// iterations by the caller to be almost free.
//
// It is important to know that the set representation used for
// startState, endState, and merges can share data for two sets where
// one is a small delta from the other.  Doing this does require a
// little care in how sets are updated, both in mergePredecessors, and
// using its result.

// p256MulAsm Parameters
#define X0    V0
#define X1    V1
#define Y0    V2
#define Y1    V3
#define T0    V4
#define T1    V5

#define PL    V30
#define PH    V31
/*
 * https://delta.cs.cinvestav.mx/~francisco/arith/julio.pdf "Software Implementation of the NIST Elliptic Curves Over Prime Fields"
 *
 * A = X₁×Z₂²
 * B = Y₁×Z₂³
 * C = X₂×Z₁²-A
 * D = Y₂×Z₁³-B
 * X₃ = D² - 2A×C² - C³

		return nil
	}
	if high == 0 {
		return []*instruction{ins}
	}

	// Split into two additions, if possible.
	// Do not split SP-writing instructions, as otherwise the recorded SP delta may be wrong.
	if p.Spadj == 0 && ins.as == AADDI && ins.imm >= -(1<<12) && ins.imm < 1<<12-1 {
		imm0 := ins.imm / 2
		imm1 := ins.imm - imm0

		// ADDI $(imm/2), REG, TO
		// ADDI $(imm-imm/2), TO, TO