5
0
mirror of https://github.com/cwinfo/matterbridge.git synced 2024-12-26 19:05:40 +00:00
matterbridge/vendor/modernc.org/cc/v3/abi.go
2022-03-20 14:57:48 +01:00

1023 lines
27 KiB
Go
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

// Copyright 2019 The CC 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 cc // import "modernc.org/cc/v3"
import (
"encoding/binary"
"fmt"
"math"
"os"
"runtime"
"lukechampine.com/uint128"
"modernc.org/mathutil"
)
var (
idAligned = String("aligned")
idGCCStruct = String("gcc_struct")
idMSStruct = String("ms_struct")
idPacked = String("packed")
complexTypedefs = map[StringID]Kind{
dict.sid("__COMPLEX_CHAR_TYPE__"): ComplexChar,
dict.sid("__COMPLEX_DOUBLE_TYPE__"): ComplexDouble,
dict.sid("__COMPLEX_FLOAT_TYPE__"): ComplexFloat,
dict.sid("__COMPLEX_INT_TYPE__"): ComplexInt,
dict.sid("__COMPLEX_LONG_TYPE__"): ComplexLong,
dict.sid("__COMPLEX_LONG_DOUBLE_TYPE__"): ComplexLongDouble,
dict.sid("__COMPLEX_LONG_LONG_TYPE__"): ComplexLongLong,
dict.sid("__COMPLEX_SHORT_TYPE__"): ComplexShort,
dict.sid("__COMPLEX_UNSIGNED_TYPE__"): ComplexUInt,
dict.sid("__COMPLEX_LONG_UNSIGNED_TYPE__"): ComplexULong,
dict.sid("__COMPLEX_LONG_LONG_UNSIGNED_TYPE__"): ComplexULongLong,
dict.sid("__COMPLEX_SHORT_UNSIGNED_TYPE__"): ComplexUShort,
}
)
// NewABI creates an ABI for a given OS and architecture. The OS and architecture values are the same as used in Go.
// The ABI type map may miss advanced types like complex numbers, etc. If the os/arch pair is not recognized, a
// *ErrUnsupportedOSArch is returned.
func NewABI(os, arch string) (ABI, error) {
order, ok := abiByteOrders[arch]
if !ok {
return ABI{}, fmt.Errorf("unsupported arch: %s", arch)
}
types, ok := abiTypes[[2]string{os, arch}]
if !ok {
return ABI{}, fmt.Errorf("unsupported os/arch pair: %s-%s", os, arch)
}
abi := ABI{
ByteOrder: order,
Types: make(map[Kind]ABIType, len(types)),
SignedChar: abiSignedChar[[2]string{os, arch}],
os: os,
arch: arch,
}
// copy the map, so it can be modified by user
for k, v := range types {
abi.Types[k] = v
}
return abi, nil
}
// NewABIFromEnv uses GOOS and GOARCH values to create a corresponding ABI.
// If those environment variables are not set, an OS/arch of a Go runtime is used.
// It returns a *ErrUnsupportedOSArch if OS/arch pair is not supported.
func NewABIFromEnv() (ABI, error) {
osv := os.Getenv("GOOS")
if osv == "" {
osv = runtime.GOOS
}
arch := os.Getenv("GOARCH")
if arch == "" {
arch = runtime.GOARCH
}
return NewABI(osv, arch)
}
// ABIType describes properties of a non-aggregate type.
type ABIType struct {
Size uintptr
Align int
FieldAlign int
}
// ABI describes selected parts of the Application Binary Interface.
