[RFA] cleanup of syscall consts in process record

[Michael Snyder]

Joel Brobecker wrote:
>> 2009-09-08  Michael Snyder  <msnyder@vmware.com>
>>
>> 	* amd64-linux-tdep.h (enum amd64_syscall): New enum consts, 
>> 	to replace literal consts used in amd64-linux-tdep.c
>> 	* linux-record.h (enum gdb_syscall): New enum consts, to replace
>> 	literal consts used in amd64-linux-tdep.c and linux-record.c.
>> 	* amd64-linux-tdep.c (amd64_canonicalize_syscall): New function,
>> 	translate from native amd64 Linux syscall id to internal gdb id.
>> 	(amd64_linux_syscall_record): Switch statement abstracted out 
>> 	and replaced with a call to amd64_canonicalize_syscall.
>> 	* linux-record.c (record_linux_system_call): Replace literal
>> 	consts with enum consts.
>> 	* i386-linux-tdep.c (i386_canonicalize_syscall): New function,
>> 	trivially translate from native i386 Linux syscalls to gdb syscalls.
>> 	(i386_linux_intx80_sysenter_record): 
> 
> Nice! I really like this version much better. The approach you took
> with i386 made me wonder whether we really need the amd64_syscall enum
> at all - we could have used a plain int as the argument to
> amd64_canonicalize_syscall, and use plain numbers there, rather than
> having an enum that's only used there. I don't mind, though, so
> don't worry about it unless you agree as well.

Nah, the idea was to get rid of magic numbers,
plus it makes the code more readable.  Self-documenting.


> Note that this should also fix the issue that Hui reported about
> building on cygwin with --enable-64-bit-bfd. So I'll remove Hui's
> patch from my list.

Yes, I broke down and included Hui's patch in this one.

> Just one comment:
> 
>> +static enum gdb_syscall
>> +i386_canonicalize_syscall (int syscall)
>> +{
>> +  enum { i386_syscall_max = 499 };
>> +
>> +  if (syscall <= i386_syscall_max)
>> +    return syscall;
> 
> I thought that we should incorporate Mark's suggestion of checking
> syscall against negative values. But I now realize that if syscall
> is negative, we'll return a value that's equivalent to returning -1.
> And the check against negative values in i386_linux_intx80_sysenter_record
> should then catch it.

Correct.

So this is approved, then?