[LLVMdev] bitwise AND selector node not commutative?

[Evan Cheng]

Fixed.

Evan

On Jun 25, 2009, at 6:09 PM, Evan Cheng wrote:

>
> On Jun 25, 2009, at 6:06 PM, Evan Cheng wrote:
>
>>
>> On Jun 25, 2009, at 4:38 PM, David Goodwin wrote:
>>
>>> Using the Thumb-2 target we see that ORN ( a | ^b) and BIC (a &  
>>> ^b) have similar patterns, as we would expect:
>>>
>>> defm t2BIC  : T2I_bin_irs<"bic", BinOpFrag<(and node:$LHS, (not  
>>> node:$RHS))>>;
>>> defm t2ORN  : T2I_bin_irs<"orn", BinOpFrag<(or  node:$LHS, (not  
>>> node:$RHS))>>;
>>>
>>> Compiling the following three works as expected:
>>>
>>>    %tmp1 = xor i32 4294967295, %b ;   %tmp2 = or i32 %a, %tmp1   -- 
>>> >  	orn r0, r0, r1
>>>    %tmp1 = xor i32 4294967295, %b ;   %tmp2 = or i32 %tmp1, %a   -- 
>>> >    orn r0, r0, r1
>>>    %tmp = xor i32 %b, 4294967295  ;   %tmp1 = and i32 %a, %tmp   -- 
>>> >    bic r0, r0, r1
>>>
>>> But this doesn't:
>>>
>>>    %tmp = xor i32 %b, 4294967295  ;   %tmp1 = and i32 %tmp, %a   -- 
>>> >    eor r1, r1, #4294967295 ; and r0, r1, r0
>>>
>>> On the surface it seems that the selector is not commuting the AND  
>>> operands. I've attached the complete test files. I can take a look  
>>> but I need a pointer to get started.
>>
>> No, isel is trying to commute the AND. See ARMGenDAGISel.inc (auto- 
>> generated by tablegen):
>>
>>     // Pattern: (and:i32 GPR:i32:$lhs, (xor:i32 t2_so_reg:i32:$rhs,  
>> (imm:i32)<<P:Predicate_immAllOnes>>))
>>     // Emits: (t2BICrs:i32 GPR:i32:$lhs, t2_so_reg:i32:$rhs)
>>     // Pattern complexity = 19  cost = 1  size = 0
>>     {
>>       ..
>>     }
>>
>>
>>     // Pattern: (and:i32 (xor:i32 t2_so_reg:i32:$rhs, (imm:i32) 
>> <<P:Predicate_immAllOnes>>), GPR:i32:$lhs)
>>     // Emits: (t2BICrs:i32 GPR:i32:$lhs, t2_so_reg:i32:$rhs)
>>     // Pattern complexity = 19  cost = 1  size = 0
>>     {
>>      ...
>>      }
>>
>> The second one is the commuted version. Looks like the issue is in  
>> SelectThumb2ShifterOperandReg.
>
> Ugh. It should try to match t2BICrr. But someone tblgen is not  
> generating the commuted version. Very strange. I'm take a look.
>
> Evan
>
>>
>> Evan
>>
>>
>>>
>>> David
>>>
>>> <RM_20_BIC.ll>
>>> <RM_112_ORN.ll>
>>>
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>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>
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