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go/src/cmd/vet/asmdecl.go
Josh Bleecher Snyder 2b8e143dc3 cmd/vet: infer asm arch from build context
If we cannot infer the asm arch from the filename
or the build tags, assume that it is the
current build arch. Assembly files with no
restrictions ought to be usable on all arches.

Updates #11041

Change-Id: I0ae807dbbd5fb67ca21d0157fe180237a074113a
Reviewed-on: https://go-review.googlesource.com/27151
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
2016-08-17 20:49:59 +00:00

693 lines
16 KiB
Go

// 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.
// Identify mismatches between assembly files and Go func declarations.
package main
import (
"bytes"
"fmt"
"go/ast"
"go/build"
"go/token"
"regexp"
"strconv"
"strings"
)
// 'kind' is a kind of assembly variable.
// The kinds 1, 2, 4, 8 stand for values of that size.
type asmKind int
// These special kinds are not valid sizes.
const (
asmString asmKind = 100 + iota
asmSlice
asmInterface
asmEmptyInterface
)
// An asmArch describes assembly parameters for an architecture
type asmArch struct {
name string
ptrSize int
intSize int
maxAlign int
bigEndian bool
stack string
lr bool
}
// An asmFunc describes the expected variables for a function on a given architecture.
type asmFunc struct {
arch *asmArch
size int // size of all arguments
vars map[string]*asmVar
varByOffset map[int]*asmVar
}
// An asmVar describes a single assembly variable.
type asmVar struct {
name string
kind asmKind
typ string
off int
size int
inner []*asmVar
}
var (
asmArch386 = asmArch{"386", 4, 4, 4, false, "SP", false}
asmArchArm = asmArch{"arm", 4, 4, 4, false, "R13", true}
asmArchArm64 = asmArch{"arm64", 8, 8, 8, false, "RSP", true}
asmArchAmd64 = asmArch{"amd64", 8, 8, 8, false, "SP", false}
asmArchAmd64p32 = asmArch{"amd64p32", 4, 4, 8, false, "SP", false}
asmArchMips64 = asmArch{"mips64", 8, 8, 8, true, "R29", true}
asmArchMips64LE = asmArch{"mips64", 8, 8, 8, false, "R29", true}
asmArchPpc64 = asmArch{"ppc64", 8, 8, 8, true, "R1", true}
asmArchPpc64LE = asmArch{"ppc64le", 8, 8, 8, false, "R1", true}
arches = []*asmArch{
&asmArch386,
&asmArchArm,
&asmArchArm64,
&asmArchAmd64,
&asmArchAmd64p32,
&asmArchMips64,
&asmArchMips64LE,
&asmArchPpc64,
&asmArchPpc64LE,
}
)
var (
re = regexp.MustCompile
asmPlusBuild = re(`//\s+\+build\s+([^\n]+)`)
asmTEXT = re(`\bTEXT\b.*·([^\(]+)\(SB\)(?:\s*,\s*([0-9A-Z|+]+))?(?:\s*,\s*\$(-?[0-9]+)(?:-([0-9]+))?)?`)
asmDATA = re(`\b(DATA|GLOBL)\b`)
asmNamedFP = re(`([a-zA-Z0-9_\xFF-\x{10FFFF}]+)(?:\+([0-9]+))\(FP\)`)
asmUnnamedFP = re(`[^+\-0-9](([0-9]+)\(FP\))`)
asmSP = re(`[^+\-0-9](([0-9]+)\(([A-Z0-9]+)\))`)
asmOpcode = re(`^\s*(?:[A-Z0-9a-z_]+:)?\s*([A-Z]+)\s*([^,]*)(?:,\s*(.*))?`)
ppc64Suff = re(`([BHWD])(ZU|Z|U|BR)?$`)
)
func asmCheck(pkg *Package) {
if !vet("asmdecl") {
return
}
// No work if no assembly files.
if !pkg.hasFileWithSuffix(".s") {
return
}
// Gather declarations. knownFunc[name][arch] is func description.
knownFunc := make(map[string]map[string]*asmFunc)
for _, f := range pkg.files {
if f.file != nil {
for _, decl := range f.file.Decls {
if decl, ok := decl.(*ast.FuncDecl); ok && decl.Body == nil {
knownFunc[decl.Name.Name] = f.asmParseDecl(decl)
}
}
}
}
Files:
for _, f := range pkg.files {
if !strings.HasSuffix(f.name, ".s") {
continue
}
Println("Checking file", f.name)
// Determine architecture from file name if possible.
