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cbe: fix ub triggered by mulw overflowing the promoted type

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Closes #21914
This commit is contained in:
Jacob Young 2025-02-09 08:10:20 -05:00 • committed by Andrew Kelley
parent 8d078f1ba2
commit 5433e0438c
2 changed files with 94 additions and 6 deletions
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44
lib/zig.h
View file

@ -650,7 +650,7 @@ typedef ptrdiff_t intptr_t;
zig_operator(Type, Type, operation, operator)
#define zig_shift_operator(Type, operation, operator) \
zig_operator(Type, uint8_t, operation, operator)
#define zig_int_helpers(w) \
#define zig_int_helpers(w, PromotedUnsigned) \
zig_basic_operator(uint##w##_t, and_u##w, &) \
zig_basic_operator( int##w##_t, and_i##w, &) \
zig_basic_operator(uint##w##_t, or_u##w, |) \
@ -726,16 +726,48 @@ typedef ptrdiff_t intptr_t;
} \
\
static inline uint##w##_t zig_mulw_u##w(uint##w##_t lhs, uint##w##_t rhs, uint8_t bits) { \
return zig_wrap_u##w(lhs * rhs, bits); \
return zig_wrap_u##w((PromotedUnsigned)lhs * rhs, bits); \
} \
\
static inline int##w##_t zig_mulw_i##w(int##w##_t lhs, int##w##_t rhs, uint8_t bits) { \
return zig_wrap_i##w((int##w##_t)((uint##w##_t)lhs * (uint##w##_t)rhs), bits); \
}
zig_int_helpers(8)
zig_int_helpers(16)
zig_int_helpers(32)
zig_int_helpers(64)
#if UINT8_MAX <= UINT_MAX
zig_int_helpers(8, unsigned int)
#elif UINT8_MAX <= ULONG_MAX
zig_int_helpers(8, unsigned long)
#elif UINT8_MAX <= ULLONG_MAX
zig_int_helpers(8, unsigned long long)
#else
zig_int_helpers(8, uint8_t)
#endif
#if UINT16_MAX <= UINT_MAX
zig_int_helpers(16, unsigned int)
#elif UINT16_MAX <= ULONG_MAX
zig_int_helpers(16, unsigned long)
#elif UINT16_MAX <= ULLONG_MAX
zig_int_helpers(16, unsigned long long)
#else
zig_int_helpers(16, uint16_t)
#endif
#if UINT32_MAX <= UINT_MAX
zig_int_helpers(32, unsigned int)
#elif UINT32_MAX <= ULONG_MAX
zig_int_helpers(32, unsigned long)
#elif UINT32_MAX <= ULLONG_MAX
zig_int_helpers(32, unsigned long long)
#else
zig_int_helpers(32, uint32_t)
#endif
#if UINT64_MAX <= UINT_MAX
zig_int_helpers(64, unsigned int)
#elif UINT64_MAX <= ULONG_MAX
zig_int_helpers(64, unsigned long)
#elif UINT64_MAX <= ULLONG_MAX
zig_int_helpers(64, unsigned long long)
#else
zig_int_helpers(64, uint64_t)
#endif
static inline bool zig_addo_u32(uint32_t *res, uint32_t lhs, uint32_t rhs, uint8_t bits) {
#if zig_has_builtin(add_overflow) || defined(zig_gnuc)

56
test/behavior/math.zig
View file

@ -778,6 +778,62 @@ fn should_not_be_zero(x: f128) !void {
try expect(x != 0.0);
}
test "umax wrapped squaring" {
if (builtin.zig_backend == .stage2_riscv64) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest;
{
var x: u4 = maxInt(u4);
x *%= x;
try expect(x == 1);
}
{
var x: u8 = maxInt(u8);
x *%= x;
try expect(x == 1);
}
{
var x: u12 = maxInt(u12);
x *%= x;
try expect(x == 1);
}
{
var x: u16 = maxInt(u16);
x *%= x;
try expect(x == 1);
}
{
var x: u24 = maxInt(u24);
x *%= x;
try expect(x == 1);
}
{
var x: u32 = maxInt(u32);
x *%= x;
try expect(x == 1);
}
{
var x: u48 = maxInt(u48);
x *%= x;
try expect(x == 1);
}
{
var x: u64 = maxInt(u64);
x *%= x;
try expect(x == 1);
}
{
var x: u96 = maxInt(u96);
x *%= x;
try expect(x == 1);
}
{
var x: u128 = maxInt(u128);
x *%= x;
try expect(x == 1);
}
}
test "128-bit multiplication" {
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO