[PATCH] Added InstCombine transform for pattern "(A | B) ^ (~A) = (~A) ^ (A | B) -> (A | ~B)"

[suyog sarda]

Committed in revision 213662 !!

Thanks Duncan for the review.


On Tue, Jul 22, 2014 at 9:12 PM, suyog <suyog.sarda at samsung.com> wrote:

> Made minor change in comment as suggested by Duncan in :
>
>
> http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140721/226719.html
>
> http://reviews.llvm.org/D4588
>
> Files:
>   lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
>   test/Transforms/InstCombine/xor2.ll
>
> Index: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
> ===================================================================
> --- lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
> +++ lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
> @@ -2446,6 +2446,12 @@
>      }
>    }
>
> +  // (A | B)^(~A) -> (A | ~B)
> +  Value *A = nullptr, *B = nullptr;
> +  if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
> +      match(Op1, m_Not(m_Specific(A))))
> +    return BinaryOperator::CreateOr(A, Builder->CreateNot(B));
> +
>    // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
>    if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
>      if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
> Index: test/Transforms/InstCombine/xor2.ll
> ===================================================================
> --- test/Transforms/InstCombine/xor2.ll
> +++ test/Transforms/InstCombine/xor2.ll
> @@ -82,3 +82,26 @@
>  ; CHECK: lshr i32 %x, 16
>  ; CHECK: ret
>  }
> +
> +
> +; (A | B) ^ (~A) -> (A | ~B)
> +define i32 @test7(i32 %a, i32 %b) #0 {
> + %or = or i32 %a, %b
> + %neg = xor i32 %a, -1
> + %xor = xor i32 %or, %neg
> + ret i32 %xor
> +; CHECK-LABEL: @test7(
> +; CHECK-NEXT: %1 = xor i32 %b, -1
> +; CHECK-NEXT: %xor = or i32 %a, %1
> +}
> +
> +; (~A) ^ (A | B) -> (A | ~B)
> +define i32 @test8(i32 %a, i32 %b) #0 {
> + %neg = xor i32 %a, -1
> + %or = or i32 %a, %b
> + %xor = xor i32 %neg, %or
> + ret i32 %xor
> +; CHECK-LABEL: @test8(
> +; CHECK-NEXT: %1 = xor i32 %b, -1
> +; CHECK-NEXT: %xor = or i32 %a, %1
> +}
>
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>


-- 
With regards,
Suyog Sarda
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