From 24d3c1d05083d2620f52a7b209e8431180d2361c Mon Sep 17 00:00:00 2001
From: Shravan Narayan <shravanrn@gmail.com>
Date: Tue, 15 Oct 2024 00:29:43 -0500
Subject: [PATCH] wasm2c: Cleanup TLS: check for __thread and declare TLS vars
 only when needed

---
 wasm2c/wasm-rt-impl.c | 10 ++++++----
 wasm2c/wasm-rt-impl.h |  2 ++
 wasm2c/wasm-rt.h      |  4 ++++
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/wasm2c/wasm-rt-impl.c b/wasm2c/wasm-rt-impl.c
index 456c30257..ed328b02c 100644
--- a/wasm2c/wasm-rt-impl.c
+++ b/wasm2c/wasm-rt-impl.c
@@ -73,7 +73,9 @@ WASM_RT_THREAD_LOCAL uint32_t wasm_rt_saved_call_stack_depth;
 static WASM_RT_THREAD_LOCAL void* g_alt_stack = NULL;
 #endif
 
+#ifndef WASM_RT_TRAP_HANDLER
 WASM_RT_THREAD_LOCAL wasm_rt_jmp_buf g_wasm_rt_jmp_buf;
+#endif
 
 #ifdef WASM_RT_TRAP_HANDLER
 extern void WASM_RT_TRAP_HANDLER(wasm_rt_trap_t code);
@@ -162,7 +164,7 @@ static bool os_has_altstack_installed() {
   /* check for altstack already in place */
   stack_t ss;
   if (sigaltstack(NULL, &ss) != 0) {
-    perror("sigaltstack failed");
+    perror("sigaltstack check failed");
     abort();
   }
 
@@ -192,7 +194,7 @@ static void os_allocate_and_install_altstack(void) {
   ss.ss_flags = 0;
   ss.ss_size = SIGSTKSZ;
   if (sigaltstack(&ss, NULL) != 0) {
-    perror("sigaltstack failed");
+    perror("sigaltstack install failed");
     abort();
   }
 }
@@ -205,7 +207,7 @@ static void os_disable_and_deallocate_altstack(void) {
   /* verify altstack was still in place */
   stack_t ss;
   if (sigaltstack(NULL, &ss) != 0) {
-    perror("sigaltstack failed");
+    perror("sigaltstack uninstall check failed");
     abort();
   }
 
@@ -219,7 +221,7 @@ static void os_disable_and_deallocate_altstack(void) {
   /* disable and free */
   ss.ss_flags = SS_DISABLE;
   if (sigaltstack(&ss, NULL) != 0) {
-    perror("sigaltstack failed");
+    perror("sigaltstack uninstall failed");
     abort();
   }
   assert(!os_has_altstack_installed());
diff --git a/wasm2c/wasm-rt-impl.h b/wasm2c/wasm-rt-impl.h
index aa6f46d98..ed46b0972 100644
--- a/wasm2c/wasm-rt-impl.h
+++ b/wasm2c/wasm-rt-impl.h
@@ -27,8 +27,10 @@
 extern "C" {
 #endif
 
+#ifndef WASM_RT_TRAP_HANDLER
 /** A setjmp buffer used for handling traps. */
 extern WASM_RT_THREAD_LOCAL wasm_rt_jmp_buf g_wasm_rt_jmp_buf;
+#endif
 
 #if WASM_RT_STACK_DEPTH_COUNT
 /** Saved call stack depth that will be restored in case a trap occurs. */
diff --git a/wasm2c/wasm-rt.h b/wasm2c/wasm-rt.h
index 3274a15d2..b1150271d 100644
--- a/wasm2c/wasm-rt.h
+++ b/wasm2c/wasm-rt.h
@@ -81,6 +81,10 @@ extern "C" {
 
 #ifdef _MSC_VER
 #define WASM_RT_THREAD_LOCAL __declspec(thread)
+// We use __thread on POSIXy systems. This is disabled on Apple systems right
+// now due to sporadic test failures.
+#elif (defined(__GNUC__) || defined(__clang__)) && !defined(__APPLE__)
+#define WASM_RT_THREAD_LOCAL __thread
 #elif defined(WASM_RT_C11_AVAILABLE)
 #define WASM_RT_THREAD_LOCAL _Thread_local
 #else