diff --git a/src/cmd/compile/internal/gc/alg.go b/src/cmd/compile/internal/gc/alg.go
index e9b5afe838..6e85438610 100644
--- a/src/cmd/compile/internal/gc/alg.go
+++ b/src/cmd/compile/internal/gc/alg.go
@@ -316,11 +316,12 @@ func genhash(sym *Sym, t *Type) {
 	// for a struct containing a reflect.Value, which itself has
 	// an unexported field of type unsafe.Pointer.
 	old_safemode := safemode
+	safemode = false
 
-	safemode = 0
 	Disable_checknil++
 	funccompile(fn)
 	Disable_checknil--
+
 	safemode = old_safemode
 }
 
@@ -509,7 +510,7 @@ func geneq(sym *Sym, t *Type) {
 	// for a struct containing a reflect.Value, which itself has
 	// an unexported field of type unsafe.Pointer.
 	old_safemode := safemode
-	safemode = 0
+	safemode = false
 
 	// Disable checknils while compiling this code.
 	// We are comparing a struct or an array,
diff --git a/src/cmd/compile/internal/gc/bexport.go b/src/cmd/compile/internal/gc/bexport.go
index eef2e2200d..e5fa3c39a6 100644
--- a/src/cmd/compile/internal/gc/bexport.go
+++ b/src/cmd/compile/internal/gc/bexport.go
@@ -261,7 +261,7 @@ func export(out *bufio.Writer, trace bool) int {
 	}
 
 	// write compiler-specific flags
-	p.bool(safemode != 0)
+	p.bool(safemode)
 	if p.trace {
 		p.tracef("\n")
 	}
diff --git a/src/cmd/compile/internal/gc/closure.go b/src/cmd/compile/internal/gc/closure.go
index 80c8d309af..db4eb3f14d 100644
--- a/src/cmd/compile/internal/gc/closure.go
+++ b/src/cmd/compile/internal/gc/closure.go
@@ -419,7 +419,7 @@ func closuredebugruntimecheck(r *Node) {
 			Warnl(r.Lineno, "stack closure, captured vars = %v", r.Func.Cvars)
 		}
 	}
-	if compiling_runtime > 0 && r.Esc == EscHeap {
+	if compiling_runtime && r.Esc == EscHeap {
 		yyerrorl(r.Lineno, "heap-allocated closure, not allowed in runtime.")
 	}
 }
diff --git a/src/cmd/compile/internal/gc/dcl.go b/src/cmd/compile/internal/gc/dcl.go
index c652c65962..e1028f681c 100644
--- a/src/cmd/compile/internal/gc/dcl.go
+++ b/src/cmd/compile/internal/gc/dcl.go
@@ -1330,7 +1330,7 @@ func makefuncsym(s *Sym) {
 	if isblanksym(s) {
 		return
 	}
-	if compiling_runtime != 0 && s.Name == "getg" {
+	if compiling_runtime && s.Name == "getg" {
 		// runtime.getg() is not a real function and so does
 		// not get a funcsym.
 		return
@@ -1440,7 +1440,7 @@ func (c *nowritebarrierrecChecker) visitcall(n *Node) {
 	if fn == nil || fn.Op != ONAME || fn.Class != PFUNC || fn.Name.Defn == nil {
 		return
 	}
-	if (compiling_runtime != 0 || fn.Sym.Pkg == Runtimepkg) && fn.Sym.Name == "allocm" {
+	if (compiling_runtime || fn.Sym.Pkg == Runtimepkg) && fn.Sym.Name == "allocm" {
 		return
 	}
 	defn := fn.Name.Defn
diff --git a/src/cmd/compile/internal/gc/export.go b/src/cmd/compile/internal/gc/export.go
index ae36657a65..cfe192f3ba 100644
--- a/src/cmd/compile/internal/gc/export.go
+++ b/src/cmd/compile/internal/gc/export.go
@@ -15,8 +15,8 @@ import (
 )
 
 var (
-	newexport    int // if set, use new export format
-	Debug_export int // if set, print debugging information about export data
+	newexport    bool // if set, use new export format
+	Debug_export int  // if set, print debugging information about export data
 	exportsize   int
 )
 
