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cmd/compile: optimize loads from abi.Type.{Size_,PtrBytes,Kind_}

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With the previous CL in place, we can now pretty easily optimize a few
more loads from abi.Type. I've done Size_, PtrBytes, and Kind_, which
are easily calculated.

Among std/cmd, this rule fires a number of times:

     75 abi.Type field Kind_
     50 abi.PtrType field Elem
     14 abi.Type field Hash
      4 abi.Type field Size_
      2 abi.Type field PtrBytes

The other ones that show up when compiling std/cmd are TFlag and GCData,
but these are not trivially calculated. Doing TFlag would probably be a
decent help given it's often used in things like switches where
statically knowing the kind could eliminate a bunch of dead code.

Change-Id: Ic7fd2113fa7479af914d06916edbca60cc71819f
Reviewed-on: https://go-review.googlesource.com/c/go/+/701298
Reviewed-by: Mark Freeman <markfreeman@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Jake Bailey 2025-09-05 13:36:47 -07:00 • committed by Gopher Robot
parent b915e14490
commit 5b218461f9
2 changed files with 23 additions and 3 deletions
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7
src/cmd/compile/internal/reflectdata/reflect.go
View file

@ -414,6 +414,10 @@ var kinds = []abi.Kind{
types.TUNSAFEPTR: abi.UnsafePointer,
}
func ABIKindOfType(t *types.Type) abi.Kind {
return kinds[t.Kind()]
}
var (
memhashvarlen *obj.LSym
memequalvarlen *obj.LSym
@ -512,8 +516,7 @@ func dcommontype(c rttype.Cursor, t *types.Type) {
c.Field("Align_").WriteUint8(uint8(t.Alignment()))
c.Field("FieldAlign_").WriteUint8(uint8(t.Alignment()))
kind := kinds[t.Kind()]
c.Field("Kind_").WriteUint8(uint8(kind))
c.Field("Kind_").WriteUint8(uint8(ABIKindOfType(t)))
c.Field("Equal").WritePtr(eqfunc)
c.Field("GCData").WritePtr(gcsym)

19
src/cmd/compile/internal/ssa/rewrite.go
View file

@ -2005,7 +2005,7 @@ func isFixedLoad(v *Value, sym Sym, off int64) bool {
for _, f := range rttype.Type.Fields() {
if f.Offset == off && copyCompatibleType(v.Type, f.Type) {
switch f.Sym.Name {
case "Hash":
case "Size_", "PtrBytes", "Hash", "Kind_":
return true
default:
// fmt.Println("unknown field", f.Sym.Name)
@ -2061,13 +2061,30 @@ func rewriteFixedLoad(v *Value, sym Sym, sb *Value, off int64) *Value {
t := (*lsym.Extra).(*obj.TypeInfo).Type.(*types.Type)
ptrSizedOpConst := OpConst64
if f.Config.PtrSize == 4 {
ptrSizedOpConst = OpConst32
}
for _, f := range rttype.Type.Fields() {
if f.Offset == off && copyCompatibleType(v.Type, f.Type) {
switch f.Sym.Name {
case "Size_":
v.reset(ptrSizedOpConst)
v.AuxInt = int64(t.Size())
return v
case "PtrBytes":
v.reset(ptrSizedOpConst)
v.AuxInt = int64(types.PtrDataSize(t))
return v
case "Hash":
v.reset(OpConst32)
v.AuxInt = int64(types.TypeHash(t))
return v
case "Kind_":
v.reset(OpConst8)
v.AuxInt = int64(reflectdata.ABIKindOfType(t))
return v
default:
base.Fatalf("unknown field %s for fixedLoad of %s at offset %d", f.Sym.Name, lsym.Name, off)
}