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go/test/codegen/mathbits.go
Michael Munday ab7a65f283 cmd/compile: clean up codegen for branch-on-carry on s390x
This CL optimizes code that uses a carry from a function such as
bits.Add64 as the condition in an if statement. For example:

    x, c := bits.Add64(a, b, 0)
    if c != 0 {
        panic("overflow")
    }

Rather than converting the carry into a 0 or a 1 value and using
that as an input to a comparison instruction the carry flag is now
used as the input to a conditional branch directly. This typically
removes an ADD LOGICAL WITH CARRY instruction when user code is
doing overflow detection and is closer to the code that a user
would expect to generate.

Change-Id: I950431270955ab72f1b5c6db873b6abe769be0da
Reviewed-on: https://go-review.googlesource.com/c/go/+/219757
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2020-04-22 20:11:06 +00:00

728 lines
15 KiB
Go

// asmcheck
// Copyright 2018 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.
package codegen
import "math/bits"
// ----------------------- //
// bits.LeadingZeros //
// ----------------------- //
func LeadingZeros(n uint) int {
// amd64:"BSRQ"
// s390x:"FLOGR"
// arm:"CLZ" arm64:"CLZ"
// mips:"CLZ"
// wasm:"I64Clz"
return bits.LeadingZeros(n)
}
func LeadingZeros64(n uint64) int {
// amd64:"BSRQ"
// s390x:"FLOGR"
// arm:"CLZ" arm64:"CLZ"
// mips:"CLZ"
// wasm:"I64Clz"
return bits.LeadingZeros64(n)
}
func LeadingZeros32(n uint32) int {
// amd64:"BSRQ","LEAQ",-"CMOVQEQ"
// s390x:"FLOGR"
// arm:"CLZ" arm64:"CLZW"
// mips:"CLZ"
// wasm:"I64Clz"
return bits.LeadingZeros32(n)
}
func LeadingZeros16(n uint16) int {
// amd64:"BSRL","LEAL",-"CMOVQEQ"
// s390x:"FLOGR"
// arm:"CLZ" arm64:"CLZ"
// mips:"CLZ"
// wasm:"I64Clz"
return bits.LeadingZeros16(n)
}
func LeadingZeros8(n uint8) int {
// amd64:"BSRL","LEAL",-"CMOVQEQ"
// s390x:"FLOGR"
// arm:"CLZ" arm64:"CLZ"
// mips:"CLZ"
// wasm:"I64Clz"
return bits.LeadingZeros8(n)
}
// --------------- //
// bits.Len* //
// --------------- //
func Len(n uint) int {
// amd64:"BSRQ"
// s390x:"FLOGR"
// arm:"CLZ" arm64:"CLZ"
// mips:"CLZ"
// wasm:"I64Clz"
return bits.Len(n)
}
func Len64(n uint64) int {
// amd64:"BSRQ"
// s390x:"FLOGR"
// arm:"CLZ" arm64:"CLZ"
// mips:"CLZ"
// wasm:"I64Clz"
return bits.Len64(n)
}
func Len32(n uint32) int {
// amd64:"BSRQ","LEAQ",-"CMOVQEQ"
// s390x:"FLOGR"
// arm:"CLZ" arm64:"CLZ"
// mips:"CLZ"
// wasm:"I64Clz"
return bits.Len32(n)
}
func Len16(n uint16) int {