type ABI struct {
ByteOrder binary.ByteOrder
Types map[Kind]ABIType
arch string
os string
types map[Kind]Type
SignedChar bool
}
func (a *ABI) sanityCheck(ctx *context, intMaxWidth int, s Scope) error {
if intMaxWidth == 0 {
intMaxWidth = 64
}
a.types = map[Kind]Type{}
for _, k := range []Kind{
Bool,
Char,
Double,
Enum,
Float,
Int,
Long,
LongDouble,
LongLong,
Ptr,
SChar,
Short,
UChar,
UInt,
ULong,
ULongLong,
UShort,
Void,
} {
v, ok := a.Types[k]
if !ok {
if ctx.err(noPos, "ABI is missing %s", k) {
return ctx.Err()
}
continue
}
if (k != Void && v.Size == 0) || v.Align == 0 || v.FieldAlign == 0 ||
v.Align > math.MaxUint8 || v.FieldAlign > math.MaxUint8 {
if ctx.err(noPos, "invalid ABI type %s: %+v", k, v) {
return ctx.Err()
}
}
if integerTypes[k] && v.Size > 8 {
if ctx.err(noPos, "invalid ABI type %s size: %v, must be <= 8", k, v.Size) {
return ctx.Err()
}
}
var f flag
if integerTypes[k] && a.isSignedInteger(k) {
f = fSigned
}
t := &typeBase{
align: byte(a.align(k)),
fieldAlign: byte(a.fieldAlign(k)),
flags: f,
kind: byte(k),
size: uintptr(a.size(k)),
}
a.types[k] = t
}
if _, ok := a.Types[Int128]; ok {
t := &typeBase{
align: byte(a.align(Int128)),
fieldAlign: byte(a.fieldAlign(Int128)),
flags: fSigned,
kind: byte(Int128),
size: uintptr(a.size(Int128)),
}
a.types[Int128] = t
}
if _, ok := a.Types[UInt128]; ok {
t := &typeBase{
align: byte(a.align(UInt128)),
fieldAlign: byte(a.fieldAlign(UInt128)),
kind: byte(UInt128),
size: uintptr(a.size(UInt128)),
}
a.types[UInt128] = t
}
return ctx.Err()
}
func (a *ABI) Type(k Kind) Type { return a.types[k] }
func (a *ABI) align(k Kind) int { return a.Types[k].Align }
func (a *ABI) fieldAlign(k Kind) int { return a.Types[k].FieldAlign }
func (a *ABI) size(k Kind) int { return int(a.Types[k].Size) }
func (a *ABI) isSignedInteger(k Kind) bool {
if !integerTypes[k] {
internalError()
}
switch k {
case Bool, UChar, UInt, ULong, ULongLong, UShort:
return false
case Char:
return a.SignedChar
default:
return true
}
}
func roundup(n, to int64) int64 {
if r := n % to; r != 0 {
return n + to - r
}
return n
}
func roundup128(n uint128.Uint128, to uint64) uint128.Uint128 {
if r := n.Mod(uint128.From64(to)); !r.IsZero() {
return n.Add64(to).Sub(r)
}
return n
}
func rounddown(n, to int64) int64 {
return n &^ (to - 1)
}
func rounddown128(n uint128.Uint128, to uint64) uint128.Uint128 {
return n.And(uint128.Uint128{Hi: ^uint64(0), Lo: ^(to - 1)})
}
func normalizeBitFieldWidth(n byte) byte {
switch {
case n <= 8:
return 8
case n <= 16:
return 16
case n <= 32:
return 32
case n <= 64:
return 64
default:
panic(todo("internal error: %v", n))
}
}
func (a *ABI) layout(ctx *context, n Node, t *structType) *structType {
if t == nil {
return nil
}
if t.typeBase.align < 1 {
t.typeBase.align = 1
}
for _, v := range t.attr {
if _, ok := v.Has(idGCCStruct); ok {
return a.gccLayout(ctx, n, t)
}
//TODO if _, ok := v.Has(idMSStruct); ok {
//TODO return a.msLayout(ctx, n, t)
//TODO }
}
switch {
case ctx.cfg.Config3.GCCStructs:
return a.gccLayout(ctx, n, t)
//TODO case ctx.cfg.Config3.MSStructs:
//TODO return a.msLayout(ctx, n, t)
}
var hasBitfields bool
defer func() {
if !hasBitfields {
return
}
m := make(map[uintptr][]*field, len(t.fields))
for _, f := range t.fields {
off := f.offset
m[off] = append(m[off], f)
}
for _, s := range m {
var first *field
var w byte
for _, f := range s {
if first == nil {
first = f
}
if f.isBitField {
n := f.bitFieldOffset + f.bitFieldWidth
if n > w {
w = n
}
}
}
w = normalizeBitFieldWidth(w)
for _, f := range s {
if f.isBitField {
f.blockStart = first
f.blockWidth = w
}