var arch string
var archDef *asmArch
for _, a := range arches {
if strings.HasSuffix(f.name, "_"+a.name+".s") {
arch = a.name
archDef = a
break
}
}
lines := strings.SplitAfter(string(f.content), "\n")
var (
fn *asmFunc
fnName string
localSize, argSize int
wroteSP bool
haveRetArg bool
retLine []int
)
flushRet := func() {
if fn != nil && fn.vars["ret"] != nil && !haveRetArg && len(retLine) > 0 {
v := fn.vars["ret"]
for _, line := range retLine {
f.Badf(token.NoPos, "%s:%d: [%s] %s: RET without writing to %d-byte ret+%d(FP)", f.name, line, arch, fnName, v.size, v.off)
}
}
retLine = nil
}
for lineno, line := range lines {
lineno++
badf := func(format string, args ...interface{}) {
f.Badf(token.NoPos, "%s:%d: [%s] %s: %s", f.name, lineno, arch, fnName, fmt.Sprintf(format, args...))
}
if arch == "" {
// Determine architecture from +build line if possible.
if m := asmPlusBuild.FindStringSubmatch(line); m != nil {
Fields:
for _, fld := range strings.Fields(m[1]) {
for _, a := range arches {
if a.name == fld {
arch = a.name
archDef = a
break Fields
}
}
}
}
}
if m := asmTEXT.FindStringSubmatch(line); m != nil {
flushRet()
if arch == "" {
for _, a := range arches {
if a.name == build.Default.GOARCH {
arch = a.name
archDef = a
break
}
}
if arch == "" {
f.Warnf(token.NoPos, "%s: cannot determine architecture for assembly file", f.name)
continue Files
}
}
fnName = m[1]
fn = knownFunc[m[1]][arch]
if fn != nil {
size, _ := strconv.Atoi(m[4])
if size != fn.size && (m[2] != "7" && !strings.Contains(m[2], "NOSPLIT") || size != 0) {
badf("wrong argument size %d; expected $...-%d", size, fn.size)
}
}
localSize, _ = strconv.Atoi(m[3])
localSize += archDef.intSize
if archDef.lr {
// Account for caller's saved LR
localSize += archDef.intSize
}
argSize, _ = strconv.Atoi(m[4])
if fn == nil && !strings.Contains(fnName, "<>") {
badf("function %s missing Go declaration", fnName)
}
wroteSP = false
haveRetArg = false
continue
} else if strings.Contains(line, "TEXT") && strings.Contains(line, "SB") {
// function, but not visible from Go (didn't match asmTEXT), so stop checking
flushRet()
fn = nil
fnName = ""
continue
}
if strings.Contains(line, "RET") {
retLine = append(retLine, lineno)
}
if fnName == "" {
continue
}
if asmDATA.FindStringSubmatch(line) != nil {
fn = nil
}
if archDef == nil {
continue
}
if strings.Contains(line, ", "+archDef.stack) || strings.Contains(line, ",\t"+archDef.stack) {
wroteSP = true
continue
}
for _, m := range asmSP.FindAllStringSubmatch(line, -1) {
if m[3] != archDef.stack || wroteSP {
continue
}
off := 0
if m[1] != "" {
off, _ = strconv.Atoi(m[2])
}
if off >= localSize {
if fn != nil {
v := fn.varByOffset[off-localSize]
if v != nil {
badf("%s should be %s+%d(FP)", m[1], v.name, off-localSize)
continue
}
}
if off >= localSize+argSize {
badf("use of %s points beyond argument frame", m[1])
continue
}
badf("use of %s to access argument frame", m[1])
}
}
if fn == nil {
continue
}
for _, m := range asmUnnamedFP.FindAllStringSubmatch(line, -1) {
off, _ := strconv.Atoi(m[2])
v := fn.varByOffset[off]
if v != nil {
badf("use of unnamed argument %s; offset %d is %s+%d(FP)", m[1], off, v.name, v.off)
} else {
badf("use of unnamed argument %s", m[1])
}
}
for _, m := range asmNamedFP.FindAllStringSubmatch(line, -1) {
name := m[1]
off := 0
if m[2] != "" {
off, _ = strconv.Atoi(m[2])
}
if name == "ret" || strings.HasPrefix(name, "ret_") {
haveRetArg = true
}
v := fn.vars[name]
if v == nil {
// Allow argframe+0(FP).
if name == "argframe" && off == 0 {
continue
}
v = fn.varByOffset[off]
if v != nil {
badf("unknown variable %s; offset %d is %s+%d(FP)", name, off, v.name, v.off)
} else {
badf("unknown variable %s", name)
}
continue
}
asmCheckVar(badf, fn, line, m[0], off, v)
}
}
flushRet()
}
}
// asmParseDecl parses a function decl for expected assembly variables.
