[Bug c/25499] New: regression: bogus 'defined but not used' warning

[rusty at rustcorp dot com dot au]

static int foo(void) { return 7; }
int main()
{
int foo(void);
return foo();
}

[EMAIL PROTECTED]:/tmp$ /usr/bin/gcc-3.4 -Wall -c foo.c
foo.c:1: warning: 'foo' defined but not used
[EMAIL PROTECTED]:/tmp$ /usr/bin/gcc-3.4 --version
gcc-3.4 (GCC) 3.4.5 (Debian 3.4.5-1)
Copyright (C) 2004 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[EMAIL PROTECTED]:/tmp$ /usr/bin/gcc-3.2 -Wall -c foo.c
[EMAIL PROTECTED]:/tmp$ /usr/bin/gcc-3.3 -Wall -c foo.c
[EMAIL PROTECTED]:/tmp$ /usr/bin/gcc-4.0 -Wall -c foo.c
[EMAIL PROTECTED]:/tmp$


-- 
   Summary: regression: bogus 'defined but not used' warning
   Product: gcc
   Version: 3.4.5
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c
AssignedTo: unassigned at gcc dot gnu dot org
    ReportedBy: rusty at rustcorp dot com dot au
  GCC host triplet: i486-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25499

[Bug c/35728] New: Inlined function via function pointer emitted unnecessarily

[rusty at rustcorp dot com dot au]

>From http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9079 now we get:

.file   "foo.c"
.section.rodata.str1.1,"aMS",@progbits,1
.LC0:
.string "Hello World.\n"
.text
.p2align 4,,15
.type   funk, @function
funk:
pushl   %ebp
movl$.LC0, %eax
movl%esp, %ebp
popl%ebp
ret
.size   funk, .-funk
.section.rodata.str1.1
.LC1:
.string "Hello World."
.text
.p2align 4,,15
.globl main
.type   main, @function
main:
leal4(%esp), %ecx
andl$-16, %esp
pushl   -4(%ecx)
pushl   %ebp
movl%esp, %ebp
pushl   %ecx
subl$4, %esp
movl$.LC1, (%esp)
callputs
addl$4, %esp
popl%ecx
popl%ebp
leal-4(%ecx), %esp
ret
.size   main, .-main
.ident  "GCC: (Ubuntu 4.3.0-1ubuntu1) 4.3.0"
.section.note.GNU-stack,"",@progbits

Note funk (a static function) is unused, and successfully inlined, but still
omitted.  Replicated on powerpc as well, so not x86-specific.


-- 
   Summary: Inlined function via function pointer emitted
unnecessarily
   Product: gcc
   Version: 4.3.1
Status: UNCONFIRMED
  Severity: minor
  Priority: P3
 Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rusty at rustcorp dot com dot au
 GCC build triplet: i386-linux-gnu-gcc-4.1
  GCC host triplet: i386-linux-gnu-gcc-4.1
GCC target triplet: i386-linux-gnu-gcc-4.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35728

[Bug tree-optimization/9079] [tree-ssa] Inline constant function pointers

[rusty at rustcorp dot com dot au]

--- Comment #16 from rusty at rustcorp dot com dot au  2008-03-28 02:38 
---
OK, this is fixed in gcc 4.3 (woot!), but the unused "funk" is still omitted.

See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35728


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9079

[Bug c/32751] New: Missed optimization with function ptrs even when inline

[rusty at rustcorp dot com dot au]

I expect "one" not to be emitted when compiling this with -O3:

=== cut here ===
static inline unsigned long one(void)
{
return 1;
}
static inline unsigned long call(unsigned long (*fn)(void))
{
return fn();
}
int test_call(void)
{
return call(one);
}
=== cut here ===
.file   "foo.c"
.text
.p2align 4,,15
.type   one, @function
one:
pushl   %ebp
movl$1, %eax
movl%esp, %ebp
popl%ebp
ret
.size   one, .-one
.p2align 4,,15
.globl test_call
.type   test_call, @function
test_call:
pushl   %ebp
movl%esp, %ebp
popl%ebp
jmp one
.size   test_call, .-test_call
.ident  "GCC: (GNU) 4.1.2 (Ubuntu 4.1.2-0ubuntu4)"
.section.note.GNU-stack,"",@progbits
=== cut here ===

The lack of this optimization means that it's inefficient to write generic
routines (eg. see include/linux/rbtree.h in the Linux sources).

Thanks,
Rusty.


-- 
   Summary: Missed optimization with function ptrs even when inline
   Product: gcc
   Version: 4.1.2
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c
AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rusty at rustcorp dot com dot au
 GCC build triplet: i486-linux-gnu
  GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32751

[Bug c/44257] New: typeof(*(struct undefined *)) fails to compile

[rusty at rustcorp dot com dot au]

struct foo; 
typeof(struct foo) *p; // This is fine.
typeof(*p) *p2; // foo.c:5: error: dereferencing pointer to incomplete type

This is important, because AFAICT the only way to declare a const pointer for a
given type is: "const typeof(*p) *" which doesn't work if p is a pointer to an
undefined struct :(


-- 
   Summary: typeof(*(struct undefined *)) fails to compile
   Product: gcc
   Version: 4.4.3
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c
AssignedTo: unassigned at gcc dot gnu dot org
    ReportedBy: rusty at rustcorp dot com dot au


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44257