cmd/compile: simplify AlgType usage

Only walk needs to distinguish different sizes of AMEM. Move
the size-distinguishing AlgType there.

Change-Id: I0a725b5bd13795a623b3668325f1068579abd340
Reviewed-on: https://go-review.googlesource.com/c/go/+/727461
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

3 files changed, 33 insertions, 34 deletions

diff --git a/src/cmd/compile/internal/reflectdata/alg.go b/src/cmd/compile/internal/reflectdata/alg.go
index c87cd8e257..eb46ed84aa 100644
--- a/src/cmd/compile/internal/reflectdata/alg.go
+++ b/src/cmd/compile/internal/reflectdata/alg.go
@@ -18,35 +18,6 @@ import (
 	"cmd/internal/obj"
 )
 
-// AlgType returns the fixed-width AMEMxx variants instead of the general
-// AMEM kind when possible.
-func AlgType(t *types.Type) types.AlgKind {
-	a := types.AlgType(t)
-	if a == types.AMEM {
-		if t.Alignment() < int64(base.Ctxt.Arch.Alignment) && t.Alignment() < t.Size() {
-			// For example, we can't treat [2]int16 as an int32 if int32s require
-			// 4-byte alignment. See issue 46283.
-			return a
-		}
-		switch t.Size() {
-		case 0:
-			return types.AMEM0
-		case 1:
-			return types.AMEM8
-		case 2:
-			return types.AMEM16
-		case 4:
-			return types.AMEM32
-		case 8:
-			return types.AMEM64
-		case 16:
-			return types.AMEM128
-		}
-	}
-
-	return a
-}
-
 // genhash returns a symbol which is the closure used to compute
 // the hash of a value of type t.
 func genhash(t *types.Type) *obj.LSym {
@@ -266,7 +237,7 @@ func sysClosure(name string) *obj.LSym {
 // geneq returns a symbol which is the closure used to compute
 // equality for two objects of type t.
 func geneq(t *types.Type) *obj.LSym {
-	switch AlgType(t) {
+	switch types.AlgType(t) {
 	case types.ANOEQ, types.ANOALG:
 		// The runtime will panic if it tries to compare
 		// a type with a nil equality function.
diff --git a/src/cmd/compile/internal/reflectdata/map.go b/src/cmd/compile/internal/reflectdata/map.go
index 2b43d4af27..30a9dcc28c 100644
--- a/src/cmd/compile/internal/reflectdata/map.go
+++ b/src/cmd/compile/internal/reflectdata/map.go
@@ -271,10 +271,10 @@ func writeMapType(t *types.Type, lsym *obj.LSym, c rttype.Cursor) {
 
 	slotTyp := gtyp.Field(1).Type.Elem()
 	elemOff := slotTyp.Field(1).Offset
-	if AlgType(t.Key()) == types.AMEM64 && elemOff != 8 {
+	if types.AlgType(t.Key()) == types.AMEM && t.Key().Size() == 8 && elemOff != 8 {
 		base.Fatalf("runtime assumes elemOff for 8-byte keys is 8, got %d", elemOff)
 	}
-	if AlgType(t.Key()) == types.ASTRING && elemOff != int64(2*types.PtrSize) {
+	if types.AlgType(t.Key()) == types.ASTRING && elemOff != int64(2*types.PtrSize) {
 		base.Fatalf("runtime assumes elemOff for string keys is %d, got %d", 2*types.PtrSize, elemOff)
 	}
 
diff --git a/src/cmd/compile/internal/walk/walk.go b/src/cmd/compile/internal/walk/walk.go
index 25add3d804..08f36095a5 100644
--- a/src/cmd/compile/internal/walk/walk.go
+++ b/src/cmd/compile/internal/walk/walk.go
@@ -10,7 +10,6 @@ import (
 
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
-	"cmd/compile/internal/reflectdata"
 	"cmd/compile/internal/rttype"
 	"cmd/compile/internal/ssagen"
 	"cmd/compile/internal/typecheck"
@@ -194,7 +193,7 @@ func mapfast(t *types.Type) int {
 	if t.Elem().Size() > abi.MapMaxElemBytes {
 		return mapslow
 	}
-	switch reflectdata.AlgType(t.Key()) {
+	switch algType(t.Key()) {
 	case types.AMEM32:
 		if !t.Key().HasPointers() {
 			return mapfast32
@@ -218,6 +217,35 @@ func mapfast(t *types.Type) int {
 	return mapslow
 }
 
+// algType returns the fixed-width AMEMxx variants instead of the general
+// AMEM kind when possible.
+func algType(t *types.Type) types.AlgKind {
+	a := types.AlgType(t)
+	if a == types.AMEM {
+		if t.Alignment() < int64(base.Ctxt.Arch.Alignment) && t.Alignment() < t.Size() {
+			// For example, we can't treat [2]int16 as an int32 if int32s require
+			// 4-byte alignment. See issue 46283.
+			return a
+		}
+		switch t.Size() {
+		case 0:
+			return types.AMEM0
+		case 1:
+			return types.AMEM8
+		case 2:
+			return types.AMEM16
+		case 4:
+			return types.AMEM32
+		case 8:
+			return types.AMEM64
+		case 16:
+			return types.AMEM128
+		}
+	}
+
+	return a
+}
+
 func walkAppendArgs(n *ir.CallExpr, init *ir.Nodes) {
 	walkExprListSafe(n.Args, init)