Date: Mon, 18 Jun 2012 00:39:30 GMT From: Eric McCorkle <eric@shadowsun.net> To: freebsd-gnats-submit@FreeBSD.org Subject: i386/169187: Bad sizeof(uint64_t) with -m32 compiler flag Message-ID: <201206180039.q5I0dUY7022002@red.freebsd.org> Resent-Message-ID: <201206180040.q5I0eBVv088320@freefall.freebsd.org>
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>Number: 169187
>Category: i386
>Synopsis: Bad sizeof(uint64_t) with -m32 compiler flag
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-i386
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Jun 18 00:40:11 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator: Eric McCorkle
>Release: 9.0, also appears on 10.0
>Organization:
>Environment:
FreeBSD atom-edge 9.0-STABLE FreeBSD 9.0-STABLE #118 r236960M: Wed Jun 13 08:44:31 EDT 2012 root@atom-edge:/usr/obj/usr/src/sys/CUSTOM amd64
>Description:
When compiling programs on an amd64 machine with the -m32 compiler flag, uint64_t variables are incorrectly sized, resulting in sizeof(uint64_t) == 4. Presumably this affects int64_t as well, and any types that are typedef'ed to one of these.
>How-To-Repeat:
Compile the following program:
#include <stdio.h>
#include <stdlib.h>
int main() { printf("%d\n", sizeof(uint64_t)); return 0; }
with the following command:
gcc -m32 -o test test.c
The output will be "4" as opposed to "8" like it should be.
>Fix:
The file <machine/_types.h> defines __uint64_t as unsigned long on amd64 platforms. When compiling with -m32, however, the compiler makes unsigned long a 32-bit integer, which seems to be the root of the problem.
A simple fix is to detect when sizeof(unsigned long) == 4, and define __uint64_t as unsigned long long instead.
>Release-Note:
>Audit-Trail:
>Unformatted:
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