rework liveness to compute reg pressure

1 files changed, 43 insertions, 34 deletions

diff --git a/lisc/live.c b/lisc/live.c
index 4569db9..dd544c1 100644
--- a/lisc/live.c
+++ b/lisc/live.c
@@ -1,10 +1,14 @@
 #include "lisc.h"
 
-static inline void
-bset(Bits *b, Ref r)
+static void
+bset(Ref r, Blk *b, int *nlv)
 {
 	if (rtype(r) == RSym)
-		BSET(*b, r.val);
+	if (!BGET(b->in, r.val)) {
+		++*nlv;
+		BSET(b->in, r.val);
+		BSET(b->gen, r.val);
+	}
 }
 
 /* liveness analysis
@@ -16,51 +20,56 @@ filllive(Fn *f)
 	Blk *b;
 	Ins *i;
 	Phi *p;
-	int z, n, chg;
+	int z, n, chg, nlv;
 	uint a;
-	Bits *kill, *use, *k, *u, bt;
+	Bits tb;
 
 	assert(f->ntmp <= NBit*BITS);
-	kill = alloc(f->nblk * sizeof kill[0]);
-	use = alloc(f->nblk * sizeof use[0]);
-	for (b=f->start; b; b=b->link) {
-		memset(&b->in, 0, sizeof(Bits));
-		memset(&b->out, 0, sizeof(Bits));
-	}
 	for (b=f->start; b; b=b->link) {
-		k = &kill[b->id];
-		u = &use[b->id];
-		for (p=b->phi; p; p=p->link) {
-			for (a=0; a<p->narg; a++)
-				bset(&p->blk[a]->out, p->arg[a]);
-			bset(k, p->to);
-		}
-		for (i=b->ins; i-b->ins < b->nins; i++) {
-			bset(k, i->to);
-			bset(u, i->arg[0]);
-			bset(u, i->arg[1]);
-		}
-		bset(u, b->jmp.arg);
+		b->in = (Bits){{0}};
+		b->out = (Bits){{0}};
+		b->gen = (Bits){{0}};
+		b->nlive = 0;
 	}
-Again:
-	chg = 0;
+	chg = 1;
+	if (0)
+	Again:
+		chg = 0;
 	for (n=f->nblk-1; n>=0; n--) {
 		b = f->rpo[n];
-		bt = b->out;
+
+		tb = b->out;
 		if (b->s1)
 			for (z=0; z<BITS; z++)
 				b->out.t[z] |= b->s1->in.t[z];
 		if (b->s2)
 			for (z=0; z<BITS; z++)
 				b->out.t[z] |= b->s2->in.t[z];
-		chg |= memcmp(&b->out, &bt, sizeof(Bits)) != 0;
-		k = &kill[n];
-		u = &use[n];
-		for (z=0; z<BITS; z++)
-			b->in.t[z] = (b->out.t[z]|u->t[z]) & ~k->t[z];
+		chg |= memcmp(&b->out, &tb, sizeof(Bits)) != 0;
+
+		b->in = b->out;
+		nlv = bcnt(&b->in);
+		bset(b->jmp.arg, b, &nlv);
+		b->nlive = nlv;
+		for (i=&b->ins[b->nins]; i!=b->ins;) {
+			i--;
+			if (!req(i->to, R)) {
+				nlv -= BGET(b->in, i->to.val);
+				BCLR(b->in, i->to.val);
+			}
+			bset(i->arg[0], b, &nlv);
+			bset(i->arg[1], b, &nlv);
+			if (nlv > b->nlive)
+				b->nlive = nlv;
+		}
+
+		for (p=b->phi; p; p=p->link) {
+			BCLR(b->in, p->to.val);
+			for (a=0; a<p->narg; a++)
+				if (rtype(p->arg[a]) == RSym)
+					BSET(p->blk[a]->out, p->arg[a].val);
+		}
 	}
 	if (chg)
 		goto Again;
-	free(kill);
-	free(use);
 }