ref: 2ec461200f2fc4ae68d8b86f4f193c9e03a00b63
parent: 5b737d5d40d349dda92aaa5aec4593d4c1f7b6c4
author: Ori Bernstein <[email protected]>
date: Sat Jun 30 10:36:30 EDT 2012
Don't do as many blits.
If we detect that the RHS of the expression is large, and can be computed
directly into the LHS, do that. It makes the assembly easier to read,
and removes difficult to read (and possibly costly) blits.
--- a/8/simp.c
+++ b/8/simp.c
@@ -48,7 +48,7 @@
};
static Node *simp(Simp *s, Node *n);
-static Node *rval(Simp *s, Node *n);
+static Node *rval(Simp *s, Node *n, Node *dst);
static Node *lval(Simp *s, Node *n);
static void declarelocal(Simp *s, Node *n);
@@ -319,7 +319,7 @@
l1 = genlbl();
l2 = genlbl();
- c = rval(s, n->ifstmt.cond);
+ c = rval(s, n->ifstmt.cond, NULL);
cjmp(s, c, l1, l2);
simp(s, l1);
simp(s, n->ifstmt.iftrue);
@@ -354,7 +354,7 @@
simp(s, n->loopstmt.body); /* body */
simp(s, n->loopstmt.step); /* step */
simp(s, lcond); /* test lbl */
- t = rval(s, n->loopstmt.cond); /* test */
+ t = rval(s, n->loopstmt.cond, NULL); /* test */
cjmp(s, t, lbody, lend); /* repeat? */
simp(s, lend); /* exit */
}
@@ -441,7 +441,7 @@
v = ucompare(s, a, b, uc->etype, off);
r = mkexpr(a->line, Oland, r, v, NULL);
r->expr.type = tyword;
- r = rval(s, r); /* Oland needs to be reduced */
+ r = rval(s, r, NULL); /* Oland needs to be reduced */
}
break;
}
@@ -460,7 +460,7 @@
f = stdout;
end = genlbl();
- val = rval(s, n->matchstmt.val); /* FIXME: don't recompute, even if pure */
+ val = rval(s, n->matchstmt.val, NULL); /* FIXME: don't recompute, even if pure */
for (i = 0; i < n->matchstmt.nmatches; i++) {m = n->matchstmt.matches[i];
@@ -562,7 +562,7 @@
else
die("Can't index type %s\n", tystr(n->expr.type));assert(t->expr.type->type == Typtr);
- u = rval(s, args[1]);
+ u = rval(s, args[1], NULL);
sz = size(n);
v = mul(u, word(n->line, sz));
r = add(t, v);
@@ -574,7 +574,7 @@
Node *t, *u, *v;
int sz;
- t = rval(s, n);
+ t = rval(s, n, NULL);
u = NULL;
switch (exprtype(n)->type) {case Typtr: u = n; break;
@@ -617,7 +617,7 @@
next = genlbl();
end = genlbl();
- a = rval(s, n->expr.args[0]);
+ a = rval(s, n->expr.args[0], NULL);
append(s, store(r, a));
if (exprop(n) == Oland)
cjmp(s, a, next, end);
@@ -624,19 +624,22 @@
else if (exprop(n) == Olor)
cjmp(s, a, end, next);
append(s, next);
- b = rval(s, n->expr.args[1]);
+ b = rval(s, n->expr.args[1], NULL);
append(s, store(r, b));
append(s, end);
return r;
}
-static Node *lowerslice(Simp *s, Node *n)
+static Node *lowerslice(Simp *s, Node *n, Node *dst)
{Node *t;
Node *base, *sz, *len;
Node *stbase, *stlen;
- t = temp(s, n);
+ if (dst)
+ t = dst;
+ else
+ t = temp(s, n);
/* *(&slice) = (void*)base + off*sz */
base = slicebase(s, n->expr.args[0], n->expr.args[1]);
len = sub(n->expr.args[2], n->expr.args[1]);
@@ -684,7 +687,7 @@
Node *r;
for (i = 0; i < n->expr.nargs; i++)
