cmd/compile: refactor out KeepAlive

Reduce the duplication in every arch by moving the code into package gc.

Change-Id: Ia111add8316492571825431ecd4f0154c8792ae1
Reviewed-on: https://go-review.googlesource.com/28481
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

src/cmd/compile/internal/amd64/ssa.go

@@ -903,17 +903,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpVarLive:
 		gc.Gvarlive(v.Aux.(*gc.Node))
 	case ssa.OpKeepAlive:
-		if !v.Args[0].Type.IsPtrShaped() {
-			v.Fatalf("keeping non-pointer alive %v", v.Args[0])
-		}
-		n, off := gc.AutoVar(v.Args[0])
-		if n == nil {
-			v.Fatalf("KeepLive with non-spilled value %s %s", v, v.Args[0])
-		}
-		if off != 0 {
-			v.Fatalf("KeepLive with non-zero offset spill location %s:%d", n, off)
-		}
-		gc.Gvarlive(n)
+		gc.KeepAlive(v)
 	case ssa.OpAMD64LoweredNilCheck:
 		// Optimization - if the subsequent block has a load or store
 		// at the same address, we don't need to issue this instruction.

src/cmd/compile/internal/arm/ssa.go

@@ -917,17 +917,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpVarLive:
 		gc.Gvarlive(v.Aux.(*gc.Node))
 	case ssa.OpKeepAlive:
-		if !v.Args[0].Type.IsPtrShaped() {
-			v.Fatalf("keeping non-pointer alive %v", v.Args[0])
-		}
-		n, off := gc.AutoVar(v.Args[0])
-		if n == nil {
-			v.Fatalf("KeepLive with non-spilled value %s %s", v, v.Args[0])
-		}
-		if off != 0 {
-			v.Fatalf("KeepLive with non-zero offset spill location %s:%d", n, off)
-		}
-		gc.Gvarlive(n)
+		gc.KeepAlive(v)
 	case ssa.OpARMEqual,
 		ssa.OpARMNotEqual,
 		ssa.OpARMLessThan,

src/cmd/compile/internal/arm64/ssa.go

@@ -690,17 +690,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpVarLive:
 		gc.Gvarlive(v.Aux.(*gc.Node))
 	case ssa.OpKeepAlive:
-		if !v.Args[0].Type.IsPtrShaped() {
-			v.Fatalf("keeping non-pointer alive %v", v.Args[0])
-		}
-		n, off := gc.AutoVar(v.Args[0])
-		if n == nil {
-			v.Fatalf("KeepLive with non-spilled value %s %s", v, v.Args[0])
-		}
-		if off != 0 {
-			v.Fatalf("KeepLive with non-zero offset spill location %s:%d", n, off)
-		}
-		gc.Gvarlive(n)
+		gc.KeepAlive(v)
 	case ssa.OpARM64Equal,
 		ssa.OpARM64NotEqual,
 		ssa.OpARM64LessThan,

src/cmd/compile/internal/gc/ssa.go

@@ -4568,6 +4568,25 @@ func CheckLoweredGetClosurePtr(v *ssa.Value) {
 	}
 }
 
+// KeepAlive marks the variable referenced by OpKeepAlive as live.
+// Called during ssaGenValue.
+func KeepAlive(v *ssa.Value) {
+	if v.Op != ssa.OpKeepAlive {
+		v.Fatalf("KeepAlive called with non-KeepAlive value: %v", v.LongString())
+	}
+	if !v.Args[0].Type.IsPtrShaped() {
+		v.Fatalf("keeping non-pointer alive %v", v.Args[0])
+	}
+	n, off := AutoVar(v.Args[0])
+	if n == nil {
+		v.Fatalf("KeepAlive with non-spilled value %s %s", v, v.Args[0])
+	}
+	if off != 0 {
+		v.Fatalf("KeepAlive with non-zero offset spill location %s:%d", n, off)
+	}
+	Gvarlive(n)
+}
+
 // AutoVar returns a *Node and int64 representing the auto variable and offset within it
 // where v should be spilled.
 func AutoVar(v *ssa.Value) (*Node, int64) {

src/cmd/compile/internal/mips64/ssa.go

@@ -713,17 +713,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpVarLive:
 		gc.Gvarlive(v.Aux.(*gc.Node))
 	case ssa.OpKeepAlive:
-		if !v.Args[0].Type.IsPtrShaped() {
-			v.Fatalf("keeping non-pointer alive %v", v.Args[0])
-		}
-		n, off := gc.AutoVar(v.Args[0])
-		if n == nil {
-			v.Fatalf("KeepLive with non-spilled value %s %s", v, v.Args[0])
-		}
-		if off != 0 {
-			v.Fatalf("KeepLive with non-zero offset spill location %s:%d", n, off)
-		}
-		gc.Gvarlive(n)
+		gc.KeepAlive(v)
 	case ssa.OpMIPS64FPFlagTrue,
 		ssa.OpMIPS64FPFlagFalse:
 		// MOVV	$0, r

src/cmd/compile/internal/ppc64/ssa.go

@@ -841,18 +841,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpVarLive:
 		gc.Gvarlive(v.Aux.(*gc.Node))
 	case ssa.OpKeepAlive:
-		if !v.Args[0].Type.IsPtrShaped() {
-			v.Fatalf("keeping non-pointer alive %v", v.Args[0])
-		}
-		n, off := gc.AutoVar(v.Args[0])
-		if n == nil {
-			v.Fatalf("KeepLive with non-spilled value %s %s", v, v.Args[0])
-		}
-		if off != 0 {
-			v.Fatalf("KeepLive with non-zero offset spill location %s:%d", n, off)
-		}
-		gc.Gvarlive(n)
-
+		gc.KeepAlive(v)
 	case ssa.OpPhi:
 		gc.CheckLoweredPhi(v)
 

src/cmd/compile/internal/x86/ssa.go

@@ -818,17 +818,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpVarLive:
 		gc.Gvarlive(v.Aux.(*gc.Node))
 	case ssa.OpKeepAlive:
-		if !v.Args[0].Type.IsPtrShaped() {
-			v.Fatalf("keeping non-pointer alive %v", v.Args[0])
-		}
-		n, off := gc.AutoVar(v.Args[0])
-		if n == nil {
-			v.Fatalf("KeepLive with non-spilled value %s %s", v, v.Args[0])
-		}
-		if off != 0 {
-			v.Fatalf("KeepLive with non-zero offset spill location %s:%d", n, off)
-		}
-		gc.Gvarlive(n)
+		gc.KeepAlive(v)
 	case ssa.Op386LoweredNilCheck:
 		// Optimization - if the subsequent block has a load or store
 		// at the same address, we don't need to issue this instruction.