st-zrt 0.1.1

//! Execution-provider option builders (feature `ep`).
//!
//! GPU/accelerator EPs (CUDA, TensorRT, ROCm, CANN, DNNL) are configured via key/value
//! "provider options". Each [`*Options`] wraps the ORT options handle (create / update /
//! as_string / release); queue one on a [`crate::SessionOptions`] via
//! [`crate::SessionOptions::with_execution_provider`] and it is appended at session
//! creation. The options structs are pure config — creating/updating them does NOT load
//! the EP — so the lifecycle is exercisable on any host; a GPU/accelerator is needed only
//! to actually *run* a session with the EP appended.
//!
//! (OpenVINO V2 and VitisAI are also wrapped — they take key/value options directly at append
//! time, with no options handle. MIGraphX and the **deprecated** OpenVINO v1 are wrapped via flat
//! `#[repr(C)]` config structs ([`MigraphxOptions`] / [`OpenvinoOptions`]); prefer OpenVINO V2
//! over v1.)
use crate::allocator::Allocator;
use crate::session_options::SessionOptions;
use crate::{api, check, sys, Result};
use std::ffi::{c_char, c_void, CString};
use std::ptr;

/// A supported execution provider. The options-struct path (CUDA/TRT/ROCm/CANN/DNNL).
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub enum EpProvider {
    Cuda,
    TensorRt,
    Rocm,
    Cann,
    Dnnl,
    /// OpenVINO — the modern V2 key/value append path (`SessionOptionsAppendExecutionProvider_OpenVINO_V2`).
    OpenVinoV2,
    /// VitisAI — key/value append path (`SessionOptionsAppendExecutionProvider_VitisAI`).
    VitisAi,
}

/// Built-in CUDA execution-provider presets.
///
/// These are pure configuration. They do not load CUDA by themselves; they become active when
/// converted into [`CudaProviderOptions`] and queued on [`SessionOptions`] with
/// [`SessionOptions::with_cuda_options`] or [`SessionOptions::with_cuda_preset`].
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub enum CudaPreset {
    /// Latency/throughput preset when memory is not the primary constraint.
    ///
    /// Uses exhaustive cuDNN search, power-of-two arena growth, default-stream copies, and TF32.
    Performance { device_id: i32 },
    /// Static-shape graph replay preset.
    ///
    /// CUDA graph capture is useful only when model shapes and memory addresses are stable
    /// across runs, which matches ZRT's reusable lane buffers.
    CudaGraph { device_id: i32 },
    /// Bounded-memory preset.
    ///
    /// `gpu_mem_limit` is passed through to ORT in bytes and arena growth is kept closer to
    /// requested allocation sizes.
    LowMemory {
        device_id: i32,
        gpu_mem_limit: usize,
    },
}

impl CudaPreset {
    #[inline]
    pub fn performance(device_id: i32) -> Self {
        Self::Performance { device_id }
    }

    #[inline]
    pub fn cuda_graph(device_id: i32) -> Self {
        Self::CudaGraph { device_id }
    }

    #[inline]
    pub fn low_memory(device_id: i32, gpu_mem_limit: usize) -> Self {
        Self::LowMemory {
            device_id,
            gpu_mem_limit,
        }
    }
}

/// CUDA device arena growth strategy.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub enum CudaArenaExtendStrategy {
    NextPowerOfTwo,
    SameAsRequested,
}

impl CudaArenaExtendStrategy {
    #[inline]
    fn as_ort_value(self) -> &'static str {
        match self {
            Self::NextPowerOfTwo => "kNextPowerOfTwo",
            Self::SameAsRequested => "kSameAsRequested",
        }
    }
}

/// cuDNN convolution algorithm search mode.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub enum CudaCudnnConvAlgoSearch {
    Exhaustive,
    Heuristic,
    Default,
}

impl CudaCudnnConvAlgoSearch {
    #[inline]
    fn as_ort_value(self) -> &'static str {
        match self {
            Self::Exhaustive => "EXHAUSTIVE",
            Self::Heuristic => "HEURISTIC",
            Self::Default => "DEFAULT",
        }
    }
}

/// Pure-value CUDA execution-provider configuration.
///
/// This covers ORT CUDA provider string options, plus runtime-only pointer options such as
/// `user_compute_stream`. Unknown future string options can be supplied with
/// [`Self::with_raw`].
#[derive(Clone, Debug, Default, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct CudaProviderOptions {
    entries: Vec<(String, String)>,
    #[cfg_attr(feature = "serde", serde(skip))]
    pointer_entries: Vec<(String, usize)>,
}

impl CudaProviderOptions {
    pub fn new() -> Self {
        Self::default()
    }

    pub fn from_preset(preset: CudaPreset) -> Self {
        match preset {
            CudaPreset::Performance { device_id } => Self::new()
                .device_id(device_id)
                .arena_extend_strategy(CudaArenaExtendStrategy::NextPowerOfTwo)
                .cudnn_conv_algo_search(CudaCudnnConvAlgoSearch::Exhaustive)
                .do_copy_in_default_stream(true)
                .use_tf32(true),
            CudaPreset::CudaGraph { device_id } => Self::new()
                .device_id(device_id)
                .arena_extend_strategy(CudaArenaExtendStrategy::NextPowerOfTwo)
                .cudnn_conv_algo_search(CudaCudnnConvAlgoSearch::Exhaustive)
                .do_copy_in_default_stream(true)
                .enable_cuda_graph(true)
                .use_tf32(true),
            CudaPreset::LowMemory {
                device_id,
                gpu_mem_limit,
            } => Self::new()
                .device_id(device_id)
                .gpu_mem_limit(gpu_mem_limit)
                .arena_extend_strategy(CudaArenaExtendStrategy::SameAsRequested)
                .cudnn_conv_algo_search(CudaCudnnConvAlgoSearch::Heuristic)
                .do_copy_in_default_stream(true)
                .use_tf32(true),
        }
    }