// amd64:"BSRL","LEAL",-"CMOVQEQ"
// s390x:"FLOGR"
// arm:"CLZ" arm64:"CLZ"
// mips:"CLZ"
// wasm:"I64Clz"
return bits.Len16(n)
}
func Len8(n uint8) int {
// amd64:"BSRL","LEAL",-"CMOVQEQ"
// s390x:"FLOGR"
// arm:"CLZ" arm64:"CLZ"
// mips:"CLZ"
// wasm:"I64Clz"
return bits.Len8(n)
}
// -------------------- //
// bits.OnesCount //
// -------------------- //
// amd64:".*x86HasPOPCNT"
func OnesCount(n uint) int {
// amd64:"POPCNTQ"
// arm64:"VCNT","VUADDLV"
// s390x:"POPCNT"
// ppc64:"POPCNTD"
// ppc64le:"POPCNTD"
// wasm:"I64Popcnt"
return bits.OnesCount(n)
}
// amd64:".*x86HasPOPCNT"
func OnesCount64(n uint64) int {
// amd64:"POPCNTQ"
// arm64:"VCNT","VUADDLV"
// s390x:"POPCNT"
// ppc64:"POPCNTD"
// ppc64le:"POPCNTD"
// wasm:"I64Popcnt"
return bits.OnesCount64(n)
}
// amd64:".*x86HasPOPCNT"
func OnesCount32(n uint32) int {
// amd64:"POPCNTL"
// arm64:"VCNT","VUADDLV"
// s390x:"POPCNT"
// ppc64:"POPCNTW"
// ppc64le:"POPCNTW"
// wasm:"I64Popcnt"
return bits.OnesCount32(n)
}
// amd64:".*x86HasPOPCNT"
func OnesCount16(n uint16) int {
// amd64:"POPCNTL"
// arm64:"VCNT","VUADDLV"
// s390x:"POPCNT"
// ppc64:"POPCNTW"
// ppc64le:"POPCNTW"
// wasm:"I64Popcnt"
return bits.OnesCount16(n)
}
func OnesCount8(n uint8) int {
// s390x:"POPCNT"
// ppc64:"POPCNTB"
// ppc64le:"POPCNTB"
// wasm:"I64Popcnt"
return bits.OnesCount8(n)
}
// ----------------------- //
// bits.ReverseBytes //
// ----------------------- //
func ReverseBytes(n uint) uint {
// amd64:"BSWAPQ"
// s390x:"MOVDBR"
// arm64:"REV"
return bits.ReverseBytes(n)
}
func ReverseBytes64(n uint64) uint64 {
// amd64:"BSWAPQ"
// s390x:"MOVDBR"
// arm64:"REV"
return bits.ReverseBytes64(n)
}
func ReverseBytes32(n uint32) uint32 {
// amd64:"BSWAPL"
// s390x:"MOVWBR"
// arm64:"REVW"
return bits.ReverseBytes32(n)
}
func ReverseBytes16(n uint16) uint16 {
// amd64:"ROLW"
// arm64:"REV16W",-"UBFX",-"ORR"
// arm/5:"SLL","SRL","ORR"
// arm/6:"REV16"
// arm/7:"REV16"
return bits.ReverseBytes16(n)
}
// --------------------- //
// bits.RotateLeft //
// --------------------- //
func RotateLeft64(n uint64) uint64 {
// amd64:"ROLQ"
// arm64:"ROR"
// ppc64:"ROTL"
// ppc64le:"ROTL"
// s390x:"RLLG"
// wasm:"I64Rotl"
return bits.RotateLeft64(n, 37)
}
func RotateLeft32(n uint32) uint32 {
// amd64:"ROLL" 386:"ROLL"
// arm:`MOVW\tR[0-9]+@>23`
// arm64:"RORW"
// ppc64:"ROTLW"
// ppc64le:"ROTLW"
// s390x:"RLL"
// wasm:"I32Rotl"
return bits.RotateLeft32(n, 9)
}
func RotateLeft16(n uint16) uint16 {
// amd64:"ROLW" 386:"ROLW"
