e99e6d0ad1
* Use the jump table for tail continues. This path is always reached when a function larger than our current length limit (currently 5000) is compiled. * Use Call Flag rather than 1L
362 lines
13 KiB
C#
362 lines
13 KiB
C#
using ARMeilleure.Decoders;
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using ARMeilleure.IntermediateRepresentation;
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using ARMeilleure.State;
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using ARMeilleure.Translation;
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using System;
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using static ARMeilleure.Instructions.InstEmitHelper;
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using static ARMeilleure.IntermediateRepresentation.OperandHelper;
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namespace ARMeilleure.Instructions
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{
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static class InstEmitFlowHelper
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{
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public const ulong CallFlag = 1;
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public static void EmitCondBranch(ArmEmitterContext context, Operand target, Condition cond)
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{
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if (cond != Condition.Al)
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{
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context.BranchIfTrue(target, GetCondTrue(context, cond));
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}
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else
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{
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context.Branch(target);
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}
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}
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public static Operand GetCondTrue(ArmEmitterContext context, Condition condition)
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{
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Operand cmpResult = context.TryGetComparisonResult(condition);
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if (cmpResult != null)
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{
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return cmpResult;
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}
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Operand value = Const(1);
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Operand Inverse(Operand val)
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{
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return context.BitwiseExclusiveOr(val, Const(1));
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}
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switch (condition)
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{
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case Condition.Eq:
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value = GetFlag(PState.ZFlag);
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break;
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case Condition.Ne:
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value = Inverse(GetFlag(PState.ZFlag));
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break;
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case Condition.GeUn:
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value = GetFlag(PState.CFlag);
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break;
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case Condition.LtUn:
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value = Inverse(GetFlag(PState.CFlag));
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break;
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case Condition.Mi:
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value = GetFlag(PState.NFlag);
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break;
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case Condition.Pl:
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value = Inverse(GetFlag(PState.NFlag));
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break;
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case Condition.Vs:
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value = GetFlag(PState.VFlag);
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break;
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case Condition.Vc:
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value = Inverse(GetFlag(PState.VFlag));
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break;
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case Condition.GtUn:
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{
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Operand c = GetFlag(PState.CFlag);
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Operand z = GetFlag(PState.ZFlag);
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value = context.BitwiseAnd(c, Inverse(z));
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break;
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}
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case Condition.LeUn:
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{
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Operand c = GetFlag(PState.CFlag);
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Operand z = GetFlag(PState.ZFlag);
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value = context.BitwiseOr(Inverse(c), z);
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break;
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}
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case Condition.Ge:
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{
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Operand n = GetFlag(PState.NFlag);
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Operand v = GetFlag(PState.VFlag);
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value = context.ICompareEqual(n, v);
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break;
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}
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case Condition.Lt:
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{
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Operand n = GetFlag(PState.NFlag);
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Operand v = GetFlag(PState.VFlag);
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value = context.ICompareNotEqual(n, v);
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break;
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}
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case Condition.Gt:
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{
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Operand n = GetFlag(PState.NFlag);
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Operand z = GetFlag(PState.ZFlag);
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Operand v = GetFlag(PState.VFlag);
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value = context.BitwiseAnd(Inverse(z), context.ICompareEqual(n, v));
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break;
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}
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case Condition.Le:
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{
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Operand n = GetFlag(PState.NFlag);
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Operand z = GetFlag(PState.ZFlag);
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Operand v = GetFlag(PState.VFlag);
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value = context.BitwiseOr(z, context.ICompareNotEqual(n, v));
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break;
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}
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}
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return value;
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}
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public static void EmitCall(ArmEmitterContext context, ulong immediate)
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{
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EmitJumpTableBranch(context, Const(immediate));
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}
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private static void EmitNativeCall(ArmEmitterContext context, Operand nativeContextPtr, Operand funcAddr, bool isJump = false)
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{
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context.StoreToContext();
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Operand returnAddress;
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if (isJump)
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{
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context.Tailcall(funcAddr, nativeContextPtr);
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}
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else
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{
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returnAddress = context.Call(funcAddr, OperandType.I64, nativeContextPtr);
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context.LoadFromContext();
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EmitContinueOrReturnCheck(context, returnAddress);
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}
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}
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private static void EmitNativeCall(ArmEmitterContext context, Operand funcAddr, bool isJump = false)
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{
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EmitNativeCall(context, context.LoadArgument(OperandType.I64, 0), funcAddr, isJump);
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}
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public static void EmitVirtualCall(ArmEmitterContext context, Operand target)
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{
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EmitVirtualCallOrJump(context, target, isJump: false);
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}
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public static void EmitVirtualJump(ArmEmitterContext context, Operand target, bool isReturn)
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{
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EmitVirtualCallOrJump(context, target, isJump: true, isReturn: isReturn);
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}
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private static void EmitVirtualCallOrJump(ArmEmitterContext context, Operand target, bool isJump, bool isReturn = false)
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{
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if (isReturn)
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{
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context.Return(target);
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}
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else
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{
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EmitJumpTableBranch(context, target, isJump);
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}
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}
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private static void EmitContinueOrReturnCheck(ArmEmitterContext context, Operand returnAddress)
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{
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// Note: The return value of a translated function is always an Int64 with the
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// address execution has returned to. We expect this address to be immediately after the
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// current instruction, if it isn't we keep returning until we reach the dispatcher.
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Operand nextAddr = Const(GetNextOpAddress(context.CurrOp));
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// Try to continue within this block.
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// If the return address isn't to our next instruction, we need to return so the JIT can figure out what to do.
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Operand lblContinue = Label();
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// We need to clear out the call flag for the return address before comparing it.
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context.BranchIfTrue(lblContinue, context.ICompareEqual(context.BitwiseAnd(returnAddress, Const(~CallFlag)), nextAddr));
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context.Return(returnAddress);
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context.MarkLabel(lblContinue);
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if (context.CurrBlock.Next == null)
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{
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// No code following this instruction, try and find the next block and jump to it.
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EmitTailContinue(context, nextAddr);
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}
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}
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private static ulong GetNextOpAddress(OpCode op)
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{
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return op.Address + (ulong)op.OpCodeSizeInBytes;
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}
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public static void EmitTailContinue(ArmEmitterContext context, Operand address, bool allowRejit = false)
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{
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bool useTailContinue = true; // Left option here as it may be useful if we need to return to managed rather than tail call in future. (eg. for debug)
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if (useTailContinue)
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{
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if (context.HighCq)
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{
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// If we're doing a tail continue in HighCq, reserve a space in the jump table to avoid calling back to the translator.
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// This will always try to get a HighCq version of our continue target as well.
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EmitJumpTableBranch(context, address, true);
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}
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else
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{
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if (allowRejit)
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{
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address = context.BitwiseOr(address, Const(CallFlag));
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}
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Operand fallbackAddr = context.Call(new _U64_U64(NativeInterface.GetFunctionAddress), address);
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EmitNativeCall(context, fallbackAddr, true);
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}
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}
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else
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{
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context.Return(address);
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}
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}
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private static void EmitNativeCallWithGuestAddress(ArmEmitterContext context, Operand funcAddr, Operand guestAddress, bool isJump)
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{
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Operand nativeContextPtr = context.LoadArgument(OperandType.I64, 0);
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context.Store(context.Add(nativeContextPtr, Const(NativeContext.GetCallAddressOffset())), guestAddress);
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EmitNativeCall(context, nativeContextPtr, funcAddr, isJump);
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}
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private static void EmitBranchFallback(ArmEmitterContext context, Operand address, bool isJump)
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{
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address = context.BitwiseOr(address, Const(address.Type, (long)CallFlag)); // Set call flag.
