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UserspaceEmulator: Delegate rounding to the actual hardware

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This also makes us a bit more accurate, due to better rounding of
intermediate results.

This also gives us the flush-to-zero and denormals-are-zero SSE settings
for free! (Assuming UE is build with SSE)
This commit is contained in:
Hendiadyoin1 2022-04-08 17:09:19 +02:00 • committed by Linus Groh
parent 56a31ab376
commit 6c41267dcf
5 changed files with 91 additions and 126 deletions
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50
Userland/DevTools/UserspaceEmulator/SoftFPU.h
View file

@ -8,6 +8,7 @@
#include "Report.h"
#include <AK/Concepts.h>
#include <AK/FPControl.h>
#include <AK/SIMD.h>
#include <LibX86/Instruction.h>
#include <LibX86/Interpreter.h>
@ -17,6 +18,8 @@
namespace UserspaceEmulator {
using namespace AK::SIMD;
using AK::RoundingMode;
class Emulator;
class SoftCPU;
@ -35,6 +38,7 @@ public:
SoftFPU(Emulator& emulator, SoftCPU& cpu)
: m_emulator(emulator)
, m_cpu(cpu)
, m_fpu_cw { 0x037F }
{
}
@ -81,13 +85,6 @@ private:
Empty = 0b11
};
enum class RoundingMode : u8 {
NEAREST = 0b00,
DOWN = 0b01,
UP = 0b10,
TRUNC = 0b11
};
void fpu_dump_env()
{
reportln("Exceptions: #I:{} #D:{} #Z:{} #O:{} #U:{} #P:{} #SF:{} Summary:{}",
@ -100,12 +97,12 @@ private:
m_fpu_error_stackfault,
m_fpu_error_summary);
reportln("Masks: #I:{} #D:{} #Z:{} #O:{} #U:{} #P:{}",
m_fpu_mask_invalid,
m_fpu_mask_denorm,
m_fpu_mask_zero_div,
m_fpu_mask_overflow,
m_fpu_mask_underflow,
m_fpu_mask_precision);
m_fpu_cw.mask_invalid,
m_fpu_cw.mask_denorm,
m_fpu_cw.mask_zero_div,
m_fpu_cw.mask_overflow,
m_fpu_cw.mask_underflow,
m_fpu_cw.mask_precision);
reportln("C0:{} C1:{} C2:{} C3:{}", c0(), c1(), c2(), c3());
reportln("fpu-stacktop: {}", m_fpu_stack_top);
reportln("fpu-stack /w stacktop (real):");
@ -261,18 +258,14 @@ private:
ALWAYS_INLINE RoundingMode fpu_get_round_mode() const
{
return RoundingMode(m_fpu_round_mode);
return m_fpu_cw.rounding_control;
}
template<Arithmetic T>
T fpu_round(long double) const;
template<Arithmetic T>
T fpu_round_checked(long double);
T round_checked(long double);
template<FloatingPoint T>
T fpu_convert(long double) const;
template<FloatingPoint T>
T fpu_convert_checked(long double);
T convert_checked(long double);
ALWAYS_INLINE void fpu_set_unordered()
{
@ -295,22 +288,7 @@ private:
};
} m_storage[8];
union {
u16 m_fpu_cw { 0x037F };
struct {
u16 m_fpu_mask_invalid : 1;
u16 m_fpu_mask_denorm : 1;
u16 m_fpu_mask_zero_div : 1;
u16 m_fpu_mask_overflow : 1;
u16 m_fpu_mask_underflow : 1;
u16 m_fpu_mask_precision : 1;
u16 : 2; // unused
u16 m_fpu_precission : 2;
u16 m_fpu_round_mode : 2;
u16 m_fpu_infinity_control : 1;
u16 : 3; // unused
};
};
AK::X87ControlWord m_fpu_cw;
union {
u16 m_fpu_sw { 0 };