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sema: fix safe integer arithmetic operations on undefined values

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Previously `@as(i64, undefined) +% 1` would produce `@as(@TypeOf(undefined), undefined)` which now gives `@as(i64, undefined)`.
Previously `@as(i64, undefined) +| 1` would hit an assertion which now gives `@as(i64, undefined)`.
This commit is contained in:
Techatrix 2023-10-30 00:02:57 +01:00 • committed by Andrew Kelley
parent 4ace1f5a7f
commit ec358d6db5
10 changed files with 261 additions and 15 deletions
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18
src/Sema.zig
View file

@ -16140,6 +16140,10 @@ fn analyzeArithmetic(
return casted_lhs;
}
if (maybe_lhs_val) |lhs_val| {
if (lhs_val.isUndef(mod)) {
return mod.undefRef(resolved_type);
}
const val = if (scalar_tag == .ComptimeInt)
try sema.intAdd(lhs_val, rhs_val, resolved_type, undefined)
else
@ -16202,7 +16206,7 @@ fn analyzeArithmetic(
},
.subwrap => {
// Integers only; floats are checked above.
// If the RHS is zero, then the other operand is returned, even if it is undefined.
// If the RHS is zero, then the LHS is returned, even if it is undefined.
// If either of the operands are undefined, the result is undefined.
if (maybe_rhs_val) |rhs_val| {
if (rhs_val.isUndef(mod)) {
@ -16223,8 +16227,8 @@ fn analyzeArithmetic(
},
.sub_sat => {
// Integers only; floats are checked above.
// If the RHS is zero, result is LHS.
// If either of the operands are undefined, result is undefined.
// If the RHS is zero, then the LHS is returned, even if it is undefined.
// If either of the operands are undefined, the result is undefined.
if (maybe_rhs_val) |rhs_val| {
if (rhs_val.isUndef(mod)) {
return mod.undefRef(resolved_type);
@ -16255,7 +16259,9 @@ fn analyzeArithmetic(
// If either of the operands are undefined, it's a compile error
// because there is a possible value for which the addition would
// overflow (max_int), causing illegal behavior.
// For floats: either operand being undef makes the result undef.
//
// For floats:
// If either of the operands are undefined, the result is undefined.
// If either of the operands are inf, and the other operand is zero,
// the result is nan.
// If either of the operands are nan, the result is nan.
@ -38093,7 +38099,7 @@ fn numberAddWrapScalar(
ty: Type,
) !Value {
const mod = sema.mod;
if (lhs.isUndef(mod) or rhs.isUndef(mod)) return Value.undef;
if (lhs.isUndef(mod) or rhs.isUndef(mod)) return mod.undefValue(ty);
if (ty.zigTypeTag(mod) == .ComptimeInt) {
return sema.intAdd(lhs, rhs, ty, undefined);
@ -38183,7 +38189,7 @@ fn numberSubWrapScalar(
ty: Type,
) !Value {
const mod = sema.mod;
if (lhs.isUndef(mod) or rhs.isUndef(mod)) return Value.undef;
if (lhs.isUndef(mod) or rhs.isUndef(mod)) return mod.undefValue(ty);
if (ty.zigTypeTag(mod) == .ComptimeInt) {
return sema.intSub(lhs, rhs, ty, undefined);

20
test/cases/compile_errors/add_on_undefined_value.zig
View file

@ -1,10 +1,24 @@
comptime {
const a: i64 = undefined;
_ = a + a;
const undef: i64 = undefined;
const not_undef: i64 = 32;
// If either of the operands are zero, then the other operand is returned.
@compileLog(undef + 0);
@compileLog(not_undef + 0);
@compileLog(0 + undef);
@compileLog(0 + not_undef);
_ = undef + undef;
}
// error
// backend=stage2
// target=native
//
// :3:13: error: use of undefined value here causes undefined behavior
// :11:17: error: use of undefined value here causes undefined behavior
//
// Compile Log Output:
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, 32)

31
test/cases/compile_errors/add_sat_on_undefined_value.zig Normal file
View file

@ -0,0 +1,31 @@
comptime {
const undef: i64 = undefined;
const not_undef: i64 = 32;
// If either of the operands are zero, then the other operand is returned.
@compileLog(undef +| 0);
@compileLog(not_undef +| 0);
@compileLog(0 +| undef);
@compileLog(0 +| not_undef);
// If either of the operands are undefined, the result is undefined.
@compileLog(undef +| 1);
@compileLog(not_undef +| 1);
@compileLog(1 +| undef);
@compileLog(1 +| not_undef);
}
// error
// backend=stage2
// target=native
//
// :6:5: error: found compile log statement
//
// Compile Log Output:
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, 33)
// @as(i64, undefined)
// @as(i64, 33)

31
test/cases/compile_errors/add_wrap_on_undefined_value.zig Normal file
View file

@ -0,0 +1,31 @@
comptime {
const undef: i64 = undefined;
const not_undef: i64 = 32;
// If either of the operands are zero, then the other operand is returned.
@compileLog(undef +% 0);
@compileLog(not_undef +% 0);
@compileLog(0 +% undef);
@compileLog(0 +% not_undef);
// If either of the operands are undefined, the result is undefined.
@compileLog(undef +% 1);
@compileLog(not_undef +% 1);
@compileLog(1 +% undef);
@compileLog(1 +% not_undef);
}
// error
// backend=stage2
// target=native
//
// :6:5: error: found compile log statement
//
// Compile Log Output:
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, 33)
// @as(i64, undefined)
// @as(i64, 33)

