add clrex instruction

Reference: /n/atom/patch/applied/5lclrex
Date: Fri Feb  6 06:05:51 CET 2015
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/5l/span.c	Fri Feb  6 06:05:28 2015
+++ /sys/src/cmd/5l/span.c	Fri Feb  6 06:05:30 2015
@@ -743,7 +743,11 @@
 			break;
 		case ASWPW:
 			oprange[ASWPBU] = oprange[r];
+			oprange[ALDREX] = oprange[r];
+			oprange[ASTREX] = oprange[r];
 			break;
+		case ALDREX:
+		case ASTREX:
 		case AB:
 		case ABL:
 		case ABX:
@@ -752,6 +756,7 @@
 		case AWORD:
 		case AMOVM:
 		case ARFE:
+		case ACLREX:
 		case ATEXT:
 		case ACASE:
 		case ABCASE:
--- /sys/src/cmd/5l/optab.c	Fri Feb  6 06:05:32 2015
+++ /sys/src/cmd/5l/optab.c	Fri Feb  6 06:05:34 2015
@@ -161,8 +161,11 @@
 	{ AMOVM,	C_SOREG,C_NONE,	C_LCON,		39, 4, 0 },
 
 	{ ASWPW,	C_SOREG,C_REG,	C_REG,		40, 4, 0 },
+	{ ALDREX,	C_SOREG,C_NONE,	C_REG,		40, 4, 0 },
+	{ ASTREX,	C_SOREG,C_REG,	C_REG,		40, 4, 0 },
 
 	{ ARFE,		C_NONE,	C_NONE,	C_NONE,		41, 4, 0 },
+ 	{ ACLREX,	C_NONE, C_NONE, C_NONE,		42, 4, 0 },
 
 	{ AMOVF,	C_FREG,	C_NONE,	C_FEXT,		50, 4, REGSB },
 	{ AMOVF,	C_FREG,	C_NONE,	C_FAUTO,	50, 4, REGSP },
--- /sys/src/cmd/5l/asm.c	Fri Feb  6 06:05:37 2015
+++ /sys/src/cmd/5l/asm.c	Fri Feb  6 06:05:39 2015
@@ -5,39 +5,6 @@
 
 static Prog *PP;
 
-ulong
-crc32(char *name, int len, vlong off)
-{
-	uchar buf[MAXIO];
-	int fd, n;
-	ulong crc;
-	static ulong *crctab;
-
-	if(crctab == nil)
-		crctab = mkcrctab(0xedb88320);
-	fd = open(name, OREAD);
-	if(fd < 0) {
-		diag("cannot open %s: %r", name);
-		errorexit();
-	}
-	seek(fd, off, 0);
-	crc = 0;
-	while(len > 0) {
-		n = len;
-		if(n > sizeof buf)
-			n = sizeof buf;
-		n = read(fd, buf, n);
-		if(n < 0) {
-			diag("cannot read %s: %r", name);
-			errorexit();
-		}
-		crc = blockcrc(crctab, crc, buf, n);
-		len -= n;
-	}
-	close(fd);
-	return crc;
-}
-
 long
 entryvalue(void)
 {
@@ -1123,6 +1090,10 @@
 
 	case 41:	/* rfe -> movm.s.w.u 0(r13),[r15] */
 		o1 = 0xe8fd8000;
+		break;
+
+	case 42:	/* clrex */
+		o1 = 0xf57ff01f;
 		break;
 
 	case 50:	/* floating point store */