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-rw-r--r--src/compiler/expr.zc68
1 files changed, 54 insertions, 14 deletions
diff --git a/src/compiler/expr.zc b/src/compiler/expr.zc
index 2935a9b..e437d2f 100644
--- a/src/compiler/expr.zc
+++ b/src/compiler/expr.zc
@@ -1072,6 +1072,7 @@ int primary() {
if (isfl(ltype[i])) xfloat = 1;
xstr = getstr(i); if (xty == tbstr) xstr = 1;
lv = 1; lvk = LV_LOCAL; lvi = i;
+ if ((ltag[i] & LCONST) && treadonly(xty)) { xconst = 1; xcval = lkval[i]; } // a local const's value is known (spec 3.14.2)
if (isalias(i)) { touch(i); xbor = lroot(i); return C_VAR + i; }
if (tracked(i) || lrskind[i] == RS_PARAM || (local_origin_mask && local_origin_mask[i])) return C_VAR + i;
return C_PLAIN;
@@ -1762,17 +1763,31 @@ int unary() {
// level tighter and emit its code sequence from the operator table. && and ||
// short-circuit with jumps; floats get their own opcodes; a * or / by a
// constant that is a power of two gets a shift hint in check mode.
+// fold a binary operator on two known integers; *ok is set to 0 when it can't be folded
+int cfold(int o, int a, int b, word ok) {
+ if (o == bname[0]) return a * b;
+ if (o == bname[1] || o == bname[2]) { if (b == 0) { ok[0] = 0; return 0; } if (o == bname[1]) return a / b; return a % b; }
+ if (o == bname[3]) return a + b;
+ if (o == bname[4]) return a - b;
+ if (o == bname[5]) return a << b;
+ if (o == bname[6]) return a >> b;
+ if (o == bname[13]) return a & b;
+ if (o == bname[14]) return a ^ b;
+ if (o == bname[15]) return a | b;
+ ok[0] = 0; return 0;
+}
int if_comparison(int name) {
return name == s_eqeq || name == s_ne || name == s_lt || name == s_gt || name == s_le || name == s_ge;
}
int bin(int minp) {
- int c = unary(), b, p, a, j, lt, lb, rb, src, lf, rf, ls, rs, fresh, top = 0, il = -1, opp, lu, ru, xu; word borrowed, rightborrow, left_mask, right_mask, infer_left, infer_right;
+ int lk = 0, lkv = 0, c = unary(), b, p, a, j, lt, lb, rb, src, lf, rf, ls, rs, fresh, top = 0, il = -1, opp, lu, ru, xu; word borrowed, rightborrow, left_mask, right_mask, infer_left, infer_right;
if (fortest == 1) { fortest = 2; top = 1; ft_nops = 0; }
while (tk == T_OP) {
b = binfind(tv);
if (b < 0) return c;
p = bprec[b];
if (p < minp) return c;
+ lk = 0;
lb = -1;
if (c >= C_VAR && tracked(c - C_VAR)) lb = lroot(c - C_VAR); else lb = xbor;
borrowed = xaf; left_mask = effect_mask(c); lf = xfloat; ls = xstr; fresh = 0;
@@ -1807,6 +1822,7 @@ int bin(int minp) {
setlit(j, here);
xfloat = 0; xstr = 0;
} else {
+ lk = xconst && !lf && !ls; lkv = xcval;
c = bin(p + 1); infer_right = if_value; rightborrow = xaf; right_mask = effect_mask(c);
rb = -1;
if (c >= C_VAR && tracked(c - C_VAR)) rb = lroot(c - C_VAR); else rb = xbor;
@@ -1818,6 +1834,7 @@ int bin(int minp) {
shifthint(opp, xcval);
}
rf = xfloat; rs = xstr;
+ if (lk && xconst && !rf && !rs && !isfl(xty)) { lk = 2; lkv = cfold(bname[b], lkv, xcval, &lk); }
if (isfl(xty)) rf = 1;
if ((ls || rs) && (bname[b] == s_plus || bname[b] == s_eqeq || bname[b] == s_ne || bname[b] == s_lt || bname[b] == s_gt || bname[b] == s_le || bname[b] == s_ge)) {
if (!(ls && rs)) serr("a byte string needs a byte string on the other side");
@@ -1856,6 +1873,7 @@ int bin(int minp) {
if (xu > 0x40000000) xu = 0 - 1;
xub = xu; xubat = here;
lv = 0; lvk = LV_NONE; c = C_PLAIN; xzero = 0; xconst = 0; xlenloc = -1; xstamp = 0; xaf = 0; xvk = 0;
+ if (lk == 2 && blen[b] > 0) { xconst = 1; xcval = lkv; } // both sides constant: the value is known
effect_value = 0; if (isptr(xty) || xty == tword) effect_value = left_mask | right_mask;
if (fresh) c = C_FRESH;
if (borrowed && borrowed[2] == 5 && (isptr(xty) || xty == tword) && (bname[b] == s_plus || bname[b] == s_minus)) xaf = borrowed;
@@ -2032,7 +2050,7 @@ int blockexpr() {
// constant expressions, evaluated while compiling: numbers, named constants,
// addresses of globals and functions, unary minus and ~, parentheses, and the
-// operators + - * | & << >>. used for array lengths, enum values, const
+// operators * / % + - << >> & ^ | at c precedence. used for array lengths, enum values, const
// initializers and asm operands.
word cprim() {
int v, s, mc;
@@ -2040,6 +2058,10 @@ word cprim() {
if (accept(s_minus)) return 0 - cprim();
if (tk == T_OP && tv == uname[2]) { next(); return ~cprim(); }
if (accept(s_lp)) { v = cexpr(); expect(s_rp); return v; }
+ if (tk == T_ID && nloc > 0) { // a local const with a constant initializer (spec 3.14.2)
+ s = findloc(tv);
+ if (s >= 0 && (ltag[s] & LCONST) && !larr[s] && ltype[s] && treadonly(ltype[s])) { next(); return lkval[s]; }
+ }
if (tk == T_ID) {
s = lookup(tv);
if (mstruct && !ginst) { mc = lookup(methname(mstruct, tv)); if (mc >= 0 && skind[mc] == K_CONST) s = mc; }
@@ -2065,20 +2087,38 @@ word cprim() {
die("expected a constant");
return 0;
}
-// compile an expression: a primary, then the operators that follow it.
-int cexpr() {
- int v = cprim(), o;
+// a constant expression with c precedence: * / % above + -, above << >>,
+// above &, above ^, above | (spec 3.14). binary operators by precedence
+// climbing, each level reading its right side one level tighter.
+int cprec(int o) {
+ if (o == bname[0] || o == bname[1] || o == bname[2]) return 10;
+ if (o == bname[3] || o == bname[4]) return 9;
+ if (o == bname[5] || o == bname[6]) return 8;
+ if (o == bname[13]) return 5;
+ if (o == bname[14]) return 4;
+ if (o == bname[15]) return 3;
+ return 0;
+}
+int cbin(int minp) {
+ int v = cprim(), o, p, w;
while (tk == T_OP) {
- o = tv;
- if (o == bname[3]) { next(); v = v + cprim(); }
- else if (o == bname[4]) { next(); v = v - cprim(); }
- else if (o == bname[0]) { next(); v = v * cprim(); }
- else if (o == bname[15]) { next(); v = v | cprim(); }
- else if (o == bname[13]) { next(); v = v & cprim(); }
- else if (o == bname[5]) { next(); v = v << cprim(); }
- else if (o == bname[6]) { next(); v = v >> cprim(); }
- else return v;
+ o = tv; p = cprec(o);
+ if (p == 0 || p < minp) return v;
+ next(); w = cbin(p + 1);
+ if (o == bname[0]) v = v * w;
+ else if (o == bname[1] || o == bname[2]) {
+ if (w == 0) { die("division by zero in a constant expression"); return 0; }
+ if (o == bname[1]) v = v / w; else v = v % w;
+ }
+ else if (o == bname[3]) v = v + w;
+ else if (o == bname[4]) v = v - w;
+ else if (o == bname[5]) v = v << w;
+ else if (o == bname[6]) v = v >> w;
+ else if (o == bname[13]) v = v & w;
+ else if (o == bname[14]) v = v ^ w;
+ else v = v | w;
}
return v;
}
+int cexpr() { return cbin(1); }
generated by cgit v1.2.3 (git 2.39.1) at 2026-10-27 22:34:14 +0000