Nick Maclaren writes:
> SandeepThorat <sathorat2003@xxxxxxxxx> wrote:
> >
> > i want to make some modification to prolouge(& epilouge) function of
> > gcc compiler. I m using version 4.1.0.
> >
> > Can anybody tel me out- which file contain these functions, How to make
> > changes & how to recompile it to take effect.
>
> I can tell you quite a lot of that, at least for the Intel x86, but
> I failed to reverse engineer the source enough to make the changes
> I wanted (even with help), and didn't have time to reverse engineer
> the code generation.
Try this. It won't work if __limit and __failure are in different
shared objects, but it should be OK otherwise.
Andrew.
Index: i386.c
===================================================================
--- i386.c (revision 124185)
+++ i386.c (working copy)
@@ -1536,6 +1536,7 @@
static void ix86_compute_frame_layout (struct ix86_frame *);
static bool ix86_expand_vector_init_one_nonzero (bool, enum machine_mode,
rtx, rtx, int);
+static rtx ix86_expand_int_compare (enum rtx_code code, rtx op0, rtx op1);
/* The svr4 ABI for the i386 says that records and unions are returned
@@ -5831,6 +5832,9 @@
/* Expand the prologue into a bunch of separate insns. */
+static GTY(()) rtx limit;
+static GTY(()) rtx failure_function;
+
void
ix86_expand_prologue (void)
{
@@ -6020,6 +6024,38 @@
REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_MAYBE_DEAD, const0_rtx, NULL);
}
+ {
+ if (limit == NULL_RTX)
+ {
+ tree foo = build_decl (VAR_DECL, get_identifier ("__limit"),
+ build_pointer_type (void_type_node));
+ DECL_EXTERNAL (foo) = true;
+ layout_decl (foo, 0);
+ rest_of_decl_compilation (foo, true, 0);
+ limit = DECL_RTL (foo);
+
+ foo = build_decl (FUNCTION_DECL, get_identifier ("__failure"),
+ build_function_type (void_type_node, void_list_node));
+ DECL_EXTERNAL (foo) = true;
+ rest_of_decl_compilation (foo, true, 0);
+ failure_function = DECL_RTL (foo);
+ }
+
+ {
+ rtx label = gen_label_rtx ();
+ rtx tmp = ix86_expand_int_compare (GEU, stack_pointer_rtx, limit);
+ tmp = gen_rtx_IF_THEN_ELSE (VOIDmode, tmp,
+ gen_rtx_LABEL_REF (VOIDmode, label),
+ pc_rtx);
+ tmp = emit_jump_insn (gen_rtx_SET (VOIDmode, pc_rtx, tmp));
+ JUMP_LABEL (tmp) = label;
+ ix86_expand_call (NULL_RTX, failure_function, const0_rtx, constm1_rtx,
+ NULL_RTX, 0);
+ emit_label (label);
+ LABEL_NUSES (label) = 1;
+ }
+ }
+
/* Prevent function calls from be scheduled before the call to mcount.
In the pic_reg_used case, make sure that the got load isn't deleted. */
if (current_function_profile)
