[dev.typeparams] cmd/compile: functions to create GC shape types/names for a concrete type

Created functions to create GC shape type and names, based on a proposal
from Keith. Kept unsigned and signed integer types as different, since
they have different shift operations.

Included adding in alignment fields where padding is
required between fields, even though that seems like it will be fairly
uncommon to use.

Added some extra unusual struct typeparams (for testing the gcshape
names/types) in index.go test.

Change-Id: I8132bbd28098bd933435b8972ac5cc0b39f4c0df
Reviewed-on: https://go-review.googlesource.com/c/go/+/329921
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Dan Scales 2021-06-21 17:04:59 -07:00
parent b47cbc2ffe
commit 8767b87ab5
2 changed files with 234 additions and 0 deletions

View file

@ -8,6 +8,7 @@
package noder
import (
"bytes"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/objw"
@ -18,6 +19,7 @@ import (
"cmd/internal/src"
"fmt"
"go/constant"
"strconv"
)
func assert(p bool) {
@ -490,6 +492,195 @@ func (g *irgen) getInstantiationForNode(inst *ir.InstExpr) (*ir.Func, ir.Node) {
}
}
func addGcType(fl []*types.Field, t *types.Type) []*types.Field {
return append(fl, types.NewField(base.Pos, typecheck.Lookup("F"+strconv.Itoa(len(fl))), t))
}
const INTTYPE = types.TINT64 // XX fix for 32-bit arch
const UINTTYPE = types.TUINT64 // XX fix for 32-bit arch
const INTSTRING = "i8" // XX fix for 32-bit arch
const UINTSTRING = "u8" // XX fix for 32-bit arch
// accumGcshape adds fields to fl resulting from the GCshape transformation of
// type t. The string associated with the GCshape transformation of t is added to
// buf. fieldSym is the sym of the field associated with type t, if it is in a
// struct. fieldSym could be used to have special naming for blank fields, etc.
func accumGcshape(fl []*types.Field, buf *bytes.Buffer, t *types.Type, fieldSym *types.Sym) []*types.Field {
// t.Kind() is already the kind of the underlying type, so no need to
// reference t.Underlying() to reference the underlying type.
assert(t.Kind() == t.Underlying().Kind())
switch t.Kind() {
case types.TINT8:
fl = addGcType(fl, types.Types[types.TINT8])
buf.WriteString("i1")
case types.TUINT8:
fl = addGcType(fl, types.Types[types.TUINT8])
buf.WriteString("u1")
case types.TINT16:
fl = addGcType(fl, types.Types[types.TINT16])
buf.WriteString("i2")
case types.TUINT16:
fl = addGcType(fl, types.Types[types.TUINT16])
buf.WriteString("u2")
case types.TINT32:
fl = addGcType(fl, types.Types[types.TINT32])
buf.WriteString("i4")
case types.TUINT32:
fl = addGcType(fl, types.Types[types.TUINT32])
buf.WriteString("u4")
case types.TINT64:
fl = addGcType(fl, types.Types[types.TINT64])
buf.WriteString("i8")
case types.TUINT64:
fl = addGcType(fl, types.Types[types.TUINT64])
buf.WriteString("u8")
case types.TINT:
fl = addGcType(fl, types.Types[INTTYPE])
buf.WriteString(INTSTRING)
case types.TUINT, types.TUINTPTR:
fl = addGcType(fl, types.Types[UINTTYPE])
buf.WriteString(UINTSTRING)
case types.TCOMPLEX64:
fl = addGcType(fl, types.Types[types.TFLOAT32])
fl = addGcType(fl, types.Types[types.TFLOAT32])
buf.WriteString("f4")
buf.WriteString("f4")
case types.TCOMPLEX128:
fl = addGcType(fl, types.Types[types.TFLOAT64])
fl = addGcType(fl, types.Types[types.TFLOAT64])
buf.WriteString("f8")
buf.WriteString("f8")
case types.TFLOAT32:
fl = addGcType(fl, types.Types[types.TFLOAT32])
buf.WriteString("f4")
case types.TFLOAT64:
fl = addGcType(fl, types.Types[types.TFLOAT64])
buf.WriteString("f8")
case types.TBOOL:
fl = addGcType(fl, types.Types[types.TINT8])
buf.WriteString("i1")
case types.TPTR:
fl = addGcType(fl, types.Types[types.TUNSAFEPTR])
buf.WriteString("p")
case types.TFUNC:
fl = addGcType(fl, types.Types[types.TUNSAFEPTR])
buf.WriteString("p")
case types.TSLICE:
fl = addGcType(fl, types.Types[types.TUNSAFEPTR])
fl = addGcType(fl, types.Types[INTTYPE])
fl = addGcType(fl, types.Types[INTTYPE])
buf.WriteString("p")