    /// Add a raw CUDA provider key/value option.
    ///
    /// Use this for ORT options added after this wrapper. Pointer-valued options should use
    /// the dedicated pointer methods instead.
    pub fn with_raw(mut self, key: impl Into<String>, value: impl Into<String>) -> Self {
        self.entries.push((key.into(), value.into()));
        self
    }

    pub fn device_id(self, device_id: i32) -> Self {
        self.with_raw("device_id", device_id.to_string())
    }

    pub fn do_copy_in_default_stream(self, enabled: bool) -> Self {
        self.with_bool("do_copy_in_default_stream", enabled)
    }

    pub fn use_ep_level_unified_stream(self, enabled: bool) -> Self {
        self.with_bool("use_ep_level_unified_stream", enabled)
    }

    pub fn gpu_mem_limit(self, bytes: usize) -> Self {
        self.with_raw("gpu_mem_limit", bytes.to_string())
    }

    pub fn arena_extend_strategy(self, strategy: CudaArenaExtendStrategy) -> Self {
        self.with_raw("arena_extend_strategy", strategy.as_ort_value())
    }

    pub fn cudnn_conv_algo_search(self, search: CudaCudnnConvAlgoSearch) -> Self {
        self.with_raw("cudnn_conv_algo_search", search.as_ort_value())
    }

    pub fn cudnn_conv_use_max_workspace(self, enabled: bool) -> Self {
        self.with_bool("cudnn_conv_use_max_workspace", enabled)
    }

    pub fn cudnn_conv1d_pad_to_nc1d(self, enabled: bool) -> Self {
        self.with_bool("cudnn_conv1d_pad_to_nc1d", enabled)
    }

    pub fn enable_cuda_graph(self, enabled: bool) -> Self {
        self.with_bool("enable_cuda_graph", enabled)
    }

    pub fn enable_skip_layer_norm_strict_mode(self, enabled: bool) -> Self {
        self.with_bool("enable_skip_layer_norm_strict_mode", enabled)
    }

    pub fn use_tf32(self, enabled: bool) -> Self {
        self.with_bool("use_tf32", enabled)
    }

    pub fn prefer_nhwc(self, enabled: bool) -> Self {
        self.with_bool("prefer_nhwc", enabled)
    }

    pub fn tunable_op_enable(self, enabled: bool) -> Self {
        self.with_bool("tunable_op_enable", enabled)
    }

    pub fn tunable_op_tuning_enable(self, enabled: bool) -> Self {
        self.with_bool("tunable_op_tuning_enable", enabled)
    }

    pub fn tunable_op_max_tuning_duration_ms(self, duration_ms: i32) -> Self {
        self.with_raw("tunable_op_max_tuning_duration_ms", duration_ms.to_string())
    }

    pub fn gpu_external_alloc_address(self, address: usize) -> Self {
        self.with_raw("gpu_external_alloc", address.to_string())
    }

    pub fn gpu_external_free_address(self, address: usize) -> Self {
        self.with_raw("gpu_external_free", address.to_string())
    }

    pub fn gpu_external_empty_cache_address(self, address: usize) -> Self {
        self.with_raw("gpu_external_empty_cache", address.to_string())
    }

    pub fn external_allocator_addresses(
        self, alloc: usize, free: usize, empty_cache: usize,
    ) -> Self {
        self.gpu_external_alloc_address(alloc)
            .gpu_external_free_address(free)
            .gpu_external_empty_cache_address(empty_cache)
    }

    /// Set ORT's pointer-valued `user_compute_stream` option.
    ///
    /// # Safety
    ///
    /// `stream` must be a valid CUDA stream pointer for the target device and must remain valid
    /// for the lifetime required by the ORT session. This option cannot be represented as a
    /// string through ORT's C API.
    pub unsafe fn user_compute_stream(mut self, stream: *mut c_void) -> Self {
        self.pointer_entries
            .push(("user_compute_stream".to_owned(), stream as usize));
        self
    }

    #[inline]
    pub fn entries(&self) -> &[(String, String)] {
        &self.entries
    }

    #[inline]
    pub fn pointer_entries(&self) -> &[(String, usize)] {
        &self.pointer_entries
    }

    fn with_bool(self, key: &'static str, enabled: bool) -> Self {
        self.with_raw(key, if enabled { "1" } else { "0" })
    }

    fn entry_refs(entries: &[(String, String)]) -> Vec<(&str, &str)> {
        entries
            .iter()
            .map(|(key, value)| (key.as_str(), value.as_str()))
            .collect()
    }
}

/// A queued EP append: which provider + its key/value options. Pure data (no handles) so
/// [`SessionOptions`] stays cloneable and free of EP types when the feature is off.
#[derive(Clone)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub(crate) struct EpConfig {
    provider: EpProvider,
    #[cfg_attr(feature = "serde", serde(with = "crate::serde_support::kv_pairs"))]
    entries: Vec<(CString, CString)>,
    #[cfg_attr(feature = "serde", serde(skip))]
    pointer_entries: Vec<(CString, usize)>,
}

/// Generate an EP options type for one provider:
/// - `new(entries)` — create the handle + apply key/value pairs
/// - `as_string()` — serialize back to `"k=v;…"`
/// - RAII release on drop
/// - `append_raw(opts)` — register on a session-options handle
macro_rules! ep_options {
    ($Type:ident, $handle:ty, $create:ident, $update:ident, $as_string:ident, $release:ident, $append:ident) => {
        /// Provider options for an execution provider. Built from key/value pairs;
        /// released on drop.
        pub struct $Type(*mut $handle);

        impl $Type {
            /// Create the options handle and apply `entries` (key/value pairs, e.g.
            /// `("device_id", "0")`). Errors if a key/value contains a NUL byte.
            pub fn new(entries: &[(&str, &str)]) -> Result<Self> {
                let api = api();
                let mut h: *mut $handle = ptr::null_mut();
                check(unsafe { api.$create()(&mut h) })?;
                let h = crate::ensure_non_null(h, "execution provider options")?;
                let me = Self(h);
                let cstrs: Vec<(CString, CString)> = entries
                    .iter()
                    .map(|(k, v)| Ok((CString::new(*k)?, CString::new(*v)?)))
                    .collect::<std::result::Result<_, std::ffi::NulError>>()
                    .map_err(|_| {
                        crate::Error::new(-1, "ep option key/value contains a NUL byte")
                    })?;
                let keys: Vec<*const c_char> = cstrs.iter().map(|(k, _)| k.as_ptr()).collect();
                let vals: Vec<*const c_char> = cstrs.iter().map(|(_, v)| v.as_ptr()).collect();
                check(unsafe { api.$update()(me.0, keys.as_ptr(), vals.as_ptr(), entries.len()) })?;
                Ok(me)
            }

