=============== =============== ============
Windows 2000 Professional
CYGWIN_NT-5.0 1.5.4(0.94/3/2)
GNU g++ version 3.2 20020927 (prerelease)
GNU objdump 2.14.90 20030901
=============== =============== ============
We can see that the same assembly code is generated for
* foo2 (char& )
and
* foo3 (char* ).
Does it mean that after parsing
a compiler "sees"/implements foo(char&) and foo(char*)
as identical function?
In other words, on the assembly stage there is no difference
between char& and char* (?).
====== C++ code : BEGIN ======
// File t1.cpp
static int sink = 0;
static void foo1 (char var) { sink += var; }
static void foo2 (char& var) { sink += var; }
static void foo3 (char* ptr) { sink += *ptr; }
static void foo4 () { sink += 1; }
====== C++ code : END ========
====== Compilation : BEGIN ======
$ g++ -c t1.cpp
====== Compilation : END ========
====== objdump : BEGIN ======
$ objdump -CSD t1.o
t1.o: file format pe-i386
Disassembly of section .text:
00000000 <foo1(char)>:
0: 55 push %ebp
1: 89 e5 mov %esp,%ebp
3: 83 ec 04 sub $0x4,%esp
6: 8b 45 08 mov 0x8(%ebp),%eax
9: 88 45 ff mov %al,0xffffffff( %ebp)
c: 0f be 45 ff movsbl 0xffffffff(%ebp ),%eax
10: 01 05 00 00 00 00 add %eax,0x0
16: c9 leave
17: c3 ret
00000018 <foo2(char&)> :
18: 55 push %ebp
19: 89 e5 mov %esp,%ebp
1b: 8b 45 08 mov 0x8(%ebp),%eax
1e: 0f be 00 movsbl (%eax),%eax
21: 01 05 00 00 00 00 add %eax,0x0
27: 5d pop %ebp
28: c3 ret
29: 90 nop
0000002a <foo3(char*)> :
2a: 55 push %ebp
2b: 89 e5 mov %esp,%ebp
2d: 8b 45 08 mov 0x8(%ebp),%eax
30: 0f be 00 movsbl (%eax),%eax
33: 01 05 00 00 00 00 add %eax,0x0
39: 5d pop %ebp
3a: c3 ret
3b: 90 nop
0000003c <foo4()>:
3c: 55 push %ebp
3d: 89 e5 mov %esp,%ebp
3f: ff 05 00 00 00 00 incl 0x0
45: 5d pop %ebp
46: c3 ret
47: 90 nop
48: 90 nop
49: 90 nop
4a: 90 nop
4b: 90 nop
4c: 90 nop
4d: 90 nop
4e: 90 nop
4f: 90 nop
Disassembly of section .data:
00000000 <sink>:
...
====== objdump : END ========
=============== =============== =======
Alex Vinokur
mailto:al****@c onnect.to
http://mathforum.org/library/view/10978.html
=============== =============== =======