@@ -377,7 +377,7 @@ func dumpexport() {
 	}
 
 	size := 0 // size of export section without enclosing markers
-	if forceNewExport || newexport != 0 {
+	if forceNewExport || newexport {
 		// binary export
 		// The linker also looks for the $$ marker - use char after $$ to distinguish format.
 		exportf("\n$$B\n") // indicate binary format
@@ -417,7 +417,7 @@ func dumpexport() {
 		exportf("\n$$\n") // indicate textual format
 		exportsize = 0
 		exportf("package %s", localpkg.Name)
-		if safemode != 0 {
+		if safemode {
 			exportf(" safe")
 		}
 		exportf("\n")
diff --git a/src/cmd/compile/internal/gc/gen.go b/src/cmd/compile/internal/gc/gen.go
index 7527452c93..cc624cce7a 100644
--- a/src/cmd/compile/internal/gc/gen.go
+++ b/src/cmd/compile/internal/gc/gen.go
@@ -246,7 +246,7 @@ func cgen_dcl(n *Node) {
 	if n.Class&PHEAP == 0 {
 		return
 	}
-	if compiling_runtime != 0 {
+	if compiling_runtime {
 		Yyerror("%v escapes to heap, not allowed in runtime.", n)
 	}
 	if prealloc[n] == nil {
diff --git a/src/cmd/compile/internal/gc/go.go b/src/cmd/compile/internal/gc/go.go
index 8411d2d0ac..af9aaf0dae 100644
--- a/src/cmd/compile/internal/gc/go.go
+++ b/src/cmd/compile/internal/gc/go.go
@@ -144,9 +144,9 @@ var nsyntaxerrors int
 
 var decldepth int32
 
-var safemode int
+var safemode bool
 
-var nolocalimports int
+var nolocalimports bool
 
 var Debug [256]int
 
@@ -261,21 +261,21 @@ var Funcdepth int32
 
 var typecheckok bool
 
-var compiling_runtime int
+var compiling_runtime bool
 
 var compiling_wrappers int
 
-var use_writebarrier int
+var use_writebarrier bool
 
-var pure_go int
+var pure_go bool
 
 var flag_installsuffix string
 
-var flag_race int
+var flag_race bool
 
-var flag_msan int
+var flag_msan bool
 
-var flag_largemodel int
+var flag_largemodel bool
 
 // Whether we are adding any sort of code instrumentation, such as
 // when the race detector is enabled.
@@ -285,7 +285,7 @@ var debuglive int
 
 var Ctxt *obj.Link
 
-var writearchive int
+var writearchive bool
 
 var bstdout *bufio.Writer
 
diff --git a/src/cmd/compile/internal/gc/inl.go b/src/cmd/compile/internal/gc/inl.go
index ea2394e7f9..f9e425618b 100644
--- a/src/cmd/compile/internal/gc/inl.go
+++ b/src/cmd/compile/internal/gc/inl.go
@@ -71,7 +71,7 @@ func typecheckinl(fn *Node) {
 	}
 
 	save_safemode := safemode
-	safemode = 0
+	safemode = false
 
 	savefn := Curfn
 	Curfn = fn
@@ -492,7 +492,7 @@ func mkinlcall(n *Node, fn *Node, isddd bool) *Node {
 	pkg := fnpkg(fn)
 
 	if pkg != localpkg && pkg != nil {
-		safemode = 0
+		safemode = false
 	}
 	n = mkinlcall1(n, fn, isddd)
 	safemode = save_safemode
diff --git a/src/cmd/compile/internal/gc/lex.go b/src/cmd/compile/internal/gc/lex.go
index 4b95bb7124..09fed98985 100644
--- a/src/cmd/compile/internal/gc/lex.go
+++ b/src/cmd/compile/internal/gc/lex.go
@@ -914,17 +914,17 @@ func (l *lexer) getlinepragma() rune {
 		case "go:noinline":
 			l.pragma |= Noinline
 		case "go:systemstack":
-			if compiling_runtime == 0 {
+			if !compiling_runtime {
 				Yyerror("//go:systemstack only allowed in runtime")
 			}
 			l.pragma |= Systemstack
 		case "go:nowritebarrier":
-			if compiling_runtime == 0 {
+			if !compiling_runtime {
 				Yyerror("//go:nowritebarrier only allowed in runtime")
 			}
 			l.pragma |= Nowritebarrier
 		case "go:nowritebarrierrec":
-			if compiling_runtime == 0 {
+			if !compiling_runtime {
 				Yyerror("//go:nowritebarrierrec only allowed in runtime")
 			}
 			l.pragma |= Nowritebarrierrec | Nowritebarrier // implies Nowritebarrier
diff --git a/src/cmd/compile/internal/gc/main.go b/src/cmd/compile/internal/gc/main.go
index 45a510d577..f41097b83b 100644
--- a/src/cmd/compile/internal/gc/main.go
+++ b/src/cmd/compile/internal/gc/main.go
@@ -142,15 +142,14 @@ func Main() {
 
 	Nacl = goos == "nacl"
 	if Nacl {
-		flag_largemodel = 1
+		flag_largemodel = true
 	}
 
-	outfile = ""
-	obj.Flagcount("+", "compiling runtime", &compiling_runtime)
+	flag.BoolVar(&compiling_runtime, "+", false, "compiling runtime")
 	obj.Flagcount("%", "debug non-static initializers", &Debug['%'])
 	obj.Flagcount("A", "for bootstrapping, allow 'any' type", &Debug['A'])
 	obj.Flagcount("B", "disable bounds checking", &Debug['B'])
-	obj.Flagstr("D", "set relative `path` for local imports", &localimport)
+	flag.StringVar(&localimport, "D", "", "set relative `path` for local imports")
 	obj.Flagcount("E", "debug symbol export", &Debug['E'])
 	obj.Flagfn1("I", "add `directory` to import search path", addidir)
 	obj.Flagcount("K", "debug missing line numbers", &Debug['K'])
@@ -162,57 +161,59 @@ func Main() {
 	obj.Flagcount("S", "print assembly listing", &Debug['S'])
 	obj.Flagfn0("V", "print compiler version", doversion)
 	obj.Flagcount("W", "debug parse tree after type checking", &Debug['W'])
-	obj.Flagstr("asmhdr", "write assembly header to `file`", &asmhdr)
-	obj.Flagstr("buildid", "record `id` as the build id in the export metadata", &buildid)
-	obj.Flagcount("complete", "compiling complete package (no C or assembly)", &pure_go)
-	obj.Flagstr("d", "print debug information about items in `list`", &debugstr)
+	flag.StringVar(&asmhdr, "asmhdr", "", "write assembly header to `file`")
+	flag.StringVar(&buildid, "buildid", "", "record `id` as the build id in the export metadata")
+	flag.BoolVar(&pure_go, "complete", false, "compiling complete package (no C or assembly)")
+	flag.StringVar(&debugstr, "d", "", "print debug information about items in `list`")
 	obj.Flagcount("e", "no limit on number of errors reported", &Debug['e'])
 	obj.Flagcount("f", "debug stack frames", &Debug['f'])
 	obj.Flagcount("g", "debug code generation", &Debug['g'])
 	obj.Flagcount("h", "halt on error", &Debug['h'])
 	obj.Flagcount("i", "debug line number stack", &Debug['i'])
 	obj.Flagfn1("importmap", "add `definition` of the form source=actual to import map", addImportMap)
-	obj.Flagstr("installsuffix", "set pkg directory `suffix`", &flag_installsuffix)
+	flag.StringVar(&flag_installsuffix, "installsuffix", "", "set pkg directory `suffix`")
 	obj.Flagcount("j", "debug runtime-initialized variables", &Debug['j'])
 	obj.Flagcount("l", "disable inlining", &Debug['l'])
 	obj.Flagcount("live", "debug liveness analysis", &debuglive)
 	obj.Flagcount("m", "print optimization decisions", &Debug['m'])
-	obj.Flagcount("msan", "build code compatible with C/C++ memory sanitizer", &flag_msan)
-	obj.Flagcount("newexport", "use new export format", &newexport) // TODO(gri) remove eventually (issue 13241)
-	obj.Flagcount("nolocalimports", "reject local (relative) imports", &nolocalimports)
-	obj.Flagstr("o", "write output to `file`", &outfile)
-	obj.Flagstr("p", "set expected package import `path`", &myimportpath)