            /// Serialize the options to a string (e.g. `"device_id=0;…"`). The buffer is
            /// engine-allocated and freed via the default allocator.
            pub fn as_string(&self) -> Result<String> {
                let api = api();
                let alloc = Allocator::get_default()?;
                let mut raw: *mut c_char = ptr::null_mut();
                check(unsafe {
                    api.$as_string()(self.0 as *const $handle, alloc.alloc, &mut raw)
                })?;
                if raw.is_null() {
                    return Ok(String::new());
                }
                let s = unsafe { crate::cstr_to_string(raw, "execution provider options") };
                let free = unsafe { alloc.free(raw as *mut c_void) };
                free?;
                s
            }

            /// Append this EP to a session-options handle (`SessionOptionsAppend…`).
            pub(crate) fn append_raw(&self, opts: *mut sys::SessionOptionsHandle) -> Result<()> {
                check(unsafe { api().$append()(opts, self.0 as *const $handle) })
            }
        }

        impl Drop for $Type {
            fn drop(&mut self) {
                unsafe { api().$release()(self.0) }
            }
        }
        unsafe impl Send for $Type {}
        unsafe impl Sync for $Type {}
    };
}

ep_options!(
    CudaOptions,
    sys::CUDAProviderOptionsV2Handle,
    create_cuda_provider_options,
    update_cuda_provider_options,
    get_cuda_provider_options_as_string,
    release_cuda_provider_options,
    session_options_append_execution_provider_cuda_v2
);

impl CudaOptions {
    /// Create CUDA provider options from a built-in preset.
    pub fn from_preset(preset: CudaPreset) -> Result<Self> {
        Self::from_config(&CudaProviderOptions::from_preset(preset))
    }

    /// Create CUDA provider options from a pure-value CUDA config.
    pub fn from_config(config: &CudaProviderOptions) -> Result<Self> {
        let refs = CudaProviderOptions::entry_refs(config.entries());
        let options = Self::new(&refs)?;
        for (key, value) in config.pointer_entries() {
            let key = CString::new(key.as_str())
                .map_err(|_| crate::Error::new(-1, "ep option key contains a NUL byte"))?;
            check(unsafe {
                api().update_cuda_provider_options_with_value()(
                    options.0,
                    key.as_ptr(),
                    *value as *mut c_void,
                )
            })?;
        }
        Ok(options)
    }

    /// Update a pointer-valued CUDA provider option on this live ORT options handle.
    ///
    /// # Safety
    ///
    /// `value` must point to an object valid for the lifetime ORT requires for `key`.
    pub unsafe fn update_with_value(&mut self, key: &str, value: *mut c_void) -> Result<&mut Self> {
        let key = CString::new(key)
            .map_err(|_| crate::Error::new(-1, "ep option key contains a NUL byte"))?;
        check(api().update_cuda_provider_options_with_value()(
            self.0,
            key.as_ptr(),
            value,
        ))?;
        Ok(self)
    }
}
ep_options!(
    TensorRtOptions,
    sys::TensorRTProviderOptionsV2Handle,
    create_tensor_rt_provider_options,
    update_tensor_rt_provider_options,
    get_tensor_rt_provider_options_as_string,
    release_tensor_rt_provider_options,
    session_options_append_execution_provider__tensor_rt_v2
);
ep_options!(
    RocmOptions,
    sys::ROCMProviderOptionsHandle,
    create_rocm_provider_options,
    update_rocm_provider_options,
    get_rocm_provider_options_as_string,
    release_rocm_provider_options,
    session_options_append_execution_provider_rocm
);
ep_options!(
    CannOptions,
    sys::CANNProviderOptionsHandle,
    create_cann_provider_options,
    update_cann_provider_options,
    get_cann_provider_options_as_string,
    release_cann_provider_options,
    session_options_append_execution_provider_cann
);
ep_options!(
    DnnlOptions,
    sys::DnnlProviderOptionsHandle,
    create_dnnl_provider_options,
    update_dnnl_provider_options,
    get_dnnl_provider_options_as_string,
    release_dnnl_provider_options,
    session_options_append_execution_provider__dnnl
);

/// Append a key/value-direct EP (OpenVINO V2, VitisAI) — no options handle; the key/value
/// pairs are passed straight to the `SessionOptionsAppend…` call.
fn append_kv(
    f: unsafe extern "C" fn(
        *mut sys::SessionOptionsHandle,
        *const *const c_char,
        *const *const c_char,
        usize,
    ) -> sys::StatusPtr,
    opts: *mut sys::SessionOptionsHandle, entries: &[(CString, CString)],
) -> Result<()> {
    let keys: Vec<*const c_char> = entries.iter().map(|(k, _)| k.as_ptr()).collect();
    let vals: Vec<*const c_char> = entries.iter().map(|(_, v)| v.as_ptr()).collect();
    check(unsafe { f(opts, keys.as_ptr(), vals.as_ptr(), entries.len()) })
}

/// Apply a queued EP config to a built session-options handle (called from
/// `SessionOptions::build_handle`). The options-handle providers create + append + release
/// (ORT copies the config during append); the key/value providers append the pairs directly.
pub(crate) fn apply(opts: *mut sys::SessionOptionsHandle, cfg: &EpConfig) -> Result<()> {
    let entries: Vec<(&str, &str)> = cfg
        .entries
        .iter()
        .map(|(k, v)| Ok((k.to_str()?, v.to_str()?)))
        .collect::<std::result::Result<_, std::str::Utf8Error>>()
        .map_err(|_| crate::Error::new(-1, "ep option entry is not UTF-8"))?;
    match cfg.provider {
        EpProvider::Cuda => {
            let options = CudaOptions::new(&entries)?;
            for (key, value) in &cfg.pointer_entries {
                check(unsafe {
                    api().update_cuda_provider_options_with_value()(
                        options.0,
                        key.as_ptr(),
                        *value as *mut c_void,
                    )
                })?;
            }
            options.append_raw(opts)
        },
        EpProvider::TensorRt => TensorRtOptions::new(&entries)?.append_raw(opts),
        EpProvider::Rocm => RocmOptions::new(&entries)?.append_raw(opts),
        EpProvider::Cann => CannOptions::new(&entries)?.append_raw(opts),
        EpProvider::Dnnl => DnnlOptions::new(&entries)?.append_raw(opts),
        // Key/value-direct appends (no options handle). On a CPU host these return
        // "EP not available" — the call still proves the index/signature is right.
        EpProvider::OpenVinoV2 => append_kv(
            unsafe { api().session_options_append_execution_provider__open_vino_v2() },
            opts,
            &cfg.entries,
        ),
        EpProvider::VitisAi => append_kv(
            unsafe { api().session_options_append_execution_provider__vitis_ai() },
            opts,
            &cfg.entries,
        ),
    }
}

// ─── MIGraphX (flat C-struct EP) ─────────────────────────────────────────────
//
// MIGraphX has no key/value append and no options handle: the caller fills a flat
// `OrtMIGraphXProviderOptions` C struct and passes it by pointer to the append. Layout is
// verified against the real header via a C probe (sizeof=88; the offsets below are pinned by
// `migraphx_struct_layout`). The `const char*` path fields are borrowed — `MigraphxOptions`
// owns the strings and builds this struct transiently for the append.

/// `OrtMIGraphXProviderOptions` (`onnxruntime_c_api.h:840`). `#[repr(C)]`; layout verified.
/// Private — reach it through the [`MigraphxOptions`] builder.
#[repr(C)]
struct MigraphxProviderOptionsRaw {
    device_id: i32,
    fp16_enable: i32,
    fp8_enable: i32,
    int8_enable: i32,
    use_native_calibration_table: i32,
    int8_calibration_table_name: *const c_char,
    save_compiled_model: i32,
    save_model_path: *const c_char,
    load_compiled_model: i32,
    load_model_path: *const c_char,
    exhaustive_tune: bool,
    mem_limit: usize,
    arena_extend_strategy: i32,
}
const _: () = assert!(std::mem::size_of::<MigraphxProviderOptionsRaw>() == 88);

/// Safe builder for the MIGraphX execution-provider config (`SessionOptionsAppendExecutionProvider_MIGraphX`).
/// Owns the path strings. Defaults match the header: `mem_limit` = `usize::MAX` (use all
/// available memory), `arena_extend_strategy` = 0 (`kNextPowerOfTwo`), all precision flags off.
/// Build one, then queue it on [`crate::SessionOptions`] via
/// [`SessionOptions::with_migraphx`].
#[derive(Clone)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct MigraphxOptions {
    device_id: i32,
    fp16_enable: i32,
    fp8_enable: i32,
    int8_enable: i32,
    use_native_calibration_table: i32,
    #[cfg_attr(feature = "serde", serde(with = "crate::serde_support::opt_cstr"))]
    int8_calibration_table_name: Option<CString>,
    save_compiled_model: i32,
    #[cfg_attr(feature = "serde", serde(with = "crate::serde_support::opt_cstr"))]
    save_model_path: Option<CString>,
    load_compiled_model: i32,
    #[cfg_attr(feature = "serde", serde(with = "crate::serde_support::opt_cstr"))]
    load_model_path: Option<CString>,
    exhaustive_tune: bool,
    mem_limit: usize,
    arena_extend_strategy: i32,
}

impl Default for MigraphxOptions {
    fn default() -> Self {
        Self {
            device_id: 0,
            fp16_enable: 0,
            fp8_enable: 0,
            int8_enable: 0,
            use_native_calibration_table: 0,
            int8_calibration_table_name: None,
            save_compiled_model: 0,
            save_model_path: None,
            load_compiled_model: 0,
            load_model_path: None,
            exhaustive_tune: false,
            mem_limit: usize::MAX,    // header default: SIZE_MAX
            arena_extend_strategy: 0, // 0 = kNextPowerOfTwo
        }
    }
}

impl MigraphxOptions {
    /// Defaults (see the type docs).
    pub fn new() -> Self {
        Self::default()
    }
    /// hip device id.
    pub fn device_id(mut self, id: i32) -> Self {
        self.device_id = id;
        self
    }
    /// FP16 precision.
    pub fn fp16(mut self, on: bool) -> Self {
        self.fp16_enable = on as i32;
        self
    }
    /// FP8 precision.
    pub fn fp8(mut self, on: bool) -> Self {
        self.fp8_enable = on as i32;
        self
    }
    /// INT8 precision.
    pub fn int8(mut self, on: bool) -> Self {
        self.int8_enable = on as i32;
        self
    }
    /// Use the native INT8 calibration table at `path`. Errors if `path` contains a NUL.
    pub fn int8_calibration_table(
        mut self, path: &str,
    ) -> std::result::Result<Self, std::ffi::NulError> {
        self.int8_calibration_table_name = Some(CString::new(path)?);
        Ok(self)
    }
    /// Save the compiled model to `path`. Errors if `path` contains a NUL.
    pub fn save_model_path(mut self, path: &str) -> std::result::Result<Self, std::ffi::NulError> {
        self.save_model_path = Some(CString::new(path)?);
        self.save_compiled_model = 1;
        Ok(self)
    }
    /// Load a compiled model from `path`. Errors if `path` contains a NUL.
    pub fn load_model_path(mut self, path: &str) -> std::result::Result<Self, std::ffi::NulError> {
        self.load_model_path = Some(CString::new(path)?);
        self.load_compiled_model = 1;
        Ok(self)
    }
    /// Tuned compile.
    pub fn exhaustive_tune(mut self, on: bool) -> Self {
        self.exhaustive_tune = on;
        self
    }
    /// Memory limit in bytes (`usize::MAX` = use all available memory).
    pub fn mem_limit(mut self, bytes: usize) -> Self {
        self.mem_limit = bytes;
        self
    }
    /// Arena-extend strategy: `0` = `kNextPowerOfTwo`, `1` = `kSameAsRequested`.
    pub fn arena_extend_strategy(mut self, strategy: i32) -> Self {
        self.arena_extend_strategy = strategy;
        self
    }

    /// Build the transient C struct and append MIGraphX to a session-options handle. On a
    /// CPU/non-MIGraphX host this returns "EP not available".
    pub(crate) fn append_raw(&self, opts: *mut sys::SessionOptionsHandle) -> Result<()> {
        let raw = MigraphxProviderOptionsRaw {
            device_id: self.device_id,
            fp16_enable: self.fp16_enable,
            fp8_enable: self.fp8_enable,
            int8_enable: self.int8_enable,
            use_native_calibration_table: self.use_native_calibration_table,
            int8_calibration_table_name: self
                .int8_calibration_table_name
                .as_ref()
                .map_or(ptr::null(), |s| s.as_ptr()),
            save_compiled_model: self.save_compiled_model,
            save_model_path: self
                .save_model_path
                .as_ref()
                .map_or(ptr::null(), |s| s.as_ptr()),
            load_compiled_model: self.load_compiled_model,
            load_model_path: self
                .load_model_path
                .as_ref()
                .map_or(ptr::null(), |s| s.as_ptr()),
            exhaustive_tune: self.exhaustive_tune,
            mem_limit: self.mem_limit,
            arena_extend_strategy: self.arena_extend_strategy,
        };
        check(unsafe {
            api().session_options_append_execution_provider_mi_graph_x()(
                opts,
                &raw as *const MigraphxProviderOptionsRaw
                    as *const sys::MIGraphXProviderOptionsHandle,
            )
        })
    }
}

// ─── OpenVINO v1 (flat C-struct EP, deprecated) ──────────────────────────────
//
// Like MIGraphX, the v1 OpenVINO append takes a flat C struct by pointer — no key/value
// options, no handle. **Deprecated upstream** (the V2 key/value path supersedes it; see
// [`EpProvider::OpenVinoV2`]); wrapped for completeness/legacy configs. Layout is verified
// against the real header via a C probe (sizeof=56; offsets pinned by `openvino_struct_layout`).
// The `const char*` fields are borrowed for the append — [`OpenvinoOptions`] owns the strings
// and builds this struct transiently.

/// `OrtOpenVINOProviderOptions` (`onnxruntime_c_api.h:879`). `#[repr(C)]`; layout verified
/// (sizeof=56). Private — reach it through the [`OpenvinoOptions`] builder.
#[repr(C)]
struct OpenvinoProviderOptionsRaw {
    device_type: *const c_char,
    enable_npu_fast_compile: u8,
    device_id: *const c_char,
    num_of_threads: usize,
    cache_dir: *const c_char,
    context: *mut c_void,
    enable_opencl_throttling: u8,
    enable_dynamic_shapes: u8,
}
const _: () = assert!(std::mem::size_of::<OpenvinoProviderOptionsRaw>() == 56);

/// Safe builder for the **deprecated** OpenVINO v1 execution-provider config
/// (`SessionOptionsAppendExecutionProvider_OpenVINO`). Prefer
/// [`SessionOptions::with_execution_provider`] with [`EpProvider::OpenVinoV2`]; this flat-struct
/// path is kept only for legacy configs. Owns the device/path strings; builds the C struct
/// transiently for the append. Defaults match the header (all fields zero/null: `device_type`
/// null, `num_of_threads` 0 = ORT default, every flag off). Build one, then queue it on a
/// [`crate::SessionOptions`] via [`SessionOptions::with_openvino`].
#[derive(Clone, Default)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct OpenvinoOptions {
    #[cfg_attr(feature = "serde", serde(with = "crate::serde_support::opt_cstr"))]
    device_type: Option<CString>,
    enable_npu_fast_compile: u8,
    #[cfg_attr(feature = "serde", serde(with = "crate::serde_support::opt_cstr"))]
    device_id: Option<CString>,
    num_of_threads: usize,
    #[cfg_attr(feature = "serde", serde(with = "crate::serde_support::opt_cstr"))]
    cache_dir: Option<CString>,
    // `context` (void*) is an advanced OpenCL interop handle, left null — not exposed.
    enable_opencl_throttling: u8,
    enable_dynamic_shapes: u8,
}

