[dev.power64] cmd/9g: use loops to do memmove in sgen()

LGTM=rsc
R=rsc, iant
CC=golang-codereviews
https://golang.org/cl/128130044

diff --git a/src/cmd/9g/cgen.c b/src/cmd/9g/cgen.c
index f8078aece3652afea1b91835580dab088334a44e..a8d628f43b3abb07cb992af280634cb796c8cf70 100644 (file)
--- a/src/cmd/9g/cgen.c
+++ b/src/cmd/9g/cgen.c
@@ -1344,10 +1344,10 @@ stkof(Node *n)
 void
 sgen(Node *n, Node *ns, int64 w)
 {
-       Node dst, src, tmp;
+       Node dst, src, tmp, nend;
        int32 c, odst, osrc;
        int dir, align, op;
-       Prog *p;
+       Prog *p, *ploop;
        NodeList *l;
        Node *res = ns;
 
@@ -1447,19 +1447,15 @@ sgen(Node *n, Node *ns, int64 w)
        regalloc(&tmp, types[tptr], N);
 
        // set up end marker
-       //memset(&nend, 0, sizeof nend);
-       //if(c >= 4) {
-       //      regalloc(&nend, types[tptr], N);
-       //      p = gins(AMOVD, &src, &nend);
-       //      p->from.type = D_CONST;
-       //      if(dir < 0)
-       //              p->from.offset = dir;
-       //      else
-       //              p->from.offset = w;
-       //}
+       memset(&nend, 0, sizeof nend);
 
        // move src and dest to the end of block if necessary
        if(dir < 0) {
+               if(c >= 4) {
+                       regalloc(&nend, types[tptr], N);
+                       p = gins(AMOVD, &src, &nend);
+               }
+
                p = gins(AADD, N, &src);
                p->from.type = D_CONST;
                p->from.offset = w;
@@ -1475,11 +1471,19 @@ sgen(Node *n, Node *ns, int64 w)
                p = gins(AADD, N, &dst);
                p->from.type = D_CONST;
                p->from.offset = -dir;
+
+               if(c >= 4) {
+                       regalloc(&nend, types[tptr], N);
+                       p = gins(AMOVD, &src, &nend);
+                       p->from.type = D_CONST;
+                       p->from.offset = w;
+               }
        }
-       
+
+
        // move
-       // TODO: enable loops and duffcopy for larger copies.
-       /*if(c >= 4) {
+       // TODO: enable duffcopy for larger copies.
+       if(c >= 4) {
                p = gins(op, &src, &tmp);
                p->from.type = D_OREG;
                p->from.offset = dir;
@@ -1489,12 +1493,11 @@ sgen(Node *n, Node *ns, int64 w)
                p->to.type = D_OREG;
                p->to.offset = dir;
 
-               p = gins(ACMP, &src, N);
-               raddr(&nend, p);
+               p = gins(ACMP, &src, &nend);
 
                patch(gbranch(ABNE, T, 0), ploop);
                regfree(&nend);
-       } else*/ {
+       } else {
                while(c-- > 0) {
                        p = gins(op, &src, &tmp);
                        p->from.type = D_OREG;