Avoid disassembling pthread_getspecific every time we need to check for fast tls...

diff --git a/mono/mini/mini-x86.c b/mono/mini/mini-x86.c
index 75c09414fb15e4539d1c5597cd1b350b29f78d1e..675fd76045fd700169dbf4a01cccd0760323a6d3 100644 (file)
--- a/mono/mini/mini-x86.c
+++ b/mono/mini/mini-x86.c
@@ -2203,6 +2203,12 @@ gboolean
 mono_x86_have_tls_get (void)
 {
 #ifdef __APPLE__
+       static gboolean have_tls_get = FALSE;
+       static gboolean inited = FALSE;
+
+       if (inited)
+               return have_tls_get;
+
        guint32 *ins = (guint32*)pthread_getspecific;
        /*
         * We're looking for these two instructions:
@@ -2210,7 +2216,11 @@ mono_x86_have_tls_get (void)
         * mov    0x4(%esp),%eax
         * mov    %gs:0x48(,%eax,4),%eax
         */
-       return ins [0] == 0x0424448b && ins [1] == 0x85048b65 && ins [2] == 0x00000048;
+       have_tls_get = ins [0] == 0x0424448b && ins [1] == 0x85048b65 && ins [2] == 0x00000048;
+
+       inited = TRUE;
+
+       return have_tls_get;
 #else
        return TRUE;
 #endif