return bits.RotateLeft16(n, 5)
}
func RotateLeft8(n uint8) uint8 {
// amd64:"ROLB" 386:"ROLB"
return bits.RotateLeft8(n, 5)
}
func RotateLeftVariable(n uint, m int) uint {
// amd64:"ROLQ"
// arm64:"ROR"
// ppc64:"ROTL"
// ppc64le:"ROTL"
// s390x:"RLLG"
// wasm:"I64Rotl"
return bits.RotateLeft(n, m)
}
func RotateLeftVariable64(n uint64, m int) uint64 {
// amd64:"ROLQ"
// arm64:"ROR"
// ppc64:"ROTL"
// ppc64le:"ROTL"
// s390x:"RLLG"
// wasm:"I64Rotl"
return bits.RotateLeft64(n, m)
}
func RotateLeftVariable32(n uint32, m int) uint32 {
// arm:`MOVW\tR[0-9]+@>R[0-9]+`
// amd64:"ROLL"
// arm64:"RORW"
// ppc64:"ROTLW"
// ppc64le:"ROTLW"
// s390x:"RLL"
// wasm:"I32Rotl"
return bits.RotateLeft32(n, m)
}
// ------------------------ //
// bits.TrailingZeros //
// ------------------------ //
func TrailingZeros(n uint) int {
// amd64:"BSFQ","MOVL\t\\$64","CMOVQEQ"
// arm:"CLZ"
// arm64:"RBIT","CLZ"
// s390x:"FLOGR"
// ppc64/power8:"ANDN","POPCNTD"
// ppc64le/power8:"ANDN","POPCNTD"
// ppc64/power9: "CNTTZD"
// ppc64le/power9: "CNTTZD"
// wasm:"I64Ctz"
return bits.TrailingZeros(n)
}
func TrailingZeros64(n uint64) int {
// amd64:"BSFQ","MOVL\t\\$64","CMOVQEQ"
// arm64:"RBIT","CLZ"
// s390x:"FLOGR"
// ppc64/power8:"ANDN","POPCNTD"
// ppc64le/power8:"ANDN","POPCNTD"
// ppc64/power9: "CNTTZD"
// ppc64le/power9: "CNTTZD"
// wasm:"I64Ctz"
return bits.TrailingZeros64(n)
}
func TrailingZeros32(n uint32) int {
// amd64:"BTSQ\\t\\$32","BSFQ"
// arm:"CLZ"
// arm64:"RBITW","CLZW"
// s390x:"FLOGR","MOVWZ"
// ppc64/power8:"ANDN","POPCNTW"
// ppc64le/power8:"ANDN","POPCNTW"
// ppc64/power9: "CNTTZW"
// ppc64le/power9: "CNTTZW"
// wasm:"I64Ctz"
return bits.TrailingZeros32(n)
}
func TrailingZeros16(n uint16) int {
// amd64:"BSFL","BTSL\\t\\$16"
// 386:"BSFL\t"
// arm:"ORR\t\\$65536","CLZ",-"MOVHU\tR"
// arm64:"ORR\t\\$65536","RBITW","CLZW",-"MOVHU\tR",-"RBIT\t",-"CLZ\t"
// s390x:"FLOGR","OR\t\\$65536"
// ppc64/power8:"POPCNTD","OR\\t\\$65536"
// ppc64le/power8:"POPCNTD","OR\\t\\$65536"
// ppc64/power9:"CNTTZD","OR\\t\\$65536"
// ppc64le/power9:"CNTTZD","OR\\t\\$65536"
// wasm:"I64Ctz"
return bits.TrailingZeros16(n)
}
func TrailingZeros8(n uint8) int {
// amd64:"BSFL","BTSL\\t\\$8"
// arm:"ORR\t\\$256","CLZ",-"MOVBU\tR"
// arm64:"ORR\t\\$256","RBITW","CLZW",-"MOVBU\tR",-"RBIT\t",-"CLZ\t"
// s390x:"FLOGR","OR\t\\$256"
// wasm:"I64Ctz"
return bits.TrailingZeros8(n)
}
// IterateBitsNN checks special handling of TrailingZerosNN when the input is known to be non-zero.
