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Sema: divide by zero safety

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This commit is contained in:
Veikka Tuominen 2022-07-16 02:55:08 +03:00
parent 9f10dfcb54
commit 0782586b15
4 changed files with 75 additions and 8 deletions
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43
src/Sema.zig
View File

@ -11877,6 +11877,45 @@ fn analyzeArithmetic(
return sema.tupleFieldValByIndex(block, src, op_ov, 0, op_ov_tuple_ty);
}
}
switch (rs.air_tag) {
.div_float, .div_exact, .div_trunc, .div_floor => {
const ok = if (resolved_type.zigTypeTag() == .Vector) ok: {
const zero_val = try Value.Tag.repeated.create(sema.arena, Value.zero);
const zero = try sema.addConstant(sema.typeOf(casted_rhs), zero_val);
const ok = try block.addCmpVector(casted_rhs, zero, .neq, try sema.addType(resolved_type));
break :ok try block.addInst(.{
.tag = .reduce,
.data = .{ .reduce = .{
.operand = ok,
.operation = .And,
} },
});
} else ok: {
const zero = try sema.addConstant(sema.typeOf(casted_rhs), Value.zero);
break :ok try block.addBinOp(.cmp_neq, casted_rhs, zero);
};
try sema.addSafetyCheck(block, ok, .divide_by_zero);
},
.rem, .mod => {
const ok = if (resolved_type.zigTypeTag() == .Vector) ok: {
const zero_val = try Value.Tag.repeated.create(sema.arena, Value.zero);
const zero = try sema.addConstant(sema.typeOf(casted_rhs), zero_val);
const ok = try block.addCmpVector(casted_rhs, zero, if (scalar_tag == .Int) .gt else .neq, try sema.addType(resolved_type));
break :ok try block.addInst(.{
.tag = .reduce,
.data = .{ .reduce = .{
.operand = ok,
.operation = .And,
} },
});
} else ok: {
const zero = try sema.addConstant(sema.typeOf(casted_rhs), Value.zero);
break :ok try block.addBinOp(if (scalar_tag == .Int) .cmp_gt else .cmp_neq, casted_rhs, zero);
};
try sema.addSafetyCheck(block, ok, .remainder_division_zero_negative);
},
else => {},
}
}
return block.addBinOp(rs.air_tag, casted_lhs, casted_rhs);
}
@ -18813,6 +18852,8 @@ pub const PanicId = enum {
integer_overflow,
shl_overflow,
shr_overflow,
divide_by_zero,
remainder_division_zero_negative,
};
fn addSafetyCheck(
@ -19031,6 +19072,8 @@ fn safetyPanic(
.integer_overflow => "integer overflow",
.shl_overflow => "left shift overflowed bits",
.shr_overflow => "right shift overflowed bits",
.divide_by_zero => "division by zero",
.remainder_division_zero_negative => "remainder division by zero or negative value",
};
const msg_inst = msg_inst: {

10
test/cases/safety/integer division by zero - vectors.zig
View File

@ -1,9 +1,11 @@
const std = @import("std");
pub fn panic(message: []const u8, stack_trace: ?*std.builtin.StackTrace) noreturn {
_ = message;
_ = stack_trace;
std.process.exit(0);
if (std.mem.eql(u8, message, "division by zero")) {
std.process.exit(0);
}
std.process.exit(1);
}
pub fn main() !void {
var a: @Vector(4, i32) = [4]i32{111, 222, 333, 444};
@ -16,5 +18,5 @@ fn div0(a: @Vector(4, i32), b: @Vector(4, i32)) @Vector(4, i32) {
return @divTrunc(a, b);
}
// run
// backend=stage1
// target=native
// backend=llvm
// target=native

10
test/cases/safety/integer division by zero.zig
View File

@ -1,9 +1,11 @@
const std = @import("std");
pub fn panic(message: []const u8, stack_trace: ?*std.builtin.StackTrace) noreturn {
_ = message;
_ = stack_trace;
std.process.exit(0);
if (std.mem.eql(u8, message, "division by zero")) {
std.process.exit(0);
}
std.process.exit(1);
}
pub fn main() !void {
const x = div0(999, 0);
@ -14,5 +16,5 @@ fn div0(a: i32, b: i32) i32 {
return @divTrunc(a, b);
}
// run
// backend=stage1
// target=native
// backend=llvm
// target=native

20
test/cases/safety/remainder division by negative number.zig Normal file
View File

@ -0,0 +1,20 @@
const std = @import("std");
pub fn panic(message: []const u8, stack_trace: ?*std.builtin.StackTrace) noreturn {
_ = stack_trace;
if (std.mem.eql(u8, message, "remainder division by zero or negative value")) {
std.process.exit(0);
}
std.process.exit(1);
}
pub fn main() !void {
const x = div0(999, -1);
_ = x;
return error.TestFailed;
}
fn div0(a: i32, b: i32) i32 {
return @rem(a, b);
}
// run
// backend=llvm
// target=native