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// Code generated by "go test -run=Generate -write=all"; DO NOT EDIT.
// Source: ../../cmd/compile/internal/types2/gcsizes.go
// Copyright 2023 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 types
type gcSizes struct {
WordSize int64 // word size in bytes - must be >= 4 (32bits)
MaxAlign int64 // maximum alignment in bytes - must be >= 1
}
func (s *gcSizes) Alignof(T Type) (result int64) {
defer func() {
assert(result >= 1)
}()
// For arrays and structs, alignment is defined in terms
// of alignment of the elements and fields, respectively.
switch t := under(T).(type) {
case *Array:
// spec: "For a variable x of array type: unsafe.Alignof(x)
// is the same as unsafe.Alignof(x[0]), but at least 1."
return s.Alignof(t.elem)
case *Struct:
if len(t.fields) == 0 && _IsSyncAtomicAlign64(T) {
// Special case: sync/atomic.align64 is an
// empty struct we recognize as a signal that
// the struct it contains must be
// 64-bit-aligned.
//
// This logic is equivalent to the logic in
// cmd/compile/internal/types/size.go:calcStructOffset
return 8
}
// spec: "For a variable x of struct type: unsafe.Alignof(x)
// is the largest of the values unsafe.Alignof(x.f) for each
// field f of x, but at least 1."
max := int64(1)
for _, f := range t.fields {
if a := s.Alignof(f.typ); a > max {
max = a
}
}
return max
case *Slice, *Interface:
// Multiword data structures are effectively structs
// in which each element has size WordSize.
// Type parameters lead to variable sizes/alignments;
// StdSizes.Alignof won't be called for them.
assert(!isTypeParam(T))
return s.WordSize
case *Basic:
// Strings are like slices and interfaces.
if t.Info()&IsString != 0 {
return s.WordSize
}
case *TypeParam, *Union:
panic("unreachable")
}
a := s.Sizeof(T) // may be 0 or negative
// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."
if a < 1 {
return 1
}
// complex{64,128} are aligned like [2]float{32,64}.
if isComplex(T) {
a /= 2
}
if a > s.MaxAlign {
return s.MaxAlign
}
return a
}
func (s *gcSizes) Offsetsof(fields []*Var) []int64 {
offsets := make([]int64, len(fields))
var offs int64
for i, f := range fields {
if offs < 0 {
// all remaining offsets are too large
offsets[i] = -1
continue
}
// offs >= 0
a := s.Alignof(f.typ)
offs = align(offs, a) // possibly < 0 if align overflows
offsets[i] = offs
if d := s.Sizeof(f.typ); d >= 0 && offs >= 0 {
offs += d // ok to overflow to < 0
} else {
offs = -1 // f.typ or offs is too large
}
}
return offsets
}
func (s *gcSizes) Sizeof(T Type) int64 {
switch t := under(T).(type) {
case *Basic:
assert(isTyped(T))
k := t.kind
if int(k) < len(basicSizes) {
if s := basicSizes[k]; s > 0 {
return int64(s)
}
}
if k == String {
return s.WordSize * 2
}
case *Array:
n := t.len
if n <= 0 {
return 0
}
// n > 0
esize := s.Sizeof(t.elem)
if esize < 0 {
return -1 // element too large
}
if esize == 0 {
return 0 // 0-size element
}
// esize > 0
// Final size is esize * n; and size must be <= maxInt64.
const maxInt64 = 1<<63 - 1
if esize > maxInt64/n {
return -1 // esize * n overflows
}
return esize * n
case *Slice:
return s.WordSize * 3
case *Struct:
n := t.NumFields()
if n == 0 {
return 0
}
offsets := s.Offsetsof(t.fields)
offs := offsets[n-1]
size := s.Sizeof(t.fields[n-1].typ)
if offs < 0 || size < 0 {
return -1 // type too large
}
// gc: The last field of a non-zero-sized struct is not allowed to
// have size 0.
if offs > 0 && size == 0 {
size = 1
}
// gc: Size includes alignment padding.
return align(offs+size, s.Alignof(t)) // may overflow to < 0 which is ok
case *Interface:
// Type parameters lead to variable sizes/alignments;
// StdSizes.Sizeof won't be called for them.
assert(!isTypeParam(T))
return s.WordSize * 2
case *TypeParam, *Union:
panic("unreachable")
}
return s.WordSize // catch-all
}
// gcSizesFor returns the Sizes used by gc for an architecture.
// The result is a nil *gcSizes pointer (which is not a valid types.Sizes)
// if a compiler/architecture pair is not known.
func gcSizesFor(compiler, arch string) *gcSizes {
if compiler != "gc" {
return nil
}
return gcArchSizes[arch]
}
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