1const compiler_rt = @import("../compiler_rt.zig");
2const symbol = compiler_rt.symbol;
3const testing = @import("std").testing;
4
5comptime {
6 symbol(&__addvsi3, "__addvsi3");
7}
8
9pub fn __addvsi3(a: i32, b: i32) callconv(.c) i32 {
10 const sum = a +% b;
11 // Overflow occurred iff both operands have the same sign, and the sign of the sum does
12 // not match it. In other words, iff the sum sign is not the sign of either operand.
13 if (((sum ^ a) & (sum ^ b)) < 0) @panic("integer overflow");
14 return sum;
15}
16
17test "addvsi3" {
18 // const min: i32 = -2147483648
19 // const max: i32 = 2147483647
20 // TODO write panic handler for testing panics
21 // try test__addvsi3(-2147483648, -1, -1); // panic
22 // try test__addvsi3(2147483647, 1, 1); // panic
23 try testing.expectEqual(-2147483648, __addvsi3(-2147483647, -1));
24 try testing.expectEqual(2147483647, __addvsi3(2147483646, 1));
25}