[dev.regabi] cmd/compile: separate ssa from other phases

isIntrinsicCall and ssaDumpInline are the only two "forward references"
to ssa by earlier phases. Make them a bit more explicit so that the
uses and the definitions can end up in different packages.

Change-Id: I02c7a27464fbedef9fee43c0e4094fa08b4d7a5c
Reviewed-on: https://go-review.googlesource.com/c/go/+/279300
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>

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

@@ -39,6 +39,9 @@ import (
 	"strings"
 )
 
+// IsIntrinsicCall reports whether the compiler back end will treat the call as an intrinsic operation.
+var IsIntrinsicCall = func(*ir.CallExpr) bool { return false }
+
 // Inlining budget parameters, gathered in one place
 const (
 	inlineMaxBudget       = 80
@@ -339,7 +342,7 @@ func (v *hairyVisitor) doNode(n ir.Node) error {
 			}
 		}
 
-		if isIntrinsicCall(n) {
+		if IsIntrinsicCall(n) {
 			// Treat like any other node.
 			break
 		}
@@ -593,7 +596,7 @@ func inlnode(n ir.Node, maxCost int32, inlMap map[*ir.Func]bool, edit func(ir.No
 		if base.Flag.LowerM > 3 {
 			fmt.Printf("%v:call to func %+v\n", ir.Line(n), call.Left())
 		}
-		if isIntrinsicCall(call) {
+		if IsIntrinsicCall(call) {
 			break
 		}
 		if fn := inlCallee(call.Left()); fn != nil && fn.Inl != nil {
@@ -768,6 +771,10 @@ func inlParam(t *types.Field, as ir.Node, inlvars map[*ir.Name]ir.Node) ir.Node
 
 var inlgen int
 
+// SSADumpInline gives the SSA back end a chance to dump the function
+// when producing output for debugging the compiler itself.
+var SSADumpInline = func(*ir.Func) {}
+
 // If n is a call node (OCALLFUNC or OCALLMETH), and fn is an ONAME node for a
 // function with an inlinable body, return an OINLCALL node that can replace n.
 // The returned node's Ninit has the parameter assignments, the Nbody is the
@@ -835,9 +842,7 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 		fmt.Printf("%v: Before inlining: %+v\n", ir.Line(n), n)
 	}
 
-	if ssaDump != "" && ssaDump == ir.FuncName(Curfn) {
-		ssaDumpInlined = append(ssaDumpInlined, fn)
-	}
+	SSADumpInline(fn)
 
 	ninit := n.Init()
 

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

@@ -191,6 +191,9 @@ func Main(archInit func(*Arch)) {
 		logopt.LogJsonOption(base.Flag.JSON)
 	}
 
+	IsIntrinsicCall = isIntrinsicCall
+	SSADumpInline = ssaDumpInline
+
 	ssaDump = os.Getenv("GOSSAFUNC")
 	ssaDir = os.Getenv("GOSSADIR")
 	if ssaDump != "" {

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

@@ -1233,10 +1233,10 @@ func (lv *Liveness) emit() (argsSym, liveSym *obj.LSym) {
 // pointer variables in the function and emits a runtime data
 // structure read by the garbage collector.
 // Returns a map from GC safe points to their corresponding stack map index.
-func liveness(e *ssafn, f *ssa.Func, pp *Progs) LivenessMap {
+func liveness(curfn *ir.Func, f *ssa.Func, stkptrsize int64, pp *Progs) LivenessMap {
 	// Construct the global liveness state.
-	vars, idx := getvariables(e.curfn)
-	lv := newliveness(e.curfn, f, vars, idx, e.stkptrsize)
+	vars, idx := getvariables(curfn)
+	lv := newliveness(curfn, f, vars, idx, stkptrsize)
 
 	// Run the dataflow framework.
 	lv.prologue()
@@ -1271,7 +1271,7 @@ func liveness(e *ssafn, f *ssa.Func, pp *Progs) LivenessMap {
 	}
 
 	// Emit the live pointer map data structures
-	ls := e.curfn.LSym
+	ls := curfn.LSym
 	fninfo := ls.Func()
 	fninfo.GCArgs, fninfo.GCLocals = lv.emit()
 

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

@@ -42,6 +42,12 @@ const maxOpenDefers = 8
 // ssaDumpInlined holds all inlined functions when ssaDump contains a function name.
 var ssaDumpInlined []*ir.Func
 
+func ssaDumpInline(fn *ir.Func) {
+	if ssaDump != "" && ssaDump == ir.FuncName(fn) {
+		ssaDumpInlined = append(ssaDumpInlined, fn)
+	}
+}
+
 func initssaconfig() {
 	types_ := ssa.NewTypes()
 
@@ -1135,7 +1141,7 @@ func (s *state) stmt(n ir.Node) {
 	// Expression statements
 	case ir.OCALLFUNC:
 		n := n.(*ir.CallExpr)
-		if isIntrinsicCall(n) {
+		if IsIntrinsicCall(n) {
 			s.intrinsicCall(n)
 			return
 		}
@@ -1204,7 +1210,7 @@ func (s *state) stmt(n ir.Node) {
 	case ir.OAS2FUNC:
 		// We come here only when it is an intrinsic call returning two values.
 		call := n.Rlist().First().(*ir.CallExpr)
-		if !isIntrinsicCall(call) {
+		if !IsIntrinsicCall(call) {
 			s.Fatalf("non-intrinsic AS2FUNC not expanded %v", call)
 		}
 		v := s.intrinsicCall(call)
@@ -2826,7 +2832,7 @@ func (s *state) expr(n ir.Node) *ssa.Value {
 
 	case ir.OCALLFUNC:
 		n := n.(*ir.CallExpr)
-		if isIntrinsicCall(n) {
+		if IsIntrinsicCall(n) {
 			return s.intrinsicCall(n)
 		}
 		fallthrough
@@ -6375,7 +6381,7 @@ func genssa(f *ssa.Func, pp *Progs) {
 
 	e := f.Frontend().(*ssafn)
 
-	s.livenessMap = liveness(e, f, pp)
+	s.livenessMap = liveness(e.curfn, f, e.stkptrsize, pp)
 	emitStackObjects(e, pp)
 
 	openDeferInfo := e.curfn.LSym.Func().OpenCodedDeferInfo

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

@@ -769,7 +769,7 @@ func walkexpr1(n ir.Node, init *ir.Nodes) ir.Node {
 		walkexprlistsafe(n.List().Slice(), init)
 		r = walkexpr(r, init)
 
-		if isIntrinsicCall(r.(*ir.CallExpr)) {
+		if IsIntrinsicCall(r.(*ir.CallExpr)) {
 			n.PtrRlist().Set1(r)
 			return n
 		}