[llvm-commits] [llvm] r152847 - /llvm/trunk/lib/Target/ARM/ARMFastISel.cpp

[Chad Rosier]

On Mar 15, 2012, at 3:06 PM, Eli Friedman <eli.friedman at gmail.com> wrote:

> On Thu, Mar 15, 2012 at 2:40 PM, Chad Rosier <mcrosier at apple.com> wrote:
>> Author: mcrosier
>> Date: Thu Mar 15 16:40:23 2012
>> New Revision: 152847
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=152847&view=rev
>> Log:
>> [fast-isel] Don't try to encode LONG_MIN using cmn instructions.
>> rdar://11038907
>> 
>> Modified:
>>    llvm/trunk/lib/Target/ARM/ARMFastISel.cpp
>> 
>> Modified: llvm/trunk/lib/Target/ARM/ARMFastISel.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMFastISel.cpp?rev=152847&r1=152846&r2=152847&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/ARM/ARMFastISel.cpp (original)
>> +++ llvm/trunk/lib/Target/ARM/ARMFastISel.cpp Thu Mar 15 16:40:23 2012
>> @@ -1384,12 +1384,16 @@
>>         SrcVT == MVT::i1) {
>>       const APInt &CIVal = ConstInt->getValue();
>>       Imm = (isZExt) ? (int)CIVal.getZExtValue() : (int)CIVal.getSExtValue();
>> -      if (Imm < 0) {
>> -        isNegativeImm = true;
>> -        Imm = -Imm;
>> +      // We can't encode LONG_MIN (i.e., 0x80000000) as an immediate because
>> +      // there is no way to represent 2147483648 as a signed 32-bit int.
>> +      if (Imm != (int)0x80000000) {
>> +        if (Imm < 0) {
>> +          isNegativeImm = true;
>> +          Imm = -Imm;
>> +        }
>> +        UseImm = isThumb2 ? (ARM_AM::getT2SOImmVal(Imm) != -1) :
>> +          (ARM_AM::getSOImmVal(Imm) != -1);
>>       }
>> -      UseImm = isThumb2 ? (ARM_AM::getT2SOImmVal(Imm) != -1) :
>> -        (ARM_AM::getSOImmVal(Imm) != -1);
> 
> Why not just skip the negation rather than forcing it not to use an
> immediate?  ARM_AM::getT2SOImmVal(INT_MIN) will succeed, AFAIK.

Ah, yes.  That would be a better fix.  I'll double check if it works.

> Also, missing test case.

Coming up!

Thanks, Eli.	

> -Eli