-	obj.Flagcount("pack", "write package file instead of object file", &writearchive)
+	flag.BoolVar(&flag_msan, "msan", false, "build code compatible with C/C++ memory sanitizer")
+	flag.BoolVar(&newexport, "newexport", false, "use new export format") // TODO(gri) remove eventually (issue 13241)
+	flag.BoolVar(&nolocalimports, "nolocalimports", false, "reject local (relative) imports")
+	flag.StringVar(&outfile, "o", "", "write output to `file`")
+	flag.StringVar(&myimportpath, "p", "", "set expected package import `path`")
+	flag.BoolVar(&writearchive, "pack", false, "write package file instead of object file")
 	obj.Flagcount("r", "debug generated wrappers", &Debug['r'])
-	obj.Flagcount("race", "enable race detector", &flag_race)
+	flag.BoolVar(&flag_race, "race", false, "enable race detector")
 	obj.Flagcount("s", "warn about composite literals that can be simplified", &Debug['s'])
-	obj.Flagstr("trimpath", "remove `prefix` from recorded source file paths", &Ctxt.LineHist.TrimPathPrefix)
-	obj.Flagcount("u", "reject unsafe code", &safemode)
+	flag.StringVar(&Ctxt.LineHist.TrimPathPrefix, "trimpath", "", "remove `prefix` from recorded source file paths")
+	flag.BoolVar(&safemode, "u", false, "reject unsafe code")
 	obj.Flagcount("v", "increase debug verbosity", &Debug['v'])
 	obj.Flagcount("w", "debug type checking", &Debug['w'])
-	use_writebarrier = 1
-	obj.Flagcount("wb", "enable write barrier", &use_writebarrier)
+	flag.BoolVar(&use_writebarrier, "wb", true, "enable write barrier")
 	obj.Flagcount("x", "debug lexer", &Debug['x'])
 	obj.Flagcount("y", "debug declarations in canned imports (with -d)", &Debug['y'])
-	var flag_shared int
+	var flag_shared bool
 	var flag_dynlink bool
 	if supportsDynlink(Thearch.LinkArch.Arch) {
-		obj.Flagcount("shared", "generate code that can be linked into a shared library", &flag_shared)
+		flag.BoolVar(&flag_shared, "shared", false, "generate code that can be linked into a shared library")
 		flag.BoolVar(&flag_dynlink, "dynlink", false, "support references to Go symbols defined in other shared libraries")
 	}
 	if Thearch.LinkArch.Family == sys.AMD64 {
-		obj.Flagcount("largemodel", "generate code that assumes a large memory model", &flag_largemodel)
+		flag.BoolVar(&flag_largemodel, "largemodel", false, "generate code that assumes a large memory model")
 	}
-	obj.Flagstr("cpuprofile", "write cpu profile to `file`", &cpuprofile)
-	obj.Flagstr("memprofile", "write memory profile to `file`", &memprofile)
-	obj.Flagint64("memprofilerate", "set runtime.MemProfileRate to `rate`", &memprofilerate)
+	flag.StringVar(&cpuprofile, "cpuprofile", "", "write cpu profile to `file`")
+	flag.StringVar(&memprofile, "memprofile", "", "write memory profile to `file`")
+	flag.Int64Var(&memprofilerate, "memprofilerate", 0, "set runtime.MemProfileRate to `rate`")
 	flag.BoolVar(&ssaEnabled, "ssa", true, "use SSA backend to generate code")
 	obj.Flagparse(usage)
 
