[M3devel] LONGREAL and m3gdb (was gettimeofday called from CheckLoadTracedRef?)

[Mika Nystrom]

Hrmph this is a bit silly.

80-bit FP ought to be supported on x86, at least, since that's the
native precision of the i387 (and 68881?)...

     Mika

Jay writes:
>
>Modula-3 only actually implements two floating point formats.
>The language spec and frontend might support three "names", but two of them are the same.
> 
> - Jay
>
>
>----------------------------------------
>> Date: Sun, 24 May 2009 08:50:14 -0500
>> From: rodney.m.bates at cox.net
>> To: m3devel at elegosoft.com
>> Subject: Re: [M3devel] LONGREAL and m3gdb (was gettimeofday called from CheckLoadTracedRef?)
>>
>> Floating point values in m3gdb is one area I have never done any
>> work on at all, but I have been aware for a long time that it probably
>> needs some. It just uses stock gdb's code, which also just uses
>> the C builtin arithmetic on C floating types. At the very least, the
>> mapping between C's two and Modula-3's three floating types, on
>> the various targets, is purely an accident right now. I recall there
>> is something wrong in the formatting too.
>>
>> Mika Nystrom wrote:
>>> Hi Modula-3ers, especially Tony,
>>>
>>> I'm seeing the following behavior a lot in a program I'm running:
>>>
>>> #0 0x68ecbba7 in gettimeofday () from /lib/libc.so.5
>>> #1 0x68611cb9 in Now () at ../src/time/POSIX/TimePosix.m3:16
>>> #2 0x685ecf06 in CollectorOn (timeOnEntry=Invalid C/C++ type code 30 in symbol table.
>>> ) at ../src/runtime/common/RTCollector.m3:674
>>> #3 0x685f2476 in CheckLoadTracedRef (ref=Invalid C/C++ type code 46 in symbol table.
>>> ) at ../src/runtime/common/RTCollector.m3:2271
>>> #4 0x68139379 in Get (tbl=Invalid C/C++ type code 26 in symbol table.
>>> )
>>> at ../FreeBSD4/SortedTotalOrderLRTbl.m3 => /usr/local/cm3/pkg/libm3/src/sortedtable/SortedTable.mg:145
>>>
>>> Is it normal for CheckLoadTracedRef to make system calls?
>>>
>>> Hmm, why is it even doing CheckLoadTracedRef? Here's the code (from SortedTable.mg):
>>>
>>>
>>> PROCEDURE Get ( tbl : Default;
>>> READONLY k : Key.T;
>>> VAR(*OUT*) v : Value.T): BOOLEAN =
>>> VAR
>>> x : Node := tbl.h.hi;
>>> cmp : Cmp;
>>> BEGIN
>>> WHILE (x # NIL) DO
>>> cmp := tbl.keyCompare (k, x.key);
>>> IF cmp = 0 THEN v := x.value; RETURN TRUE; END;
>>> IF (cmp < 0)
>>> THEN x := x.lo; (* line 145 *)
>>> ELSE x := x.hi;
>>> END;
>>> END;
>>> RETURN FALSE;
>>> END Get;
>>>
>>> where Node is defined as
>>>
>>> TYPE
>>> Node = REF RECORD
>>> key : Key.T;
>>> value : Value.T;
>>> lo : Node := NIL;
>>> hi : Node := NIL;
>>> priority: INTEGER (* random num; tree is a heap on these *)
>>> END;
>>>
>>> It seems odd to me that, under these circumstances, x := x.lo would
>>> cause any sort of checking activity...
>>>
>>> I'm using a CM3 that's about a month old, on FreeBSD4.
>>>
>>> Mika
>>>
>>> P.S. Needless to say, the code in question runs about 10x faster under
>>> PM3 than with this relatively new CM3... but my m3gdb is having trouble
>>> with PM3's LONGREALs for some reason.
>>>
>>>
>>