http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46596
Summary: misbehavior when mixing always_inline and alias
attributes in the same compilation unit
Product: gcc
Version: 4.5.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: vap...@gentoo.org
i have a function "foo". its header sets up an always_inline function that
does sanity checks when constants are involved. otherwise it delays the
non-constant checking to another function. here is the portion from the
header:
extern void foo(int i);
extern void __in(int i);
extern inline __attribute__((always_inline))
void foo(int i) { __in(i); }
where i actually define "foo", there is an alias used to setup multiple
symbols. also in that file is another function which calls the inline checking
function. together, gcc barfs. here is the portion of the file:
void bar(int i) { foo(i + 1234); }
void __foo(int i) {}
extern typeof(__foo) foo __attribute__((alias("__foo")));
combine them into one and compile like so (this is 4.5.1):
gcc -O2 -c test.c -std=gnu99 -fgnu89-inline -Winline
this produces the error:
test.c: In function ‘bar’:
test.c:18:22: sorry, unimplemented: inlining failed in call to ‘foo’: function
body not available
test.c:14:5: sorry, unimplemented: called from here
that doesnt seem right since the function body *is* available. if i split the
__foo/foo definitions into their own dedicated file, then everything compiles
just fine as i'd expect.
what's even more odd though is that -Winline affects code generation. if you
compile without that flag, you dont get any errors, but the generated code is
wrong:
gcc -O2 -c test.c -std=gnu99 -fgnu89-inline
objdump -dr test.o
...
0000000000000000 <bar>:
0: 81 c7 d2 04 00 00 add $0x4d2,%edi
6: e9 00 00 00 00 jmpq b <bar+0xb>
7: R_X86_64_PC32 foo-0x4
b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
...
clearly it's just jumping straight to the definition of foo rather than going
through the inline function.
doesnt seem to be a regression ... every gcc version ive tested fails in the
same way: 4.0.4, 4.1.2, 4.2.4, 4.3.5, 4.4.4, 4.5.1. versions before 4.2.x had
the -fgnu89-inline flag dropped since that was the default behavior and so was
unnecessary (and unrecognized).
