profile

//go:build !windows

package main

import (
	"fmt"

	"github.com/consensys/gnark-crypto/ecc"
	"github.com/consensys/gnark/frontend"
	"github.com/consensys/gnark/frontend/cs/r1cs"
	"github.com/consensys/gnark/profile"
)

type Circuit struct {
	A frontend.Variable
}

type obj struct {
}

func (circuit *Circuit) Define(api frontend.API) error {
	var o obj
	o.Define(api, circuit.A)
	// api.AssertIsEqual(api.Mul(circuit.A, circuit.A), circuit.A)
	return nil
}

func (o *obj) Define(api frontend.API, A frontend.Variable) error {
	api.AssertIsEqual(api.Mul(A, A), A)
	return nil
}

func main() {
	// default options generate gnark.pprof in current dir
	// use pprof as usual (go tool pprof -http=:8080 gnark.pprof) to read the profile file
	// overlapping profiles are allowed (define profiles inside Define or subfunction to profile
	// part of the circuit only)
	p := profile.Start()
	_, _ = frontend.Compile(ecc.BN254.ScalarField(), r1cs.NewBuilder, &Circuit{})
	p.Stop()

	// expected output fmt.Println(p.Top())
	const _ = `Showing nodes accounting for 2, 100% of 2 total
----------------------------------------------------------+-------------
      flat  flat%   sum%        cum   cum%   calls calls% + context              
----------------------------------------------------------+-------------
                                                 1   100% |   profile_test.(*Circuit).Define profile/profile_test.go:21
         1 50.00% 50.00%          1 50.00%                | r1cs.(*builder).AssertIsEqual frontend/cs/r1cs/api_assertions.go:37
----------------------------------------------------------+-------------
                                                 1   100% |   profile_test.(*Circuit).Define profile/profile_test.go:21
         1 50.00%   100%          1 50.00%                | r1cs.(*builder).Mul frontend/cs/r1cs/api.go:221
----------------------------------------------------------+-------------
         0     0%   100%          2   100%                | profile_test.(*Circuit).Define profile/profile_test.go:21
                                                 1 50.00% |   r1cs.(*builder).AssertIsEqual frontend/cs/r1cs/api_assertions.go:37
                                                 1 50.00% |   r1cs.(*builder).Mul frontend/cs/r1cs/api.go:221
----------------------------------------------------------+-------------`

	fmt.Println(p.NbConstraints())
}

Output:
2

Example_operations demonstrates how to use operation profiling with emulated arithmetic.

package main

import (
	"github.com/consensys/gnark-crypto/ecc"
	"github.com/consensys/gnark/frontend"
	"github.com/consensys/gnark/frontend/cs/scs"
	"github.com/consensys/gnark/profile"
	"github.com/consensys/gnark/std/math/emulated"
)

// EmulatedCircuit performs emulated arithmetic which uses deferred constraints
type EmulatedCircuit struct {
	A, B emulated.Element[emulated.Secp256k1Fp]
}

func (c *EmulatedCircuit) Define(api frontend.API) error {
	f, err := emulated.NewField[emulated.Secp256k1Fp](api)
	if err != nil {
		return err
	}

	res := f.Mul(&c.A, &c.B)
	res = f.Mul(res, &c.A)
	f.AssertIsEqual(res, &c.B)

	return nil
}

func main() {
	// Start profiling - operations will be tracked at call sites
	p := profile.Start(profile.WithNoOutput())

	// Compile a circuit using emulated arithmetic
	_, _ = frontend.Compile(ecc.BN254.ScalarField(), scs.NewBuilder, &EmulatedCircuit{})

	p.Stop()

	// View actual constraints (default)
	// go tool pprof -sample_index=0 gnark.pprof

	// View operations (shows where Mul/AssertIsEqual were called)
	// go tool pprof -sample_index=1 gnark.pprof

	// Or programmatically:
	// p.Top() - shows constraint tree
	// p.TopOperations() - shows operation tree
}

Output: