view release on metacpan or  search on metacpan

infix/src/arch/x64/abi_win_x64.c  view on Meta::CPAN

/**
 * Copyright (c) 2025 Sanko Robinson
 *
 * This source code is dual-licensed under the Artistic License 2.0 or the MIT License.
 * You may choose to use this code under the terms of either license.
 *
 * SPDX-License-Identifier: (Artistic-2.0 OR MIT)
 *
 * The documentation blocks within this file are licensed under the
 * Creative Commons Attribution 4.0 International License (CC BY 4.0).
 *
 * SPDX-License-Identifier: CC-BY-4.0
 */
/**
 * @file abi_win_x64.c
 * @brief Implements the FFI logic for the Windows x64 calling convention.
 * @ingroup internal_abi_x64
 *
 * @internal
 * This file provides the concrete implementation of the ABI spec for the Microsoft
 * x64 calling convention, used on all 64-bit versions of Windows.
 *
 * Key features and differences from the System V ABI implemented here:
 *
 * - **Register "Slots":** The first four arguments are passed in registers, but the
 *   slots are shared. RCX/XMM0 is the first slot, RDX/XMM1 is the second, etc.
 *   An `int` followed by a `float` would use RCX and XMM1.
 *
 * - **Shadow Space:** The caller must allocate a 32-byte "shadow space" on the stack
 *   for the callee.
 *
 * - **By-Reference Passing:** Aggregates (structs/unions) are passed by reference
 *   if their size is not a power of two (1, 2, 4, or 8 bytes), or if they have
 *   special constructors.
 *   **Crucially, all SIMD vectors > 16 bytes (__m256, __m512) are passed by reference.**
 *   **__m128 (16 bytes) is passed by value in XMM.**
 *
 * - **Return Values:**
 *   - Scalars and __m128 are returned in registers (RAX/XMM0).
 *   - **__m256 and __m512 are returned in registers (YMM0/ZMM0).**
 *   - Aggregates > 8 bytes (excluding vectors) are returned via a hidden pointer.
 * @endinternal
 */
// This file performs many safe conversions from size_t to int32_t for instruction
// offsets. The library's internal limits (INFIX_MAX_STACK_ALLOC) ensure these
// conversions do not lose data. We disable the warning to produce a clean build.
#if defined(INFIX_COMPILER_MSVC)
#pragma warning(push)
#pragma warning(disable : 4267)  // conversion from 'size_t' to 'int32_t'
#endif
#include "arch/x64/abi_x64_common.h"
#include "arch/x64/abi_x64_emitters.h"
#include "common/infix_internals.h"
#include "common/utility.h"
#include <stdbool.h>
#include <stdlib.h>
/** An array of GPRs used for passing the first four integer/pointer arguments. */
static const x64_gpr GPR_ARGS[] = {RCX_REG, RDX_REG, R8_REG, R9_REG};
/** An array of XMM registers used for passing the first four floating-point arguments. */
static const x64_xmm XMM_ARGS[] = {XMM0_REG, XMM1_REG, XMM2_REG, XMM3_REG};
/** The number of register "slots" available for arguments. */
#define NUM_GPR_ARGS 4
/** The number of XMM registers used for arguments. */
#define NUM_XMM_ARGS 4
/** The size in bytes of the mandatory stack space reserved by the caller for the callee. */
#define SHADOW_SPACE 32

/** @brief The v-table of Windows x64 functions for generating forward trampolines. */
static infix_status prepare_forward_call_frame_win_x64(infix_arena_t * arena,
                                                       infix_call_frame_layout ** out_layout,
                                                       infix_type * ret_type,
                                                       infix_type ** arg_types,
                                                       size_t num_args,
                                                       size_t num_fixed_args,
                                                       void * target_fn);
static infix_status generate_forward_prologue_win_x64(code_buffer * buf, infix_call_frame_layout * layout);
static infix_status generate_forward_argument_moves_win_x64(code_buffer * buf,
                                                            infix_call_frame_layout * layout,
                                                            infix_type ** arg_types,
                                                            size_t num_args,
                                                            size_t num_fixed_args);
static infix_status generate_forward_call_instruction_win_x64(code_buffer *, infix_call_frame_layout *);
static infix_status generate_forward_epilogue_win_x64(code_buffer * buf,
                                                      infix_call_frame_layout * layout,
                                                      infix_type * ret_type);
const infix_forward_abi_spec g_win_x64_forward_spec = {