buf.WriteString(INTSTRING)
buf.WriteString(INTSTRING)
case types.TARRAY:
n := t.NumElem()
if n == 1 {
fl = accumGcshape(fl, buf, t.Elem(), nil)
} else if n > 0 {
// Represent an array with more than one element as its
// unique type, since it must be treated differently for
// regabi.
fl = addGcType(fl, t)
buf.WriteByte('[')
buf.WriteString(strconv.Itoa(int(n)))
buf.WriteString("](")
var ignore []*types.Field
// But to determine its gcshape name, we must call
// accumGcShape() on t.Elem().
accumGcshape(ignore, buf, t.Elem(), nil)
buf.WriteByte(')')
}
case types.TSTRUCT:
nfields := t.NumFields()
for i, f := range t.Fields().Slice() {
fl = accumGcshape(fl, buf, f.Type, f.Sym)
// Check if we need to add an alignment field.
var pad int64
if i < nfields-1 {
pad = t.Field(i+1).Offset - f.Offset - f.Type.Width
} else {
pad = t.Width - f.Offset - f.Type.Width
}
if pad > 0 {
// There is padding between fields or at end of
// struct. Add an alignment field.
fl = addGcType(fl, types.NewArray(types.Types[types.TUINT8], pad))
buf.WriteString("a")
buf.WriteString(strconv.Itoa(int(pad)))
}
}
case types.TCHAN:
fl = addGcType(fl, types.Types[types.TUNSAFEPTR])
buf.WriteString("p")
case types.TMAP:
fl = addGcType(fl, types.Types[types.TUNSAFEPTR])
buf.WriteString("p")
case types.TINTER:
fl = addGcType(fl, types.Types[types.TUNSAFEPTR])
fl = addGcType(fl, types.Types[types.TUNSAFEPTR])
buf.WriteString("pp")
case types.TFORW, types.TANY:
assert(false)
case types.TSTRING:
fl = addGcType(fl, types.Types[types.TUNSAFEPTR])
fl = addGcType(fl, types.Types[INTTYPE])
buf.WriteString("p")
buf.WriteString(INTSTRING)
case types.TUNSAFEPTR:
fl = addGcType(fl, types.Types[types.TUNSAFEPTR])
buf.WriteString("p")
default: // Everything TTYPEPARAM and below in list of Kinds
assert(false)
}
return fl
}
// gcshapeType returns the GCshape type and name corresponding to type t.
func gcshapeType(t *types.Type) (*types.Type, string) {
var fl []*types.Field
buf := bytes.NewBufferString("")
// Call CallSize so type sizes and field offsets are available.
types.CalcSize(t)
fl = accumGcshape(fl, buf, t, nil)
// TODO: Should gcshapes be in a global package, so we don't have to
// duplicate in each package? Or at least in the specified source package
// of a function/method instantiation?
gcshape := types.NewStruct(types.LocalPkg, fl)
assert(gcshape.Size() == t.Size())
return gcshape, buf.String()
}
// getInstantiation gets the instantiantion and dictionary of the function or method nameNode
// with the type arguments targs. If the instantiated function is not already
// cached, then it calls genericSubst to create the new instantiation.
@ -506,6 +697,13 @@ func (g *irgen) getInstantiation(nameNode *ir.Name, targs []*types.Type, isMeth
sym := typecheck.MakeInstName(nameNode.Sym(), targs, isMeth)
st := g.target.Stencils[sym]
if st == nil {
if false {
// Testing out gcshapeType() and gcshapeName()
for i, t := range targs {
gct, gcs := gcshapeType(t)
fmt.Printf("targ %d: %v %v\n", i, gct, gcs)
}
}
// If instantiation doesn't exist yet, create it and add
// to the list of decls.
st = g.genericSubst(sym, nameNode, targs, isMeth)

View file

@ -26,6 +26,26 @@ type obj struct {
x int
}
type obj2 struct {
x int8
y float64
}
type obj3 struct {
x int64
y int8
}
type inner struct {
y int64
z int32
}
type obj4 struct {
x int32
s inner
}
func main() {
want := 2
@ -43,4 +63,20 @@ func main() {
if got := Index(vec3, vec3[2]); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
vec4 := []obj2{obj2{2, 3.0}, obj2{3, 4.0}, obj2{4, 5.0}}
if got := Index(vec4, vec4[2]); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
vec5 := []obj3{obj3{2, 3}, obj3{3, 4}, obj3{4, 5}}
if got := Index(vec5, vec5[2]); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
vec6 := []obj4{obj4{2, inner{3, 4}}, obj4{3, inner{4, 5}}, obj4{4, inner{5, 6}}}
if got := Index(vec6, vec6[2]); got != want {
panic(fmt.Sprintf("got %d, want %d", got, want))
}
}