fix fat copy of overlapping data
R=r
OCL=14417
CL=14417
diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index bbd904d..b4ae1df 100644
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -282,13 +282,6 @@
fatal("agen: unknown op %N", n);
break;
-// case ONAME:
-// regalloc(&n1, types[tptr], res);
-// gins(optoas(OADDR, types[tptr]), n, &n1);
-// gmove(&n1, res);
-// regfree(&n1);
-// break;
-
case OCALLMETH:
cgen_callmeth(n, 0);
cgen_aret(n, res);
@@ -330,8 +323,6 @@
agen_inter(n, res);
break;
-// case OINDREG:
-
case OINDEX:
w = n->type->width;
if(nr->addable)
@@ -585,11 +576,27 @@
;
}
+int32
+stkof(Node *n)
+{
+ switch(n->op) {
+ case OS2I:
+ return 2*widthptr;
+ case OI2I:
+ return 1*widthptr;
+ case OINDREG:
+ return n->xoffset;
+ }
+ // botch - probably failing to recognize address
+ // arithmetic on the above. eg INDEX and DOT
+ return -1;
+}
+
void
sgen(Node *n, Node *ns, uint32 w)
{
Node nodl, nodr;
- int32 c;
+ int32 c, q, odst, osrc;
if(debug['g']) {
dump("\nsgen-res", ns);
@@ -601,6 +608,14 @@
fatal("sgen UINF");
}
+ // offset on the stack
+ odst = stkof(ns);
+ osrc = stkof(n);
+ if(osrc < 0)
+ odst = odst;
+ if(odst < 0)
+ osrc = odst;
+
nodreg(&nodl, types[tptr], D_DI);
nodreg(&nodr, types[tptr], D_SI);
@@ -611,20 +626,52 @@
agen(ns, &nodl);
agen(n, &nodr);
}
- gins(ACLD, N, N); // clear direction flag
- c = w / 8;
- if(c > 0) {
- gconreg(AMOVQ, c, D_CX);
- gins(AREP, N, N); // repeat
- gins(AMOVSQ, N, N); // MOVQ *(SI)+,*(DI)+
+ c = w % 8; // bytes
+ q = w / 8; // quads
+
+ // if we are copying forward on the stack and
+ // the src and dst overlap, then reverse direction
+ if(odst > osrc && odst-osrc < w) {
+ // reverse direction
+ gins(ASTD, N, N); // set direction flag
+ if(c > 0) {
+ gconreg(AADDQ, w-1, D_SI);
+ gconreg(AADDQ, w-1, D_DI);
+
+ gconreg(AMOVQ, c, D_CX);
+ gins(AREP, N, N); // repeat
+ gins(AMOVSB, N, N); // MOVB *(SI)-,*(DI)-
+ }
+
+ if(q > 0) {
+ if(c > 0) {
+ gconreg(AADDQ, -7, D_SI);
+ gconreg(AADDQ, -7, D_DI);
+ } else {
+ gconreg(AADDQ, w-8, D_SI);
+ gconreg(AADDQ, w-8, D_DI);
+ }
+ gconreg(AMOVQ, q, D_CX);
+ gins(AREP, N, N); // repeat
+ gins(AMOVSQ, N, N); // MOVQ *(SI)-,*(DI)-
+ }
+ // for future optimization
+ // we leave with the flag clear
+ gins(ACLD, N, N);
+ } else {
+ // normal direction
+ gins(ACLD, N, N); // clear direction flag
+ if(q > 0) {
+ gconreg(AMOVQ, q, D_CX);
+ gins(AREP, N, N); // repeat
+ gins(AMOVSQ, N, N); // MOVQ *(SI)+,*(DI)+
+ }
+
+ if(c > 0) {
+ gconreg(AMOVQ, c, D_CX);
+ gins(AREP, N, N); // repeat
+ gins(AMOVSB, N, N); // MOVB *(SI)+,*(DI)+
+ }
}
-
- c = w % 8;
- if(c > 0) {
- gconreg(AMOVQ, c, D_CX);
- gins(AREP, N, N); // repeat
- gins(AMOVSB, N, N); // MOVB *(SI)+,*(DI)+
- }
-
}
