shithub: riscv

Info  •  Files  •  Log  •  Branches

7l: use floating point immediates where possible

--- a/sys/src/cmd/7l/asm.c

+++ b/sys/src/cmd/7l/asm.c

@@ -589,27 +589,17 @@

 	write(cout, buf.dbuf, n);

 }

-static Ieee chipfloats[] = {

-	{0x00000000, 0x00000000}, /* 0 */

-	{0x00000000, 0x3ff00000}, /* 1 */

-	{0x00000000, 0x40000000}, /* 2 */

-	{0x00000000, 0x40080000}, /* 3 */

-	{0x00000000, 0x40100000}, /* 4 */

-	{0x00000000, 0x40140000}, /* 5 */

-	{0x00000000, 0x3fe00000}, /* .5 */

-	{0x00000000, 0x40240000}, /* 10 */

-};

-

 int

 chipfloat(Ieee *e)

 {

-	Ieee *p;

-	int n;

+	int n, Bbbbbbbbb;

-	for(n = sizeof(chipfloats)/sizeof(chipfloats[0]); --n >= 0;){

-		p = &chipfloats[n];

-		if(p->l == e->l && p->h == e->h && 0)

-			return n;		/* TO DO: return imm8 encoding */

-	}

-	return -1;

+	if(e->l != 0 || (e->h & 0xffffU) != 0)

+		return -1;

+	n = e->h >> 16;

+	Bbbbbbbbb = (n>>6) & 0x1ff;

+	if(Bbbbbbbbb != 0x100 && Bbbbbbbbb != 0xff)

+		return -1;

+	n = (n & 0x8000) >> 8 | (n & 0x7f);

+	return n;

 }

--- a/sys/src/cmd/7l/asmout.c

+++ b/sys/src/cmd/7l/asmout.c

@@ -742,12 +742,11 @@

 		o1 = oprrr(p->as);

 		if(p->from.type == D_FCONST) {

 			rf = chipfloat(p->from.ieee);

-			if(rf < 0 || 1){

+			if(rf < 0)

 				diag("invalid floating-point immediate\n%P", p);

-				rf = 0;

-			}

-			rf |= (1<<3);

-		} else

+			rf = rf<<(13-5) | 1<<(12-5);

+			o1 &= ~(0x10<<10);

+		}else

 			rf = p->from.reg;

 		rt = p->to.reg;

 		r = p->reg;

@@ -756,7 +755,7 @@

 			rf = 0;

 		}else if(r == NREG)

 			r = rt;

-		o1 |= (rf << 16) | (r<<5) | rt;

+		o1 |= rf<<16 | r<<5 | rt;

 		break;

 	case 56:	/* floating point compare */