- n->expr.args[i] = rval(s, n->expr.args[i]);
+ n->expr.args[i] = rval(s, n->expr.args[i], NULL);
if (ispure(n)) {r = n;
} else {@@ -699,7 +702,7 @@
return r;
}
-static Node *lowerucon(Simp *s, Node *n)
+static Node *lowerucon(Simp *s, Node *n, Node *dst)
{Node *tmp, *u, *tag, *elt, *sz;
Node *r;
@@ -716,7 +719,10 @@
}
}
- tmp = temp(s, n);
+ if (dst)
+ tmp = dst;
+ else
+ tmp = temp(s, n);
u = addr(tmp, exprtype(n));
tag = word(n->line, uc->id);
append(s, store(u, tag));
@@ -723,7 +729,7 @@
if (!uc->etype)
return tmp;
- elt = rval(s, n->expr.args[1]);
+ elt = rval(s, n->expr.args[1], NULL);
u = add(u, wordsz);
if (tysize(uc->etype) > Wordsz) {elt = addr(elt, uc->etype);
@@ -736,7 +742,7 @@
return tmp;
}
-static Node *rval(Simp *s, Node *n)
+static Node *rval(Simp *s, Node *n, Node *dst)
{Node *r; /* expression result */
Node *t, *u, *v; /* temporary nodes */
@@ -767,7 +773,7 @@
r = word(n->line, size(args[0]));
break;
case Oslice:
- r = lowerslice(s, n);
+ r = lowerslice(s, n, dst);
break;
case Oidx:
t = idxaddr(s, n);
@@ -786,7 +792,7 @@
}
break;
case Ocons:
- r = lowerucon(s, n);
+ r = lowerucon(s, n, dst);
break;
case Ocast:
/* slice -> ptr cast */
@@ -800,8 +806,8 @@
case Oaddeq: case Osubeq: case Omuleq: case Odiveq: case Omodeq:
case Oboreq: case Obandeq: case Obxoreq: case Obsleq: case Obsreq:
assert(fusedmap[exprop(n)] != Obad);
- u = rval(s, args[0]);
- v = rval(s, args[1]);
+ u = rval(s, args[0], NULL);
+ v = rval(s, args[1], NULL);
v = mkexpr(n->line, fusedmap[exprop(n)], u, v, NULL);
v->expr.type = u->expr.type;
r = store(u, v);
@@ -854,7 +860,7 @@
break;
case Oret:
if (s->isbigret) {- t = rval(s, args[0]);
+ t = rval(s, args[0], NULL);
t = addr(t, exprtype(args[0]));
u = word(n->line, size(args[0]));
v = mkexpr(n->line, Oblit, s->ret, t, u, NULL);
@@ -861,7 +867,7 @@
append(s, v);
} else if (n->expr.nargs && n->expr.args[0]) {t = s->ret;
- t = store(t, rval(s, args[0]));
+ t = store(t, rval(s, args[0], NULL));
append(s, t);
}
jmp(s, s->endlbl);
@@ -868,8 +874,13 @@
break;
case Oasn:
t = lval(s, args[0]);
- u = rval(s, args[1]);
- if (size(n) > Wordsz) {+ u = rval(s, args[1], t);
+
+ /* if we stored the result into t, rval() should return that,
+ * and we know our work is done. */
+ if (u == t) {+ r = t;
+ } else if (size(n) > Wordsz) {t = addr(t, exprtype(n));
u = addr(u, exprtype(n));
v = word(n->line, size(n));
@@ -883,7 +894,7 @@
r = temp(s, n);
linsert(&n->expr.args, &n->expr.nargs, 1, addr(r, exprtype(n)));
for (i = 0; i < n->expr.nargs; i++)
- n->expr.args[i] = rval(s, n->expr.args[i]);
+ n->expr.args[i] = rval(s, n->expr.args[i], NULL);
append(s, n);
} else {r = visit(s, n);
@@ -929,7 +940,7 @@
case Nloopstmt: simploop(s, n); break;
case Nmatchstmt: simpmatch(s, n); break;
case Nexpr:
- r = rval(s, n);
+ r = rval(s, n, NULL);
if (r)
append(s, r);
/* drain the increment queue for this expr */