func (f *File) asmParseDecl(decl *ast.FuncDecl) map[string]*asmFunc {
var (
arch *asmArch
fn *asmFunc
offset int
failed bool
)
addVar := func(outer string, v asmVar) {
if vo := fn.vars[outer]; vo != nil {
vo.inner = append(vo.inner, &v)
}
fn.vars[v.name] = &v
for i := 0; i < v.size; i++ {
fn.varByOffset[v.off+i] = &v
}
}
addParams := func(list []*ast.Field) {
for i, fld := range list {
// Determine alignment, size, and kind of type in declaration.
var align, size int
var kind asmKind
names := fld.Names
typ := f.gofmt(fld.Type)
switch t := fld.Type.(type) {
default:
switch typ {
default:
f.Warnf(fld.Type.Pos(), "unknown assembly argument type %s", typ)
failed = true
return
case "int8", "uint8", "byte", "bool":
size = 1
case "int16", "uint16":
size = 2
case "int32", "uint32", "float32":
size = 4
case "int64", "uint64", "float64":
align = arch.maxAlign
size = 8
case "int", "uint":
size = arch.intSize
case "uintptr", "iword", "Word", "Errno", "unsafe.Pointer":
size = arch.ptrSize
case "string", "ErrorString":
size = arch.ptrSize * 2
align = arch.ptrSize
kind = asmString
}
case *ast.ChanType, *ast.FuncType, *ast.MapType, *ast.StarExpr:
size = arch.ptrSize
case *ast.InterfaceType:
align = arch.ptrSize
size = 2 * arch.ptrSize
if len(t.Methods.List) > 0 {
kind = asmInterface
} else {
kind = asmEmptyInterface
}
case *ast.ArrayType:
if t.Len == nil {
size = arch.ptrSize + 2*arch.intSize
align = arch.ptrSize
kind = asmSlice
break
}
f.Warnf(fld.Type.Pos(), "unsupported assembly argument type %s", typ)
failed = true
case *ast.StructType:
f.Warnf(fld.Type.Pos(), "unsupported assembly argument type %s", typ)
failed = true
}
if align == 0 {
align = size
}
if kind == 0 {
kind = asmKind(size)
}
offset += -offset & (align - 1)
// Create variable for each name being declared with this type.
if len(names) == 0 {
name := "unnamed"
if decl.Type.Results != nil && len(decl.Type.Results.List) > 0 && &list[0] == &decl.Type.Results.List[0] && i == 0 {
// Assume assembly will refer to single unnamed result as r.
name = "ret"
}
names = []*ast.Ident{{Name: name}}
}
for _, id := range names {
name := id.Name
addVar("", asmVar{
name: name,
kind: kind,
typ: typ,
off: offset,
size: size,
})
switch kind {
case 8:
if arch.ptrSize == 4 {
w1, w2 := "lo", "hi"
if arch.bigEndian {
w1, w2 = w2, w1
}
addVar(name, asmVar{
name: name + "_" + w1,
kind: 4,
typ: "half " + typ,
off: offset,
size: 4,
})
addVar(name, asmVar{
name: name + "_" + w2,
kind: 4,
typ: "half " + typ,
off: offset + 4,
size: 4,
})
}
case asmEmptyInterface:
addVar(name, asmVar{
name: name + "_type",
kind: asmKind(arch.ptrSize),
typ: "interface type",
off: offset,
size: arch.ptrSize,
})
addVar(name, asmVar{
name: name + "_data",
kind: asmKind(arch.ptrSize),
typ: "interface data",
off: offset + arch.ptrSize,
size: arch.ptrSize,
})
case asmInterface:
addVar(name, asmVar{
name: name + "_itable",
kind: asmKind(arch.ptrSize),
typ: "interface itable",
off: offset,
size: arch.ptrSize,
})
addVar(name, asmVar{
name: name + "_data",
kind: asmKind(arch.ptrSize),
typ: "interface data",
off: offset + arch.ptrSize,
size: arch.ptrSize,
})
case asmSlice:
addVar(name, asmVar{
name: name + "_base",
kind: asmKind(arch.ptrSize),
typ: "slice base",
off: offset,
size: arch.ptrSize,
})
addVar(name, asmVar{
name: name + "_len",
kind: asmKind(arch.intSize),
typ: "slice len",
off: offset + arch.ptrSize,
size: arch.intSize,
})
addVar(name, asmVar{
name: name + "_cap",
kind: asmKind(arch.intSize),
typ: "slice cap",
off: offset + arch.ptrSize + arch.intSize,
size: arch.intSize,
})
case asmString:
addVar(name, asmVar{
name: name + "_base",
kind: asmKind(arch.ptrSize),
typ: "string base",
off: offset,
size: arch.ptrSize,
})
addVar(name, asmVar{
name: name + "_len",
kind: asmKind(arch.intSize),
typ: "string len",
off: offset + arch.ptrSize,
size: arch.intSize,
})
}
offset += size
}
}
}
m := make(map[string]*asmFunc)
for _, arch = range arches {
fn = &asmFunc{
arch: arch,
vars: make(map[string]*asmVar),
varByOffset: make(map[int]*asmVar),
}
offset = 0
addParams(decl.Type.Params.List)
if decl.Type.Results != nil && len(decl.Type.Results.List) > 0 {
offset += -offset & (arch.maxAlign - 1)
addParams(decl.Type.Results.List)
}
fn.size = offset
m[arch.name] = fn
}
if failed {
return nil
}
return m
}
// asmCheckVar checks a single variable reference.
