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fix: spurious unsigned overflows #590

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merged 4 commits into from
Dec 3, 2023
+14 −4
Merged

fix: spurious unsigned overflows #590

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f170c62
fix: spurious unsigned add and mul overflows
eightfilms Nov 29, 2023
289b756
address comments
eightfilms Nov 29, 2023
a0cb4f8
add check for sub and div
eightfilms Nov 30, 2023
5d93208
add one more test for mul
eightfilms Nov 30, 2023
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12 changes: 8 additions & 4 deletions src/aro/Parser.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -6445,9 +6445,11 @@ fn addExpr(p: *Parser) Error!Result {
const lhs_ty = lhs.ty;
if (try lhs.adjustTypes(minus.?, &rhs, p, if (plus != null) .add else .sub)) {
if (plus != null) {
if (try lhs.val.add(lhs.val, rhs.val, lhs.ty, p.comp)) try p.errOverflow(plus.?, lhs);
if (try lhs.val.add(lhs.val, rhs.val, lhs.ty, p.comp) and
lhs.ty.signedness(p.comp) != .unsigned) try p.errOverflow(plus.?, lhs);
} else {
if (try lhs.val.sub(lhs.val, rhs.val, lhs.ty, p.comp)) try p.errOverflow(minus.?, lhs);
if (try lhs.val.sub(lhs.val, rhs.val, lhs.ty, p.comp) and
lhs.ty.signedness(p.comp) != .unsigned) try p.errOverflow(minus.?, lhs);
}
}
if (lhs.ty.specifier != .invalid and lhs_ty.isPtr() and !lhs_ty.isVoidStar() and lhs_ty.elemType().hasIncompleteSize()) {
Expand Down Expand Up @@ -6484,9 +6486,11 @@ fn mulExpr(p: *Parser) Error!Result {

if (try lhs.adjustTypes(percent.?, &rhs, p, if (tag == .mod_expr) .integer else .arithmetic)) {
if (mul != null) {
if (try lhs.val.mul(lhs.val, rhs.val, lhs.ty, p.comp)) try p.errOverflow(mul.?, lhs);
if (try lhs.val.mul(lhs.val, rhs.val, lhs.ty, p.comp) and
lhs.ty.signedness(p.comp) != .unsigned) try p.errOverflow(mul.?, lhs);
} else if (div != null) {
if (try lhs.val.div(lhs.val, rhs.val, lhs.ty, p.comp)) try p.errOverflow(mul.?, lhs);
if (try lhs.val.div(lhs.val, rhs.val, lhs.ty, p.comp) and
lhs.ty.signedness(p.comp) != .unsigned) try p.errOverflow(mul.?, lhs);
} else {
var res = try Value.rem(lhs.val, rhs.val, lhs.ty, p.comp);
if (res.opt_ref == .none) {
Expand Down
6 changes: 6 additions & 0 deletions test/cases/arithmetic overflow.c
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Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
_Static_assert(0xFFFFFFFF + 1 == 0, "'");
_Static_assert(1 + 0xFFFFFFFF == 0, "'");
_Static_assert(0 - 0x00000001 == 0xFFFFFFFF, "'");
_Static_assert(0x00000000 - 0x00000001 == 0xFFFFFFFF, "'");
_Static_assert(0x80000000 * 2 == 0, "'");
_Static_assert(2 * 0x80000000 == 0, "'");
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