From e006b992c29decb01865b0749e35a4cfc872bdaf Mon Sep 17 00:00:00 2001
From: Fangrui Song <i@maskray.me>
Date: Thu, 19 Sep 2019 00:04:29 -0700
Subject: [PATCH] typedef rb_jmpbuf_t to void *[5] if __builtin_setjmp is used

The built-in version operates on a buffer of 5 words, much smaller than
the size of jmp_buf defined in libc.
Note, powerpc requires 5 words, while arm and x86_64 just require 3.
---
 tool/m4/ruby_setjmp_type.m4 | 2 +-
 vm_core.h                   | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/tool/m4/ruby_setjmp_type.m4 b/tool/m4/ruby_setjmp_type.m4
index e054a544c5..9da9a88680 100644
--- a/tool/m4/ruby_setjmp_type.m4
+++ b/tool/m4/ruby_setjmp_type.m4
@@ -47,6 +47,6 @@ AS_IF([test x$setjmp_prefix:$setjmp_sigmask = xsig:], [
 AC_MSG_RESULT(${setjmp_prefix}setjmp${setjmp_suffix}${setjmp_cast:+\($setjmp_cast\)}${setjmp_sigmask})
 AC_DEFINE_UNQUOTED([RUBY_SETJMP(env)], [${setjmp_prefix}setjmp${setjmp_suffix}($setjmp_cast(env)${setjmp_sigmask})])
 AC_DEFINE_UNQUOTED([RUBY_LONGJMP(env,val)], [${setjmp_prefix}longjmp($setjmp_cast(env),val)])
-AC_DEFINE_UNQUOTED(RUBY_JMP_BUF, ${setjmp_sigmask+${setjmp_prefix}}jmp_buf)
+AS_IF([test x$setjmp_prefix != x__builtin_], AC_DEFINE_UNQUOTED(RUBY_JMP_BUF, ${setjmp_sigmask+${setjmp_prefix}}jmp_buf))
 AS_IF([test x$setjmp_suffix = xex], [AC_DEFINE_UNQUOTED(RUBY_USE_SETJMPEX, 1)])
 ])dnl
diff --git a/vm_core.h b/vm_core.h
index 99c4d13f66..bc7e6bec55 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -775,7 +775,11 @@ enum rb_thread_status {
     THREAD_KILLED
 };
 
+#ifdef RUBY_JMP_BUF
 typedef RUBY_JMP_BUF rb_jmpbuf_t;
+#else
+typedef void *rb_jmpbuf_t[5];
+#endif
 
 /*
   the members which are written in EC_PUSH_TAG() should be placed at