func IterateBits(n uint) int {
i := 0
for n != 0 {
// amd64:"BSFQ",-"CMOVEQ"
i += bits.TrailingZeros(n)
n &= n - 1
}
return i
}
func IterateBits64(n uint64) int {
i := 0
for n != 0 {
// amd64:"BSFQ",-"CMOVEQ"
i += bits.TrailingZeros64(n)
n &= n - 1
}
return i
}
func IterateBits32(n uint32) int {
i := 0
for n != 0 {
// amd64:"BSFL",-"BTSQ"
i += bits.TrailingZeros32(n)
n &= n - 1
}
return i
}
func IterateBits16(n uint16) int {
i := 0
for n != 0 {
// amd64:"BSFL",-"BTSL"
// arm64:"RBITW","CLZW",-"ORR"
i += bits.TrailingZeros16(n)
n &= n - 1
}
return i
}
func IterateBits8(n uint8) int {
i := 0
for n != 0 {
// amd64:"BSFL",-"BTSL"
// arm64:"RBITW","CLZW",-"ORR"
i += bits.TrailingZeros8(n)
n &= n - 1
}
return i
}
// --------------- //
// bits.Add* //
// --------------- //
func Add(x, y, ci uint) (r, co uint) {
// arm64:"ADDS","ADCS","ADC",-"ADD\t",-"CMP"
// amd64:"NEGL","ADCQ","SBBQ","NEGQ"
// s390x:"ADDE","ADDC\t[$]-1,"
return bits.Add(x, y, ci)
}
func AddC(x, ci uint) (r, co uint) {
// arm64:"ADDS","ADCS","ADC",-"ADD\t",-"CMP"
// amd64:"NEGL","ADCQ","SBBQ","NEGQ"
// s390x:"ADDE","ADDC\t[$]-1,"
return bits.Add(x, 7, ci)
}
func AddZ(x, y uint) (r, co uint) {
// arm64:"ADDS","ADC",-"ADCS",-"ADD\t",-"CMP"
// amd64:"ADDQ","SBBQ","NEGQ",-"NEGL",-"ADCQ"
// s390x:"ADDC",-"ADDC\t[$]-1,"
return bits.Add(x, y, 0)
}
func AddR(x, y, ci uint) uint {
// arm64:"ADDS","ADCS",-"ADD\t",-"CMP"
// amd64:"NEGL","ADCQ",-"SBBQ",-"NEGQ"
// s390x:"ADDE","ADDC\t[$]-1,"
r, _ := bits.Add(x, y, ci)
return r
}
func AddM(p, q, r *[3]uint) {
var c uint
r[0], c = bits.Add(p[0], q[0], c)
// arm64:"ADCS",-"ADD\t",-"CMP"
// amd64:"ADCQ",-"NEGL",-"SBBQ",-"NEGQ"
// s390x:"ADDE",-"ADDC\t[$]-1,"
r[1], c = bits.Add(p[1], q[1], c)
r[2], c = bits.Add(p[2], q[2], c)
}
func Add64(x, y, ci uint64) (r, co uint64) {
// arm64:"ADDS","ADCS","ADC",-"ADD\t",-"CMP"
// amd64:"NEGL","ADCQ","SBBQ","NEGQ"
// ppc64: "ADDC", "ADDE", "ADDZE"
// ppc64le: "ADDC", "ADDE", "ADDZE"
// s390x:"ADDE","ADDC\t[$]-1,"
return bits.Add64(x, y, ci)
}
func Add64C(x, ci uint64) (r, co uint64) {
// arm64:"ADDS","ADCS","ADC",-"ADD\t",-"CMP"
// amd64:"NEGL","ADCQ","SBBQ","NEGQ"
// ppc64: "ADDC", "ADDE", "ADDZE"
// ppc64le: "ADDC", "ADDE", "ADDZE"
// s390x:"ADDE","ADDC\t[$]-1,"
return bits.Add64(x, 7, ci)
}
func Add64Z(x, y uint64) (r, co uint64) {
// arm64:"ADDS","ADC",-"ADCS",-"ADD\t",-"CMP"
// amd64:"ADDQ","SBBQ","NEGQ",-"NEGL",-"ADCQ"
// ppc64: "ADDC", "ADDE", "ADDZE"
// ppc64le: "ADDC", "ADDE", "ADDZE"
// s390x:"ADDC",-"ADDC\t[$]-1,"
return bits.Add64(x, y, 0)
}
func Add64R(x, y, ci uint64) uint64 {
// arm64:"ADDS","ADCS",-"ADD\t",-"CMP"
// amd64:"NEGL","ADCQ",-"SBBQ",-"NEGQ"
// ppc64: "ADDC", "ADDE", "ADDZE"
// ppc64le: "ADDC", "ADDE", "ADDZE"
// s390x:"ADDE","ADDC\t[$]-1,"
