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R/ARMeilleure/Instructions/InstEmitSystem32.cs
riperiperi 9db73f74cf
ARMeilleure: Respect FZ/RM flags for all floating point operations (#4618) 
* ARMeilleure: Respect Fz flag for all floating point operations.

This is a change in strategy for emulating the Fz FPCR flag. Before, it was set before instructions that "needed it" and reset after. However, this missed a few hot instructions like the multiplication instruction, and the entirety of A32.

The new strategy is to set the Fz flag only in the following circumstances:

- Set to match FPCR before translated functions/loop are executed.
- Reset when calling SoftFloat methods, set when returning.
- Reset when exiting execution.

This allows us to remove the code around the existing Fz aware instructions, and get the accuracy benefits on all floating point instructions executed while in translated code.

Single step executions now need to be called with a context wrapper - right now it just contains the Fz flag initialization, and won't actually do anything on ARM.

This fixes a bug in Breath of the Wild where some physics interactions could randomly crash the game due to subnormal values not flushing to zero.

This is draft right now because I need to answer the questions:
- Does dotnet avoid changing the value of Mxcsr?
- Is it a good idea to assume that? Or should the flag set/restore be done on every managed method call, not just softfloat?
- If we assume that, do we want a unit test to verify the behaviour?

I recommend testing a bunch of games, especially games affected when this was originally added, such as #1611.

* Remove unused method

* Use FMA for Fmadd, Fmsub, Fnmadd, Fnmsub, Fmla, Fmls

...when available.

Similar implementation to A32

* Use FMA for Frecps, Frsqrts

* Don't set DAZ.

* Add round mode to ARM FP mode

* Fix mistakes

* Add test for FP state when calling managed methods

* Add explanatory comment to test.

