[Synth] Add MajorityInverterOp (synth.mig.maj_inv) to Synth dialect #8912
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This commit introduces a new MajorityInverterOp operation to represent majority-inverter gates in Majority-Inverter Graphs (MIG) for synthesis. Majority-Inverter Graphs have become a prominent representation for logic synthesis in recent years, offering advantages in certain optimization scenarios alongside traditional And-Inverter Graphs (AIG). The implementation provides a synth.mig.maj_inv operation that computes the majority function of its inputs with optional inversion per operand. The operation requires an odd number of operands to avoid ties in majority computation and uses a custom assembly format with 'not' keyword prefix for inverted inputs. Comprehensive verification and error handling ensure correctness, while shared custom directives enable consistent parsing and printing of invertible operands across both MIG and AIG operations. The majority function returns 1 when more than half of the inputs are 1. For three inputs, it's equivalent to: (a & b) | (a & c) | (b & c). This addition aligns with the goal of making the circt-synth pipeline handle both AIG and MIG representations seamlessly, providing flexibility in choosing the most appropriate intermediate representation for different synthesis tasks. Example usage: %r1 = synth.mig.maj_inv %a, %b, %c : i1 %r2 = synth.mig.maj_inv not %a, %b, not %c : i1
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| let assemblyFormat = [{ | ||
| custom<VariadicInvertibleOperands>($inputs, type($result), $inverted, attr-dict) | ||
| }]; |
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Very cool! Love the use of custom here 🙌
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Towards #8786, this commit introduces a new MajorityInverterOp operation to represent majority-inverter gates in Majority-Inverter Graphs (MIG) for synthesis (https://ieeexplore.ieee.org/document/7293649). Majority-Inverter Graphs have become a prominent representation for logic synthesis in recent years, offering advantages in certain optimization scenarios alongside And-Inverter Graphs (AIG).
The implementation provides a synth.mig.maj_inv operation that computes the majority function of its inputs with optional inversion per operand. The operation requires an odd number of operands to avoid ties in majority computation and uses a custom assembly format with 'not' keyword prefix for inverted inputs.
The majority function returns 1 when more than half of the inputs are 1. For three inputs, it's equivalent to: (a & b) | (a & c) | (b & c).
This addition aligns with the goal of making the circt-synth pipeline handle both AIG and MIG representations seamlessly, providing flexibility in choosing the most appropriate intermediate representation (or mix them). Also MIG can represent and/or/carry in a single depth (and-inverter takes 2 depth for or/carry) so would be slightly accurate metric as logic depth.
Example usage: