cmd/compile: tweaks to unindent some code

Prioritized the chunks of code with 8 or more levels of indentation.
Basically early breaks/returns and joining nested ifs.

Change-Id: I6817df1303226acf2eb904a29f2db720e4f7427a
Reviewed-on: https://go-review.googlesource.com/55630
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

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

@@ -463,9 +463,8 @@ func walkclosure(func_ *Node, init *Nodes) *Node {
 			Warnl(func_.Pos, "closure converted to global")
 		}
 		return func_.Func.Closure.Func.Nname
-	} else {
-		closuredebugruntimecheck(func_)
 	}
+	closuredebugruntimecheck(func_)
 
 	// Create closure in the form of a composite literal.
 	// supposing the closure captures an int i and a string s

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

@@ -1554,7 +1554,10 @@ func (e *EscState) esccall(call *Node, parent *Node) {
 					call.Right = arg
 				}
 				e.escassignWhyWhere(n, arg, "arg to recursive call", call) // TODO this message needs help.
-				if arg != args[0] {
+				if arg == args[0] {
+					args = args[1:]
+					continue
+				}
 				// "..." arguments are untracked
 				for _, a := range args {
 					if Debug['m'] > 3 {
@@ -1565,9 +1568,6 @@ func (e *EscState) esccall(call *Node, parent *Node) {
 				// No more PPARAM processing, but keep
 				// going for PPARAMOUT.
 				args = nil
-					continue
-				}
-				args = args[1:]
 
 			case PPARAMOUT:
 				cE.Retval.Append(n)

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

@@ -233,7 +233,9 @@ func (s *phiState) insertVarPhis(n int, var_ *Node, defs []*ssa.Block, typ *type
 					// a D-edge, or an edge whose target is in currentRoot's subtree.
 					continue
 				}
-				if !hasPhi.contains(c.ID) {
+				if hasPhi.contains(c.ID) {
+					continue
+				}
 				// Add a phi to block c for variable n.
 				hasPhi.add(c.ID)
 				v := c.NewValue0I(currentRoot.Pos, ssa.OpPhi, typ, int64(n)) // TODO: line number right?
@@ -252,7 +254,6 @@ func (s *phiState) insertVarPhis(n int, var_ *Node, defs []*ssa.Block, typ *type
 					hasDef.add(c.ID)
 				}
 			}
-			}
 
 			// Visit children if they have not been visited yet.
 			for c := s.tree[b.ID].firstChild; c != nil; c = s.tree[c.ID].sibling {

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

@@ -497,14 +497,12 @@ func dgopkgpathOff(s *obj.LSym, ot int, pkg *types.Pkg) int {
 func isExportedField(ft *types.Field) (bool, *types.Pkg) {
 	if ft.Sym != nil && ft.Embedded == 0 {
 		return exportname(ft.Sym.Name), ft.Sym.Pkg
-	} else {
+	}
 	if ft.Type.Sym != nil &&
 		(ft.Type.Sym.Pkg == builtinpkg || !exportname(ft.Type.Sym.Name)) {
 		return false, ft.Type.Sym.Pkg
-		} else {
-			return true, nil
-		}
 	}
+	return true, nil
 }
 
 // dnameField dumps a reflect.name for a struct field.

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

@@ -480,9 +480,8 @@ func staticassign(l *Node, r *Node, out *[]*Node) bool {
 			n := *l
 			gdata(&n, r.Func.Closure.Func.Nname, Widthptr)
 			return true
-		} else {
-			closuredebugruntimecheck(r)
 		}
+		closuredebugruntimecheck(r)
 
 	case OCONVIFACE:
 		// This logic is mirrored in isStaticCompositeLiteral.

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

@@ -661,24 +661,26 @@ func (s *state) stmt(n *Node) {
 				}
 				rhs = nil
 			case OAPPEND:
-				// If we're writing the result of an append back to the same slice,
-				// handle it specially to avoid write barriers on the fast (non-growth) path.
+				// Check whether we're writing the result of an append back to the same slice.
+				// If so, we handle it specially to avoid write barriers on the fast
+				// (non-growth) path.
+				if !samesafeexpr(n.Left, rhs.List.First()) {
+					break
+				}
 				// If the slice can be SSA'd, it'll be on the stack,
 				// so there will be no write barriers,
 				// so there's no need to attempt to prevent them.
-				if samesafeexpr(n.Left, rhs.List.First()) {
-					if !s.canSSA(n.Left) {
-						if Debug_append > 0 {
-							Warnl(n.Pos, "append: len-only update")
-						}
-						s.append(rhs, true)
-						return
-					} else {
+				if s.canSSA(n.Left) {
 					if Debug_append > 0 { // replicating old diagnostic message
 						Warnl(n.Pos, "append: len-only update (in local slice)")
 					}
+					break
 				}
+				if Debug_append > 0 {
+					Warnl(n.Pos, "append: len-only update")
 				}
+				s.append(rhs, true)
+				return
 			}
 		}
 

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

@@ -2636,8 +2636,7 @@ func typecheckaste(op Op, call *Node, isddd bool, tstruct *types.Type, nl Nodes,
 	n = nil
 	if nl.Len() == 1 {
 		n = nl.First()
-		if n.Type != nil {
-			if n.Type.IsFuncArgStruct() {
+		if n.Type != nil && n.Type.IsFuncArgStruct() {
 			if !hasddd(tstruct) {
 				n1 := tstruct.NumFields()
 				n2 := n.Type.NumFields()
@@ -2685,7 +2684,6 @@ func typecheckaste(op Op, call *Node, isddd bool, tstruct *types.Type, nl Nodes,
 			goto out
 		}
 	}
-	}
 
 	n1 = tstruct.NumFields()
 	n2 = nl.Len()