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Operand fallbackAddr = context.Call(new _U64_U64(NativeInterface.GetFunctionAddress), address);
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EmitNativeCall(context, fallbackAddr, isJump);
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}
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public static void EmitDynamicTableCall(ArmEmitterContext context, Operand tableAddress, Operand address, bool isJump)
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{
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// Loop over elements of the dynamic table. Unrolled loop.
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Operand endLabel = Label();
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Operand fallbackLabel = Label();
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Action<Operand> emitTableEntry = (Operand entrySkipLabel) =>
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{
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// Try to take this entry in the table if its guest address equals 0.
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Operand gotResult = context.CompareAndSwap(tableAddress, Const(0L), address);
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// Is the address ours? (either taken via CompareAndSwap (0), or what was already here)
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context.BranchIfFalse(entrySkipLabel, context.BitwiseOr(context.ICompareEqual(gotResult, address), context.ICompareEqual(gotResult, Const(0L))));
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// It's ours, so what function is it pointing to?
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Operand targetFunctionPtr = context.Add(tableAddress, Const(8L));
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Operand targetFunction = context.Load(OperandType.I64, targetFunctionPtr);
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// Call the function.
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// We pass in the entry address as the guest address, as the entry may need to be updated by the indirect call stub.
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EmitNativeCallWithGuestAddress(context, targetFunction, tableAddress, isJump);
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context.Branch(endLabel);
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};
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// Currently this uses a size of 1, as higher values inflate code size for no real benefit.
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for (int i = 0; i < JumpTable.DynamicTableElems; i++)
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{
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if (i == JumpTable.DynamicTableElems - 1)
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{
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emitTableEntry(fallbackLabel); // If this is the last entry, avoid emitting the additional label and add.
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}
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else
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{
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Operand nextLabel = Label();
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emitTableEntry(nextLabel);
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context.MarkLabel(nextLabel);
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tableAddress = context.Add(tableAddress, Const((long)JumpTable.JumpTableStride)); // Move to the next table entry.
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}
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}
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context.MarkLabel(fallbackLabel);
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EmitBranchFallback(context, address, isJump);
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context.MarkLabel(endLabel);
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}
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public static void EmitJumpTableBranch(ArmEmitterContext context, Operand address, bool isJump = false)
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{
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if (address.Type == OperandType.I32)
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{
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address = context.ZeroExtend32(OperandType.I64, address);
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}
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// TODO: Constant folding. Indirect calls are slower in the best case and emit more code so we want to avoid them when possible.
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bool isConst = address.Kind == OperandKind.Constant;
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long constAddr = (long)address.Value;
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if (!context.HighCq)
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{
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// Don't emit indirect calls or jumps if we're compiling in lowCq mode.
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// This avoids wasting space on the jump and indirect tables.
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// Just ask the translator for the function address.
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EmitBranchFallback(context, address, isJump);
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}
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else if (!isConst)
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{
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// Virtual branch/call - store first used addresses on a small table for fast lookup.
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int entry = context.JumpTable.ReserveDynamicEntry(isJump);
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int jumpOffset = entry * JumpTable.JumpTableStride * JumpTable.DynamicTableElems;
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Operand dynTablePtr = Const(context.JumpTable.DynamicPointer.ToInt64() + jumpOffset);
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EmitDynamicTableCall(context, dynTablePtr, address, isJump);
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}
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else
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{
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int entry = context.JumpTable.ReserveTableEntry(context.BaseAddress & (~3L), constAddr, isJump);
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int jumpOffset = entry * JumpTable.JumpTableStride + 8; // Offset directly to the host address.
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// TODO: Relocatable jump table ptr for AOT. Would prefer a solution to patch this constant into functions as they are loaded rather than calculate at runtime.
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Operand tableEntryPtr = Const(context.JumpTable.JumpPointer.ToInt64() + jumpOffset);
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Operand funcAddr = context.Load(OperandType.I64, tableEntryPtr);
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EmitNativeCallWithGuestAddress(context, funcAddr, address, isJump); // Call the function directly. If it's not present yet, this will call the direct call stub.
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}
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}
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}
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}
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