Faster crc32 implementation (#1294)

* Add Pclmulqdq intrinsic

* Implement crc32 in terms of pclmulqdq

* Address PR comments

1 files changed, 129 insertions, 8 deletions

diff --git a/ARMeilleure/Instructions/InstEmitHash.cs b/ARMeilleure/Instructions/InstEmitHash.cs
index 0be8458e..8a539666 100644
--- a/ARMeilleure/Instructions/InstEmitHash.cs
+++ b/ARMeilleure/Instructions/InstEmitHash.cs
@@ -1,9 +1,13 @@
+// https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf
+
 using ARMeilleure.Decoders;
 using ARMeilleure.IntermediateRepresentation;
 using ARMeilleure.Translation;
 using System;
 
 using static ARMeilleure.Instructions.InstEmitHelper;
+using static ARMeilleure.Instructions.InstEmitSimdHelper;
+using static ARMeilleure.IntermediateRepresentation.OperandHelper;
 
 namespace ARMeilleure.Instructions
 {
@@ -11,42 +15,159 @@ namespace ARMeilleure.Instructions
     {
         public static void Crc32b(ArmEmitterContext context)
         {
-            EmitCrc32Call(context, new _U32_U32_U8(SoftFallback.Crc32b));
+            if (Optimizations.UsePclmulqdq)
+            {
+                EmitCrc32Optimized(context, false, 8);
+            }
+            else
+            {
+                EmitCrc32Call(context, new _U32_U32_U8(SoftFallback.Crc32b));
+            }
         }
 
         public static void Crc32h(ArmEmitterContext context)
         {
-            EmitCrc32Call(context, new _U32_U32_U16(SoftFallback.Crc32h));
+            if (Optimizations.UsePclmulqdq)
+            {
+                EmitCrc32Optimized(context, false, 16);
+            }
+            else
+            {
+                EmitCrc32Call(context, new _U32_U32_U16(SoftFallback.Crc32h));
+            }
         }
 
         public static void Crc32w(ArmEmitterContext context)
         {
-            EmitCrc32Call(context, new _U32_U32_U32(SoftFallback.Crc32w));
+            if (Optimizations.UsePclmulqdq)
+            {
+                EmitCrc32Optimized(context, false, 32);
+            }
+            else
+            {
+                EmitCrc32Call(context, new _U32_U32_U32(SoftFallback.Crc32w));
+            }
         }
 
         public static void Crc32x(ArmEmitterContext context)
         {
-            EmitCrc32Call(context, new _U32_U32_U64(SoftFallback.Crc32x));
+            if (Optimizations.UsePclmulqdq)
+            {
+                EmitCrc32Optimized64(context, false);
+            }
+            else
+            {
+                EmitCrc32Call(context, new _U32_U32_U64(SoftFallback.Crc32x));
+            }
         }
 
         public static void Crc32cb(ArmEmitterContext context)
         {
-            EmitCrc32Call(context, new _U32_U32_U8(SoftFallback.Crc32cb));
+            if (Optimizations.UsePclmulqdq)
+            {
+                EmitCrc32Optimized(context, true, 8);
+            }
+            else
+            {
+                EmitCrc32Call(context, new _U32_U32_U8(SoftFallback.Crc32cb));
+            }
         }
 
         public static void Crc32ch(ArmEmitterContext context)
         {
-            EmitCrc32Call(context, new _U32_U32_U16(SoftFallback.Crc32ch));
+            if (Optimizations.UsePclmulqdq)
+            {
+                EmitCrc32Optimized(context, true, 16);
+            }
+            else
+            {
+                EmitCrc32Call(context, new _U32_U32_U16(SoftFallback.Crc32ch));
+            }
         }
 
         public static void Crc32cw(ArmEmitterContext context)
         {
-            EmitCrc32Call(context, new _U32_U32_U32(SoftFallback.Crc32cw));
+            if (Optimizations.UsePclmulqdq)
+            {
+                EmitCrc32Optimized(context, true, 32);
+            }
+            else
+            {
+                EmitCrc32Call(context, new _U32_U32_U32(SoftFallback.Crc32cw));
+            }
         }
 
