[llvm-commits] [llvm] r171270 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp test/Transforms/InstCombine/icmp.ll

[Jakub Staszak]

Thanks, added in r171310.

- Kuba

On Dec 31, 2012, at 1:38 PM, Nuno Lopes <nunoplopes at sapo.pt> wrote:

> This patch almost confused me.. It is correct because we have the invariant that C1 <= C2.
> BTW, you should add a 'CHECK: ret i1 %2' line to the test, otherwise it won't check that the 'or' instruction was replaced as intended.
> 
> Nuno
> 
> ----- Original Message -----
>> Author: kuba
>> Date: Sun Dec 30 18:34:55 2012
>> New Revision: 171270
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=171270&view=rev
>> Log:
>> Transform (A == C1 || A == C2) into (A & ~(C1 ^ C2)) == C1
>> if C1 and C2 differ only with one bit.
>> Fixes PR14708.
>> 
>> Modified:
>>   llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
>>   llvm/trunk/test/Transforms/InstCombine/icmp.ll
>> 
>> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=171270&r1=171269&r2=171270&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
>> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Sun Dec 30 18:34:55 2012
>> @@ -1524,6 +1524,18 @@
>>        AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
>>        return Builder->CreateICmpULT(Add, AddCST);
>>      }
>> +
>> +      if (LHS->getOperand(0) == RHS->getOperand(0)) {
>> +        // if LHSCst and RHSCst differ with only one bit:
>> +        // (A == C1 || A == C2) -> (A & ~(C1 ^ C2)) == C1
>> +        APInt Xor = LHSCst->getValue() ^ RHSCst->getValue();
>> +        if (Xor.isPowerOf2()) {
>> +          Value *NegCst = Builder->getInt(~Xor);
>> +          Value *And = Builder->CreateAnd(LHS->getOperand(0), NegCst);
>> +          return Builder->CreateICmp(ICmpInst::ICMP_EQ, And, LHSCst);
>> +        }
>> +      }
>> +
>>      break;                         // (X == 13 | X == 15) -> no change
>>    case ICmpInst::ICMP_UGT:         // (X == 13 | X u> 14) -> no change
>>    case ICmpInst::ICMP_SGT:         // (X == 13 | X s> 14) -> no change
>> 
>> Modified: llvm/trunk/test/Transforms/InstCombine/icmp.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp.ll?rev=171270&r1=171269&r2=171270&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/InstCombine/icmp.ll (original)
>> +++ llvm/trunk/test/Transforms/InstCombine/icmp.ll Sun Dec 30 18:34:55 2012
>> @@ -694,3 +694,14 @@
>>  %cmp = icmp sgt i32 %and, 30
>>  ret i1 %cmp
>> }
>> +
>> +; PR14708
>> +; CHECK: @test69
>> +; CHECK: %1 = and i32 %c, -33
>> +; CHECK: %2 = icmp eq i32 %1, 65
>> +define i1 @test69(i32 %c) nounwind uwtable {
>> +  %1 = icmp eq i32 %c, 97
>> +  %2 = icmp eq i32 %c, 65
>> +  %3 = or i1 %1, %2
>> +  ret i1 %3
>> +}
>> 
>> 
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