if a.ByteOrder == binary.BigEndian {
f.bitFieldOffset = w - f.bitFieldWidth - f.bitFieldOffset
f.bitFieldMask = (uint64(1)<<f.bitFieldWidth - 1) << f.bitFieldOffset
}
}
}
}()
var off int64 // bit offset
align := int(t.typeBase.align)
switch {
case t.Kind() == Union:
for _, f := range t.fields {
ft := f.Type()
sz := ft.Size()
if n := int64(8 * sz); n > off {
off = n
}
al := ft.FieldAlign()
if al == 0 {
al = 1
}
if al > align {
align = al
}
if f.isBitField {
hasBitfields = true
f.bitFieldMask = 1<<f.bitFieldWidth - 1
}
f.promote = integerPromotion(a, ft)
}
t.align = byte(align)
t.fieldAlign = byte(align)
off = roundup(off, 8*int64(align))
t.size = uintptr(off >> 3)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
default:
var i int
var group byte
var f, lf *field
for i, f = range t.fields {
ft := f.Type()
var sz uintptr
switch {
case ft.Kind() == Array && i == len(t.fields)-1:
if ft.IsIncomplete() || ft.Len() == 0 {
t.hasFlexibleMember = true
f.isFlexible = true
break
}
fallthrough
default:
sz = ft.Size()
}
bitSize := 8 * int(sz)
al := ft.FieldAlign()
if al == 0 {
al = 1
}
if al > align {
align = al
}
switch {
case f.isBitField:
hasBitfields = true
eal := 8 * al
if eal < bitSize {
eal = bitSize
}
down := off &^ (int64(eal) - 1)
bitoff := off - down
downMax := off &^ (int64(bitSize) - 1)
skip := lf != nil && lf.isBitField && lf.bitFieldWidth == 0 ||
lf != nil && lf.bitFieldWidth == 0 && ctx.cfg.NoFieldAndBitfieldOverlap
switch {
case skip || int(off-downMax)+int(f.bitFieldWidth) > bitSize:
group = 0
off = roundup(off, 8*int64(al))
f.offset = uintptr(off >> 3)
f.bitFieldOffset = 0
f.bitFieldMask = 1<<f.bitFieldWidth - 1
off += int64(f.bitFieldWidth)
if f.bitFieldWidth == 0 {
lf = f
continue
}
default:
f.offset = uintptr(down >> 3)
f.bitFieldOffset = byte(bitoff)
f.bitFieldMask = (1<<f.bitFieldWidth - 1) << byte(bitoff)
off += int64(f.bitFieldWidth)
}
group += f.bitFieldWidth
default:
if n := group % 64; n != 0 {
group -= n
off += int64(normalizeBitFieldWidth(group) - group)
}
off0 := off
off = roundup(off, 8*int64(al))
f.pad = byte(off-off0) >> 3
f.offset = uintptr(off) >> 3
off += 8 * int64(sz)
group = 0
}
f.promote = integerPromotion(a, ft)
lf = f
}
t.align = byte(align)
t.fieldAlign = byte(align)
off0 := off
off = roundup(off, 8*int64(align))
if f != nil && !f.IsBitField() {
f.pad = byte(off-off0) >> 3
}
t.size = uintptr(off >> 3)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
}
return t
}
func (a *ABI) Ptr(n Node, t Type) Type {
base := t.base()
base.align = byte(a.align(Ptr))
base.fieldAlign = byte(a.fieldAlign(Ptr))
base.kind = byte(Ptr)
base.size = uintptr(a.size(Ptr))
base.flags &^= fIncomplete
return &pointerType{
elem: t,
typeBase: base,
}
}
func (a *ABI) gccLayout(ctx *context, n Node, t *structType) (r *structType) {
if t.IsPacked() {
return a.gccPackedLayout(ctx, n, t)
}
if t.Kind() == Union {
var off uint128.Uint128 // In bits.
align := int(t.typeBase.align)
for _, f := range t.fields {
switch {
case f.isBitField:
f.offset = 0
f.bitFieldOffset = 0
f.bitFieldMask = 1<<f.bitFieldWidth - 1
if uint64(f.bitFieldWidth) > off.Lo {
off.Lo = uint64(f.bitFieldWidth)
}
default:
al := f.Type().Align()
if al > align {
align = al
}
f.offset = 0
off2 := uint128.From64(uint64(f.Type().Size())).Mul64(8)
if off2.Cmp(off) > 0 {
off = off2
}
}
f.promote = integerPromotion(a, f.Type())
}
t.align = byte(align)
t.fieldAlign = byte(align)
off = roundup128(off, 8*uint64(align))
t.size = uintptr(off.Rsh(3).Lo)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
return t
}
var off uint128.Uint128 // In bits.
align := int(t.typeBase.align)
for i, f := range t.fields {
switch {
case f.isBitField:
al := f.Type().Align()
// http://jkz.wtf/bit-field-packing-in-gcc-and-clang
// 1. Jump backwards to nearest address that would support this type. For
// example if we have an int jump to the closest address where an int could be
// stored according to the platform alignment rules.
down := rounddown128(off, 8*uint64(al))
// 2. Get sizeof(current field) bytes from that address.
alloc := int64(f.Type().Size()) * 8
need := int64(f.bitFieldWidth)
if need == 0 && i != 0 {
off = roundup128(off, 8*uint64(al))
continue
}
if al > align {
align = al
}
used := int64(off.Sub(down).Lo)
switch {
case alloc-used >= need:
// 3. If the number of bits that we need to store can be stored in these bits,
// put the bits in the lowest possible bits of this block.
off = down.Add64(uint64(used))
f.offset = uintptr(down.Rsh(3).Lo)
f.bitFieldOffset = byte(used)
f.bitFieldMask = (1<<f.bitFieldWidth - 1) << used
off = off.Add64(uint64(f.bitFieldWidth))
f.promote = integerPromotion(a, f.Type())
default:
// 4. Otherwise, pad the rest of this block with zeros, and store the bits that
// make up this bit-field in the lowest bits of the next block.
off = roundup128(off, 8*uint64(al))
f.offset = uintptr(off.Rsh(3).Lo)
f.bitFieldOffset = 0
f.bitFieldMask = 1<<f.bitFieldWidth - 1
off = off.Add64(uint64(f.bitFieldWidth))
f.promote = integerPromotion(a, f.Type())
}
default:
al := f.Type().Align()
if al > align {
align = al
}
off = roundup128(off, 8*uint64(al))
f.offset = uintptr(off.Rsh(3).Lo)
sz := uint128.From64(uint64(f.Type().Size()))
off = off.Add(sz.Mul64(8))
f.promote = integerPromotion(a, f.Type())
}
}
var lf *field
for _, f := range t.fields {
if lf != nil && !lf.isBitField && !f.isBitField {
lf.pad = byte(f.offset - lf.offset - lf.Type().Size())
}
lf = f
}
t.align = byte(align)
t.fieldAlign = byte(align)
off0 := off
off = roundup128(off, 8*uint64(align))
if lf != nil && !lf.IsBitField() {
lf.pad = byte(off.Sub(off0).Rsh(3).Lo)
}
t.size = uintptr(off.Rsh(3).Lo)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
return t
}
func (a *ABI) gccPackedLayout(ctx *context, n Node, t *structType) (r *structType) {
switch a.arch {
case "arm", "arm64":
return a.gccPackedLayoutARM(ctx, n, t)
}
if t.typeBase.flags&fAligned == 0 {
t.align = 1
}
t.fieldAlign = t.align
if t.Kind() == Union {
var off int64 // In bits.
for _, f := range t.fields {
switch {
case f.isBitField:
panic(todo("%v: ", n.Position()))
default:
f.offset = 0
if off2 := 8 * int64(f.Type().Size()); off2 > off {
off = off2
}
f.promote = integerPromotion(a, f.Type())
}
}
off = roundup(off, 8)
t.size = uintptr(off >> 3)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
return t
}
var off int64 // In bits.
for i, f := range t.fields {
switch {
case f.isBitField:
if f.bitFieldWidth == 0 {
if i != 0 {
off = roundup(off, 8*int64(f.Type().Align()))
}
continue
}
if b := f.Type().base(); b.flags&fAligned != 0 {
off = roundup(off, 8*int64(a.Types[f.Type().Kind()].Align))
}
f.offset = uintptr(off >> 3)
f.bitFieldOffset = byte(off & 7)
f.bitFieldMask = (1<<f.bitFieldWidth - 1) << f.bitFieldOffset
off += int64(f.bitFieldWidth)
f.promote = integerPromotion(a, f.Type())
default:
al := f.Type().Align()
off = roundup(off, 8*int64(al))
f.offset = uintptr(off) >> 3
off += 8 * int64(f.Type().Size())
f.promote = integerPromotion(a, f.Type())
}
}
var lf *field
for _, f := range t.fields {
if lf != nil && !lf.isBitField && !f.isBitField {
lf.pad = byte(f.offset - lf.offset - lf.Type().Size())
}
lf = f
}
off0 := off
off = roundup(off, 8*int64(t.Align()))
if lf != nil && !lf.IsBitField() {
lf.pad = byte(off-off0) >> 3
}
t.size = uintptr(off >> 3)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
return t
}
func (a *ABI) gccPackedLayoutARM(ctx *context, n Node, t *structType) (r *structType) {
align := 1
if t.typeBase.flags&fAligned == 0 {
t.align = 1
}
t.fieldAlign = t.align
if t.Kind() == Union {
var off int64 // In bits.
for _, f := range t.fields {
switch {
case f.isBitField:
panic(todo("%v: ", n.Position()))
default:
f.offset = 0
if off2 := 8 * int64(f.Type().Size()); off2 > off {
off = off2
}
f.promote = integerPromotion(a, f.Type())
}
}
off = roundup(off, 8)
t.size = uintptr(off >> 3)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
return t
}
var off int64 // In bits.
for i, f := range t.fields {
switch {
case f.isBitField:
if f.bitFieldWidth == 0 {
al := f.Type().Align()
if al > align {
align = al
}
if i != 0 {
off = roundup(off, 8*int64(f.Type().Align()))
}
continue
}
if b := f.Type().base(); b.flags&fAligned != 0 {
off = roundup(off, 8*int64(a.Types[f.Type().Kind()].Align))
}
f.offset = uintptr(off >> 3)
f.bitFieldOffset = byte(off & 7)
f.bitFieldMask = (1<<f.bitFieldWidth - 1) << f.bitFieldOffset
off += int64(f.bitFieldWidth)
f.promote = integerPromotion(a, f.Type())
default:
al := f.Type().Align()
off = roundup(off, 8*int64(al))
f.offset = uintptr(off) >> 3
off += 8 * int64(f.Type().Size())
f.promote = integerPromotion(a, f.Type())
}
}
var lf *field
for _, f := range t.fields {
if lf != nil && !lf.isBitField && !f.isBitField {
lf.pad = byte(f.offset - lf.offset - lf.Type().Size())
}
lf = f
}
if b := t.base(); b.flags&fAligned == 0 {
t.align = byte(align)
t.fieldAlign = byte(align)
}
off0 := off
off = roundup(off, 8*int64(t.Align()))
if lf != nil && !lf.IsBitField() {
lf.pad = byte(off-off0) >> 3
}
t.size = uintptr(off >> 3)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
return t
}
// https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html#x86-Options
//
// -mno-ms-bitfields
//
// Enable/disable bit-field layout compatible with the native Microsoft Windows
// compiler.
//
// If packed is used on a structure, or if bit-fields are used, it may be that
// the Microsoft ABI lays out the structure differently than the way GCC
// normally does. Particularly when moving packed data between functions
// compiled with GCC and the native Microsoft compiler (either via function
// call or as data in a file), it may be necessary to access either format.
//
// This option is enabled by default for Microsoft Windows targets. This
// behavior can also be controlled locally by use of variable or type
// attributes. For more information, see x86 Variable Attributes and x86 Type
// Attributes.
//
// The Microsoft structure layout algorithm is fairly simple with the exception
// of the bit-field packing. The padding and alignment of members of structures
// and whether a bit-field can straddle a storage-unit boundary are determine
// by these rules:
//
// Structure members are stored sequentially in the order in which they are
// declared: the first member has the lowest memory address and the last member
// the highest. Every data object has an alignment requirement. The alignment
// requirement for all data except structures, unions, and arrays is either the
// size of the object or the current packing size (specified with either the
// aligned attribute or the pack pragma), whichever is less. For structures,
// unions, and arrays, the alignment requirement is the largest alignment
// requirement of its members. Every object is allocated an offset so that:
// offset % alignment_requirement == 0 Adjacent bit-fields are packed into the
// same 1-, 2-, or 4-byte allocation unit if the integral types are the same
// size and if the next bit-field fits into the current allocation unit without
// crossing the boundary imposed by the common alignment requirements of the
// bit-fields. MSVC interprets zero-length bit-fields in the following ways:
//
// If a zero-length bit-field is inserted between two bit-fields that are
// normally coalesced, the bit-fields are not coalesced. For example:
//
// struct
// {
// unsigned long bf_1 : 12;
// unsigned long : 0;
// unsigned long bf_2 : 12;
// } t1;
//
// The size of t1 is 8 bytes with the zero-length bit-field. If the zero-length
// bit-field were removed, t1s size would be 4 bytes.
