fix #6098, crash on stack overflow splicing big argument lists

still slow as hell and still a bad idea, but at least it doesn't segfault

Author: JeffBezanson

src/builtins.c

@@ -266,6 +266,9 @@ JL_CALLABLE(jl_f_apply)
                             jl_tuple_len(args[1]));
         }
     }
+    jl_value_t *argarr = NULL;
+    JL_GC_PUSH1(&argarr);
+    jl_value_t *result;
     jl_value_t **newargs;
     size_t n=0, i, j;
     for(i=1; i < nargs; i++) {
@@ -285,15 +288,27 @@ JL_CALLABLE(jl_f_apply)
                     JL_TYPECHK(apply, tuple, args[i]);
                 }
             }
-            goto fancy_apply;
+            argarr = jl_apply(jl_append_any_func, &args[1], nargs-1);
+            assert(jl_typeis(argarr, jl_array_any_type));
+            result = jl_apply((jl_function_t*)args[0], jl_cell_data(argarr), jl_array_len(argarr));
+            JL_GC_POP();
+            return result;
         }
     }
-    newargs = (jl_value_t**)alloca(n * sizeof(jl_value_t*));
+    if (n > 64000) {
+        // put arguments on the heap if there are too many
+        argarr = (jl_value_t*)jl_alloc_cell_1d(n);
+        newargs = jl_cell_data(argarr);
+    }
+    else {
+        newargs = (jl_value_t**)alloca(n * sizeof(jl_value_t*));
+    }
     n = 0;
     for(i=1; i < nargs; i++) {
         if (jl_is_tuple(args[i])) {
             jl_tuple_t *t = (jl_tuple_t*)args[i];
-            for(j=0; j < jl_tuple_len(t); j++)
+            size_t al = jl_tuple_len(t);
+            for(j=0; j < al; j++)
                 newargs[n++] = jl_tupleref(t, j);
         }
         else {
@@ -302,14 +317,7 @@ JL_CALLABLE(jl_f_apply)
                 newargs[n++] = jl_cellref(args[i], j);
         }
     }
-    return jl_apply((jl_function_t*)args[0], newargs, n);
-
- fancy_apply: ;
-    jl_value_t *argarr = jl_apply(jl_append_any_func, &args[1], nargs-1);
-    JL_GC_PUSH1(&argarr);
-    assert(jl_typeis(argarr, jl_array_any_type));
-    jl_value_t *result = jl_apply((jl_function_t*)args[0],
-                                  jl_cell_data(argarr), jl_array_len(argarr));
+    result = jl_apply((jl_function_t*)args[0], newargs, n);
     JL_GC_POP();
     return result;
 }