From fc010adcd7005f6eaf646b6edde50d09cac69fc1 Mon Sep 17 00:00:00 2001
From: Ken Thompson <ken@golang.org>
Date: Thu, 18 Feb 2010 17:55:11 -0800
Subject: [PATCH] complex constant multiply and divide

R=rsc
CC=golang-dev
https://golang.org/cl/217041
---
 src/cmd/gc/builtin.c.boot |  1 +
 src/cmd/gc/const.c        | 84 ++++++++++++++++++++++++++++++++++++---
 src/cmd/gc/runtime.go     |  1 +
 src/cmd/gc/typecheck.c    |  4 ++
 src/cmd/gc/walk.c         | 12 ++++--
 5 files changed, 92 insertions(+), 10 deletions(-)

diff --git a/src/cmd/gc/builtin.c.boot b/src/cmd/gc/builtin.c.boot
index 1d881c9d8ea..6eed40230d4 100644
--- a/src/cmd/gc/builtin.c.boot
+++ b/src/cmd/gc/builtin.c.boot
@@ -9,6 +9,7 @@ char *runtimeimport =
 	"func \"\".printfloat (? float64)\n"
 	"func \"\".printint (? int64)\n"
 	"func \"\".printuint (? uint64)\n"
+	"func \"\".printcomplex (? complex128)\n"
 	"func \"\".printstring (? string)\n"
 	"func \"\".printpointer (? any)\n"
 	"func \"\".printiface (? any)\n"
diff --git a/src/cmd/gc/const.c b/src/cmd/gc/const.c
index 1727e775a2b..f16c52d58cf 100644
--- a/src/cmd/gc/const.c
+++ b/src/cmd/gc/const.c
@@ -5,10 +5,12 @@
 #include	"go.h"
 #define	TUP(x,y)	(((x)<<16)|(y))
 
-static Val tocplx(Val);
-static Val toflt(Val);
-static Val tostr(Val);
-static Val copyval(Val);
+static	Val	tocplx(Val);
+static	Val	toflt(Val);
+static	Val	tostr(Val);
+static	Val	copyval(Val);
+static	void	cmplxmpy(Mpcplx *v, Mpcplx *rv);
+static	void	cmplxdiv(Mpcplx *v, Mpcplx *rv);
 
 /*
  * truncate float literal fv to 32-bit or 64-bit precision
@@ -614,9 +616,10 @@ evconst(Node *n)
 		mpsubfltflt(&v.u.cval->imag, &rv.u.cval->imag);
 		break;
 	case TUP(OMUL, CTCPLX):
-		goto illegal;	// TODO
+		cmplxmpy(v.u.cval, rv.u.cval);
+		break;
 	case TUP(ODIV, CTCPLX):
-		goto illegal;	// TODO
+		cmplxdiv(v.u.cval, rv.u.cval);
 		break;
 
 	case TUP(OEQ, CTNIL):
@@ -793,6 +796,13 @@ unary:
 		mpnegflt(v.u.fval);
 		break;
 
+	case TUP(OPLUS, CTCPLX):
+		break;
+	case TUP(OMINUS, CTCPLX):
+		mpnegflt(&v.u.cval->real);
+		mpnegflt(&v.u.cval->imag);
+		break;
+
 	case TUP(ONOT, CTBOOL):
 		if(!v.u.bval)
 			goto settrue;
@@ -1187,3 +1197,65 @@ convconst(Node *con, Type *t, Val *val)
 	fatal("convconst %lT constant", t);
 
