6a, 6c, 6l: fix copy propagation

Without an explicit signal for a truncation, copy propagation will
sometimes propagate a 32-bit truncation and end up overwriting uses of
the original 64-bit value.

This was independently discovered and fixed in Go. See:
	http://golang.org/issue/1315
	https://codereview.appspot.com/6002043/

Thanks Charles Forsyth for tips and advice.

4 files changed, 46 insertions, 29 deletions

diff --git a/sys/src/cmd/6c/6.out.h b/sys/src/cmd/6c/6.out.h
index 0766ea3d2..947e5a5ef 100644
--- a/sys/src/cmd/6c/6.out.h
+++ b/sys/src/cmd/6c/6.out.h
@@ -698,6 +698,8 @@ enum	as
 	ASWAPGS,
 
 	AMODE,
+	
+	AMOVQL,
 
 	ALAST
 };
diff --git a/sys/src/cmd/6c/peep.c b/sys/src/cmd/6c/peep.c
index 351dc887d..e977b5c1f 100644
--- a/sys/src/cmd/6c/peep.c
+++ b/sys/src/cmd/6c/peep.c
@@ -404,6 +404,7 @@ subprop(Reg *r0)
 
 		case AMOVSL:
 		case AMOVSQ:
+		case AMOVQL:
 			return 0;
 
 		case AMOVL:
@@ -602,6 +603,7 @@ copyu(Prog *p, Adr *v, Adr *s)
 	case AMOVWLZX:
 	case AMOVWQSX:
 	case AMOVWQZX:
+	case AMOVQL:
 
 	case AMOVSS:
 	case AMOVSD:
diff --git a/sys/src/cmd/6c/reg.c b/sys/src/cmd/6c/reg.c
index 43e21a4f3..82a32a1db 100644
--- a/sys/src/cmd/6c/reg.c
+++ b/sys/src/cmd/6c/reg.c
@@ -183,6 +183,7 @@ regopt(Prog *p)
 		case AMOVWLZX:
 		case AMOVWQSX:
 		case AMOVWQZX:
+		case AMOVQL:
 
 		case AMOVSS:
 		case AMOVSD:
diff --git a/sys/src/cmd/6c/txt.c b/sys/src/cmd/6c/txt.c
index e3b9a9ee5..85c4f2a46 100644
--- a/sys/src/cmd/6c/txt.c
+++ b/sys/src/cmd/6c/txt.c
@@ -767,7 +767,6 @@ gmove(Node *f, Node *t)
 	case CASE(	TUINT,	TCHAR):
 	case CASE(	TLONG,	TCHAR):
 	case CASE(	TULONG,	TCHAR):
-	case CASE(	TIND,	TCHAR):
 
 	case CASE(	TCHAR,	TUCHAR):
 	case CASE(	TUCHAR,	TUCHAR):
@@ -777,7 +776,6 @@ gmove(Node *f, Node *t)
 	case CASE(	TUINT,	TUCHAR):
 	case CASE(	TLONG,	TUCHAR):
 	case CASE(	TULONG,	TUCHAR):
-	case CASE(	TIND,	TUCHAR):
 
 	case CASE(	TSHORT,	TSHORT):
 	case CASE(	TUSHORT,TSHORT):
@@ -785,7 +783,6 @@ gmove(Node *f, Node *t)
 	case CASE(	TUINT,	TSHORT):
 	case CASE(	TLONG,	TSHORT):
 	case CASE(	TULONG,	TSHORT):
-	case CASE(	TIND,	TSHORT):
 
 	case CASE(	TSHORT,	TUSHORT):
 	case CASE(	TUSHORT,TUSHORT):
@@ -793,42 +790,26 @@ gmove(Node *f, Node *t)
 	case CASE(	TUINT,	TUSHORT):
 	case CASE(	TLONG,	TUSHORT):
 	case CASE(	TULONG,	TUSHORT):
-	case CASE(	TIND,	TUSHORT):
 
 	case CASE(	TINT,	TINT):
 	case CASE(	TUINT,	TINT):
 	case CASE(	TLONG,	TINT):
-	case CASE(	TULONG,	TINT):
-	case CASE(	TIND,	TINT):
+	case CASE(	TULONG,	TINT)::
 
 	case CASE(	TINT,	TUINT):
 	case CASE(	TUINT,	TUINT):
 	case CASE(	TLONG,	TUINT):
 	case CASE(	TULONG,	TUINT):
-	case CASE(	TIND,	TUINT):
-
-	case CASE(	TUINT,	TIND):
-	case CASE(	TVLONG,	TUINT):
-	case CASE(	TVLONG,	TULONG):
-	case CASE(	TUVLONG, TUINT):
-	case CASE(	TUVLONG, TULONG):
  *****/
 		a = AMOVL;
 		break;
 
