cmd/compile: mark generated eq/hash functions as //go:noinline

Instead of having the inliner specially recognize that eq/hash
functions can't be inlined, change the geneq and genhash to mark them
as //go:noinline.

This is a prereq for a subsequent CL that will move more logic for
handling rtypes from package types to package reflectdata.

Change-Id: I091a9ededcc083fe8305cf5443a9af7d3a9053b6
Reviewed-on: https://go-review.googlesource.com/c/go/+/518955
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>

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

@@ -438,13 +438,6 @@ func InlineImpossible(fn *ir.Func) string {
 		return reason
 	}
 
-	// If fn is synthetic hash or eq function, cannot inline it.
-	// The function is not generated in Unified IR frontend at this moment.
-	if ir.IsEqOrHashFunc(fn) {
-		reason = "type eq/hash function"
-		return reason
-	}
-
 	return ""
 }
 

src/cmd/compile/internal/ir/func.go

@@ -301,14 +301,6 @@ func LinkFuncName(f *Func) string {
 	return objabi.PathToPrefix(pkg.Path) + "." + s.Name
 }
 
-// IsEqOrHashFunc reports whether f is type eq/hash function.
-func IsEqOrHashFunc(f *Func) bool {
-	if f == nil || f.Nname == nil {
-		return false
-	}
-	return types.IsTypePkg(f.Sym().Pkg)
-}
-
 var CurFunc *Func
 
 // WithFunc invokes do with CurFunc and base.Pos set to curfn and

src/cmd/compile/internal/reflectdata/alg.go

@@ -152,6 +152,8 @@ func hashFunc(t *types.Type) *ir.Func {
 
 	fn := typecheck.DeclFunc(sym, nil, args, results)
 	sym.Def = fn.Nname
+	fn.Pragma |= ir.Noinline // TODO(mdempsky): We need to emit this during the unified frontend instead, to allow inlining.
+
 	np := ir.AsNode(fn.Type().Params().Field(0).Nname)
 	nh := ir.AsNode(fn.Type().Params().Field(1).Nname)
 
@@ -375,6 +377,8 @@ func eqFunc(t *types.Type) *ir.Func {
 		[]*ir.Field{ir.NewField(base.Pos, typecheck.Lookup("r"), types.Types[types.TBOOL])},
 	)
 	sym.Def = fn.Nname
+	fn.Pragma |= ir.Noinline // TODO(mdempsky): We need to emit this during the unified frontend instead, to allow inlining.
+
 	np := ir.AsNode(fn.Type().Params().Field(0).Nname)
 	nq := ir.AsNode(fn.Type().Params().Field(1).Nname)
 	nr := ir.AsNode(fn.Type().Results().Field(0).Nname)

src/cmd/compile/internal/types/type.go

@@ -1858,11 +1858,6 @@ func IsReflectPkg(p *Pkg) bool {
 	return p.Path == "reflect"
 }
 
-// IsTypePkg reports whether p is pesudo package type.
-func IsTypePkg(p *Pkg) bool {
-	return p == typepkg
-}
-
 // IsNoInstrumentPkg reports whether p is a package that
 // should not be instrumented.
 func IsNoInstrumentPkg(p *Pkg) bool {