 }
+
+// complex multiply v *= rv
+//	(a, b) * (c, d) = (a*c - b*d, b*c + a*d)
+static void
+cmplxmpy(Mpcplx *v, Mpcplx *rv)
+{
+	Mpflt ac, bd, bc, ad;
+
+	mpmovefltflt(&ac, &v->real);
+	mpmulfltflt(&ac, &rv->real);	// ac
+
+	mpmovefltflt(&bd, &v->imag);
+	mpmulfltflt(&bd, &rv->imag);	// bd
+
+	mpmovefltflt(&bc, &v->imag);
+	mpmulfltflt(&bc, &rv->real);	// bc
+
+	mpmovefltflt(&ad, &v->real);
+	mpmulfltflt(&ad, &rv->imag);	// ad
+
+	mpmovefltflt(&v->real, &ac);
+	mpsubfltflt(&v->real, &bd);	// ac-bd
+
+	mpmovefltflt(&v->imag, &bc);
+	mpaddfltflt(&v->imag, &ad);	// bc+ad
+}
+
+// complex divide v /= rv
+//	(a, b) / (c, d) = ((a*c + b*d), (b*c - a*d))/(c*c + d*d)
+static void
+cmplxdiv(Mpcplx *v, Mpcplx *rv)
+{
+	Mpflt ac, bd, bc, ad, cc_plus_dd;
+
+	mpmovefltflt(&cc_plus_dd, &rv->real);
+	mpmulfltflt(&cc_plus_dd, &rv->real);	// cc
+
+	mpmovefltflt(&ac, &rv->imag);
+	mpmulfltflt(&ac, &rv->imag);		// dd
+
+	mpaddfltflt(&cc_plus_dd, &ac);		// cc+dd
+
+	mpmovefltflt(&ac, &v->real);
+	mpmulfltflt(&ac, &rv->real);		// ac
+
+	mpmovefltflt(&bd, &v->imag);
+	mpmulfltflt(&bd, &rv->imag);		// bd
+
+	mpmovefltflt(&bc, &v->imag);
+	mpmulfltflt(&bc, &rv->real);		// bc
+
+	mpmovefltflt(&ad, &v->real);
+	mpmulfltflt(&ad, &rv->imag);		// ad
+
+	mpmovefltflt(&v->real, &ac);
+	mpaddfltflt(&v->real, &bd);		// ac+bd
+	mpdivfltflt(&v->real, &cc_plus_dd);	// (ac+bd)/(cc+dd)
+
+	mpmovefltflt(&v->imag, &bc);
+	mpsubfltflt(&v->imag, &ad);		// bc-ad
+	mpdivfltflt(&v->imag, &cc_plus_dd);	// (bc+ad)/(cc+dd)
+}
diff --git a/src/cmd/gc/runtime.go b/src/cmd/gc/runtime.go
index 4b9b97136b3..e350c282dd0 100644
--- a/src/cmd/gc/runtime.go
+++ b/src/cmd/gc/runtime.go
@@ -20,6 +20,7 @@ func printbool(bool)
 func printfloat(float64)
 func printint(int64)
 func printuint(uint64)
+func printcomplex(complex128)
 func printstring(string)
 func printpointer(any)
 func printiface(any)
diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index d36775b0285..9804220d1d4 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -1370,6 +1370,10 @@ checkconv(Type *nt, Type *t, int explicit, int *op, int *et, char *desc)
 	if(isint[nt->etype] || isfloat[nt->etype])
 		return 1;
 
+	// between versions of complex
+	if(iscomplex[t->etype] || iscomplex[nt->etype])
+		return 1;
+
 	// to string
 	if(istype(t, TSTRING)) {
 		// integer rune
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index e528e3f6c00..e28cf288fc1 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -794,11 +794,13 @@ walkexpr(Node **np, NodeList **init)
 	case OCONV:
 	case OCONVNOP:
 		if(thechar == '5') {
-			if(isfloat[n->left->type->etype] && (n->type->etype == TINT64 || n->type->etype == TUINT64)) {
+			if(isfloat[n->left->type->etype] &&
+			   (n->type->etype == TINT64 || n->type->etype == TUINT64)) {
 				n = mkcall("float64toint64", n->type, init, conv(n->left, types[TFLOAT64]));
 				goto ret;
 			}
-			if((n->left->type->etype == TINT64 || n->left->type->etype == TUINT64) && isfloat[n->type->etype]) {
+			if((n->left->type->etype == TINT64 || n->left->type->etype == TUINT64) &&
+			   isfloat[n->type->etype]) {
 				n = mkcall("int64tofloat64", n->type, init, conv(n->left, types[TINT64]));
 				goto ret;
 			}
@@ -1727,7 +1729,7 @@ walkprint(Node *nn, NodeList **init, int defer)
 		} else if(iscomplex[et]) {
 			if(defer) {
 				fmtprint(&fmt, "%%f");
-				t = types[TFLOAT64];
+				t = types[TCOMPLEX128];
 			} else
 				on = syslook("printcomplex", 0);
 		} else if(et == TBOOL) {
@@ -2036,8 +2038,10 @@ convas(Node *n, NodeList **init)
 	if(lt == T || rt == T)
 		goto out;
 
-	if(isblank(n->left))
+	if(isblank(n->left)) {
+		defaultlit(&n->right, T);
 		goto out;
+	}
 
 	if(n->left->op == OINDEXMAP) {
 		n = mkcall1(mapfn("mapassign1", n->left->left->type), T, init,