disable inline of functions which call alloca(), causes stack overrun in 176.gcc

[r19226]

diff --git a/ir/opt/opt_inline.c b/ir/opt/opt_inline.c
index 009545c..9f88455 100644 (file)
--- a/ir/opt/opt_inline.c
+++ b/ir/opt/opt_inline.c
@@ -753,6 +753,22 @@ static void find_addr(ir_node *node, void *env) {
                        is_Start(get_Proj_pred(node)) &&
                        get_Proj_proj(node) == pn_Start_P_value_arg_base) {
                *allow_inline = 0;
+       } else if (is_Alloc(node) && get_Alloc_where(node) == stack_alloc) {
+               /* From GCC:
+                * Refuse to inline alloca call unless user explicitly forced so as this
+                * may change program's memory overhead drastically when the function
+                * using alloca is called in loop.  In GCC present in SPEC2000 inlining
+                * into schedule_block cause it to require 2GB of ram instead of 256MB.
+                *
+                * Sorryly this is true with our implementation also.
+                * Moreover, we cannot differentiate between alloca() and VLA yet, so this
+                * disables inlining of functions using VLA (with are completely save).
+                *
+                * 2 Solutions:
+                * - add a flag to the Alloc node for "real" alloca() calls
+                * - add a new Stack-Restore node at the end of a function using alloca()
+                */
+               *allow_inline = 0;
        }
 }