func asmCheckVar(badf func(string, ...interface{}), fn *asmFunc, line, expr string, off int, v *asmVar) {
m := asmOpcode.FindStringSubmatch(line)
if m == nil {
if !strings.HasPrefix(strings.TrimSpace(line), "//") {
badf("cannot find assembly opcode")
}
return
}
// Determine operand sizes from instruction.
// Typically the suffix suffices, but there are exceptions.
var src, dst, kind asmKind
op := m[1]
switch fn.arch.name + "." + op {
case "386.FMOVLP":
src, dst = 8, 4
case "arm.MOVD":
src = 8
case "arm.MOVW":
src = 4
case "arm.MOVH", "arm.MOVHU":
src = 2
case "arm.MOVB", "arm.MOVBU":
src = 1
// LEA* opcodes don't really read the second arg.
// They just take the address of it.
case "386.LEAL":
dst = 4
case "amd64.LEAQ":
dst = 8
case "amd64p32.LEAL":
dst = 4
default:
switch fn.arch.name {
case "386", "amd64":
if strings.HasPrefix(op, "F") && (strings.HasSuffix(op, "D") || strings.HasSuffix(op, "DP")) {
// FMOVDP, FXCHD, etc
src = 8
break
}
if strings.HasPrefix(op, "P") && strings.HasSuffix(op, "RD") {
// PINSRD, PEXTRD, etc
src = 4
break
}
if strings.HasPrefix(op, "F") && (strings.HasSuffix(op, "F") || strings.HasSuffix(op, "FP")) {
// FMOVFP, FXCHF, etc
src = 4
break
}
if strings.HasSuffix(op, "SD") {
// MOVSD, SQRTSD, etc
src = 8
break
}
if strings.HasSuffix(op, "SS") {
// MOVSS, SQRTSS, etc
src = 4
break
}
if strings.HasPrefix(op, "SET") {
// SETEQ, etc
src = 1
break
}
switch op[len(op)-1] {
case 'B':
src = 1
case 'W':
src = 2
case 'L':
src = 4
case 'D', 'Q':
src = 8
}
case "ppc64", "ppc64le":
// Strip standard suffixes to reveal size letter.
m := ppc64Suff.FindStringSubmatch(op)
if m != nil {
switch m[1][0] {
case 'B':
src = 1
case 'H':
src = 2
case 'W':
src = 4
case 'D':
src = 8
}
}
case "mips64", "mips64le":
switch op {
case "MOVB", "MOVBU":
src = 1
case "MOVH", "MOVHU":
src = 2
case "MOVW", "MOVWU", "MOVF":
src = 4
case "MOVV", "MOVD":
src = 8
}
}
}
if dst == 0 {
dst = src
}
// Determine whether the match we're holding
// is the first or second argument.
if strings.Index(line, expr) > strings.Index(line, ",") {
kind = dst
} else {
kind = src
}
vk := v.kind
vt := v.typ
switch vk {
case asmInterface, asmEmptyInterface, asmString, asmSlice:
// allow reference to first word (pointer)
vk = v.inner[0].kind
vt = v.inner[0].typ
}
if off != v.off {
var inner bytes.Buffer
for i, vi := range v.inner {
if len(v.inner) > 1 {
fmt.Fprintf(&inner, ",")
}
fmt.Fprintf(&inner, " ")
if i == len(v.inner)-1 {
fmt.Fprintf(&inner, "or ")
}
fmt.Fprintf(&inner, "%s+%d(FP)", vi.name, vi.off)
}
badf("invalid offset %s; expected %s+%d(FP)%s", expr, v.name, v.off, inner.String())
return
}
if kind != 0 && kind != vk {
var inner bytes.Buffer
if len(v.inner) > 0 {
fmt.Fprintf(&inner, " containing")
for i, vi := range v.inner {
if i > 0 && len(v.inner) > 2 {
fmt.Fprintf(&inner, ",")
}
fmt.Fprintf(&inner, " ")
if i > 0 && i == len(v.inner)-1 {
fmt.Fprintf(&inner, "and ")
}
fmt.Fprintf(&inner, "%s+%d(FP)", vi.name, vi.off)
}
}
badf("invalid %s of %s; %s is %d-byte value%s", op, expr, vt, vk, inner.String())
}
}