context := build.Context{
				GOOS:      "linux", // darwin has custom assembly
				GOARCH:    GOARCH,
				GOROOT:    testenv.GOROOT(t),
				Compiler:  build.Default.Compiler,
				BuildTags: []string{"purego", "math_big_pure_go"},
			}

			pkg, err := context.Import(pkgName, "", 0)
			if err != nil {
				t.Fatal(err)
			}
			if len(pkg.SFiles) == 0 {
				continue
			}

	// Run Go bootstrap to build binaries.
	// Use the math_big_pure_go build tag to disable the assembly in math/big
	// which may contain unsupported instructions.
	// Use the purego build tag to disable other assembly code,
	// such as in cmd/internal/notsha256.
	cmd := []string{
		pathf("%s/bin/go", goroot_bootstrap),
		"install",
		"-tags=math_big_pure_go compiler_bootstrap purego",
	}
	if vflag > 0 {

			"flag.mustBeExported",
			"flag.kind",
			"flag.ro",
		},
		"regexp": {
			"(*bitState).push",
		},
		"math/big": {
			"bigEndianWord",
			// The following functions require the math_big_pure_go build tag.
			"addVW",
			"subVW",
		},
		"math/rand": {
			"(*rngSource).Int63",
			"(*rngSource).Uint64",
		},
		"net": {
			"(*UDPConn).ReadFromUDP",
		},
		"sync": {

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !math_big_pure_go

#include "textflag.h"

// This file provides fast assembly versions for the elementary
// arithmetic operations on vectors implemented in arith.go.

// func addVV(z, x, y []Word) (c Word)
TEXT ·addVV(SB),NOSPLIT,$0
	MOVL z+0(FP), DI
	MOVL x+12(FP), SI

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !math_big_pure_go

#include "textflag.h"

// This file provides fast assembly versions for the elementary
// arithmetic operations on vectors implemented in arith.go.

// func addVV(z, x, y []Word) (c Word)
TEXT ·addVV(SB),NOSPLIT,$0
	ADD.S	$0, R0		// clear carry flag

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !math_big_pure_go

#include "textflag.h"

// This file provides fast assembly versions for the elementary
// arithmetic operations on vectors implemented in arith.go.

// The carry bit is saved with SBBQ Rx, Rx: if the carry was set, Rx is -1, otherwise it is 0.

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !math_big_pure_go

#include "textflag.h"

// This file provides fast assembly versions for the elementary
// arithmetic operations on vectors implemented in arith.go.

// TODO: Consider re-implementing using Advanced SIMD
// once the assembler supports those instructions.

// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !math_big_pure_go

#include "textflag.h"

// This file provides fast assembly versions for the elementary
// arithmetic operations on vectors implemented in arith.go.

// DI = R3, CX = R4, SI = r10, r8 = r8, r9=r9, r10 = r2, r11 = r5, r12 = r6, r13 = r7, r14 = r1 (R0 set to 0) + use R11

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !math_big_pure_go && (ppc64 || ppc64le)

#include "textflag.h"

// This file provides fast assembly versions for the elementary
// arithmetic operations on vectors implemented in arith.go.

// func addVV(z, y, y []Word) (c Word)
// z[i] = x[i] + y[i] for all i, carrying