If we have thread local storage, use it instead of posix_getspecific().

Declare and use a variable PL_current_context to store a pointer to the
thread's interpreter struct. Use this to implement implicit context undef
ITHREADS, instead of a call to posix_getspecific().

For normal threaded code, this will eliminate function calls. For threaded
code in shared objects (the typical configuration for Linux distribution
builds) there still needs to be a function call to get the pointer to
thread local variables, but there will only be one per function, not one
per read of the variable.

1 files changed, 8 insertions, 0 deletions

diff --git a/globals.c b/globals.c
index 045c71ca3f..5a78c81166 100644
--- a/globals.c
+++ b/globals.c
@@ -30,6 +30,14 @@
  */
 #include "regcomp.h"
 
+/* We need somewhere to declare this. This file seems a good place.
+ * This is not a regular "global" in that we don't know whether it needs to
+ * exist until we include threads.h, and we don't want it as part of any
+ * global struct (if that or something similar is re-introduced. */
+
+#if defined(USE_ITHREADS) && defined(PERL_THREAD_LOCAL)
+PERL_THREAD_LOCAL void *PL_current_context;
+#endif
 
 /*
  * ex: set ts=8 sts=4 sw=4 et: