//@ compile-flags: -Zautodiff=Enable -C opt-level=3  -Clto=fat
//@ no-prefer-dynamic
//@ needs-enzyme
//
// In Enzyme, we test against a large range of LLVM versions (5+) and don't have overly many
// breakages. One benefit is that we match the IR generated by Enzyme only after running it
// through LLVM's O3 pipeline, which will remove most of the noise.
// However, our integration test could also be affected by changes in how rustc lowers MIR into
// LLVM-IR, which could cause additional noise and thus breakages. If that's the case, we should
// reduce this test to only match the first lines and the ret instructions.
//
// The function tested here has 4 inputs and 5 outputs, so we could either call forward-mode
// autodiff 4 times, or reverse mode 5 times. Since a forward-mode call is usually faster than
// reverse mode, we prefer it here. This file also tests a new optimization (batch mode), which
// allows us to call forward-mode autodiff only once, and get all 5 outputs in a single call.
//
// We support 2 different batch modes. `d_square2` has the same interface as scalar forward-mode,
// but each shadow argument is `width` times larger (thus 16 and 20 elements here).
// `d_square3` instead takes `width` (4) shadow arguments, which are all the same size as the
// original function arguments.
//
// FIXME(autodiff): We currently can't test `d_square1` and `d_square3` in the same file, since they
// generate the same dummy functions which get merged by LLVM, breaking pieces of our pipeline which
// try to rewrite the dummy functions later. We should consider to change to pure declarations both
// in our frontend and in the llvm backend to avoid these issues.

#![feature(autodiff)]

use std::autodiff::autodiff;

#[no_mangle]
//#[autodiff(d_square1, Forward, Dual, Dual)]
#[autodiff(d_square2, Forward, 4, Dualv, Dualv)]
#[autodiff(d_square3, Forward, 4, Dual, Dual)]
fn square(x: &[f32], y: &mut [f32]) {
    assert!(x.len() >= 4);
    assert!(y.len() >= 5);
    y[0] = 4.3 * x[0] + 1.2 * x[1] + 3.4 * x[2] + 2.1 * x[3];
    y[1] = 2.3 * x[0] + 4.5 * x[1] + 1.7 * x[2] + 6.4 * x[3];
    y[2] = 1.1 * x[0] + 3.3 * x[1] + 2.5 * x[2] + 4.7 * x[3];
    y[3] = 5.2 * x[0] + 1.4 * x[1] + 2.6 * x[2] + 3.8 * x[3];
    y[4] = 1.0 * x[0] + 2.0 * x[1] + 3.0 * x[2] + 4.0 * x[3];
}

fn main() {
    let x1 = std::hint::black_box(vec![0.0, 1.0, 2.0, 3.0]);

    let dx1 = std::hint::black_box(vec![1.0; 12]);

    let z1 = std::hint::black_box(vec![1.0, 0.0, 0.0, 0.0]);
    let z2 = std::hint::black_box(vec![0.0, 1.0, 0.0, 0.0]);
    let z3 = std::hint::black_box(vec![0.0, 0.0, 1.0, 0.0]);
    let z4 = std::hint::black_box(vec![0.0, 0.0, 0.0, 1.0]);

    let z5 = std::hint::black_box(vec![
        1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0,
    ]);

    let mut y1 = std::hint::black_box(vec![0.0; 5]);
    let mut y2 = std::hint::black_box(vec![0.0; 5]);
    let mut y3 = std::hint::black_box(vec![0.0; 5]);
    let mut y4 = std::hint::black_box(vec![0.0; 5]);

    let mut y5 = std::hint::black_box(vec![0.0; 5]);

    let mut y6 = std::hint::black_box(vec![0.0; 5]);

    let mut dy1_1 = std::hint::black_box(vec![0.0; 5]);
    let mut dy1_2 = std::hint::black_box(vec![0.0; 5]);
    let mut dy1_3 = std::hint::black_box(vec![0.0; 5]);
    let mut dy1_4 = std::hint::black_box(vec![0.0; 5]);

    let mut dy2 = std::hint::black_box(vec![0.0; 20]);

    let mut dy3_1 = std::hint::black_box(vec![0.0; 5]);
    let mut dy3_2 = std::hint::black_box(vec![0.0; 5]);
    let mut dy3_3 = std::hint::black_box(vec![0.0; 5]);
    let mut dy3_4 = std::hint::black_box(vec![0.0; 5]);

    // scalar.
    //d_square1(&x1, &z1, &mut y1, &mut dy1_1);
    //d_square1(&x1, &z2, &mut y2, &mut dy1_2);
    //d_square1(&x1, &z3, &mut y3, &mut dy1_3);
    //d_square1(&x1, &z4, &mut y4, &mut dy1_4);

    // assert y1 == y2 == y3 == y4
    //for i in 0..5 {
    //    assert_eq!(y1[i], y2[i]);
    //    assert_eq!(y1[i], y3[i]);
    //    assert_eq!(y1[i], y4[i]);
    //}

    // batch mode A)
    d_square2(&x1, &z5, &mut y5, &mut dy2);

    // assert y1 == y2 == y3 == y4 == y5
    //for i in 0..5 {
    //    assert_eq!(y1[i], y5[i]);
    //}

    // batch mode B)
    d_square3(&x1, &z1, &z2, &z3, &z4, &mut y6, &mut dy3_1, &mut dy3_2, &mut dy3_3, &mut dy3_4);
    for i in 0..5 {
        assert_eq!(y5[i], y6[i]);
    }

    for i in 0..5 {
        assert_eq!(dy2[0..5][i], dy3_1[i]);
        assert_eq!(dy2[5..10][i], dy3_2[i]);
        assert_eq!(dy2[10..15][i], dy3_3[i]);
        assert_eq!(dy2[15..20][i], dy3_4[i]);
    }
}