impl OpenvinoOptions {
    /// Defaults (see the type docs).
    pub fn new() -> Self {
        Self::default()
    }
    /// Device type. Valid settings: `"CPU_FP32"`, `"CPU_FP16"`, `"GPU_FP32"`, `"GPU_FP16"`.
    /// Errors if `ty` contains a NUL.
    pub fn device_type(mut self, ty: &str) -> std::result::Result<Self, std::ffi::NulError> {
        self.device_type = Some(CString::new(ty)?);
        Ok(self)
    }
    /// Enable NPU fast compile.
    pub fn enable_npu_fast_compile(mut self, on: bool) -> Self {
        self.enable_npu_fast_compile = on as u8;
        self
    }
    /// Device id (e.g. `"0"`). Errors if `id` contains a NUL.
    pub fn device_id(mut self, id: &str) -> std::result::Result<Self, std::ffi::NulError> {
        self.device_id = Some(CString::new(id)?);
        Ok(self)
    }
    /// Number of threads (`0` = ORT default).
    pub fn num_of_threads(mut self, n: usize) -> Self {
        self.num_of_threads = n;
        self
    }
    /// Model-compile cache directory. Errors if `path` contains a NUL.
    pub fn cache_dir(mut self, path: &str) -> std::result::Result<Self, std::ffi::NulError> {
        self.cache_dir = Some(CString::new(path)?);
        Ok(self)
    }
    /// Enable OpenCL throttling.
    pub fn enable_opencl_throttling(mut self, on: bool) -> Self {
        self.enable_opencl_throttling = on as u8;
        self
    }
    /// Enable dynamic shapes.
    pub fn enable_dynamic_shapes(mut self, on: bool) -> Self {
        self.enable_dynamic_shapes = on as u8;
        self
    }

    /// Build the transient C struct and append OpenVINO v1 to a session-options handle. On a
    /// CPU/non-OpenVINO host this returns "EP not available".
    pub(crate) fn append_raw(&self, opts: *mut sys::SessionOptionsHandle) -> Result<()> {
        let raw = OpenvinoProviderOptionsRaw {
            device_type: self
                .device_type
                .as_ref()
                .map_or(ptr::null(), |s| s.as_ptr()),
            enable_npu_fast_compile: self.enable_npu_fast_compile,
            device_id: self.device_id.as_ref().map_or(ptr::null(), |s| s.as_ptr()),
            num_of_threads: self.num_of_threads,
            cache_dir: self.cache_dir.as_ref().map_or(ptr::null(), |s| s.as_ptr()),
            context: ptr::null_mut(),
            enable_opencl_throttling: self.enable_opencl_throttling,
            enable_dynamic_shapes: self.enable_dynamic_shapes,
        };
        check(unsafe {
            api().session_options_append_execution_provider__open_vino()(
                opts,
                &raw as *const OpenvinoProviderOptionsRaw
                    as *const sys::OpenVINOProviderOptionsHandle,
            )
        })
    }
}

impl SessionOptions {
    /// Queue an execution provider with the given key/value options; appended at session
    /// creation (`Session::new`). A GPU/accelerator is required only to *run* the session.
    pub fn with_execution_provider(
        mut self, provider: EpProvider, entries: &[(&str, &str)],
    ) -> Result<Self> {
        let kv: Vec<(CString, CString)> = entries
            .iter()
            .map(|(k, v)| Ok((CString::new(*k)?, CString::new(*v)?)))
            .collect::<std::result::Result<_, std::ffi::NulError>>()
            .map_err(|_| crate::Error::new(-1, "ep option key/value contains a NUL byte"))?;
        self.ep_configs.push(EpConfig {
            provider,
            entries: kv,
            pointer_entries: Vec::new(),
        });
        Ok(self)
    }

    /// Queue a typed CUDA execution-provider configuration.
    pub fn with_cuda_options(mut self, options: CudaProviderOptions) -> Result<Self> {
        let entries: Vec<(CString, CString)> = options
            .entries
            .into_iter()
            .map(|(k, v)| Ok((CString::new(k)?, CString::new(v)?)))
            .collect::<std::result::Result<_, std::ffi::NulError>>()
            .map_err(|_| crate::Error::new(-1, "cuda ep option key/value contains a NUL byte"))?;
        let pointer_entries: Vec<(CString, usize)> = options
            .pointer_entries
            .into_iter()
            .map(|(k, v)| Ok((CString::new(k)?, v)))
            .collect::<std::result::Result<_, std::ffi::NulError>>()
            .map_err(|_| crate::Error::new(-1, "cuda ep option key contains a NUL byte"))?;
        self.ep_configs.push(EpConfig {
            provider: EpProvider::Cuda,
            entries,
            pointer_entries,
        });
        Ok(self)
    }

    /// Queue a built-in CUDA preset.
    pub fn with_cuda_preset(self, preset: CudaPreset) -> Result<Self> {
        self.with_cuda_options(CudaProviderOptions::from_preset(preset))
    }

    /// Queue the MIGraphX execution provider (AMD ROCm graph EP). MIGraphX takes a flat config
    /// struct, not key/value options, so it has its own builder — see [`MigraphxOptions`]. A
    /// MIGraphX-capable GPU is required only to *run* the session.
    pub fn with_migraphx(mut self, options: &MigraphxOptions) -> Self {
        self.migraphx.push(options.clone());
        self
    }

    /// Queue the **deprecated** OpenVINO v1 execution provider (flat config struct). Prefer
    /// [`Self::with_execution_provider`] with [`EpProvider::OpenVinoV2`]; this is for legacy
    /// configs. An OpenVINO-capable device is required only to *run* the session.
    pub fn with_openvino(mut self, options: &OpenvinoOptions) -> Self {
        self.openvino.push(options.clone());
        self
    }