 	if flag_dynlink {
-		flag_shared = 1
+		flag_shared = true
+	}
+	if flag_shared {
+		// TODO(mdempsky): Change Flag_shared to bool.
+		Ctxt.Flag_shared = 1
 	}
-	Ctxt.Flag_shared = int32(flag_shared)
 	Ctxt.Flag_dynlink = flag_dynlink
 	Ctxt.Flag_optimize = Debug['N'] == 0
 
@@ -225,17 +226,17 @@ func Main() {
 
 	startProfile()
 
-	if flag_race != 0 {
+	if flag_race {
 		racepkg = mkpkg("runtime/race")
 		racepkg.Name = "race"
 	}
-	if flag_msan != 0 {
+	if flag_msan {
 		msanpkg = mkpkg("runtime/msan")
 		msanpkg.Name = "msan"
 	}
-	if flag_race != 0 && flag_msan != 0 {
+	if flag_race && flag_msan {
 		log.Fatal("cannot use both -race and -msan")
-	} else if flag_race != 0 || flag_msan != 0 {
+	} else if flag_race || flag_msan {
 		instrumenting = true
 	}
 
@@ -471,7 +472,7 @@ func Main() {
 		fninit(xtop)
 	}
 
-	if compiling_runtime != 0 {
+	if compiling_runtime {
 		checknowritebarrierrec()
 	}
 
@@ -569,7 +570,7 @@ func islocalname(name string) bool {
 
 func findpkg(name string) (file string, ok bool) {
 	if islocalname(name) {
-		if safemode != 0 || nolocalimports != 0 {
+		if safemode || nolocalimports {
 			return "", false
 		}
 
@@ -612,10 +613,10 @@ func findpkg(name string) (file string, ok bool) {
 		if flag_installsuffix != "" {
 			suffixsep = "_"
 			suffix = flag_installsuffix
-		} else if flag_race != 0 {
+		} else if flag_race {
 			suffixsep = "_"
 			suffix = "race"
-		} else if flag_msan != 0 {
+		} else if flag_msan {
 			suffixsep = "_"
 			suffix = "msan"
 		}
@@ -694,7 +695,7 @@ func importfile(f *Val, indent []byte) {
 	}
 
 	if path_ == "unsafe" {
-		if safemode != 0 {
+		if safemode {
 			Yyerror("cannot import package unsafe")
 			errorexit()
 		}
@@ -818,7 +819,7 @@ func importfile(f *Val, indent []byte) {
 		errorexit()
 	}
 
-	if safemode != 0 && !importpkg.Safe {
+	if safemode && !importpkg.Safe {
 		Yyerror("cannot import unsafe package %q", importpkg.Path)
 	}
 }
@@ -896,7 +897,7 @@ func mkpackage(pkgname string) {
 			p = p[:i]
 		}
 		suffix := ".o"
-		if writearchive > 0 {
+		if writearchive {
 			suffix = ".a"
 		}
 		outfile = p + suffix
diff --git a/src/cmd/compile/internal/gc/obj.go b/src/cmd/compile/internal/gc/obj.go
index eed0ed6e24..59ce0547c8 100644
--- a/src/cmd/compile/internal/gc/obj.go
+++ b/src/cmd/compile/internal/gc/obj.go
@@ -33,7 +33,7 @@ func dumpobj() {
 
 	startobj := int64(0)
 	var arhdr [ArhdrSize]byte
-	if writearchive != 0 {
+	if writearchive {
 		bout.WriteString("!<arch>\n")
 		arhdr = [ArhdrSize]byte{}
 		bout.Write(arhdr[:])
@@ -43,7 +43,7 @@ func dumpobj() {
 	fmt.Fprintf(bout, "go object %s %s %s %s\n", obj.Getgoos(), obj.Getgoarch(), obj.Getgoversion(), obj.Expstring())
 	dumpexport()
 
-	if writearchive != 0 {
+	if writearchive {
 		bout.Flush()
 		size := bout.Offset() - startobj
 		if size&1 != 0 {
@@ -62,7 +62,7 @@ func dumpobj() {
 	}
 
 	if pragcgobuf != "" {
-		if writearchive != 0 {
+		if writearchive {
 			// write empty export section; must be before cgo section
 			fmt.Fprintf(bout, "\n$$\n\n$$\n\n")
 		}
@@ -90,7 +90,7 @@ func dumpobj() {
 	dumpdata()
 	obj.Writeobjdirect(Ctxt, bout)
 
-	if writearchive != 0 {
+	if writearchive {
 		bout.Flush()
 		size := bout.Offset() - startobj
 		if size&1 != 0 {
diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go
index baa960bf75..7b9b91e7b0 100644
--- a/src/cmd/compile/internal/gc/pgen.go
+++ b/src/cmd/compile/internal/gc/pgen.go
@@ -364,7 +364,7 @@ func compile(fn *Node) {
 	dowidth(Curfn.Type)
 
 	if len(fn.Nbody.Slice()) == 0 {
-		if pure_go != 0 || strings.HasPrefix(fn.Func.Nname.Sym.Name, "init.") {
+		if pure_go || strings.HasPrefix(fn.Func.Nname.Sym.Name, "init.") {
 			Yyerror("missing function body for %q", fn.Func.Nname.Sym.Name)
 			return
 		}
diff --git a/src/cmd/compile/internal/gc/racewalk.go b/src/cmd/compile/internal/gc/racewalk.go
index f6e65146d6..a8a5e92485 100644
--- a/src/cmd/compile/internal/gc/racewalk.go
+++ b/src/cmd/compile/internal/gc/racewalk.go
@@ -54,14 +54,14 @@ func instrument(fn *Node) {
 		return
 	}
 
