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The fun pattern of `union { struct { u32 a : 1; u64 b : 7; }; u8 x; }` produces complete garbage on windows, this commit fixes the two instances of those that exist in AK. This commit also makes sure that the generated unions have the correct size (whereas FloatExtractor<f32> previously did not!) by adding some nice static_asserts.
125 lines
2.9 KiB
C++
125 lines
2.9 KiB
C++
/*
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* Copyright (c) 2022, Leon Albrecht <leon.a@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Types.h>
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// FIXME: Add equivalent datastructures for aarch64
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VALIDATE_IS_X86();
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namespace AK {
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enum class RoundingMode : u16 {
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NEAREST = 0b00,
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DOWN = 0b01,
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UP = 0b10,
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TRUNC = 0b11
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};
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union X87ControlWord {
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u16 cw;
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struct {
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u16 mask_invalid : 1; // IM
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u16 mask_denorm : 1; // DM
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u16 mask_zero_div : 1; // ZM
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u16 mask_overflow : 1; // OM
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u16 mask_underflow : 1; // UM
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u16 mask_precision : 1; // PM
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u16 : 2; // unused
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u16 precision : 2; // PC
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RoundingMode rounding_control : 2; // RC
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u16 infinity_control : 1; // X
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u16 : 3; // unused
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};
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};
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static_assert(sizeof(X87ControlWord) == sizeof(u16));
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union MXCSR {
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u32 mxcsr;
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struct {
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u32 invalid_operation_flag : 1; // IE
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u32 denormal_operation_flag : 1; // DE
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u32 divide_by_zero_flag : 1; // ZE
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u32 overflow_flag : 1; // OE
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u32 underflow_flag : 1; // UE
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u32 precision_flag : 1; // PE
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u32 denormals_are_zero : 1; // DAZ
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u32 invalid_operation_mask : 1; // IM
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u32 denormal_operation_mask : 1; // DM
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u32 divide_by_zero_mask : 1; // ZM
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u32 overflow_mask : 1; // OM
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u32 underflow_mask : 1; // UM
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u32 precision_mask : 1; // PM
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RoundingMode rounding_control : 2; // RC
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u32 flush_to_zero : 1; // FTZ
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u32 __reserved : 16;
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};
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};
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static_assert(sizeof(MXCSR) == sizeof(u32));
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ALWAYS_INLINE X87ControlWord get_cw_x87()
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{
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X87ControlWord control_word;
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asm("fnstcw %0"
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: "=m"(control_word));
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return control_word;
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}
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ALWAYS_INLINE void set_cw_x87(X87ControlWord control_word)
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{
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asm("fldcw %0" ::"m"(control_word));
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}
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ALWAYS_INLINE MXCSR get_mxcsr()
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{
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MXCSR mxcsr;
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asm("stmxcsr %0"
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: "=m"(mxcsr));
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return mxcsr;
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}
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ALWAYS_INLINE void set_mxcsr(MXCSR mxcsr)
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{
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asm("ldmxcsr %0" ::"m"(mxcsr));
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}
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class X87RoundingModeScope {
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public:
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X87RoundingModeScope(RoundingMode rounding_mode)
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{
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m_cw = get_cw_x87();
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auto cw = m_cw;
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cw.rounding_control = rounding_mode;
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set_cw_x87(cw);
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}
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~X87RoundingModeScope()
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{
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set_cw_x87(m_cw);
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}
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private:
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X87ControlWord m_cw;
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};
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class SSERoundingModeScope {
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public:
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SSERoundingModeScope(RoundingMode rounding_mode)
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{
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m_mxcsr = get_mxcsr();
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auto mxcsr = m_mxcsr;
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mxcsr.rounding_control = rounding_mode;
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set_mxcsr(mxcsr);
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}
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~SSERoundingModeScope()
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{
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set_mxcsr(m_mxcsr);
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}
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private:
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MXCSR m_mxcsr;
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};
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}
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