From bd62bceca6f43a92618a6d362f186918268d84c1 Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Sat, 8 Dec 2018 11:25:35 +0000
Subject: [PATCH] Fix BigInt normalization issue #293

---
 src/big_int.cpp     | 25 ++++++++++++++++++++-----
 src/check_expr.cpp  |  7 +++++++
 src/exact_value.cpp |  2 +-
 3 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/src/big_int.cpp b/src/big_int.cpp
index 8a64fbf21..f6b9b2eca 100644
--- a/src/big_int.cpp
+++ b/src/big_int.cpp
@@ -160,6 +160,10 @@ void big_int_rem_eq(BigInt *dst, BigInt const *x) {
 
 
 void big_int_normalize(BigInt *dst) {
+	if (dst->len == 1 && dst->d.word == 0) {
+		dst->len = 0;
+		return;
+	}
 	u64 const *words = big_int_ptr(dst);
 
 	i32 count_minus_one = -1;
@@ -172,6 +176,10 @@ void big_int_normalize(BigInt *dst) {
 
 	if (count_minus_one < 0) {
 		dst->neg = false;
+		if (words[0] == 0) {
+			dst->len = 0;
+			return;
+		}
 	}
 	dst->len = count_minus_one+1;
 	if (count_minus_one == 0) {
@@ -227,6 +235,7 @@ void big_int_init(BigInt *dst, BigInt const *src) {
 	big_int_alloc(dst, src->len, src->len);
 	u64 const *s = big_int_ptr(src);
 	gb_memmove(dst->d.words, s, gb_size_of(u64)*dst->len);
+	big_int_normalize(dst);
 }
 
 BigInt big_int_make(BigInt const *b, bool abs) {
@@ -258,10 +267,6 @@ BigInt big_int_make_i64(i64 x) {
 
 
 void big_int_from_string(BigInt *dst, String const &s) {
-#if 0
-	u64 u = u64_from_string(s);
-	big_int_from_u64(dst, u);
-#else
 	u64 base = 10;
 	bool has_prefix = false;
 	if (s.len > 2 && s[0] == '0') {
@@ -299,7 +304,7 @@ void big_int_from_string(BigInt *dst, String const &s) {
 		big_int_mul_eq(dst, &b);
 		big_int_add_eq(dst, &val);
 	}
-#endif
+	big_int_normalize(dst);
 }
 
 
@@ -547,6 +552,7 @@ void big_int_sub(BigInt *dst, BigInt const *x, BigInt const *y) {
 	BigInt neg_y = {};
 	big_int_neg(&neg_y, y);
 	big_int_add(dst, x, &neg_y);
+	big_int_normalize(dst);
 	return;
 }
 
@@ -585,6 +591,7 @@ void big_int_shl(BigInt *dst, BigInt const *x, BigInt const *y) {
 		if (dst->d.word > xd[0]) {
 			dst->len = 1;
 			dst->neg = x->neg;
+			big_int_normalize(dst);
 			return;
 		}
 	}
@@ -606,6 +613,7 @@ void big_int_shl(BigInt *dst, BigInt const *x, BigInt const *y) {
 			carry = 0;
 		}
 	}
+	big_int_normalize(dst);
 }
 
 void big_int_shr(BigInt *dst, BigInt const *x, BigInt const *y) {
@@ -662,6 +670,7 @@ void big_int_shr(BigInt *dst, BigInt const *x, BigInt const *y) {
 
 		carry = v << (64ull - remaining_shift_len);
 	}
+	big_int_normalize(dst);
 }
 
 void big_int_mul_u64(BigInt *dst, BigInt const *x, u64 y) {
@@ -690,6 +699,7 @@ void big_int_mul_u64(BigInt *dst, BigInt const *x, u64 y) {
 		big_int_add(&tmp, &shifted, &carry_shifted);
 		big_int_add(dst, &tmp, &result);
 	}
+	big_int_normalize(dst);
 }
 
 
@@ -1139,11 +1149,13 @@ void big_int_and_not(BigInt *dst, BigInt const *x, BigInt const *y) {
 
 			big_int__and_not_abs(dst, &y1, &x1);
 			dst->neg = false;
+			big_int_normalize(dst);
 			return;
 		}
 
 		big_int__and_not_abs(dst, x, y);
 		dst->neg = false;
+		big_int_normalize(dst);
 		return;
 	}
 
@@ -1157,6 +1169,7 @@ void big_int_and_not(BigInt *dst, BigInt const *x, BigInt const *y) {
 		big_int_or(&z1, &x1, &y1);
 		big_int_add(dst, &z1, &BIG_INT_ONE);
 		dst->neg = true;
+		big_int_normalize(dst);
 		return;
 	}
 
@@ -1166,6 +1179,7 @@ void big_int_and_not(BigInt *dst, BigInt const *x, BigInt const *y) {
 	big_int_sub_eq(&y1, &BIG_INT_ONE);
 	big_int_and(dst, &x1, &y1);
 	dst->neg = false;
+	big_int_normalize(dst);
 	return;
 }
 
@@ -1177,6 +1191,7 @@ void big_int__xor_abs(BigInt *dst, BigInt const *x, BigInt const *y) {
 	if (x->len == 1 && y->len == 1) {
 		dst->len = 1;
 		dst->d.word = xd[0] ^ yd[0];
+		big_int_normalize(dst);
 		return;
 	}
 
diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 86ff4f0cd..12616c9dd 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -1647,6 +1647,13 @@ void check_comparison(CheckerContext *c, Operand *x, Operand *y, TokenKind op) {
 						}
 					}
 				} else {
+					if (is_type_integer(x->type)) {
+						i64 i = exact_value_to_i64(x->value);
+						if (i == 0) {
+							auto bi = x->value.value_integer;
+							gb_printf_err("%s %d %lld\n", expr_to_string(x->expr), bi.len, bi.d.word);
+						}
+					}
 					x->value = exact_value_bool(compare_exact_values(op, x->value, y->value));
 				}
 			} else {
diff --git a/src/exact_value.cpp b/src/exact_value.cpp
index a4ceb5fa0..d1d44b7dd 100644
--- a/src/exact_value.cpp
+++ b/src/exact_value.cpp
@@ -553,7 +553,7 @@ ExactValue exact_binary_operator_value(TokenKind op, ExactValue x, ExactValue y)
 		case Token_Shr:    big_int_shr(&c, a, b);     break;
 		default: goto error;
 		}
-
+		big_int_normalize(&c);
 		ExactValue res = {ExactValue_Integer};
 		res.value_integer = c;
 		return res;