* Cleanup

* Add A64 FPCR flags

* Vrintx_S A32 fast path on A64 backend

* Address feedback 1, re-enable DAZ

* Fix FMA instructions By Elem

* Address feedback
2023-04-10 12:22:58 +02:00

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using ARMeilleure.Decoders;
using ARMeilleure.IntermediateRepresentation;
using ARMeilleure.State;
using ARMeilleure.Translation;
using System;
using System.Reflection;
using static ARMeilleure.Instructions.InstEmitHelper;
using static ARMeilleure.IntermediateRepresentation.Operand.Factory;
namespace ARMeilleure.Instructions
{
static partial class InstEmit32
{
public static void Mcr(ArmEmitterContext context)
{
OpCode32System op = (OpCode32System)context.CurrOp;
if (op.Coproc != 15 || op.Opc1 != 0)
{
InstEmit.Und(context);
return;
}
MethodInfo info;
switch (op.CRn)
{
case 13: // Process and Thread Info.
if (op.CRm != 0)
{
throw new NotImplementedException($"Unknown MRC CRm 0x{op.CRm:X} at 0x{op.Address:X} (0x{op.RawOpCode:X}).");
}
switch (op.Opc2)
{
case 2:
info = typeof(NativeInterface).GetMethod(nameof(NativeInterface.SetTpidrEl032)); break;
default:
throw new NotImplementedException($"Unknown MRC Opc2 0x{op.Opc2:X} at 0x{op.Address:X} (0x{op.RawOpCode:X}).");
}
break;
case 7:
switch (op.CRm) // Cache and Memory barrier.
{
case 10:
switch (op.Opc2)
{
case 5: // Data Memory Barrier Register.
return; // No-op.
default:
throw new NotImplementedException($"Unknown MRC Opc2 0x{op.Opc2:X16} at 0x{op.Address:X16} (0x{op.RawOpCode:X}).");
}
default:
throw new NotImplementedException($"Unknown MRC CRm 0x{op.CRm:X16} at 0x{op.Address:X16} (0x{op.RawOpCode:X}).");
}
default:
throw new NotImplementedException($"Unknown MRC 0x{op.RawOpCode:X8} at 0x{op.Address:X16}.");
}
context.Call(info, GetIntA32(context, op.Rt));
}
public static void Mrc(ArmEmitterContext context)
{
OpCode32System op = (OpCode32System)context.CurrOp;
if (op.Coproc != 15 || op.Opc1 != 0)
{
InstEmit.Und(context);
return;
}
MethodInfo info;
switch (op.CRn)
{
case 13: // Process and Thread Info.
if (op.CRm != 0)
{
throw new NotImplementedException($"Unknown MRC CRm 0x{op.CRm:X} at 0x{op.Address:X} (0x{op.RawOpCode:X}).");
}
switch (op.Opc2)
{
case 2:
info = typeof(NativeInterface).GetMethod(nameof(NativeInterface.GetTpidrEl032)); break;
case 3:
info = typeof(NativeInterface).GetMethod(nameof(NativeInterface.GetTpidr32)); break;
default:
throw new NotImplementedException($"Unknown MRC Opc2 0x{op.Opc2:X} at 0x{op.Address:X} (0x{op.RawOpCode:X}).");
}
break;
default:
throw new NotImplementedException($"Unknown MRC 0x{op.RawOpCode:X} at 0x{op.Address:X}.");
}
if (op.Rt == RegisterAlias.Aarch32Pc)
{
// Special behavior: copy NZCV flags into APSR.
EmitSetNzcv(context, context.Call(info));
return;
}
else
{
SetIntA32(context, op.Rt, context.Call(info));
}
}
public static void Mrrc(ArmEmitterContext context)
{
OpCode32System op = (OpCode32System)context.CurrOp;
if (op.Coproc != 15)
{
InstEmit.Und(context);
return;
}
int opc = op.MrrcOp;
MethodInfo info;
switch (op.CRm)
{
case 14: // Timer.
switch (opc)
{
case 0:
info = typeof(NativeInterface).GetMethod(nameof(NativeInterface.GetCntpctEl0)); break;
default:
throw new NotImplementedException($"Unknown MRRC Opc1 0x{opc:X} at 0x{op.Address:X} (0x{op.RawOpCode:X}).");
}
break;
default:
throw new NotImplementedException($"Unknown MRRC 0x{op.RawOpCode:X} at 0x{op.Address:X}.");
}
Operand result = context.Call(info);
SetIntA32(context, op.Rt, context.ConvertI64ToI32(result));
SetIntA32(context, op.CRn, context.ConvertI64ToI32(context.ShiftRightUI(result, Const(32))));
}
public static void Mrs(ArmEmitterContext context)
{
OpCode32Mrs op = (OpCode32Mrs)context.CurrOp;
if (op.R)
{
throw new NotImplementedException("SPSR");
}
else
{
Operand spsr = context.ShiftLeft(GetFlag(PState.VFlag), Const((int)PState.VFlag));
spsr = context.BitwiseOr(spsr, context.ShiftLeft(GetFlag(PState.CFlag), Const((int)PState.CFlag)));
spsr = context.BitwiseOr(spsr, context.ShiftLeft(GetFlag(PState.ZFlag), Const((int)PState.ZFlag)));