         public static void Crc32cx(ArmEmitterContext context)
         {
-            EmitCrc32Call(context, new _U32_U32_U64(SoftFallback.Crc32cx));
+            if (Optimizations.UsePclmulqdq)
+            {
+                EmitCrc32Optimized64(context, true);
+            }
+            else
+            {
+                EmitCrc32Call(context, new _U32_U32_U64(SoftFallback.Crc32cx));
+            }
+        }
+
+        private static void EmitCrc32Optimized(ArmEmitterContext context, bool castagnoli, int bitsize)
+        {
+            OpCodeAluBinary op = (OpCodeAluBinary)context.CurrOp;
+
+            long mu = castagnoli ? 0x0DEA713F1 : 0x1F7011641; // mu' = floor(x^64/P(x))'
+            long polynomial = castagnoli ? 0x105EC76F0 : 0x1DB710641; // P'(x) << 1
+
+            Operand crc = GetIntOrZR(context, op.Rn);
+            Operand data = GetIntOrZR(context, op.Rm);
+
+            crc = context.VectorInsert(context.VectorZero(), crc, 0);
+
+            switch (bitsize)
+            {
+                case 8: data = context.VectorInsert8(context.VectorZero(), data, 0); break;
+                case 16: data = context.VectorInsert16(context.VectorZero(), data, 0); break;
+                case 32: data = context.VectorInsert(context.VectorZero(), data, 0); break;
+            }
+
+            Operand tmp = context.AddIntrinsic(Intrinsic.X86Pxor, crc, data);
+            tmp = context.AddIntrinsic(Intrinsic.X86Psllq, tmp, Const(64 - bitsize));
+            tmp = context.AddIntrinsic(Intrinsic.X86Pclmulqdq, tmp, X86GetScalar(context, mu), Const(0));
+            tmp = context.AddIntrinsic(Intrinsic.X86Pclmulqdq, tmp, X86GetScalar(context, polynomial), Const(0));
+
+            if (bitsize < 32)
+            {
+                crc = context.AddIntrinsic(Intrinsic.X86Pslldq, crc, Const((64 - bitsize) / 8));
+                tmp = context.AddIntrinsic(Intrinsic.X86Pxor, tmp, crc);
+            }
+
+            SetIntOrZR(context, op.Rd, context.VectorExtract(OperandType.I32, tmp, 2));
+        }
+
+        private static void EmitCrc32Optimized64(ArmEmitterContext context, bool castagnoli)
+        {
+            OpCodeAluBinary op = (OpCodeAluBinary)context.CurrOp;
+
+            long mu = castagnoli ? 0x0DEA713F1 : 0x1F7011641; // mu' = floor(x^64/P(x))'
+            long polynomial = castagnoli ? 0x105EC76F0 : 0x1DB710641; // P'(x) << 1
+
+            Operand crc = GetIntOrZR(context, op.Rn);
+            Operand data = GetIntOrZR(context, op.Rm);
+
+            crc = context.VectorInsert(context.VectorZero(), crc, 0);
+            data = context.VectorInsert(context.VectorZero(), data, 0);
+
+            Operand tmp = context.AddIntrinsic(Intrinsic.X86Pxor, crc, data);
+            Operand res = context.AddIntrinsic(Intrinsic.X86Pslldq, tmp, Const(4));
+
+            tmp = context.AddIntrinsic(Intrinsic.X86Pclmulqdq, res, X86GetScalar(context, mu), Const(0));
+            tmp = context.AddIntrinsic(Intrinsic.X86Pclmulqdq, tmp, X86GetScalar(context, polynomial), Const(0));
+
+            tmp = context.AddIntrinsic(Intrinsic.X86Pxor, tmp, res);
+            tmp = context.AddIntrinsic(Intrinsic.X86Psllq, tmp, Const(32));
+
+            tmp = context.AddIntrinsic(Intrinsic.X86Pclmulqdq, tmp, X86GetScalar(context, mu), Const(1));
+            tmp = context.AddIntrinsic(Intrinsic.X86Pclmulqdq, tmp, X86GetScalar(context, polynomial), Const(0));
+
+            SetIntOrZR(context, op.Rd, context.VectorExtract(OperandType.I32, tmp, 2));
         }
 
         private static void EmitCrc32Call(ArmEmitterContext context, Delegate dlg)