-	if flag_race == 0 || !ispkgin(norace_inst_pkgs) {
+	if !flag_race || !ispkgin(norace_inst_pkgs) {
 		instrumentlist(fn.Nbody, nil)
 
 		// nothing interesting for race detector in fn->enter
 		instrumentlist(fn.Func.Exit, nil)
 	}
 
-	if flag_race != 0 {
+	if flag_race {
 		// nodpc is the PC of the caller as extracted by
 		// getcallerpc. We use -widthptr(FP) for x86.
 		// BUG: this will not work on arm.
@@ -503,7 +503,7 @@ func callinstr(np **Node, init *Nodes, wr int, skip int) bool {
 		n = treecopy(n, 0)
 		makeaddable(n)
 		var f *Node
-		if flag_msan != 0 {
+		if flag_msan {
 			name := "msanread"
 			if wr != 0 {
 				name = "msanwrite"
@@ -515,7 +515,7 @@ func callinstr(np **Node, init *Nodes, wr int, skip int) bool {
 				Fatalf("instrument: %v badwidth", t)
 			}
 			f = mkcall(name, nil, init, uintptraddr(n), Nodintconst(w))
-		} else if flag_race != 0 && (t.IsStruct() || t.IsArray()) {
+		} else if flag_race && (t.IsStruct() || t.IsArray()) {
 			name := "racereadrange"
 			if wr != 0 {
 				name = "racewriterange"
@@ -527,7 +527,7 @@ func callinstr(np **Node, init *Nodes, wr int, skip int) bool {
 				Fatalf("instrument: %v badwidth", t)
 			}
 			f = mkcall(name, nil, init, uintptraddr(n), Nodintconst(w))
-		} else if flag_race != 0 {
+		} else if flag_race {
 			name := "raceread"
 			if wr != 0 {
 				name = "racewrite"
diff --git a/src/cmd/compile/internal/gc/reflect.go b/src/cmd/compile/internal/gc/reflect.go
index 70a75f9324..df68f46d4c 100644
--- a/src/cmd/compile/internal/gc/reflect.go
+++ b/src/cmd/compile/internal/gc/reflect.go
@@ -1424,10 +1424,10 @@ func dumptypestructs() {
 		// add paths for runtime and main, which 6l imports implicitly.
 		dimportpath(Runtimepkg)
 
-		if flag_race != 0 {
+		if flag_race {
 			dimportpath(racepkg)
 		}
-		if flag_msan != 0 {
+		if flag_msan {
 			dimportpath(msanpkg)
 		}
 		dimportpath(mkpkg("main"))
diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index fdd14953e6..4a93dc1087 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -554,7 +554,7 @@ func (s *state) stmt(n *Node) {
 	case OCALLFUNC, OCALLMETH, OCALLINTER:
 		s.call(n, callNormal)
 		if n.Op == OCALLFUNC && n.Left.Op == ONAME && n.Left.Class == PFUNC &&
-			(compiling_runtime != 0 && n.Left.Sym.Name == "throw" ||
+			(compiling_runtime && n.Left.Sym.Name == "throw" ||
 				n.Left.Sym.Pkg == Runtimepkg && (n.Left.Sym.Name == "gopanic" || n.Left.Sym.Name == "selectgo" || n.Left.Sym.Name == "block")) {
 			m := s.mem()
 			b := s.endBlock()
@@ -579,7 +579,7 @@ func (s *state) stmt(n *Node) {
 		if n.Left.Class&PHEAP == 0 {
 			return
 		}
-		if compiling_runtime != 0 {
+		if compiling_runtime {
 			Fatalf("%v escapes to heap, not allowed in runtime.", n)
 		}
 
diff --git a/src/cmd/compile/internal/gc/subr.go b/src/cmd/compile/internal/gc/subr.go
index 776eb9c64e..f6af11adba 100644
--- a/src/cmd/compile/internal/gc/subr.go
+++ b/src/cmd/compile/internal/gc/subr.go
@@ -750,7 +750,7 @@ func assignop(src *Type, dst *Type, why *string) Op {
 
