[dev.regabi] cmd/compile: remove gc ↔ ssa cycle hacks

The cycle hacks existed because gc needed to import ssa
which need to know about gc.Node. But now that's ir.Node,
and there's no cycle anymore.

Don't know how much it matters but LocalSlot is now
one word shorter than before, because it holds a pointer
instead of an interface for the *Node. That won't last long.

Now that they're not necessary for interface satisfaction,
IsSynthetic and IsAutoTmp can move to top-level ir functions.

Change-Id: Ie511e93466cfa2b17d9a91afc4bd8d53fdb80453
Reviewed-on: https://go-review.googlesource.com/c/go/+/272931
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

1 files changed, 15 insertions, 14 deletions

diff --git a/src/cmd/compile/internal/ssa/deadstore.go b/src/cmd/compile/internal/ssa/deadstore.go
index 0664013b39..0f1cd4bc9f 100644
--- a/src/cmd/compile/internal/ssa/deadstore.go
+++ b/src/cmd/compile/internal/ssa/deadstore.go
@@ -5,6 +5,7 @@
 package ssa
 
 import (
+	"cmd/compile/internal/ir"
 	"cmd/compile/internal/types"
 	"cmd/internal/src"
 )
@@ -136,9 +137,9 @@ func dse(f *Func) {
 // reaches stores then we delete all the stores. The other operations will then
 // be eliminated by the dead code elimination pass.
 func elimDeadAutosGeneric(f *Func) {
-	addr := make(map[*Value]GCNode) // values that the address of the auto reaches
-	elim := make(map[*Value]GCNode) // values that could be eliminated if the auto is
-	used := make(map[GCNode]bool)   // used autos that must be kept
+	addr := make(map[*Value]*ir.Node) // values that the address of the auto reaches
+	elim := make(map[*Value]*ir.Node) // values that could be eliminated if the auto is
+	used := make(map[*ir.Node]bool)   // used autos that must be kept
 
 	// visit the value and report whether any of the maps are updated
 	visit := func(v *Value) (changed bool) {
@@ -146,8 +147,8 @@ func elimDeadAutosGeneric(f *Func) {
 		switch v.Op {
 		case OpAddr, OpLocalAddr:
 			// Propagate the address if it points to an auto.
-			n, ok := v.Aux.(GCNode)
-			if !ok || n.StorageClass() != ClassAuto {
+			n, ok := v.Aux.(*ir.Node)
+			if !ok || n.Class() != ir.PAUTO {
 				return
 			}
 			if addr[v] == nil {
@@ -157,8 +158,8 @@ func elimDeadAutosGeneric(f *Func) {
 			return
 		case OpVarDef, OpVarKill:
 			// v should be eliminated if we eliminate the auto.
-			n, ok := v.Aux.(GCNode)
-			if !ok || n.StorageClass() != ClassAuto {
+			n, ok := v.Aux.(*ir.Node)
+			if !ok || n.Class() != ir.PAUTO {
 				return
 			}
 			if elim[v] == nil {
@@ -173,8 +174,8 @@ func elimDeadAutosGeneric(f *Func) {
 			// for open-coded defers from being removed (since they
 			// may not be used by the inline code, but will be used by
 			// panic processing).
-			n, ok := v.Aux.(GCNode)
-			if !ok || n.StorageClass() != ClassAuto {
+			n, ok := v.Aux.(*ir.Node)
+			if !ok || n.Class() != ir.PAUTO {
 				return
 			}
 			if !used[n] {
@@ -221,7 +222,7 @@ func elimDeadAutosGeneric(f *Func) {
 		}
 
 		// Propagate any auto addresses through v.
-		node := GCNode(nil)
+		var node *ir.Node
 		for _, a := range args {
 			if n, ok := addr[a]; ok && !used[n] {
 				if node == nil {
@@ -298,15 +299,15 @@ func elimUnreadAutos(f *Func) {
 	// Loop over all ops that affect autos taking note of which
 	// autos we need and also stores that we might be able to
 	// eliminate.
-	seen := make(map[GCNode]bool)
+	seen := make(map[*ir.Node]bool)
 	var stores []*Value
 	for _, b := range f.Blocks {
 		for _, v := range b.Values {
-			n, ok := v.Aux.(GCNode)
+			n, ok := v.Aux.(*ir.Node)
 			if !ok {
 				continue
 			}
-			if n.StorageClass() != ClassAuto {
+			if n.Class() != ir.PAUTO {
 				continue
 			}
 
@@ -334,7 +335,7 @@ func elimUnreadAutos(f *Func) {
 
 	// Eliminate stores to unread autos.
 	for _, store := range stores {
-		n, _ := store.Aux.(GCNode)
+		n, _ := store.Aux.(*ir.Node)
 		if seen[n] {
 			continue
 		}