+// Arithmetic.
+defm WriteALU : X86SchedWritePair; // Simple integer ALU op.
+defm WriteIMul : X86SchedWritePair; // Integer multiplication.
+defm WriteIDiv : X86SchedWritePair; // Integer division.
+def WriteLEA : SchedWrite; // LEA instructions can't fold loads.
+
+// Integer shifts and rotates.
+defm WriteShift : X86SchedWritePair;
+
+// Loads, stores, and moves, not folded with other operations.
+def WriteLoad : SchedWrite;
+def WriteStore : SchedWrite;
+def WriteMove : SchedWrite;
+
+// Branches don't produce values, so they have no latency, but they still
+// consume resources. Indirect branches can fold loads.
+defm WriteJump : X86SchedWritePair;
+
+// Floating point. This covers both scalar and vector operations.
+defm WriteFAdd : X86SchedWritePair; // Floating point add/sub/compare.
+defm WriteFMul : X86SchedWritePair; // Floating point multiplication.
+defm WriteFDiv : X86SchedWritePair; // Floating point division.
+defm WriteFSqrt : X86SchedWritePair; // Floating point square root.
+defm WriteFRcp : X86SchedWritePair; // Floating point reciprocal.
+
+// Vector integer operations.
+defm WriteVecALU : X86SchedWritePair; // Vector integer ALU op, no logicals.
+defm WriteVecShift : X86SchedWritePair; // Vector integer shifts.
+defm WriteVecIMul : X86SchedWritePair; // Vector integer multiply.
+
+// Vector bitwise operations.
+// These are often used on both floating point and integer vectors.
+defm WriteVecLogic : X86SchedWritePair; // Vector and/or/xor.
+defm WriteShuffle : X86SchedWritePair; // Vector shuffles and blends.
+
+// Conversion between integer and float.
+defm WriteCvtF2I : X86SchedWritePair; // Float -> Integer.
+defm WriteCvtI2F : X86SchedWritePair; // Integer -> Float.
+defm WriteCvtF2F : X86SchedWritePair; // Float -> Float size conversion.