cmd/compile: remove a few unused bits of code

Just the low-hanging fruit; code that was either never used, or its last
use was removed a while ago.

Change-Id: Ic7f90aeee3e6daf7edc16cde3c0a767d67e617ee
Reviewed-on: https://go-review.googlesource.com/c/go/+/192618
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

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

@@ -102,9 +102,3 @@ func fninit(n []*Node) {
 	// It's not quite read only, the state field must be modifiable.
 	ggloblsym(lsym, int32(ot), obj.NOPTR)
 }
-
-func (n *Node) checkInitFuncSignature() {
-	if n.Type.NumRecvs()+n.Type.NumParams()+n.Type.NumResults() > 0 {
-		Fatalf("init function cannot have receiver, params, or results: %v (%v)", n, n.Type)
-	}
-}

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

@@ -11,8 +11,6 @@ import "cmd/compile/internal/types"
 // builtinpkg is a fake package that declares the universe block.
 var builtinpkg *types.Pkg
 
-var itable *types.Type // distinguished *byte
-
 var basicTypes = [...]struct {
 	name  string
 	etype types.EType
@@ -361,8 +359,6 @@ func typeinit() {
 
 	dowidth(types.Types[TSTRING])
 	dowidth(types.Idealstring)
-
-	itable = types.NewPtr(types.Types[TUINT8])
 }
 
 func makeErrorInterface() *types.Type {

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

@@ -6,21 +6,6 @@ package ssa
 
 import "testing"
 
-type lca interface {
-	find(a, b *Block) *Block
-}
-
-func lcaEqual(f *Func, lca1, lca2 lca) bool {
-	for _, b := range f.Blocks {
-		for _, c := range f.Blocks {
-			if lca1.find(b, c) != lca2.find(b, c) {
-				return false
-			}
-		}
-	}
-	return true
-}
-
 func testLCAgen(t *testing.T, bg blockGen, size int) {
 	c := testConfig(t)
 	fun := c.Fun("entry", bg(size)...)

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

@@ -474,11 +474,6 @@ func NeedsFixUp(v *Value) bool {
 	return v.AuxInt == 0
 }
 
-// i2f is used in rules for converting from an AuxInt to a float.
-func i2f(i int64) float64 {
-	return math.Float64frombits(uint64(i))
-}
-
 // auxFrom64F encodes a float64 value so it can be stored in an AuxInt.
 func auxFrom64F(f float64) int64 {
 	return int64(math.Float64bits(f))