[dev.regabi] cmd/compile: flatten dependency graph [generated]

This CL shuffles a couple functions around to help flatten the package
dependency graph somewhat:

1. ssa.LosesStmtMark is only ever used in associated with an
objw.Prog, so we might as well move it to that package. This removes a
dependency from objw (a relatively low-level utility package that
wraps cmd/internal/obj) on ssa (a large and relatively high-level
package).

2. Moves liveness.SetTypeBits into a new package typebits. A
single-function package is a bit on the silly side, but reflectdata
shouldn't need to depend on liveness (nor vice versa).

[git-generate]
cd src/cmd/compile/internal/ssa
rf '
	mv LosesStmtMark prog.go
	mv prog.go cmd/compile/internal/objw
'

cd ../liveness
rf '
	mv SetTypeBits Set
	mv Set typebits.go
	rm typebits.go:/Copyright/+4,/^package/-0
	mv typebits.go cmd/compile/internal/typebits
'

Change-Id: Ic9a983f0ad6c0cf1a537f99889699a8444699e6e
Reviewed-on: https://go-review.googlesource.com/c/go/+/280447
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/src/cmd/compile/internal/objw/prog.go b/src/cmd/compile/internal/objw/prog.go
index 54028e47fd..8d24f94aa5 100644
--- a/src/cmd/compile/internal/objw/prog.go
+++ b/src/cmd/compile/internal/objw/prog.go
@@ -33,7 +33,6 @@ package objw
 import (
 	"cmd/compile/internal/base"
 	"cmd/compile/internal/ir"
-	"cmd/compile/internal/ssa"
 	"cmd/internal/obj"
 	"cmd/internal/objabi"
 	"cmd/internal/src"
@@ -173,7 +172,7 @@ func (pp *Progs) Prog(as obj.As) *obj.Prog {
 	p.Pos = pp.Pos
 	if pp.Pos.IsStmt() == src.PosIsStmt {
 		// Clear IsStmt for later Progs at this pos provided that as can be marked as a stmt
-		if ssa.LosesStmtMark(as) {
+		if LosesStmtMark(as) {
 			return p
 		}
 		pp.Pos = pp.Pos.WithNotStmt()
@@ -216,3 +215,12 @@ func (pp *Progs) SetText(fn *ir.Func) {
 	ptxt.From.Name = obj.NAME_EXTERN
 	ptxt.From.Sym = fn.LSym
 }
+
+// LosesStmtMark reports whether a prog with op as loses its statement mark on the way to DWARF.
+// The attributes from some opcodes are lost in translation.
+// TODO: this is an artifact of how funcpctab combines information for instructions at a single PC.
+// Should try to fix it there.
+func LosesStmtMark(as obj.As) bool {
+	// is_stmt does not work for these; it DOES for ANOP even though that generates no code.
+	return as == obj.APCDATA || as == obj.AFUNCDATA
+}