[dmd-internals] 64 bit bug: rndtol fails.

[Brad Roberts]

Another one down.. 18 phobos tests left.  22 dmd tests left (was 29 and 33 at
last report on Jan 6).

On 1/18/2011 8:39 PM, Walter Bright wrote:
> Thanks, Brad & Don. Commit 882.
> 
> Brad Roberts wrote:
>> On 1/12/2011 1:45 PM, Don Clugston wrote:
>>  
>>> ---
>>> import std.math;
>>>
>>> void main()
>>> {
>>>       assert( rndtol(-3.0) == -3 );
>>> }
>>> ---
>>>
>>> This is the only failure in std.mathspecial.
>>>     
>>
>> Confirmed buggy in d1 as well.
>>
>> The generated code:
>> _Dmain:
>>                 push    RBP
>>                 mov     RBP,RSP
>>                 sub     RSP,010h
>>                 fld     tbyte ptr FLAT:.rodata[00h][RIP]
>>                 fistp   long64 ptr -8[RBP]
>>                 mov     EAX,-8[RBP]
>>                 cmp     RAX,0FFFFFFFDh
>>                 je      L25
>>                 mov     EDI,7
>>                 call      _D3bug8__assertFiZv at PC32
>> L25:            xor     EAX,EAX
>>                 leave
>>                 ret
>>
>> Comparing it with the 32 bit version, the tbyte ptr part is fine, but the mov
>> EAX is almost certainly wrong.
>>
>> Try this change.. tested only with this repro case so far:
>>
>> Index: backend/cg87.c
>> ===================================================================
>> --- backend/cg87.c      (revision 880)
>> +++ backend/cg87.c      (working copy)
>> @@ -3063,7 +3063,11 @@
>>              genfltreg(c2,0x8B,findreglsw(retregs),0);
>>          }
>>          else
>> +        {
>>              c2 = genfltreg(c2,0x8B,reg,0);      // MOV reg,floatreg
>> +            if (tysize(tym) == 8 && I64)
>> +                code_orrex(c2, REX_W);
>> +        }
>>          c2 = cat(c2,fixresult(e,retregs,pretregs));
>>
>>          return cat(c1,c2);
>>
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>>
>>
>>   
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