//
// If a zero-length bit-field is inserted after a bit-field, foo, and the
// alignment of the zero-length bit-field is greater than the member that
// follows it, bar, bar is aligned as the type of the zero-length bit-field.
// For example:
//
// struct
// {
// char foo : 4;
// short : 0;
// char bar;
// } t2;
//
// struct
// {
// char foo : 4;
// short : 0;
// double bar;
// } t3;
//
// For t2, bar is placed at offset 2, rather than offset 1. Accordingly, the
// size of t2 is 4. For t3, the zero-length bit-field does not affect the
// alignment of bar or, as a result, the size of the structure.
//
// Taking this into account, it is important to note the following:
//
// If a zero-length bit-field follows a normal bit-field, the type of the
// zero-length bit-field may affect the alignment of the structure as whole.
// For example, t2 has a size of 4 bytes, since the zero-length bit-field
// follows a normal bit-field, and is of type short. Even if a zero-length
// bit-field is not followed by a normal bit-field, it may still affect the
// alignment of the structure:
//
// struct
// {
// char foo : 6;
// long : 0;
// } t4;
//
// Here, t4 takes up 4 bytes.
//
// Zero-length bit-fields following non-bit-field members are ignored:
//
// struct
// {
// char foo;
// long : 0;
// char bar;
// } t5;
//
// Here, t5 takes up 2 bytes.
func (a *ABI) msLayout(ctx *context, n Node, t *structType) (r *structType) {
if t.IsPacked() {
return a.msPackedLayout(ctx, n, t)
}
if t.Kind() == Union {
panic(todo(""))
}
var off int64 // In bits.
align := int(t.typeBase.align)
var prev *field
for i, f := range t.fields {
switch {
case f.isBitField:
al := f.Type().Align()
if prev != nil {
switch {
case prev.isBitField && prev.Type().Size() != f.Type().Size():
off = roundup(off, 8*int64(prev.Type().Align()))
off = roundup(off, 8*int64(al))
case !prev.isBitField:
off = roundup(off, 8*int64(al))
default:
// Adjacent bit-fields are packed into the same 1-, 2-, or 4-byte allocation
// unit if the integral types are the same size and if the next bit-field fits
// into the current allocation unit without crossing the boundary imposed by
// the common alignment requirements of the bit-fields.
}
}
// http://jkz.wtf/bit-field-packing-in-gcc-and-clang
// 1. Jump backwards to nearest address that would support this type. For
// example if we have an int jump to the closest address where an int could be
// stored according to the platform alignment rules.
down := rounddown(off, 8*int64(al))
// 2. Get sizeof(current field) bytes from that address.
alloc := int64(f.Type().Size()) * 8
need := int64(f.bitFieldWidth)
if need == 0 && i != 0 {
off = roundup(off, 8*int64(al))
continue
}
if al > align {
align = al
}
used := off - down
switch {
case alloc-used >= need:
// 3. If the number of bits that we need to store can be stored in these bits,
// put the bits in the lowest possible bits of this block.
off = down + used
f.offset = uintptr(down >> 3)
f.bitFieldOffset = byte(used)
f.bitFieldMask = (1<<f.bitFieldWidth - 1) << used
off += int64(f.bitFieldWidth)
f.promote = integerPromotion(a, f.Type())
default:
// 4. Otherwise, pad the rest of this block with zeros, and store the bits that
// make up this bit-field in the lowest bits of the next block.
