added missing sgen reverse character copy code.

R=rsc
http://go/go-review/1018006

diff --git a/src/cmd/5g/cgen.c b/src/cmd/5g/cgen.c
index bcbc979245a42bfd6405e3cbc81345ddf7f65e75..e46efdae74f21a6bfc2cc7b1e2c74e303a8fbc1e 100644 (file)
--- a/src/cmd/5g/cgen.c
+++ b/src/cmd/5g/cgen.c
@@ -1084,7 +1084,7 @@ sgen(Node *n, Node *res, int32 w)
        regalloc(&dst, types[tptr], res);
 
        if(n->ullman >= res->ullman) {
-               agen(n, &dst);
+               agen(n, &dst);  // temporarily use dst
                regalloc(&src, types[tptr], N);
                gins(AMOVW, &dst, &src);
                agen(res, &dst);
@@ -1137,6 +1137,29 @@ sgen(Node *n, Node *res, int32 w)
                        patch(gbranch(ABNE, T), ploop);
 
                        regfree(&nend);
+               } else {
+                       // move src and dest to the end of block
+                       p = gins(AMOVW, &src, &src);
+                       p->from.type = D_CONST;
+                       p->from.offset = (q-1)*4;
+
+                       p = gins(AMOVW, &dst, &dst);
+                       p->from.type = D_CONST;
+                       p->from.offset = (q-1)*4;
+
+                       while(q > 0) {
+                               p = gins(AMOVW, &src, &tmp);
+                               p->from.type = D_OREG;
+                               p->from.offset = -4;
+                               p->scond |= C_PBIT;
+
+                               p = gins(AMOVW, &tmp, &dst);
+                               p->to.type = D_OREG;
+                               p->to.offset = -4;
+                               p->scond |= C_PBIT;
+
+                               q--;
+                       }
                }
        } else {
                // normal direction