spsr = context.BitwiseOr(spsr, context.ShiftLeft(GetFlag(PState.NFlag), Const((int)PState.NFlag)));
spsr = context.BitwiseOr(spsr, context.ShiftLeft(GetFlag(PState.QFlag), Const((int)PState.QFlag)));
// TODO: Remaining flags.
SetIntA32(context, op.Rd, spsr);
}
}
public static void Msr(ArmEmitterContext context)
{
OpCode32MsrReg op = (OpCode32MsrReg)context.CurrOp;
if (op.R)
{
throw new NotImplementedException("SPSR");
}
else
{
if ((op.Mask & 8) != 0)
{
Operand value = GetIntA32(context, op.Rn);
EmitSetNzcv(context, value);
Operand q = context.BitwiseAnd(context.ShiftRightUI(value, Const((int)PState.QFlag)), Const(1));
SetFlag(context, PState.QFlag, q);
}
if ((op.Mask & 4) != 0)
{
throw new NotImplementedException("APSR_g");
}
if ((op.Mask & 2) != 0)
{
throw new NotImplementedException("CPSR_x");
}
if ((op.Mask & 1) != 0)
{
throw new NotImplementedException("CPSR_c");
}
}
}
public static void Nop(ArmEmitterContext context) { }
public static void Vmrs(ArmEmitterContext context)
{
OpCode32SimdSpecial op = (OpCode32SimdSpecial)context.CurrOp;
if (op.Rt == RegisterAlias.Aarch32Pc && op.Sreg == 0b0001)
{
// Special behavior: copy NZCV flags into APSR.
SetFlag(context, PState.VFlag, GetFpFlag(FPState.VFlag));
SetFlag(context, PState.CFlag, GetFpFlag(FPState.CFlag));
SetFlag(context, PState.ZFlag, GetFpFlag(FPState.ZFlag));
SetFlag(context, PState.NFlag, GetFpFlag(FPState.NFlag));
return;
}
switch (op.Sreg)
{
case 0b0000: // FPSID
throw new NotImplementedException("Supervisor Only");
case 0b0001: // FPSCR
EmitGetFpscr(context); return;
case 0b0101: // MVFR2
throw new NotImplementedException("MVFR2");
case 0b0110: // MVFR1
throw new NotImplementedException("MVFR1");
case 0b0111: // MVFR0
throw new NotImplementedException("MVFR0");
case 0b1000: // FPEXC
throw new NotImplementedException("Supervisor Only");
default:
throw new NotImplementedException($"Unknown VMRS 0x{op.RawOpCode:X} at 0x{op.Address:X}.");
}
}
public static void Vmsr(ArmEmitterContext context)
{
OpCode32SimdSpecial op = (OpCode32SimdSpecial)context.CurrOp;
switch (op.Sreg)
{
case 0b0000: // FPSID
throw new NotImplementedException("Supervisor Only");
case 0b0001: // FPSCR
EmitSetFpscr(context); return;
case 0b0101: // MVFR2
throw new NotImplementedException("MVFR2");
case 0b0110: // MVFR1
throw new NotImplementedException("MVFR1");
case 0b0111: // MVFR0
throw new NotImplementedException("MVFR0");
case 0b1000: // FPEXC
throw new NotImplementedException("Supervisor Only");
default:
throw new NotImplementedException($"Unknown VMSR 0x{op.RawOpCode:X} at 0x{op.Address:X}.");
}
}
private static void EmitSetNzcv(ArmEmitterContext context, Operand t)
{
Operand v = context.BitwiseAnd(context.ShiftRightUI(t, Const((int)PState.VFlag)), Const(1));
Operand c = context.BitwiseAnd(context.ShiftRightUI(t, Const((int)PState.CFlag)), Const(1));
Operand z = context.BitwiseAnd(context.ShiftRightUI(t, Const((int)PState.ZFlag)), Const(1));
Operand n = context.BitwiseAnd(context.ShiftRightUI(t, Const((int)PState.NFlag)), Const(1));
SetFlag(context, PState.VFlag, v);
SetFlag(context, PState.CFlag, c);
SetFlag(context, PState.ZFlag, z);
SetFlag(context, PState.NFlag, n);
}
private static void EmitGetFpscr(ArmEmitterContext context)
{
OpCode32SimdSpecial op = (OpCode32SimdSpecial)context.CurrOp;
Operand fpscr = Const(0);
for (int flag = 0; flag < RegisterConsts.FpFlagsCount; flag++)
{
if (FPSCR.Mask.HasFlag((FPSCR)(1u << flag)))
{
fpscr = context.BitwiseOr(fpscr, context.ShiftLeft(GetFpFlag((FPState)flag), Const(flag)));
}
}
SetIntA32(context, op.Rt, fpscr);
}
private static void EmitSetFpscr(ArmEmitterContext context)
{
OpCode32SimdSpecial op = (OpCode32SimdSpecial)context.CurrOp;
Operand fpscr = GetIntA32(context, op.Rt);
for (int flag = 0; flag < RegisterConsts.FpFlagsCount; flag++)
{
if (FPSCR.Mask.HasFlag((FPSCR)(1u << flag)))
{
SetFpFlag(context, (FPState)flag, context.BitwiseAnd(context.ShiftRightUI(fpscr, Const(flag)), Const(1)));
}
}
context.UpdateArmFpMode();
}
}
}
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