Improve instruction scheduling for the PPC POWER7

Aside from a few minor latency corrections, the major change here is a new
hazard recognizer which focuses on better dispatch-group formation on the
POWER7. As with the PPC970's hazard recognizer, the most important thing it
does is avoid load-after-store hazards within the same dispatch group. It uses
the POWER7's special dispatch-group-terminating nop instruction (instead of
inserting multiple regular nop instructions). This new hazard recognizer makes
use of the scheduling dependency graph itself, built using AA information, to
robustly detect the possibility of load-after-store hazards.

significant test-suite performance changes (the error bars are 99.5% confidence
intervals based on 5 test-suite runs both with and without the change --
speedups are negative):

speedups:

MultiSource/Benchmarks/FreeBench/pcompress2/pcompress2
	-0.55171% +/- 0.333168%

MultiSource/Benchmarks/TSVC/CrossingThresholds-dbl/CrossingThresholds-dbl
	-17.5576% +/- 14.598%

MultiSource/Benchmarks/TSVC/Reductions-dbl/Reductions-dbl
	-29.5708% +/- 7.09058%

MultiSource/Benchmarks/TSVC/Reductions-flt/Reductions-flt
	-34.9471% +/- 11.4391%

SingleSource/Benchmarks/BenchmarkGame/puzzle
	-25.1347% +/- 11.0104%

SingleSource/Benchmarks/Misc/flops-8
	-17.7297% +/- 9.79061%

SingleSource/Benchmarks/Shootout-C++/ary3
	-35.5018% +/- 23.9458%

SingleSource/Regression/C/uint64_to_float
	-56.3165% +/- 25.4234%

SingleSource/UnitTests/Vectorizer/gcc-loops
	-18.5309% +/- 6.8496%

regressions:

MultiSource/Benchmarks/ASCI_Purple/SMG2000/smg2000
	18.351% +/- 12.156%

SingleSource/Benchmarks/Shootout-C++/methcall
	27.3086% +/- 14.4733%

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197099 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 64 insertions, 2 deletions

diff --git a/lib/Target/PowerPC/PPCInstrInfo.cpp b/lib/Target/PowerPC/PPCInstrInfo.cpp
index c4582c540b..bd3b4924cc 100644
--- a/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -74,6 +74,9 @@ ScheduleHazardRecognizer *PPCInstrInfo::CreateTargetPostRAHazardRecognizer(
   const ScheduleDAG *DAG) const {
   unsigned Directive = TM.getSubtarget<PPCSubtarget>().getDarwinDirective();
 
+  if (Directive == PPC::DIR_PWR7)
+    return new PPCDispatchGroupSBHazardRecognizer(II, DAG);
+
   // Most subtargets use a PPC970 recognizer.
   if (Directive != PPC::DIR_440 && Directive != PPC::DIR_A2 &&
       Directive != PPC::DIR_E500mc && Directive != PPC::DIR_E5500) {
@@ -85,6 +88,56 @@ ScheduleHazardRecognizer *PPCInstrInfo::CreateTargetPostRAHazardRecognizer(
   return new ScoreboardHazardRecognizer(II, DAG);
 }
 
+
+int PPCInstrInfo::getOperandLatency(const InstrItineraryData *ItinData,
+                                    const MachineInstr *DefMI, unsigned DefIdx,
+                                    const MachineInstr *UseMI,
+                                    unsigned UseIdx) const {
+  int Latency = PPCGenInstrInfo::getOperandLatency(ItinData, DefMI, DefIdx,
+                                                   UseMI, UseIdx);
+
+  const MachineOperand &DefMO = DefMI->getOperand(DefIdx);
+  unsigned Reg = DefMO.getReg();
+
+  const TargetRegisterInfo *TRI = &getRegisterInfo();
+  bool IsRegCR;
+  if (TRI->isVirtualRegister(Reg)) {
+    const MachineRegisterInfo *MRI =
+      &DefMI->getParent()->getParent()->getRegInfo();
+    IsRegCR = MRI->getRegClass(Reg)->hasSuperClassEq(&PPC::CRRCRegClass) ||
+              MRI->getRegClass(Reg)->hasSuperClassEq(&PPC::CRBITRCRegClass);
+  } else {
+    IsRegCR = PPC::CRRCRegClass.contains(Reg) ||
+              PPC::CRBITRCRegClass.contains(Reg);
+  }
+
+  if (UseMI->isBranch() && IsRegCR) {
+    if (Latency < 0)
+      Latency = getInstrLatency(ItinData, DefMI);
+
+    // On some cores, there is an additional delay between writing to a condition
+    // register, and using it from a branch.
+    unsigned Directive = TM.getSubtarget<PPCSubtarget>().getDarwinDirective();
+    switch (Directive) {
+    default: break;
+    case PPC::DIR_7400:
+    case PPC::DIR_750:
+    case PPC::DIR_970:
+    case PPC::DIR_E5500:
+    case PPC::DIR_PWR4:
+    case PPC::DIR_PWR5:
+    case PPC::DIR_PWR5X:
+    case PPC::DIR_PWR6:
+    case PPC::DIR_PWR6X:
+    case PPC::DIR_PWR7:
+      Latency += 2;
+      break;
+    }
+  }
+
+  return Latency;
+}
+
 // Detect 32 -> 64-bit extensions where we may reuse the low sub-register.
 bool PPCInstrInfo::isCoalescableExtInstr(const MachineInstr &MI,
                                          unsigned &SrcReg, unsigned &DstReg,
@@ -218,11 +271,20 @@ PPCInstrInfo::commuteInstruction(MachineInstr *MI, bool NewMI) const {
 
 void PPCInstrInfo::insertNoop(MachineBasicBlock &MBB,
                               MachineBasicBlock::iterator MI) const {
+  // This function is used for scheduling, and the nop wanted here is the type
+  // that terminates dispatch groups on the POWER cores.
+  unsigned Directive = TM.getSubtarget<PPCSubtarget>().getDarwinDirective();
+  unsigned Opcode;
+  switch (Directive) {
+  default:            Opcode = PPC::NOP; break;
+  case PPC::DIR_PWR6: Opcode = PPC::NOP_GT_PWR6; break;
+  case PPC::DIR_PWR7: Opcode = PPC::NOP_GT_PWR7; break;
+  }
+
   DebugLoc DL;
-  BuildMI(MBB, MI, DL, get(PPC::NOP));
+  BuildMI(MBB, MI, DL, get(Opcode));
 }
 
-
 // Branch analysis.
 // Note: If the condition register is set to CTR or CTR8 then this is a
 // BDNZ (imm == 1) or BDZ (imm == 0) branch.