34
test/cases/compile_errors/mult_on_undefined_value.zig
View file

@ -1,10 +1,38 @@
comptime {
const a: i64 = undefined;
_ = a * a;
const undef: i64 = undefined;
const not_undef: i64 = 32;
// If either of the operands are zero, the result is zero.
@compileLog(undef * 0);
@compileLog(not_undef * 0);
@compileLog(0 * undef);
@compileLog(0 * not_undef);
// If either of the operands are one, the result is the other
// operand, even if it is undefined.
@compileLog(undef * 1);
@compileLog(not_undef * 1);
@compileLog(1 * undef);
@compileLog(1 * not_undef);
// If either of the operands are undefined, it's a compile error
// because there is a possible value for which the addition would
// overflow (max_int), causing illegal behavior.
_ = undef * undef;
}
// error
// backend=stage2
// target=native
//
// :3:13: error: use of undefined value here causes undefined behavior
// :21:17: error: use of undefined value here causes undefined behavior
//
// Compile Log Output:
// @as(i64, 0)
// @as(i64, 0)
// @as(i64, 0)
// @as(i64, 0)
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, 32)

38
test/cases/compile_errors/mult_sat_on_undefined_value.zig Normal file
View file

@ -0,0 +1,38 @@
comptime {
const undef: i64 = undefined;
const not_undef: i64 = 32;
// If either of the operands are zero, the result is zero.
@compileLog(undef *| 0);
@compileLog(not_undef *| 0);
@compileLog(0 *| undef);
@compileLog(0 *| not_undef);
// If either of the operands are one, result is the other operand.
@compileLog(undef *| 1);
@compileLog(not_undef *| 1);
@compileLog(1 *| undef);
@compileLog(1 *| not_undef);
// If either of the operands are undefined, result is undefined.
@compileLog(undef *| 2);
@compileLog(2 *| undef);
}
// error
// backend=stage2
// target=native
//
// :6:5: error: found compile log statement
//
// Compile Log Output:
// @as(i64, 0)
// @as(i64, 0)
// @as(i64, 0)
// @as(i64, 0)
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, undefined)

38
test/cases/compile_errors/mult_wrap_on_undefined_value.zig Normal file
View file

@ -0,0 +1,38 @@
comptime {
const undef: i64 = undefined;
const not_undef: i64 = 32;
// If either of the operands are zero, the result is zero.
@compileLog(undef *% 0);
@compileLog(not_undef *% 0);
@compileLog(0 *% undef);
@compileLog(0 *% not_undef);
// If either of the operands are one, result is the other operand.
@compileLog(undef *% 1);
@compileLog(not_undef *% 1);
@compileLog(1 *% undef);
@compileLog(1 *% not_undef);
// If either of the operands are undefined, result is undefined.
@compileLog(undef *% 2);
@compileLog(2 *% undef);
}
// error
// backend=stage2
// target=native
//
// :6:5: error: found compile log statement
//
// Compile Log Output:
// @as(i64, 0)
// @as(i64, 0)
// @as(i64, 0)
// @as(i64, 0)
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, undefined)

16
test/cases/compile_errors/sub_on_undefined_value.zig
View file

@ -1,10 +1,20 @@
comptime {
const a: i64 = undefined;
_ = a - a;
const undef: i64 = undefined;
const not_undef: i64 = 32;
// If the rhs is zero, then the other operand is returned, even if it is undefined.
@compileLog(undef - 0);
@compileLog(not_undef - 0);
_ = undef - undef;
}
// error
// backend=stage2
// target=native
//
// :3:13: error: use of undefined value here causes undefined behavior
// :9:17: error: use of undefined value here causes undefined behavior
//
// Compile Log Output:
// @as(i64, undefined)
// @as(i64, 32)

25
test/cases/compile_errors/sub_sat_on_undefined_value.zig Normal file
View file

@ -0,0 +1,25 @@
comptime {
const undef: i64 = undefined;
const not_undef: i64 = 32;
// If the RHS is zero, then the LHS is returned, even if it is undefined.
@compileLog(undef -| 0);
@compileLog(not_undef -| 0);
// If either of the operands are undefined, the result is undefined.
@compileLog(undef -| not_undef);
@compileLog(not_undef -| undef);
@compileLog(undef -| undef);
}
// error
// backend=stage2
// target=native
//
// :6:5: error: found compile log statement
//
// Compile Log Output:
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, undefined)
// @as(i64, undefined)

25
test/cases/compile_errors/sub_wrap_on_undefined_value.zig Normal file
View file

@ -0,0 +1,25 @@
comptime {
const undef: i64 = undefined;
const not_undef: i64 = 32;
// If the RHS is zero, then the LHS is returned, even if it is undefined.
@compileLog(undef -% 0);
@compileLog(not_undef -% 0);
// If either of the operands are undefined, the result is undefined.
@compileLog(undef -% not_undef);
@compileLog(not_undef -% undef);
@compileLog(undef -% undef);
}
// error
// backend=stage2
// target=native
//
// :6:5: error: found compile log statement
//
// Compile Log Output:
// @as(i64, undefined)
// @as(i64, 32)
// @as(i64, undefined)
// @as(i64, undefined)
// @as(i64, undefined)