bounds: body scan, loop-entry hoisting, pointer proofs from requested size, --explain-checks v1 (non-o3 code)

1 files changed, 26 insertions, 7 deletions

diff --git a/src/compiler/expr.zc b/src/compiler/expr.zc
index a548f8d..8768658 100644
--- a/src/compiler/expr.zc
+++ b/src/compiler/expr.zc
@@ -647,6 +647,7 @@ word closure_layout(int closure_index, int count) {
 // variable in. ctx_push / ctx_pop save and restore the enclosing function's
 // compiler state around the body.
 int closure() {
+	char* xcf;
 	int np = 0; char*[24] pn; word[24] pty; int hop, entry, i, t, envl, ncap, c, result, declared = 0, tags = 0, tag, lt, lfl = tline; word[24] ptags;
 	word expected = closure_expected; closure_expected = 0;
 	reserve_closures(nclo + 1);
@@ -679,6 +680,7 @@ int closure() {
 	hop = hole(); op(O_JMP);
 	entry = here;
 	fn_begin(1, 0); fbnd = ctx_bnd();
+	xcf = xc_fn; xc_fn = "<closure>";
 	lt = lt_begin(entry, "<closure>", lfl);
 	if (declared) fty = declared;
 	prologue(); borrow_prologue();
@@ -700,7 +702,7 @@ int closure() {
 	if (result <= 0 || live) result = tword;
 	if (declared) result = declared;
 	epilogue();
-	lt_end(lt, here);
+	lt_end(lt, here); xc_fn = xcf;
 	nclo--;
 	c = nclo;
 	ncap = clo_n[c];
@@ -1363,7 +1365,7 @@ int ptr_chk(int sz) {
 // through rt.bchk, which only knows the size of a heap block's first word.
 int postfix() { return postfix_tail(primary()); }
 int postfix_tail(int c) {
-	int b, n, t, et; word ft; word[8] bs; int k, ci, was, al, ix, enh, cz, cj, place, offset, temporary, call_owner, readonly, ub, bl, ic, inr; word storage, storage_mask, call_origins;
+	int b, n, t, et; word ft; word[8] bs; int k, ci, was, al, ix, enh, cz, cj, place, offset, temporary, call_owner, readonly, ub, bl, ic, inr, hg, pn; word storage, storage_mask, call_origins;
 	while (1) {
 		if (tk == T_ID && tv == s_as) {	// e as T: same bits, another type
 			next(); t = ptype(); rval(); if (!xaf || xaf[2] != 5) xaf = 0; vf_coerce(t, 0);
@@ -1415,7 +1417,7 @@ int postfix_tail(int c) {
 					op(O_SWAP); lit(2); op(O_ADD); op(O_LD); lit(8); op(15); op(O_SWAP);
 					if (tbytes(et) != 1) { lit(tbytes(et)); op(15); }
 					op(O_ADD);
-				} else callname(intern("datb"));
+				} else { callname(intern("datb")); xc_note(0, XC_PACKED, place); }
 				et = tpk(et);
 			} else if (xty[0] == TY_DYN) {	// a growable array: bounds-checked, through the runtime
 				et = xty[4];
@@ -1468,7 +1470,7 @@ int postfix_tail(int c) {
 					setlit(k, here);
 					op(O_SWAP); lit(2); op(O_ADD); op(O_LD); op(O_SWAP);
 					mulsz(et); op(O_ADD);
-				} else callname(s_dat);
+				} else { callname(s_dat); xc_note(0, xc_reason(ix, al), place); }
 			} else {
 				tcneed(isptr(xty) || xty == tword, "only pointers and arrays can be indexed", xty);
 				et = telem(xty);
@@ -1490,9 +1492,26 @@ int postfix_tail(int c) {
 				tcneed(isnum(xty) || xty == tword, "an index has to be a number", xty);
 				expect(s_rk);
 				if (!ub && !inr) {
-					if (n >= 0) { if (!ic && !(ix >= 0 && proven_n(ix, n))) fixed_chk(n); }
-					else if (tbytes(et)) ptr_chk(0 - tbytes(et));
-					else ptr_chk(tsz(et));
+					if (n >= 0) {
+						if (!ic && !(ix >= 0 && proven_n(ix, n))) {
+							hg = hoist_guard(ix, n, 0 - 1);
+							fixed_chk(n);
+							if (hg >= 0) { setlit(hg, here); xc_note(0, XC_HOISTED, place); }
+							else xc_note(0, xc_reason(ix, 0 - 1), place);
+						}
+					} else {
+						pn = ptr_elems(storage, et, bl);
+						if (pn < 0) pn = ptr_elems(entry_fact(ix, bl), et, bl);	// the loop top forgot the fact; the body leaves the pointer alone (hoist_guard and proven_p check)
+						if (pn >= 0 && ix >= 0 && proven_p(ix, pn, bl)) pn = pn;	// the loop test proved it
+						else {
+							hg = 0 - 1; if (pn >= 0) hg = hoist_guard(ix, pn, bl);
+							if (tbytes(et)) ptr_chk(0 - tbytes(et));
+							else ptr_chk(tsz(et));
+							if (hg >= 0) { setlit(hg, here); xc_note(1, XC_HOISTED, place); }
+							else if (pn < 0) xc_note(1, XC_SIZE, place);
+							else xc_note(1, xc_reason(ix, bl), place);
+						}
+					}
 				}
 				if (tbytes(et)) {	// packed: byte address = base * 8 + index * bytes
 					if (tbytes(et) != 1) { lit(tbytes(et)); op(15); }