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Optimization for "~x + 1" to "-x" (#69003) #69600

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merged 4 commits into from
Jun 7, 2022
Merged

Optimization for "~x + 1" to "-x" (#69003) #69600

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c40ab69
Optimization for "~x + 1" to "-x" (#69003)
SkiFoD May 20, 2022
bc447a7
op1 now inherits VNs from add node (#69003)
SkiFoD May 20, 2022
326d03b
Add optimizations for other constants (#69003)
SkiFoD May 21, 2022
62b3dc0
Revert changes made for constant support (#69003)
SkiFoD May 23, 2022
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9 changes: 9 additions & 0 deletions src/coreclr/jit/morph.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12874,6 +12874,15 @@ GenTree* Compiler::fgOptimizeAddition(GenTreeOp* add)
return op1;
}

// Fold (~x + 1) to -x.
if (op1->OperIs(GT_NOT) && op2->IsIntegralConst(1))
{
op1->SetOper(GT_NEG);
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It's good practice here to call op1->SetVNsFromNode(add) after this to inherit the VN from the add. Also, I suggest we move this under OptimizationEnabled() below.

DEBUG_DESTROY_NODE(op2);
DEBUG_DESTROY_NODE(add);
return op1;
}

// Note that these transformations are legal for floating-point ADDs as well.
if (opts.OptimizationEnabled())
{
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