cmd/internal/obj: unify Setuintxx and WriteInt

They do basically the same work.

Setuintxx was only used in a single place,
so eliminate it in favor of WriteInt.

duintxxLSym's alignment rounding was not used in practice;
change it into alignment assertion.

Passes toolstash-check. No compiler performance changes.

Change-Id: I0f7410cf2ccffbdc02ad796eaf973ee6a83074f8
Reviewed-on: https://go-review.googlesource.com/40863
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -252,12 +252,15 @@ func duintxx(s *types.Sym, off int, v uint64, wid int) int {
 }
 
 func duintxxLSym(s *obj.LSym, off int, v uint64, wid int) int {
-	// Update symbol data directly instead of generating a
-	// DATA instruction that liblink will have to interpret later.
-	// This reduces compilation time and memory usage.
-	off = int(Rnd(int64(off), int64(wid)))
-
-	return int(obj.Setuintxx(Ctxt, s, int64(off), v, int64(wid)))
+	if s.Type == 0 {
+		// TODO(josharian): Do this in obj.prepwrite instead.
+		s.Type = obj.SDATA
+	}
+	if off&(wid-1) != 0 {
+		Fatalf("duintxxLSym: misaligned: v=%d wid=%d off=%d", v, wid, off)
+	}
+	s.WriteInt(Ctxt, int64(off), wid, int64(v))
+	return off + wid
 }
 
 func duint8(s *types.Sym, off int, v uint8) int {

src/cmd/internal/obj/data.go

@@ -181,26 +181,3 @@ func Addrel(s *LSym) *Reloc {
 	s.R = append(s.R, Reloc{})
 	return &s.R[len(s.R)-1]
 }
-
-func Setuintxx(ctxt *Link, s *LSym, off int64, v uint64, wid int64) int64 {
-	if s.Type == 0 {
-		s.Type = SDATA
-	}
-	if s.Size < off+wid {
-		s.Size = off + wid
-		s.Grow(s.Size)
-	}
-
-	switch wid {
-	case 1:
-		s.P[off] = uint8(v)
-	case 2:
-		ctxt.Arch.ByteOrder.PutUint16(s.P[off:], uint16(v))
-	case 4:
-		ctxt.Arch.ByteOrder.PutUint32(s.P[off:], uint32(v))
-	case 8:
-		ctxt.Arch.ByteOrder.PutUint64(s.P[off:], v)
-	}
-
-	return off + wid
-}