better job on 2007043

better registerization

R=rsc
CC=golang-dev
https://golang.org/cl/1955049

diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index 76776d70295cecd9f216250eea93cbe2b9388a45..9bca759961ee83e8b6ada1c37b0cb636d76658fe 100644 (file)
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -1109,6 +1109,22 @@ sgen(Node *n, Node *ns, int32 w)
        restx(&cx, &oldcx);
 }
 
+static int
+cadable(Node *n)
+{
+       if(!n->addable) {
+               // dont know how it happens,
+               // but it does
+               return 0;
+       }
+
+       switch(n->op) {
+       case ONAME:
+               return 1;
+       }
+       return 0;
+}
+
 /*
  * copy a structure component by component
  * return 1 if can do, 0 if cant.
@@ -1118,20 +1134,36 @@ int
 componentgen(Node *nr, Node *nl)
 {
        Node nodl, nodr;
-       int free;
+       int freel, freer;
 
-       free = 0;
-       if(!nl->addable || nl->op != ONAME)
+       freel = 0;
+       freer = 0;
+
+       switch(nl->type->etype) {
+       default:
                goto no;
 
+       case TARRAY:
+               if(!isslice(nl->type))
+                       goto no;
+       case TSTRING:
+       case TINTER:
+               break;
+       }
+
        nodl = *nl;
-       if(nr != N) {
-               if(!nr->addable || nr->op != ONAME)
+       if(!cadable(nl)) {
+               if(nr == N || !cadable(nr))
                        goto no;
+               igen(nl, &nodl, N);
+               freel = 1;
+       }
+
+       if(nr != N) {
                nodr = *nr;
-               if(nr->op != ONAME && nr->op != OINDREG) {
+               if(!cadable(nr)) {
                        igen(nr, &nodr, N);
-                       free = 1;
+                       freer = 1;
                }
        }
 
@@ -1173,7 +1205,6 @@ componentgen(Node *nr, Node *nl)
                goto yes;
 
        case TSTRING:
-
                nodl.xoffset += Array_array;
                nodl.type = ptrto(types[TUINT8]);
 
@@ -1197,7 +1228,6 @@ componentgen(Node *nr, Node *nl)
                goto yes;
 
        case TINTER:
-
                nodl.xoffset += Array_array;
                nodl.type = ptrto(types[TUINT8]);
 
@@ -1225,12 +1255,16 @@ componentgen(Node *nr, Node *nl)
        }
 
 no:
-       if(free)
+       if(freer)
                regfree(&nodr);
+       if(freel)
+               regfree(&nodl);
        return 0;
 
 yes:
-       if(free)
+       if(freer)
                regfree(&nodr);
+       if(freel)
+               regfree(&nodl);
        return 1;
 }