Replace goobledigoobs trick with consistent and future-proof assembly.

Stackless/core/slp_transfer.c

@@ -81,7 +81,6 @@ extern int slp_switch(void);
 #endif
 
 /* a write only variable used to prevent overly optimisation */
-intptr_t *global_goobledigoobs;
 static int
 climb_stack_and_transfer(PyCStackObject **cstprev, PyCStackObject *cst,
                          PyTaskletObject *prev)
@@ -96,15 +95,9 @@ climb_stack_and_transfer(PyCStackObject **cstprev, PyCStackObject *cst,
     intptr_t probe;
     register ptrdiff_t needed = &probe - ts->st.cstack_base;
     /* in rare cases, the need might have vanished due to the recursion */
-    register intptr_t *goobledigoobs;
     if (needed > 0) {
-        goobledigoobs = alloca(needed * sizeof(intptr_t));
-        if (goobledigoobs == NULL)
-            return -1;
-        /* hinder the compiler to optimise away 
-           goobledigoobs and the alloca call. 
-           This happens with gcc 4.7.x and -O2 */
-        global_goobledigoobs = goobledigoobs;
+        void* stack_ptr_tmp = alloca(needed * sizeof(intptr_t));
+        __asm__ volatile("" : : "g"(stack_ptr_tmp) : "memory");
     }
     return slp_transfer(cstprev, cst, prev);
 }

Stackless/core/stacklesseval.c

@@ -281,11 +281,9 @@ climb_stack_and_eval_frame(PyFrameObject *f)
     intptr_t probe;
     ptrdiff_t needed = &probe - ts->st.cstack_base;
     /* in rare cases, the need might have vanished due to the recursion */
-    intptr_t *goobledigoobs;
     if (needed > 0) {
-        goobledigoobs = alloca(needed * sizeof(intptr_t));
-        if (goobledigoobs == NULL)
-            return NULL;
+        void* stack_ptr_tmp = alloca(needed * sizeof(intptr_t));
+        __asm__ volatile("" : : "g"(stack_ptr_tmp) : "memory");
     }
     return slp_eval_frame(f);
 }