    /// Queue one or more discovered [`crate::EpDevice`]s (all from the same EP) for attach at
    /// session creation (`SessionOptionsAppendExecutionProvider_V2`). Obtain devices via
    /// [`crate::get_ep_devices`]; `options` are optional key/value config. The devices are
    /// borrowed — the [`crate::Environment`] they came from must outlive every session built
    /// from these options (an ORT invariant). A capable device is required only to *run*.
    pub fn append_execution_provider_device(
        mut self, devices: &[&crate::EpDevice], options: &[(&str, &str)],
    ) -> Result<Self> {
        let opts: Vec<(CString, CString)> = options
            .iter()
            .map(|(k, v)| Ok((CString::new(*k)?, CString::new(*v)?)))
            .collect::<std::result::Result<_, std::ffi::NulError>>()
            .map_err(|_| crate::Error::new(-1, "ep device option key/value contains a NUL byte"))?;
        self.ep_device_attach
            .push(crate::ep_device::EpDeviceAttach {
                devices: devices.iter().map(|d| d.as_ptr()).collect(),
                options: opts,
            });
        Ok(self)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// Exercises the provider-options lifecycle (create + update + as_string + release)
    /// via DNNL. The options are pure config, so this needs no EP/GPU installed; if the
    /// host can't create them, we skip — the FFI call still proves the index/signature is
    /// right (a wrong index crashes, it doesn't error cleanly).
    #[test]
    fn dnnl_options_lifecycle() {
        let opts = match DnnlOptions::new(&[("num_threads", "4")]) {
            Ok(o) => o,
            Err(e) => {
                eprintln!("dnnl provider options unavailable on this host — skipping ({e})");
                return;
            },
        };
        let s = opts.as_string().expect("as_string");
        eprintln!("dnnl options: {s}");
        assert!(
            s.contains("num_threads"),
            "as_string should echo the configured key: {s}"
        );
    }

    #[test]
    fn cuda_provider_options_cover_ort_keys() {
        let options = unsafe {
            CudaProviderOptions::new()
                .device_id(2)
                .do_copy_in_default_stream(false)
                .use_ep_level_unified_stream(true)
                .gpu_mem_limit(1024)
                .arena_extend_strategy(CudaArenaExtendStrategy::SameAsRequested)
                .cudnn_conv_algo_search(CudaCudnnConvAlgoSearch::Default)
                .cudnn_conv_use_max_workspace(true)
                .cudnn_conv1d_pad_to_nc1d(true)
                .enable_cuda_graph(true)
                .enable_skip_layer_norm_strict_mode(true)
                .use_tf32(false)
                .prefer_nhwc(true)
                .tunable_op_enable(true)
                .tunable_op_tuning_enable(true)
                .tunable_op_max_tuning_duration_ms(25)
                .external_allocator_addresses(11, 12, 13)
                .with_raw("future_cuda_option", "x")
                .user_compute_stream(0x1234usize as *mut c_void)
        };
        let entries = options.entries();
        let has = |key: &str, value: &str| entries.iter().any(|(k, v)| k == key && v == value);
        assert!(has("device_id", "2"));
        assert!(has("do_copy_in_default_stream", "0"));
        assert!(has("use_ep_level_unified_stream", "1"));
        assert!(has("gpu_mem_limit", "1024"));
        assert!(has("arena_extend_strategy", "kSameAsRequested"));
        assert!(has("cudnn_conv_algo_search", "DEFAULT"));
        assert!(has("cudnn_conv_use_max_workspace", "1"));
        assert!(has("cudnn_conv1d_pad_to_nc1d", "1"));
        assert!(has("enable_cuda_graph", "1"));
        assert!(has("enable_skip_layer_norm_strict_mode", "1"));
        assert!(has("use_tf32", "0"));
        assert!(has("prefer_nhwc", "1"));
        assert!(has("tunable_op_enable", "1"));
        assert!(has("tunable_op_tuning_enable", "1"));
        assert!(has("tunable_op_max_tuning_duration_ms", "25"));
        assert!(has("gpu_external_alloc", "11"));
        assert!(has("gpu_external_free", "12"));
        assert!(has("gpu_external_empty_cache", "13"));
        assert!(has("future_cuda_option", "x"));
        assert_eq!(
            options.pointer_entries(),
            &[("user_compute_stream".to_owned(), 0x1234)]
        );

        let low_mem = CudaProviderOptions::from_preset(CudaPreset::low_memory(2, 1024));
        assert!(low_mem
            .entries()
            .iter()
            .any(|(k, v)| k == "arena_extend_strategy" && v == "kSameAsRequested"));
    }

    /// OpenVINO V2 + VitisAI take key/value options directly at append time (no options
    /// handle). On a CPU host the append returns "EP not available" — which proves the FFI
    /// index/signature is right (a wrong index crashes; this errors cleanly).
    #[test]
    fn openvino_v2_and_vitisai_append_reach_ffi() {
        let h = SessionOptions::default()
            .build_handle()
            .expect("opts handle");
        for provider in [EpProvider::OpenVinoV2, EpProvider::VitisAi] {
            let cfg = EpConfig {
                provider,
                entries: Vec::new(),
                pointer_entries: Vec::new(),
            };
            let res = apply(h, &cfg);
            eprintln!("{provider:?} apply -> {res:?}");
            assert!(
                res.is_err(),
                "{provider:?} append should error (EP not available on CPU), got Ok"
            );
        }
        unsafe {
            api().release_session_options()(h);
        }
    }

    /// Pins `MigraphxProviderOptionsRaw` field offsets to the values a C probe returned
    /// against the real header (sizeof=88; device_id@0, int8_cal_table_name@24,
    /// save_model_path@40, load_model_path@56, exhaustive_tune@64, mem_limit@72,
    /// arena_extend_strategy@80). Catches a transcription/field-order error — the size
    /// const-assert only catches a wrong count. (`addr_of!` never reads through the dangling
    /// pointer, so this is sound.)
    #[test]
    fn migraphx_struct_layout() {
        use core::ptr::{addr_of, NonNull};
        let p = NonNull::<MigraphxProviderOptionsRaw>::dangling().as_ptr();
        let base = p as usize;
        macro_rules! off {
            ($f:ident) => {
                unsafe { (addr_of!((*p).$f) as usize) - base }
            };
        }
        assert_eq!(off!(device_id), 0);
        assert_eq!(off!(int8_calibration_table_name), 24);
        assert_eq!(off!(save_model_path), 40);
        assert_eq!(off!(load_model_path), 56);
        assert_eq!(off!(exhaustive_tune), 64);
        assert_eq!(off!(mem_limit), 72);
        assert_eq!(off!(arena_extend_strategy), 80);
    }