 	// TODO(rsc,lvd): This behaves poorly in the presence of inlining.
 	// https://golang.org/issue/2795
-	if safemode != 0 && importpkg == nil && src != nil && src.Etype == TUNSAFEPTR {
+	if safemode && importpkg == nil && src != nil && src.Etype == TUNSAFEPTR {
 		Yyerror("cannot use unsafe.Pointer")
 		errorexit()
 	}
diff --git a/src/cmd/compile/internal/gc/typecheck.go b/src/cmd/compile/internal/gc/typecheck.go
index 7089d7de72..6067677738 100644
--- a/src/cmd/compile/internal/gc/typecheck.go
+++ b/src/cmd/compile/internal/gc/typecheck.go
@@ -1354,7 +1354,7 @@ OpSwitch:
 		if t.Results().NumFields() == 1 {
 			n.Type = l.Type.Results().Field(0).Type
 
-			if n.Op == OCALLFUNC && n.Left.Op == ONAME && (compiling_runtime != 0 || n.Left.Sym.Pkg == Runtimepkg) && n.Left.Sym.Name == "getg" {
+			if n.Op == OCALLFUNC && n.Left.Op == ONAME && (compiling_runtime || n.Left.Sym.Pkg == Runtimepkg) && n.Left.Sym.Name == "getg" {
 				// Emit code for runtime.getg() directly instead of calling function.
 				// Most such rewrites (for example the similar one for math.Sqrt) should be done in walk,
 				// so that the ordering pass can make sure to preserve the semantics of the original code
@@ -2176,7 +2176,7 @@ OpSwitch:
 		}
 	}
 
-	if safemode != 0 && incannedimport == 0 && importpkg == nil && compiling_wrappers == 0 && t != nil && t.Etype == TUNSAFEPTR {
+	if safemode && incannedimport == 0 && importpkg == nil && compiling_wrappers == 0 && t != nil && t.Etype == TUNSAFEPTR {
 		Yyerror("cannot use unsafe.Pointer")
 	}
 
diff --git a/src/cmd/compile/internal/gc/unsafe.go b/src/cmd/compile/internal/gc/unsafe.go
index 338f3c0eae..e1d3b40098 100644
--- a/src/cmd/compile/internal/gc/unsafe.go
+++ b/src/cmd/compile/internal/gc/unsafe.go
@@ -9,7 +9,7 @@ func unsafenmagic(nn *Node) *Node {
 	fn := nn.Left
 	args := nn.List
 
-	if safemode != 0 || fn == nil || fn.Op != ONAME {
+	if safemode || fn == nil || fn.Op != ONAME {
 		return nil
 	}
 	s := fn.Sym
diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index 3e5f5161db..78bad8d348 100644
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -594,8 +594,7 @@ opswitch:
 		// for a struct containing a reflect.Value, which itself has
 		// an unexported field of type unsafe.Pointer.
 		old_safemode := safemode
-
-		safemode = 0
+		safemode = false
 		n = walkcompare(n, init)
 		safemode = old_safemode
 
@@ -1938,7 +1937,7 @@ func walkprint(nn *Node, init *Nodes) *Node {
 			on = substArgTypes(on, n.Type) // any-1
 		} else if Isint[et] {
 			if et == TUINT64 {
-				if (t.Sym.Pkg == Runtimepkg || compiling_runtime != 0) && t.Sym.Name == "hex" {
+				if (t.Sym.Pkg == Runtimepkg || compiling_runtime) && t.Sym.Name == "hex" {
 					on = syslook("printhex")
 				} else {
 					on = syslook("printuint")
@@ -2041,7 +2040,7 @@ func isglobal(n *Node) bool {
 
 // Do we need a write barrier for the assignment l = r?
 func needwritebarrier(l *Node, r *Node) bool {
-	if use_writebarrier == 0 {
+	if !use_writebarrier {
 		return false
 	}
 
@@ -2550,7 +2549,7 @@ func paramstoheap(params *Type, out bool) []*Node {
 		}
 
 		// generate allocation & copying code
-		if compiling_runtime != 0 {
+		if compiling_runtime {
 			Yyerror("%v escapes to heap, not allowed in runtime.", v)
 		}
 		if prealloc[v] == nil {