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RE: memset (0, 0, 0);
From: |
Thomas,Stephen |
Subject: |
RE: memset (0, 0, 0); |
Date: |
Mon, 7 Apr 2003 10:22:04 +0100 |
Hi,
gdb appears to call memset(0,0,0) from build_regcache() in gdb/regcache.c. I
can't really claim to understand how this works, but this function appears to
get called 3 times during gdb initialization:
static void build_regcache (void)
{
...
int sizeof_register_valid;
...
sizeof_register_valid = ((NUM_REGS + NUM_PSEUDO_REGS) * sizeof
(*register_valid));
register_valid = xmalloc (sizeof_register_valid);
memset (register_valid, 0, sizeof_register_valid);
}
On the 1st time of calling, none of the gdbarch stuff is set up, so NUM_REGS =
NUM_PSEUDO_REGS = 0. So xmalloc gets called with size=0. That returns 0 as the
'address', which gets passed to memset. I guess this just works OK on other
architectures (it does on x86 anyway).
Easy enough to fix I suppose, but is that really the point?
Steve Thomas
SuperH (UK) Ltd.
-----Original Message-----
From: Andrew Cagney [mailto:address@hidden
Sent: 04 April 2003 16:17
To: Rennecke,Joern
Cc: address@hidden; address@hidden; address@hidden; Thomas,Stephen;
McGoogan,Sean
Subject: Re: memset (0, 0, 0);
> This conflicts with gdb usage of memset (0, 0, 0); in some places.
> There are three practical questions here:
> - should gdb use this idiom?
> - should all target-specific variants of newlib's memset implement it?
> - should all target-specific variants of glibc's memset implement it?
I'm not sure why you're refering to GDB here. GDB assumes ISO C and
hence should never use memset in ways that violate the ISO C spec. If
it is, then someone gets to fix it.
Andrew
- memset (0, 0, 0);, Joern Rennecke, 2003/04/04
- Re: memset (0, 0, 0);, Daniel Jacobowitz, 2003/04/04
- Re: memset (0, 0, 0);, Andrew Cagney, 2003/04/04
- Re: memset (0, 0, 0);, Andreas Schwab, 2003/04/04
- Re: memset (0, 0, 0);, Petr Vandrovec, 2003/04/04
- RE: memset (0, 0, 0);,
Thomas,Stephen <=
- Re: memset (0, 0, 0);, Wolfram Gloger, 2003/04/07
- Re: memset (0, 0, 0);, Daniel Jacobowitz, 2003/04/07
- Re: memset (0, 0, 0);, Geoff Keating, 2003/04/07
- RE: memset (0, 0, 0);, Thomas,Stephen, 2003/04/07
- RE: memset (0, 0, 0);, Thomas,Stephen, 2003/04/08