cmd/compile: change Mp{int,flt} functions into methods

Also give them more idiomatic Go names. Adding godocs is outside the
scope of this CL. (Besides, the method names almost all directly
parallel an underlying math/big.Int or math/big.Float method.)

CL prepared mechanically with sed (for rewriting mpint.go/mpfloat.go)
and gofmt (for rewriting call sites).

Passes toolstash -cmp.

Change-Id: Id76f4aee476ba740f48db33162463e7978c2083d
Reviewed-on: https://go-review.googlesource.com/20909
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
diff --git a/src/cmd/compile/internal/gc/gen.go b/src/cmd/compile/internal/gc/gen.go
index 72b606e..67b344c 100644
--- a/src/cmd/compile/internal/gc/gen.go
+++ b/src/cmd/compile/internal/gc/gen.go
@@ -319,12 +319,12 @@
 	switch Simtype[n.Type.Etype] {
 	case TCOMPLEX64, TCOMPLEX128:
 		z.SetVal(Val{new(Mpcplx)})
-		Mpmovecflt(&z.Val().U.(*Mpcplx).Real, 0.0)
-		Mpmovecflt(&z.Val().U.(*Mpcplx).Imag, 0.0)
+		z.Val().U.(*Mpcplx).Real.SetFloat64(0.0)
+		z.Val().U.(*Mpcplx).Imag.SetFloat64(0.0)
 
 	case TFLOAT32, TFLOAT64:
 		var zero Mpflt
-		Mpmovecflt(&zero, 0.0)
+		zero.SetFloat64(0.0)
 		z.SetVal(Val{&zero})
 
 	case TPTR32, TPTR64, TCHAN, TMAP:
@@ -342,7 +342,7 @@
 		TUINT32,
 		TUINT64:
 		z.SetVal(Val{new(Mpint)})
-		Mpmovecfix(z.Val().U.(*Mpint), 0)
+		z.Val().U.(*Mpint).SetInt64(0)
 
 	default:
 		Fatalf("clearslim called on type %v", n.Type)