Hi:
I doubt this could be a bug. A lot of code would break with it. Maybe it does violates the short circuit in the small number of cases where that can be done. As in this case, it doesn't matters.
Regards Waldo
________________________________
From: ros-dev-bounces@reactos.com on behalf of Hartmut Birr Sent: Tue 5/3/2005 2:43 PM To: ReactOS Development List Subject: [ros-dev] gcc problem or not
Hi,
I've looked on a map file from an optimized build. I found the following code:
/* * If the directory containing the file to open doesn't exist then * fail immediately */ if (Status == STATUS_OBJECT_PATH_NOT_FOUND || 12015: 83 c4 0c add $0xc,%esp 12018: 89 c3 mov %eax,%ebx 1201a: 3d 3a 00 00 c0 cmp $0xc000003a,%eax 1201f: 0f 94 c2 sete %dl 12022: 3d 0d 00 00 c0 cmp $0xc000000d,%eax 12027: 0f 94 c0 sete %al 1202a: 09 d0 or %edx,%eax 1202c: a8 01 test $0x1,%al 1202e: 0f 85 42 01 00 00 jne 12176 <_VfatCreateFile+0x2e9> 12034: 81 fb 56 00 00 c0 cmp $0xc0000056,%ebx 1203a: 0f 84 36 01 00 00 je 12176 <_VfatCreateFile+0x2e9> Status == STATUS_INVALID_PARAMETER || Status == STATUS_DELETE_PENDING) { if (ParentFcb) { vfatReleaseFCB (DeviceExt, ParentFcb); } return(Status); }
I was always the opinion that the examination of a test condition stops if the result can not change again. A test condition like this:
if (pointer == NULL || pointer->member == 0)
should never access pointer->member if pointer is zero. Compared with the code above, it is possible that gcc build the result from the right side of the OR statement. This may hit a page fault. Is this a bug in gcc?
- Hartmut
_______________________________________________ Ros-dev mailing list Ros-dev@reactos.com http://reactos.com:8080/mailman/listinfo/ros-dev
-
Waldo Alvarez Cañizares