off = roundup(off, 8*int64(al))
f.offset = uintptr(off >> 3)
f.bitFieldOffset = 0
f.bitFieldMask = 1<<f.bitFieldWidth - 1
off += int64(f.bitFieldWidth)
f.promote = integerPromotion(a, f.Type())
}
default:
if prev != nil && prev.isBitField {
off = roundup(off, 8*int64(prev.Type().Align()))
}
al := f.Type().Align()
if al > align {
align = al
}
off = roundup(off, 8*int64(al))
f.offset = uintptr(off) >> 3
off += 8 * int64(f.Type().Size())
f.promote = integerPromotion(a, f.Type())
}
prev = f
}
var lf *field
for _, f := range t.fields {
if lf != nil && !lf.isBitField && !f.isBitField {
lf.pad = byte(f.offset - lf.offset - lf.Type().Size())
}
lf = f
}
t.align = byte(align)
t.fieldAlign = byte(align)
off0 := off
off = roundup(off, 8*int64(align))
if lf != nil && !lf.IsBitField() {
lf.pad = byte(off-off0) >> 3
}
t.size = uintptr(off >> 3)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
return t
}
func (a *ABI) msPackedLayout(ctx *context, n Node, t *structType) (r *structType) {
if t.typeBase.flags&fAligned == 0 {
t.align = 1
}
t.fieldAlign = t.align
if t.Kind() == Union {
panic(todo(""))
var off int64 // In bits.
for _, f := range t.fields {
switch {
case f.isBitField:
panic(todo("%v: ", n.Position()))
default:
f.offset = 0
if off2 := 8 * int64(f.Type().Size()); off2 > off {
off = off2
}
f.promote = integerPromotion(a, f.Type())
}
}
off = roundup(off, 8)
t.size = uintptr(off >> 3)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
return t
}
var off int64 // In bits.
var prev *field
align := int(t.typeBase.align)
for i, f := range t.fields {
out:
switch {
case f.isBitField:
al := f.Type().Align()
switch {
case prev != nil && prev.IsBitField() && prev.Type().Size() != f.Type().Size():
off = mathutil.MaxInt64(off, int64(prev.Offset()*8)+int64(prev.BitFieldOffset()+8*prev.Type().Align()))
off = roundup(off, 8*int64(align))
f.offset = uintptr(off >> 3)
f.bitFieldOffset = 0
f.bitFieldMask = 1<<f.bitFieldWidth - 1
off += int64(f.bitFieldWidth)
f.promote = integerPromotion(a, f.Type())
break out
}
// http://jkz.wtf/bit-field-packing-in-gcc-and-clang
// 1. Jump backwards to nearest address that would support this type. For
// example if we have an int jump to the closest address where an int could be
// stored according to the platform alignment rules.
down := rounddown(off, 8*int64(al))
// 2. Get sizeof(current field) bytes from that address.
alloc := int64(f.Type().Size()) * 8
need := int64(f.bitFieldWidth)
if need == 0 && i != 0 {
off = roundup(off, 8*int64(al))
continue
}
used := off - down
switch {
case alloc-used >= need:
// 3. If the number of bits that we need to store can be stored in these bits,
// put the bits in the lowest possible bits of this block.
off = down + used
f.offset = uintptr(down >> 3)
f.bitFieldOffset = byte(used)
f.bitFieldMask = (1<<f.bitFieldWidth - 1) << used
off += int64(f.bitFieldWidth)
f.promote = integerPromotion(a, f.Type())
default:
// 4. Otherwise, pad the rest of this block with zeros, and store the bits that
// make up this bit-field in the lowest bits of the next block.
off = roundup(off, 8*int64(al))
f.offset = uintptr(off >> 3)
f.bitFieldOffset = 0
f.bitFieldMask = 1<<f.bitFieldWidth - 1
off += int64(f.bitFieldWidth)
f.promote = integerPromotion(a, f.Type())
}
default:
off = roundup(off, 8)
f.offset = uintptr(off) >> 3
off += 8 * int64(f.Type().Size())
f.promote = integerPromotion(a, f.Type())
}
prev = f
}
var lf *field
for _, f := range t.fields {
if lf != nil && !lf.isBitField && !f.isBitField {
lf.pad = byte(f.offset - lf.offset - lf.Type().Size())
}
lf = f
}
t.align = byte(align)
t.fieldAlign = byte(align)
switch {
case lf != nil && lf.IsBitField():
off = mathutil.MaxInt64(off, int64(lf.Offset()*8)+int64(lf.BitFieldOffset()+8*lf.Type().Align()))
off = roundup(off, 8*int64(align))
default:
off0 := off
off = roundup(off, 8*int64(align))
if lf != nil && !lf.IsBitField() {
lf.pad = byte(off-off0) >> 3
}
}
t.size = uintptr(off >> 3)
ctx.structs[StructInfo{Size: t.size, Align: t.Align()}] = struct{}{}
return t
}