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go/cmd/vet/asmdecl.go
Rob Pike 01f8cd246d go.tools: add go/types, ssa, and cmd/vet
They will be deleted from their current homes once this has landed.
Changes made to import paths to make the code compile, and to find
errchk in the right place in cmd/vet's Makefile.
TODO in a later CL: tidy up vet.

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/9495043
2013-05-17 13:20:39 -07:00

534 lines
12 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/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
bigEndian 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, false}
asmArchArm = asmArch{"arm", 4, 4, false}
asmArchAmd64 = asmArch{"amd64", 8, 8, false}
arches = []*asmArch{
&asmArch386,
&asmArchArm,
&asmArchAmd64,
}
)
var (
re = regexp.MustCompile
asmPlusBuild = re(`//\s+\+build\s+([^\n]+)`)
asmTEXT = re(`\bTEXT\b.*·([^\(]+)\(SB\)(?:\s*,\s*([0-9]+))?(?:\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]+)\(FP\))`)
asmOpcode = re(`^\s*(?:[A-Z0-9a-z_]+:)?\s*([A-Z]+)\s*([^,]*)(?:,\s*(.*))?`)
)
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)
}
}
}
}
var fn *asmFunc
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
for _, a := range arches {
if strings.HasSuffix(f.name, "_"+a.name+".s") {
arch = a.name
break
}
}
lines := strings.SplitAfter(string(f.content), "\n")
for lineno, line := range lines {
lineno++
warnf := func(format string, args ...interface{}) {
f.Warnf(token.NoPos, "%s:%d: [%s] %s", f.name, lineno, arch, 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
break Fields
}
}
}
}
}
if m := asmTEXT.FindStringSubmatch(line); m != nil {
if arch == "" {
f.Warnf(token.NoPos, "%s: cannot determine architecture for assembly file", f.name)
return
}
fn = knownFunc[m[1]][arch]
if fn != nil {
size, _ := strconv.Atoi(m[4])
if size != fn.size && (m[2] != "7" || size != 0) {
warnf("wrong argument size %d; expected $...-%d", size, fn.size)
}
}
continue
} else if strings.Contains(line, "TEXT") && strings.Contains(line, "SB") {
// function, but not visible from Go (didn't match asmTEXT), so stop checking
fn = nil
continue
}
if asmDATA.FindStringSubmatch(line) != nil {
fn = nil
}
if fn == nil {
continue
}
for _, m := range asmUnnamedFP.FindAllStringSubmatch(line, -1) {
warnf("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])
}
v := fn.vars[name]
if v == nil {
// Allow argframe+0(FP).
if name == "argframe" && off == 0 {
continue
}
v = fn.varByOffset[off]
if v != nil {
warnf("unknown variable %s; offset %d is %s+%d(FP)", name, off, v.name, v.off)
} else {
warnf("unknown variable %s", name)
}
continue
}
asmCheckVar(warnf, fn, line, m[0], off, v)
}
}
}
}
// 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.ptrSize
size = 8
case "int", "uint":
size = arch.intSize
case "uintptr", "iword", "Word", "Errno", "unsafe.Pointer":
size = arch.ptrSize
case "string":
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.ptrSize - 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(warnf func(string, ...interface{}), fn *asmFunc, line, expr string, off int, v *asmVar) {
m := asmOpcode.FindStringSubmatch(line)
if m == nil {
warnf("cannot find assembly opcode")
}
// 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
default:
if fn.arch.name == "386" || fn.arch.name == "amd64" {
if strings.HasPrefix(op, "F") && (strings.HasSuffix(op, "D") || strings.HasSuffix(op, "DP")) {
// FMOVDP, FXCHD, etc
src = 8
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
}
}
}
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)
}
warnf("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)
}
}
warnf("invalid %s of %s; %s is %d-byte value%s", op, expr, vt, vk, inner.String())
}
}