r, _ := bits.Add64(x, y, ci)
return r
}
func Add64M(p, q, r *[3]uint64) {
var c uint64
r[0], c = bits.Add64(p[0], q[0], c)
// arm64:"ADCS",-"ADD\t",-"CMP"
// amd64:"ADCQ",-"NEGL",-"SBBQ",-"NEGQ"
// ppc64: "ADDC", "ADDE", "ADDZE"
// ppc64le: "ADDC", "ADDE", "ADDZE"
// s390x:"ADDE",-"ADDC\t[$]-1,"
r[1], c = bits.Add64(p[1], q[1], c)
r[2], c = bits.Add64(p[2], q[2], c)
}
func Add64PanicOnOverflowEQ(a, b uint64) uint64 {
r, c := bits.Add64(a, b, 0)
// s390x:"BRC\t[$]3,",-"ADDE"
if c == 1 {
panic("overflow")
}
return r
}
func Add64PanicOnOverflowNE(a, b uint64) uint64 {
r, c := bits.Add64(a, b, 0)
// s390x:"BRC\t[$]3,",-"ADDE"
if c != 0 {
panic("overflow")
}
return r
}
func Add64PanicOnOverflowGT(a, b uint64) uint64 {
r, c := bits.Add64(a, b, 0)
// s390x:"BRC\t[$]3,",-"ADDE"
if c > 0 {
panic("overflow")
}
return r
}
func Add64MPanicOnOverflowEQ(a, b [2]uint64) [2]uint64 {
var r [2]uint64
var c uint64
r[0], c = bits.Add64(a[0], b[0], c)
r[1], c = bits.Add64(a[1], b[1], c)
// s390x:"BRC\t[$]3,"
if c == 1 {
panic("overflow")
}
return r
}
func Add64MPanicOnOverflowNE(a, b [2]uint64) [2]uint64 {
var r [2]uint64
var c uint64
r[0], c = bits.Add64(a[0], b[0], c)
r[1], c = bits.Add64(a[1], b[1], c)
// s390x:"BRC\t[$]3,"
if c != 0 {
panic("overflow")
}
return r
}
func Add64MPanicOnOverflowGT(a, b [2]uint64) [2]uint64 {
var r [2]uint64
var c uint64
r[0], c = bits.Add64(a[0], b[0], c)
r[1], c = bits.Add64(a[1], b[1], c)
// s390x:"BRC\t[$]3,"
if c > 0 {
panic("overflow")
}
return r
}
// --------------- //
// bits.Sub* //
// --------------- //
func Sub(x, y, ci uint) (r, co uint) {
// amd64:"NEGL","SBBQ","NEGQ"
// arm64:"NEGS","SBCS","NGC","NEG",-"ADD",-"SUB",-"CMP"
// s390x:"SUBE"
return bits.Sub(x, y, ci)
}
func SubC(x, ci uint) (r, co uint) {
// amd64:"NEGL","SBBQ","NEGQ"
// arm64:"NEGS","SBCS","NGC","NEG",-"ADD",-"SUB",-"CMP"
// s390x:"SUBE"
return bits.Sub(x, 7, ci)
}
func SubZ(x, y uint) (r, co uint) {
// amd64:"SUBQ","SBBQ","NEGQ",-"NEGL"
// arm64:"SUBS","NGC","NEG",-"SBCS",-"ADD",-"SUB\t",-"CMP"
// s390x:"SUBC"
return bits.Sub(x, y, 0)
}
func SubR(x, y, ci uint) uint {
// amd64:"NEGL","SBBQ",-"NEGQ"
// arm64:"NEGS","SBCS",-"NGC",-"NEG\t",-"ADD",-"SUB",-"CMP"
// s390x:"SUBE"
r, _ := bits.Sub(x, y, ci)
return r
}
func SubM(p, q, r *[3]uint) {
var c uint
r[0], c = bits.Sub(p[0], q[0], c)
// amd64:"SBBQ",-"NEGL",-"NEGQ"
// arm64:"SBCS",-"NEGS",-"NGC",-"NEG",-"ADD",-"SUB",-"CMP"
// s390x:"SUBE"
r[1], c = bits.Sub(p[1], q[1], c)
r[2], c = bits.Sub(p[2], q[2], c)
}
func Sub64(x, y, ci uint64) (r, co uint64) {
// amd64:"NEGL","SBBQ","NEGQ"
// arm64:"NEGS","SBCS","NGC","NEG",-"ADD",-"SUB",-"CMP"
// s390x:"SUBE"
return bits.Sub64(x, y, ci)
}
func Sub64C(x, ci uint64) (r, co uint64) {
// amd64:"NEGL","SBBQ","NEGQ"