-	case CASE(	TVLONG,	TCHAR):
-	case	CASE(	TVLONG,	TSHORT):
-	case CASE(	TVLONG,	TINT):
-	case CASE(	TVLONG,	TLONG):
-	case CASE(	TUVLONG, TCHAR):
-	case	CASE(	TUVLONG, TSHORT):
-	case CASE(	TUVLONG, TINT):
-	case CASE(	TUVLONG, TLONG):
+	case CASE(	TINT,	TIND):
 	case CASE(	TINT,	TVLONG):
 	case CASE(	TINT,	TUVLONG):
-	case CASE(	TLONG,	TVLONG):
-	case CASE(	TINT,	TIND):
 	case CASE(	TLONG,	TIND):
+	case CASE(	TLONG,	TVLONG):
+	case CASE(	TLONG,	TUVLONG):
 		a = AMOVLQSX;
 		if(f->op == OCONST) {
 			f->vconst &= (uvlong)0xffffffffU;
@@ -844,22 +825,53 @@ gmove(Node *f, Node *t)
 	case CASE(	TULONG,	TVLONG):
 	case CASE(	TULONG,	TUVLONG):
 	case CASE(	TULONG,	TIND):
-		a = AMOVL;	/* same effect as AMOVLQZX */
+		a = AMOVLQZX;
 		if(f->op == OCONST) {
 			f->vconst &= (uvlong)0xffffffffU;
 			a = AMOVQ;
 		}
 		break;
 
+	case CASE(	TIND,	TCHAR):
+	case CASE(	TIND,	TUCHAR):
+	case CASE(	TIND,	TSHORT):
+	case CASE(	TIND,	TUSHORT):
+	case CASE(	TIND,	TINT):
+	case CASE(	TIND,	TUINT):
+	case CASE(	TIND,	TLONG):
+	case CASE(	TIND,	TULONG):
+	case CASE(	TVLONG,	TCHAR):
+	case CASE(	TVLONG,	TUCHAR):
+	case CASE(	TVLONG,	TSHORT):
+	case CASE(	TVLONG,	TUSHORT):
+	case CASE(	TVLONG,	TINT):
+	case CASE(	TVLONG,	TUINT):
+	case CASE(	TVLONG,	TLONG):
+	case CASE(	TVLONG,	TULONG):
+	case CASE(	TUVLONG,	TCHAR):
+	case CASE(	TUVLONG,	TUCHAR):
+	case CASE(	TUVLONG,	TSHORT):
+	case CASE(	TUVLONG,	TUSHORT):
+	case CASE(	TUVLONG,	TINT):
+	case CASE(	TUVLONG,	TUINT):
+	case CASE(	TUVLONG,	TLONG):
+	case CASE(	TUVLONG,	TULONG):
+		a = AMOVQL;
+		if(f->op == OCONST) {
+			f->vconst &= 0xffffffffU;
+			a = AMOVL;
+		}
+		break;
+
+	case CASE(	TIND,	TIND):
 	case CASE(	TIND,	TVLONG):
-	case CASE(	TVLONG,	TVLONG):
-	case CASE(	TUVLONG,	TVLONG):
-	case CASE(	TVLONG,	TUVLONG):
-	case CASE(	TUVLONG,	TUVLONG):
 	case CASE(	TIND,	TUVLONG):
 	case CASE(	TVLONG,	TIND):
+	case CASE(	TVLONG,	TVLONG):
+	case CASE(	TVLONG,	TUVLONG):
 	case CASE(	TUVLONG,	TIND):
-	case CASE(	TIND,	TIND):
+	case CASE(	TUVLONG,	TVLONG):
+	case CASE(	TUVLONG,	TUVLONG):
 		a = AMOVQ;
 		break;