[llvm] r177942 - Add a scheduling model for Intel Sandy Bridge microarchitecture.

[Jakob Stoklund Olesen]

Author: stoklund
Date: Mon Mar 25 18:37:17 2013
New Revision: 177942

URL: http://llvm.org/viewvc/llvm-project?rev=177942&view=rev
Log:
Add a scheduling model for Intel Sandy Bridge microarchitecture.

The model isn't hooked up by this patch because the instruction set
isn't fully annotated yet.

Added:
    llvm/trunk/lib/Target/X86/X86SchedSandyBridge.td

Added: llvm/trunk/lib/Target/X86/X86SchedSandyBridge.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86SchedSandyBridge.td?rev=177942&view=auto
==============================================================================
--- llvm/trunk/lib/Target/X86/X86SchedSandyBridge.td (added)
+++ llvm/trunk/lib/Target/X86/X86SchedSandyBridge.td Mon Mar 25 18:37:17 2013
@@ -0,0 +1,123 @@
+//=- X86SchedSandyBridge.td - X86 Sandy Bridge Scheduling ----*- tablegen -*-=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the machine model for Sandy Bridge to support instruction
+// scheduling and other instruction cost heuristics.
+//
+//===----------------------------------------------------------------------===//
+
+def SandyBridgeModel : SchedMachineModel {
+  // All x86 instructions are modeled as a single micro-op, and SB can decode 4
+  // instructions per cycle.
+  // FIXME: Identify instructions that aren't a single fused micro-op.
+  let IssueWidth = 4;
+  let MinLatency = 0; // 0 = Out-of-order execution.
+  let LoadLatency = 4;
+  let ILPWindow = 30;
+  let MispredictPenalty = 16;
+}
+
+let SchedModel = SandyBridgeModel in {
+
+// Sandy Bridge can issue micro-ops to 6 different ports in one cycle.
+
+// Ports 0, 1, and 5 handle all computation.
+def SBPort0 : ProcResource<1>;
+def SBPort1 : ProcResource<1>;
+def SBPort5 : ProcResource<1>;
+
+// Ports 2 and 3 are identical. They handle loads and the address half of
+// stores.
+def SBPort23 : ProcResource<2>;
+
+// Port 4 gets the data half of stores. Store data can be available later than
+// the store address, but since we don't model the latency of stores, we can
+// ignore that.
+def SBPort4 : ProcResource<1>;
+
+// Many micro-ops are capable of issuing on multiple ports.
+def SBPort01  : ProcResGroup<[SBPort0, SBPort1]>;
+def SBPort05  : ProcResGroup<[SBPort0, SBPort5]>;
+def SBPort15  : ProcResGroup<[SBPort1, SBPort5]>;
+def SBPort015 : ProcResGroup<[SBPort0, SBPort1, SBPort5]>;
+
+// Integer division issued on port 0, but uses the non-pipelined divider.
+def SBDivider : ProcResource<1> { let Buffered = 0; }
+
+// Loads are 4 cycles, so ReadAfterLd registers needn't be available until 4
+// cycles after the memory operand.
+def : ReadAdvance<ReadAfterLd, 4>;
+
+// Many SchedWrites are defined in pairs with and without a folded load.
+// Instructions with folded loads are usually micro-fused, so they only appear
+// as two micro-ops when queued in the reservation station.
+// This multiclass defines the resource usage for variants with and without
+// folded loads.
+multiclass SBWriteResPair<X86FoldableSchedWrite SchedRW,
+                          ProcResourceKind ExePort,
+                          int Lat> {
+  // Register variant is using a single cycle on ExePort.
+  def : WriteRes<SchedRW, [ExePort]> { let Latency = Lat; }
+
+  // Memory variant also uses a cycle on port 2/3 and adds 4 cycles to the
+  // latency.
+  def : WriteRes<SchedRW.Folded, [SBPort23, ExePort]> {
+     let Latency = !add(Lat, 4);
+  }
+}
+
+// A folded store needs a cycle on port 4 for the store data, but it does not
+// need an extra port 2/3 cycle to recompute the address.
+def : WriteRes<WriteRMW, [SBPort4]>;
+
+def : WriteRes<WriteStore, [SBPort23, SBPort4]>;
+def : WriteRes<WriteLoad,  [SBPort23]> { let Latency = 4; }
+def : WriteRes<WriteMove,  [SBPort015]>;
+def : WriteRes<WriteZero,  []>;
+
+defm : SBWriteResPair<WriteALU,   SBPort015, 1>;
+defm : SBWriteResPair<WriteIMul,  SBPort1,   3>;
+defm : SBWriteResPair<WriteShift, SBPort05,  1>;
+defm : SBWriteResPair<WriteJump,  SBPort5,   1>;
+
+// This is for simple LEAs with one or two input operands.
+// The complex ones can only execute on port 1, and they require two cycles on
+// the port to read all inputs. We don't model that.
+def : WriteRes<WriteLEA, [SBPort15]>;
+
+// This is quite rough, latency depends on the dividend.
+def : WriteRes<WriteIDiv, [SBPort0, SBDivider]> {
+  let Latency = 25;
+  let ResourceCycles = [1, 10];
+}
+def : WriteRes<WriteIDivLd, [SBPort23, SBPort0, SBDivider]> {
+  let Latency = 29;
+  let ResourceCycles = [1, 1, 10];
+}
+
+// Scalar and vector floating point.
+defm : SBWriteResPair<WriteFAdd,   SBPort1, 3>;
+defm : SBWriteResPair<WriteFMul,   SBPort0, 5>;
+defm : SBWriteResPair<WriteFDiv,   SBPort0, 12>; // 10-14 cycles.
+defm : SBWriteResPair<WriteFRcp,   SBPort0, 5>;
+defm : SBWriteResPair<WriteFSqrt,  SBPort0, 15>;
+defm : SBWriteResPair<WriteCvtF2I, SBPort1, 3>;
+defm : SBWriteResPair<WriteCvtI2F, SBPort1, 4>;
+defm : SBWriteResPair<WriteCvtF2F, SBPort1, 3>;
+
+// Vector integer operations.
+defm : SBWriteResPair<WriteVecShift, SBPort05,  1>;
+defm : SBWriteResPair<WriteVecLogic, SBPort015, 1>;
+defm : SBWriteResPair<WriteVecALU,   SBPort15,  1>;
+defm : SBWriteResPair<WriteVecIMul,  SBPort0,   5>;
+defm : SBWriteResPair<WriteShuffle,  SBPort15,  1>;
+
+def : WriteRes<WriteSystem,     [SBPort015]> { let Latency = 100; }
+def : WriteRes<WriteMicrocoded, [SBPort015]> { let Latency = 100; }
+} // SchedModel