1 files changed, 100 insertions, 0 deletions
diff --git a/llvm/lib/Target/ARM/ARMHazardRecognizer.cpp b/llvm/lib/Target/ARM/ARMHazardRecognizer.cpp
new file mode 100644
index 000000000000..0fa32a0abeff
--- /dev/null
+++ b/llvm/lib/Target/ARM/ARMHazardRecognizer.cpp
@@ -0,0 +1,100 @@
+//===-- ARMHazardRecognizer.cpp - ARM postra hazard recognizer ------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "ARMHazardRecognizer.h"
+#include "ARMBaseInstrInfo.h"
+#include "ARMBaseRegisterInfo.h"
+#include "ARMSubtarget.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/CodeGen/TargetRegisterInfo.h"
+using namespace llvm;
+
+static bool hasRAWHazard(MachineInstr *DefMI, MachineInstr *MI,
+                         const TargetRegisterInfo &TRI) {
+  // FIXME: Detect integer instructions properly.
+  const MCInstrDesc &MCID = MI->getDesc();
+  unsigned Domain = MCID.TSFlags & ARMII::DomainMask;
+  if (MI->mayStore())
+    return false;
+  unsigned Opcode = MCID.getOpcode();
+  if (Opcode == ARM::VMOVRS || Opcode == ARM::VMOVRRD)
+    return false;
+  if ((Domain & ARMII::DomainVFP) || (Domain & ARMII::DomainNEON))
+    return MI->readsRegister(DefMI->getOperand(0).getReg(), &TRI);
+  return false;
+}
+
+ScheduleHazardRecognizer::HazardType
+ARMHazardRecognizer::getHazardType(SUnit *SU, int Stalls) {
+  assert(Stalls == 0 && "ARM hazards don't support scoreboard lookahead");
+
+  MachineInstr *MI = SU->getInstr();
+
+  if (!MI->isDebugInstr()) {
+    // Look for special VMLA / VMLS hazards. A VMUL / VADD / VSUB following
+    // a VMLA / VMLS will cause 4 cycle stall.
+    const MCInstrDesc &MCID = MI->getDesc();
+    if (LastMI && (MCID.TSFlags & ARMII::DomainMask) != ARMII::DomainGeneral) {
+      MachineInstr *DefMI = LastMI;
+      const MCInstrDesc &LastMCID = LastMI->getDesc();
+      const MachineFunction *MF = MI->getParent()->getParent();
+      const ARMBaseInstrInfo &TII = *static_cast<const ARMBaseInstrInfo *>(
+                                        MF->getSubtarget().getInstrInfo());
+
+      // Skip over one non-VFP / NEON instruction.
+      if (!LastMI->isBarrier() &&
+          !(TII.getSubtarget().hasMuxedUnits() && LastMI->mayLoadOrStore()) &&
+          (LastMCID.TSFlags & ARMII::DomainMask) == ARMII::DomainGeneral) {
+        MachineBasicBlock::iterator I = LastMI;
+        if (I != LastMI->getParent()->begin()) {
+          I = std::prev(I);
+          DefMI = &*I;
+        }
+      }
+
+      if (TII.isFpMLxInstruction(DefMI->getOpcode()) &&
+          (TII.canCauseFpMLxStall(MI->getOpcode()) ||
+           hasRAWHazard(DefMI, MI, TII.getRegisterInfo()))) {
+        // Try to schedule another instruction for the next 4 cycles.
+        if (FpMLxStalls == 0)
+          FpMLxStalls = 4;
+        return Hazard;
+      }
+    }
+  }
+
+  return ScoreboardHazardRecognizer::getHazardType(SU, Stalls);
+}
+
+void ARMHazardRecognizer::Reset() {
+  LastMI = nullptr;
+  FpMLxStalls = 0;
+  ScoreboardHazardRecognizer::Reset();
+}
+
+void ARMHazardRecognizer::EmitInstruction(SUnit *SU) {
+  MachineInstr *MI = SU->getInstr();
+  if (!MI->isDebugInstr()) {
+    LastMI = MI;
+    FpMLxStalls = 0;
+  }
+
+  ScoreboardHazardRecognizer::EmitInstruction(SU);
+}
+
+void ARMHazardRecognizer::AdvanceCycle() {
+  if (FpMLxStalls && --FpMLxStalls == 0)
+    // Stalled for 4 cycles but still can't schedule any other instructions.
+    LastMI = nullptr;
+  ScoreboardHazardRecognizer::AdvanceCycle();
+}
+
+void ARMHazardRecognizer::RecedeCycle() {
+  llvm_unreachable("reverse ARM hazard checking unsupported");
+}