Using both -fomit-frame-pointer and -momit-leaf-frame-pointer _enables_ frame
pointers for non-leaf functions.
> cat x.c
int foo(void) { return 0; }
int bar(void) { return foo() + 1; }
> gcc-3.4 -O2 -fomit-frame-pointer -c x.c && objdump -d x.o
[...]
00000010 <bar>:
10: e8 fc ff ff ff call 11 <bar+0x1>
15: 40 inc %eax
16: c3 ret
[...]
> gcc-3.4 -O2 -fomit-frame-pointer -momit-leaf-frame-pointer -c x.c && objdump
-d x.o
[...]
00000010 <bar>:
10: 55 push %ebp
11: 89 e5 mov %esp,%ebp
13: e8 fc ff ff ff call 14 <bar+0x4>
18: 5d pop %ebp
19: 40 inc %eax
1a: c3 ret
[...]
This check in i386.c ix86_frame_pointer_required() could be the cause:
/* In override_options, TARGET_OMIT_LEAF_FRAME_POINTER turns off
the frame pointer by default. Turn it back on now if we've not
got a leaf function. */
if (TARGET_OMIT_LEAF_FRAME_POINTER
&& (!current_function_is_leaf))
return 1;
--
Summary: [x86] using both -fomit-frame-pointer and -momit-leaf-
frame-pointer enables frame pointers for non-leaf
functions
Product: gcc
Version: 3.4.3
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: markus at oberhumer dot com
CC: gcc-bugs at gcc dot gnu dot org
GCC host triplet: i386-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18759
