vendor/llvm/llvm-r126079

1 files changed, 121 insertions, 0 deletions

diff --git a/lib/Target/ARM/ARMHazardRecognizer.cpp b/lib/Target/ARM/ARMHazardRecognizer.cpp
new file mode 100644
index 000000000000..676b01e91c53
--- /dev/null
+++ b/lib/Target/ARM/ARMHazardRecognizer.cpp
@@ -0,0 +1,121 @@
+//===-- ARMHazardRecognizer.cpp - ARM postra hazard recognizer ------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ARMHazardRecognizer.h"
+#include "ARMBaseInstrInfo.h"
+#include "ARMBaseRegisterInfo.h"
+#include "ARMSubtarget.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+using namespace llvm;
+
+static bool hasRAWHazard(MachineInstr *DefMI, MachineInstr *MI,
+                         const TargetRegisterInfo &TRI) {
+  // FIXME: Detect integer instructions properly.
+  const TargetInstrDesc &TID = MI->getDesc();
+  unsigned Domain = TID.TSFlags & ARMII::DomainMask;
+  if (Domain == ARMII::DomainVFP) {
+    unsigned Opcode = MI->getOpcode();
+    if (Opcode == ARM::VSTRS || Opcode == ARM::VSTRD ||
+        Opcode == ARM::VMOVRS || Opcode == ARM::VMOVRRD)
+      return false;
+  } else if (Domain == ARMII::DomainNEON) {
+    if (MI->getDesc().mayStore() || MI->getDesc().mayLoad())
+      return false;
+  } else
+    return false;
+  return MI->readsRegister(DefMI->getOperand(0).getReg(), &TRI);
+}
+
+ScheduleHazardRecognizer::HazardType
+ARMHazardRecognizer::getHazardType(SUnit *SU, int Stalls) {
+  assert(Stalls == 0 && "ARM hazards don't support scoreboard lookahead");
+
+  MachineInstr *MI = SU->getInstr();
+
+  if (!MI->isDebugValue()) {
+    if (ITBlockSize && MI != ITBlockMIs[ITBlockSize-1])
+      return Hazard;
+
+    // Look for special VMLA / VMLS hazards. A VMUL / VADD / VSUB following
+    // a VMLA / VMLS will cause 4 cycle stall.
+    const TargetInstrDesc &TID = MI->getDesc();
+    if (LastMI && (TID.TSFlags & ARMII::DomainMask) != ARMII::DomainGeneral) {
+      MachineInstr *DefMI = LastMI;
+      const TargetInstrDesc &LastTID = LastMI->getDesc();
+      // Skip over one non-VFP / NEON instruction.
+      if (!LastTID.isBarrier() &&
+          (LastTID.TSFlags & ARMII::DomainMask) == ARMII::DomainGeneral) {
+        MachineBasicBlock::iterator I = LastMI;
+        if (I != LastMI->getParent()->begin()) {
+          I = llvm::prior(I);
+          DefMI = &*I;
+        }
+      }
+
+      if (TII.isFpMLxInstruction(DefMI->getOpcode()) &&
+          (TII.canCauseFpMLxStall(MI->getOpcode()) ||
+           hasRAWHazard(DefMI, MI, TRI))) {
+        // 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 = 0;
+  FpMLxStalls = 0;
+  ITBlockSize = 0;
+  ScoreboardHazardRecognizer::Reset();
+}
+
+void ARMHazardRecognizer::EmitInstruction(SUnit *SU) {
+  MachineInstr *MI = SU->getInstr();
+  unsigned Opcode = MI->getOpcode();
+  if (ITBlockSize) {
+    --ITBlockSize;
+  } else if (Opcode == ARM::t2IT) {
+    unsigned Mask = MI->getOperand(1).getImm();
+    unsigned NumTZ = CountTrailingZeros_32(Mask);
+    assert(NumTZ <= 3 && "Invalid IT mask!");
+    ITBlockSize = 4 - NumTZ;
+    MachineBasicBlock::iterator I = MI;
+    for (unsigned i = 0; i < ITBlockSize; ++i) {
+      // Advance to the next instruction, skipping any dbg_value instructions.
+      do {
+        ++I;
+      } while (I->isDebugValue());
+      ITBlockMIs[ITBlockSize-1-i] = &*I;
+    }
+  }
+
+  if (!MI->isDebugValue()) {
+    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 = 0;
+  ScoreboardHazardRecognizer::AdvanceCycle();
+}
+
+void ARMHazardRecognizer::RecedeCycle() {
+  llvm_unreachable("reverse ARM hazard checking unsupported");
+}