http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50242
Bug #: 50242
Summary: __attribute__((naked)) is ignored on IA32 (x86)
Classification: Unclassified
Product: gcc
Version: 4.5.2
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: congru...@yahoo.co.uk
Given the follow c++ file:
---(start)---
__attribute__((naked)) void test(int a)
{
asm("//Do stuff");
asm("ret $4");
};
struct myclass
{
__attribute__((naked)) ~myclass()
{
asm("//Do stuff");
asm("ret");
}
virtual void virt() { };
};
void testmyclass()
{
myclass x;
}
---(end)---
The compiler will give the following complaints:
testnaked.cpp:1:39: warning: 'naked' attribute directive ignored
testnaked.cpp:9:34: warning: 'naked' attribute directive ignored
Additionally, prolog and epilog code is generated. The relevant parts of the
assembler output with added commentary follow:
---(start)---
__Z4testi: //test(int)
/APP
# 3 "testnaked.cpp" 1
//Do stuff
# 0 "" 2
# 4 "testnaked.cpp" 1
ret $4
# 0 "" 2
/NO_APP
ret // This ret shouldn't be here.
...(snip)...
__ZN7myclassD1Ev: //myclass::~myclass()
movl 4(%esp), %eax // Destructor prolog that restores the vtable.
movl $__ZTV7myclass+8, (%eax) // These 2 lines shouldn't be present.
/APP
# 11 "testnaked.cpp" 1
//Do stuff
# 0 "" 2
# 12 "testnaked.cpp" 1
ret
# 0 "" 2
/NO_APP
ret // This ret shouldn't be here.
---(end)---
My apologies for the AT&T syntax, but that's what -S yields.