// arm64:"NEGS","SBCS","NGC","NEG",-"ADD",-"SUB",-"CMP"
// s390x:"SUBE"
return bits.Sub64(x, 7, ci)
}
func Sub64Z(x, y uint64) (r, co uint64) {
// amd64:"SUBQ","SBBQ","NEGQ",-"NEGL"
// arm64:"SUBS","NGC","NEG",-"SBCS",-"ADD",-"SUB\t",-"CMP"
// s390x:"SUBC"
return bits.Sub64(x, y, 0)
}
func Sub64R(x, y, ci uint64) uint64 {
// amd64:"NEGL","SBBQ",-"NEGQ"
// arm64:"NEGS","SBCS",-"NGC",-"NEG\t",-"ADD",-"SUB",-"CMP"
// s390x:"SUBE"
r, _ := bits.Sub64(x, y, ci)
return r
}
func Sub64M(p, q, r *[3]uint64) {
var c uint64
r[0], c = bits.Sub64(p[0], q[0], c)
// amd64:"SBBQ",-"NEGL",-"NEGQ"
// arm64:"SBCS",-"NEGS",-"NGC",-"NEG",-"ADD",-"SUB",-"CMP"
// s390x:"SUBE"
r[1], c = bits.Sub64(p[1], q[1], c)
r[2], c = bits.Sub64(p[2], q[2], c)
}
func Sub64PanicOnOverflowEQ(a, b uint64) uint64 {
r, b := bits.Sub64(a, b, 0)
// s390x:"BRC\t[$]12,",-"ADDE",-"SUBE"
if b == 1 {
panic("overflow")
}
return r
}
func Sub64PanicOnOverflowNE(a, b uint64) uint64 {
r, b := bits.Sub64(a, b, 0)
// s390x:"BRC\t[$]12,",-"ADDE",-"SUBE"
if b != 0 {
panic("overflow")
}
return r
}
func Sub64PanicOnOverflowGT(a, b uint64) uint64 {
r, b := bits.Sub64(a, b, 0)
// s390x:"BRC\t[$]12,",-"ADDE",-"SUBE"
if b > 0 {
panic("overflow")
}
return r
}
func Sub64MPanicOnOverflowEQ(a, b [2]uint64) [2]uint64 {
var r [2]uint64
var c uint64
r[0], c = bits.Sub64(a[0], b[0], c)
r[1], c = bits.Sub64(a[1], b[1], c)
// s390x:"BRC\t[$]12,"
if c == 1 {
panic("overflow")
}
return r
}
func Sub64MPanicOnOverflowNE(a, b [2]uint64) [2]uint64 {
var r [2]uint64
var c uint64
r[0], c = bits.Sub64(a[0], b[0], c)
r[1], c = bits.Sub64(a[1], b[1], c)
// s390x:"BRC\t[$]12,"
if c != 0 {
panic("overflow")
}
return r
}
func Sub64MPanicOnOverflowGT(a, b [2]uint64) [2]uint64 {
var r [2]uint64
var c uint64
r[0], c = bits.Sub64(a[0], b[0], c)
r[1], c = bits.Sub64(a[1], b[1], c)
// s390x:"BRC\t[$]12,"
if c > 0 {
panic("overflow")
}
return r
}
// --------------- //
// bits.Mul* //
// --------------- //
func Mul(x, y uint) (hi, lo uint) {
// amd64:"MULQ"
// arm64:"UMULH","MUL"
// ppc64:"MULHDU","MULLD"
// ppc64le:"MULHDU","MULLD"
// s390x:"MLGR"
// mips64: "MULVU"
return bits.Mul(x, y)
}
func Mul64(x, y uint64) (hi, lo uint64) {
// amd64:"MULQ"
// arm64:"UMULH","MUL"
// ppc64:"MULHDU","MULLD"
// ppc64le:"MULHDU","MULLD"
// s390x:"MLGR"
// mips64: "MULVU"
return bits.Mul64(x, y)
}
// --------------- //
// bits.Div* //
// --------------- //
func Div(hi, lo, x uint) (q, r uint) {
// amd64:"DIVQ"
return bits.Div(hi, lo, x)
}
func Div32(hi, lo, x uint32) (q, r uint32) {
// arm64:"ORR","UDIV","MSUB",-"UREM"
return bits.Div32(hi, lo, x)
}
func Div64(hi, lo, x uint64) (q, r uint64) {
// amd64:"DIVQ"
return bits.Div64(hi, lo, x)
}
func Div64degenerate(x uint64) (q, r uint64) {
// amd64:-"DIVQ"
return bits.Div64(0, x, 5)
}