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ChocolArm64: More accurate implementation of Frecpe

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This commit is contained in:
MerryMage 2018-07-08 00:42:44 +01:00
parent 0bec547b9d
commit 05e4a6ec0a
3 changed files with 103 additions and 61 deletions
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49
ChocolArm64/Instruction/AInstEmitSimdArithmetic.cs
View file

@ -641,53 +641,18 @@ namespace ChocolArm64.Instruction
public static void Frecpe_S(AILEmitterCtx Context)
{
EmitFrecpe(Context, 0, Scalar: true);
EmitScalarUnaryOpF(Context, () =>
{
EmitUnarySoftFloatCall(Context, nameof(ASoftFloat.RecipEstimate));
});
}
public static void Frecpe_V(AILEmitterCtx Context)
{
AOpCodeSimd Op = (AOpCodeSimd)Context.CurrOp;
int SizeF = Op.Size & 1;
int Bytes = Context.CurrOp.GetBitsCount() >> 3;
for (int Index = 0; Index < Bytes >> SizeF + 2; Index++)
EmitVectorUnaryOpF(Context, () =>
{
EmitFrecpe(Context, Index, Scalar: false);
}
if (Op.RegisterSize == ARegisterSize.SIMD64)
{
EmitVectorZeroUpper(Context, Op.Rd);
}
}
private static void EmitFrecpe(AILEmitterCtx Context, int Index, bool Scalar)
{
AOpCodeSimd Op = (AOpCodeSimd)Context.CurrOp;
int SizeF = Op.Size & 1;
if (SizeF == 0)
{
Context.EmitLdc_R4(1);
}
else /* if (SizeF == 1) */
{
Context.EmitLdc_R8(1);
}
EmitVectorExtractF(Context, Op.Rn, Index, SizeF);
Context.Emit(OpCodes.Div);
if (Scalar)
{
EmitVectorZeroAll(Context, Op.Rd);
}
EmitVectorInsertF(Context, Op.Rd, Index, SizeF);
EmitUnarySoftFloatCall(Context, nameof(ASoftFloat.RecipEstimate));
});
}
public static void Frecps_S(AILEmitterCtx Context)

85
ChocolArm64/Instruction/ASoftFloat.cs
View file

@ -7,8 +7,10 @@ namespace ChocolArm64.Instruction
static ASoftFloat()
{
InvSqrtEstimateTable = BuildInvSqrtEstimateTable();
RecipEstimateTable = BuildRecipEstimateTable();
}
private static readonly byte[] RecipEstimateTable;
private static readonly byte[] InvSqrtEstimateTable;
private static byte[] BuildInvSqrtEstimateTable()
@ -38,6 +40,22 @@ namespace ChocolArm64.Instruction
return Table;
}
private static byte[] BuildRecipEstimateTable()
{
byte[] Table = new byte[256];
for (ulong index = 0; index < 256; index++)
{
ulong a = index | 0x100;
a = (a << 1) + 1;
ulong b = 0x80000 / a;
b = (b + 1) >> 1;
Table[index] = (byte)(b & 0xFF);
}
return Table;
}
public static float InvSqrtEstimate(float x)
{
return (float)InvSqrtEstimate((double)x);
@ -99,5 +117,72 @@ namespace ChocolArm64.Instruction
ulong result = x_sign | (result_exp << 52) | fraction;
return BitConverter.Int64BitsToDouble((long)result);
}
public static float RecipEstimate(float x)
{
return (float)RecipEstimate((double)x);
}
public static double RecipEstimate(double x)
{
ulong x_bits = (ulong)BitConverter.DoubleToInt64Bits(x);
ulong x_sign = x_bits & 0x8000000000000000;
ulong x_exp = (x_bits >> 52) & 0x7FF;
ulong scaled = x_bits & ((1ul << 52) - 1);
if (x_exp >= 2045)
{
if (x_exp == 0x7ff && scaled != 0)
{
// NaN
return BitConverter.Int64BitsToDouble((long)(x_bits | 0x0008000000000000));
}
// Infinity, or Out of range -> Zero
return BitConverter.Int64BitsToDouble((long)x_sign);
}
if (x_exp == 0)
{
if (scaled == 0)
{
// Zero -> Infinity
return BitConverter.Int64BitsToDouble((long)(x_sign | 0x7ff0000000000000));
}
// Denormal
if ((scaled & (1ul << 51)) == 0)
{
x_exp = ~0ul;
scaled <<= 2;
}
else
{
scaled <<= 1;
}
}
scaled >>= 44;
scaled &= 0xFF;
ulong result_exp = (2045 - x_exp) & 0x7FF;
ulong estimate = (ulong)RecipEstimateTable[scaled];
ulong fraction = estimate << 44;
if (result_exp == 0)
{
fraction >>= 1;
fraction |= 1ul << 51;
}
else if (result_exp == 0x7FF)
{
result_exp = 0;
fraction >>= 2;
fraction |= 1ul << 50;
}
ulong result = x_sign | (result_exp << 52) | fraction;
return BitConverter.Int64BitsToDouble((long)result);
}
}
}

30
Ryujinx.Tests/Cpu/CpuTestSimdArithmetic.cs
View file

@ -163,26 +163,18 @@ namespace Ryujinx.Tests.Cpu
Assert.That(Sse41.Extract(ThreadState.V6, (byte)0), Is.EqualTo(A * B));
}
[Test, Description("FRECPE D0, D1")]
public void Frecpe_S([Random(100)] double A)
[TestCase(0x00000000u, 0x7F800000u)]
[TestCase(0x80000000u, 0xFF800000u)]
[TestCase(0x00FFF000u, 0x7E000000u)]
[TestCase(0x41200000u, 0x3DCC8000u)]
[TestCase(0xC1200000u, 0xBDCC8000u)]
[TestCase(0x001FFFFFu, 0x7F800000u)]
[TestCase(0x007FF000u, 0x7E800000u)]
public void Frecpe_S(uint A, uint Result)
{
AThreadState ThreadState = SingleOpcode(0x5EE1D820, V1: MakeVectorE0(A));
Assert.That(VectorExtractDouble(ThreadState.V0, 0), Is.EqualTo(1 / A));
}
[Test, Description("FRECPE V2.4S, V0.4S")]
public void Frecpe_V([Random(100)] float A)
{
AThreadState ThreadState = SingleOpcode(0x4EA1D802, V0: Sse.SetAllVector128(A));
Assert.Multiple(() =>
{
Assert.That(Sse41.Extract(ThreadState.V2, (byte)0), Is.EqualTo(1 / A));
Assert.That(Sse41.Extract(ThreadState.V2, (byte)1), Is.EqualTo(1 / A));
Assert.That(Sse41.Extract(ThreadState.V2, (byte)2), Is.EqualTo(1 / A));
Assert.That(Sse41.Extract(ThreadState.V2, (byte)3), Is.EqualTo(1 / A));
});
Vector128<float> V1 = MakeVectorE0(A);
AThreadState ThreadState = SingleOpcode(0x5EA1D820, V1: V1);
Assert.AreEqual(Result, GetVectorE0(ThreadState.V0));
}
[Test, Description("FRECPS D0, D1, D2")]