    /// MIGraphX has no options handle — the flat C struct is passed by pointer to the append.
    /// On a CPU host the append returns "EP not available", proving the index/signature is
    /// right (a wrong index crashes; this errors cleanly). Also exercises the builder.
    #[test]
    fn migraphx_append_reaches_ffi() {
        let h = SessionOptions::default()
            .build_handle()
            .expect("opts handle");
        let opts = MigraphxOptions::new()
            .device_id(0)
            .fp16(true)
            .mem_limit(1 << 30);
        let res = opts.append_raw(h);
        eprintln!("migraphx append -> {res:?}");
        assert!(
            res.is_err(),
            "MIGraphX append should error (EP not available on CPU), got Ok"
        );
        unsafe {
            api().release_session_options()(h);
        }
    }

    /// Pins `OpenvinoProviderOptionsRaw` field offsets to the C-probe values (sizeof=56;
    /// device_type@0, enable_npu_fast_compile@8, device_id@16, num_of_threads@24,
    /// cache_dir@32, context@40, enable_opencl_throttling@48, enable_dynamic_shapes@49).
    /// Catches a field-order/typing error — the size const-assert only catches a wrong count.
    /// (`addr_of!` never reads through the dangling pointer, so this is sound.)
    #[test]
    fn openvino_struct_layout() {
        use core::ptr::{addr_of, NonNull};
        let p = NonNull::<OpenvinoProviderOptionsRaw>::dangling().as_ptr();
        let base = p as usize;
        macro_rules! off {
            ($f:ident) => {
                unsafe { (addr_of!((*p).$f) as usize) - base }
            };
        }
        assert_eq!(off!(device_type), 0);
        assert_eq!(off!(enable_npu_fast_compile), 8);
        assert_eq!(off!(device_id), 16);
        assert_eq!(off!(num_of_threads), 24);
        assert_eq!(off!(cache_dir), 32);
        assert_eq!(off!(context), 40);
        assert_eq!(off!(enable_opencl_throttling), 48);
        assert_eq!(off!(enable_dynamic_shapes), 49);
    }

    /// OpenVINO v1 has no options handle — the flat C struct is passed by pointer to the append.
    /// On a CPU host the append returns "EP not available", proving the index/signature is right
    /// (a wrong index crashes; this errors cleanly). Also exercises the builder.
    #[test]
    fn openvino_append_reaches_ffi() {
        let h = SessionOptions::default()
            .build_handle()
            .expect("opts handle");
        let opts = OpenvinoOptions::new()
            .device_type("GPU_FP16")
            .expect("device_type")
            .device_id("0")
            .expect("device_id")
            .num_of_threads(4);
        let res = opts.append_raw(h);
        eprintln!("openvino v1 append -> {res:?}");
        assert!(
            res.is_err(),
            "OpenVINO v1 append should error (EP not available on CPU), got Ok"
        );
        unsafe {
            api().release_session_options()(h);
        }
    }
}

#[cfg(all(test, feature = "serde"))]
mod serde_tests {
    use super::*;

    #[test]
    fn ep_provider_round_trip() {
        for p in [
            EpProvider::Cuda,
            EpProvider::TensorRt,
            EpProvider::Rocm,
            EpProvider::Cann,
            EpProvider::Dnnl,
            EpProvider::OpenVinoV2,
            EpProvider::VitisAi,
        ] {
            let json = serde_json::to_string(&p).expect("serialize");
            let back: EpProvider = serde_json::from_str(&json).expect("deserialize");
            assert_eq!(p, back, "{p:?} did not round-trip via {json}");
        }
    }

    #[test]
    fn ep_config_round_trip() {
        let cfg = EpConfig {
            provider: EpProvider::Cuda,
            entries: vec![
                (
                    CString::new("device_id").unwrap(),
                    CString::new("0").unwrap(),
                ),
                (
                    CString::new("arena_extend_strategy").unwrap(),
                    CString::new("kSameAsRequested").unwrap(),
                ),
            ],
            pointer_entries: Vec::new(),
        };
        let json = serde_json::to_string(&cfg).expect("serialize");
        eprintln!("EpConfig JSON: {json}");
        assert!(json.contains("\"device_id\""), "cuda kv present: {json}");
        let back: EpConfig = serde_json::from_str(&json).expect("deserialize");
        assert_eq!(back.provider, EpProvider::Cuda);
        assert_eq!(back.entries.len(), 2);
        assert_eq!(back.entries[0].0.to_str().unwrap(), "device_id");
        assert_eq!(back.entries[1].1.to_str().unwrap(), "kSameAsRequested");
    }

    #[test]
    fn flat_ep_options_round_trip() {
        let m = MigraphxOptions::new()
            .device_id(1)
            .fp16(true)
            .mem_limit(1 << 30)
            .save_model_path("/tmp/m")
            .expect("path");
        let json = serde_json::to_string(&m).expect("serialize");
        eprintln!("MigraphxOptions JSON: {json}");
        assert!(json.contains("\"/tmp/m\""), "path present: {json}");
        let back: MigraphxOptions = serde_json::from_str(&json).expect("deserialize");
        assert_eq!(back.device_id, 1);
        assert_ne!(back.fp16_enable, 0);
        assert_eq!(back.mem_limit, 1 << 30);
        assert_eq!(
            back.save_model_path.as_ref().unwrap().to_str().unwrap(),
            "/tmp/m"
        );

        let o = OpenvinoOptions::new()
            .device_type("GPU_FP16")
            .expect("dt")
            .device_id("0")
            .expect("id")
            .num_of_threads(4);
        let json = serde_json::to_string(&o).expect("serialize");
        eprintln!("OpenvinoOptions JSON: {json}");
        let back: OpenvinoOptions = serde_json::from_str(&json).expect("deserialize");
        assert_eq!(
            back.device_type.as_ref().unwrap().to_str().unwrap(),
            "GPU_FP16"
        );
        assert_eq!(back.num_of_threads, 4);
        assert_eq!(back.device_id.as_ref().unwrap().to_str().unwrap(), "0");
    }
}