syntax.Geq: ir.OGE,

	syntax.Add: ir.OADD,
	syntax.Sub: ir.OSUB,
	syntax.Or:  ir.OOR,
	syntax.Xor: ir.OXOR,

	syntax.Mul:    ir.OMUL,
	syntax.Div:    ir.ODIV,
	syntax.Rem:    ir.OMOD,
	syntax.And:    ir.OAND,
	syntax.AndNot: ir.OANDNOT,
	syntax.Shl:    ir.OLSH,
	syntax.Shr:    ir.ORSH,
}

// error is called concurrently if files are parsed concurrently.

// Otherwise, it returns p.
func (p *P256Point) SetBytes(b []byte) (*P256Point, error) {
	// p256Mul operates in the Montgomery domain with R = 2²⁵⁶ mod p. Thus rr
	// here is R in the Montgomery domain, or R×R mod p. See comment in
	// P256OrdInverse about how this is used.
	rr := p256Element{0x0000000000000003, 0xfffffffbffffffff,
		0xfffffffffffffffe, 0x00000004fffffffd}

	switch {

package modload

import (
	"cmd/go/internal/cfg"
	"cmd/go/internal/gover"
	"cmd/go/internal/mvs"
	"cmd/go/internal/par"
	"context"
	"errors"
	"fmt"
	"maps"
	"os"
	"slices"

	"golang.org/x/mod/module"
)

// editRequirements returns an edited version of rs such that:
//
//  1. Each module version in mustSelect is selected.
//
//  2. Each module version in tryUpgrade is upgraded toward the indicated

	tmpdir, err := os.MkdirTemp("", "cshared")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tmpdir)

	copyFile(t, filepath.Join(tmpdir, "src", "testcshared", "go.mod"), "go.mod")
	copyFile(t, filepath.Join(tmpdir, "src", "testcshared", "libgo", "libgo.go"), filepath.Join("libgo", "libgo.go"))
	copyFile(t, filepath.Join(tmpdir, "src", "testcshared", "p", "p.go"), filepath.Join("p", "p.go"))

		{name: "SHRW", argLength: 2, reg: gp21shift, asm: "SHRW", resultInArg0: true, clobberFlags: true},               // unsigned arg0 >> arg1, shift amount is mod 32
		{name: "SHRB", argLength: 2, reg: gp21shift, asm: "SHRB", resultInArg0: true, clobberFlags: true},               // unsigned arg0 >> arg1, shift amount is mod 32

		}
		out, err := format.Source(buf.Bytes())
		if err != nil {
			log.Fatal(err)
		}
		if _, err := f.Write(out); err != nil {
			log.Fatal(err)
		}

		// If p = 3 mod 4, implement modular square root by exponentiation.
		mod4 := new(big.Int).Mod(c.Params.P, big.NewInt(4))
		if mod4.Cmp(big.NewInt(3)) != 0 {
			continue
		}

		exp := new(big.Int).Add(c.Params.P, big.NewInt(1))
		exp.Div(exp, big.NewInt(4))

		t.Skipf("can't find objcopy: %v", err)
	}

	dir := t.TempDir()

	gopath := filepath.Join(dir, "GOPATH")
	env := append(os.Environ(), "GOPATH="+gopath)

	if err := os.WriteFile(filepath.Join(dir, "go.mod"), []byte("module elf_test\n"), 0666); err != nil {
		t.Fatal(err)
	}

	asmFile := filepath.Join(dir, "x.s")
	if err := os.WriteFile(asmFile, []byte(asmSource), 0444); err != nil {
		t.Fatal(err)
	}

	// this used to give confusing error messages because the
	// linker would find an undefined reference to "zero" created
	// by the runtime package.

	write("go.mod", "module testunresolved\n")
	write("main.go", `package main

func main() {
        x()
}

func x()
`)
	write("main.s", `
TEXT ·x(SB),0,$0
        MOVD zero<>(SB), AX

		// mul
		OpMul64, OpMul32, OpMul16, OpMul8,
		OpMul32F, OpMul64F,
		// div
		OpDiv32F, OpDiv64F,
		OpDiv8, OpDiv16, OpDiv32, OpDiv64,
		OpDiv8u, OpDiv16u, OpDiv32u, OpDiv64u, //TODO: support div128u
		// mod
		OpMod8, OpMod16, OpMod32, OpMod64,
		OpMod8u, OpMod16u, OpMod32u, OpMod64u,
		// compare
		OpEq64, OpEq32, OpEq16, OpEq8,
		OpEq32F, OpEq64F,
		OpLess64, OpLess32, OpLess16, OpLess8,

		return false
	}
	e.Set(candidate)
	return true
}

// p521SqrtCandidate sets z to a square root candidate for x. z and x must not overlap.
func p521SqrtCandidate(z, x *fiat.P521Element) {
	// Since p = 3 mod 4, exponentiation by (p + 1) / 4 yields a square root candidate.
	//
	// The sequence of 0 multiplications and 519 squarings is derived from the
	// following addition chain generated with github.com/mmcloughlin/addchain v0.4.0.