled code.
       else if (sig == SIGTRAP && TrapBasedICMissChecks &&
                nativeInstruction_at(pc)->is_sigtrap_ic_miss_check()) {
@@ -282,6 +294,7 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
           tty->print_cr("trap: null_check at " INTPTR_FORMAT " (SIGSEGV)", p2i(pc));
         }
         stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::IMPLICIT_NULL);
+        goto run_stub;
       }
 
 #ifdef COMPILER2
@@ -296,17 +309,6 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
       }
 #endif
 
-      // SIGTRAP-based nmethod entry barriers.
-      else if (sig == SIGTRAP && TrapBasedNMethodEntryBarriers &&
-               nativeInstruction_at(pc)->is_sigtrap_nmethod_entry_barrier() &&
-               CodeCache::contains((void*) pc)) {
-        if (TraceTraps) {
-          tty->print_cr("trap: nmethod entry barrier at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));
-        }
-        stub = StubRoutines::method_entry_barrier();
-        uc->uc_mcontext.jmp_context.lr = (uintptr_t)(pc + BytesPerInstWord); // emulate call by setting LR
-      }
-
       else if (sig == SIGFPE /* && info->si_code == FPE_INTDIV */) {
         if (TraceTraps) {
           tty->print_raw_cr("Fix SIGFPE handler, trying divide by zero handler.");

src/hotspot/os_cpu/linux_ppc/os_linux_ppc.cpp

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2024 SAP SE. All rights reserved.
+ * Copyright (c) 2012, 2025 SAP SE. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -286,6 +286,17 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
         stub = SharedRuntime::polling_page_return_handler_blob()->entry_point();
       }
 
+      // SIGTRAP-based nmethod entry barriers.
+      else if (sig == SIGTRAP && TrapBasedNMethodEntryBarriers &&
+               nativeInstruction_at(pc)->is_sigtrap_nmethod_entry_barrier() &&
+               CodeCache::contains((void*) pc)) {
+        if (TraceTraps) {
+          tty->print_cr("trap: nmethod entry barrier at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));
+        }
+        stub = StubRoutines::method_entry_barrier();
+        uc->uc_mcontext.regs->link = (uintptr_t)(pc + BytesPerInstWord); // emulate call by setting LR
+      }
+
       // SIGTRAP-based ic miss check in compiled code.
       else if (sig == SIGTRAP && TrapBasedICMissChecks &&
                nativeInstruction_at(pc)->is_sigtrap_ic_miss_check()) {
@@ -325,17 +336,6 @@ bool PosixSignals::pd_hotspot_signal_handler(int sig, siginfo_t* info,
       }
 #endif
 
-      // SIGTRAP-based nmethod entry barriers.
-      else if (sig == SIGTRAP && TrapBasedNMethodEntryBarriers &&
-               nativeInstruction_at(pc)->is_sigtrap_nmethod_entry_barrier() &&
-               CodeCache::contains((void*) pc)) {
-        if (TraceTraps) {
-          tty->print_cr("trap: nmethod entry barrier at " INTPTR_FORMAT " (SIGTRAP)", p2i(pc));
-        }
-        stub = StubRoutines::method_entry_barrier();
-        uc->uc_mcontext.regs->link = (uintptr_t)(pc + BytesPerInstWord); // emulate call by setting LR
-      }
-
       // stop on request
       else if (sig == SIGTRAP && (stop_type = nativeInstruction_at(pc)->get_stop_type()) != -1) {
         bool msg_present = (stop_type & MacroAssembler::stop_msg_present);