BPF backend

[oota-llvm.git] / lib / Target / BPF / BPFInstrInfo.cpp

diff --git a/lib/Target/BPF/BPFInstrInfo.cpp b/lib/Target/BPF/BPFInstrInfo.cpp
new file mode 100644 (file)
index 0000000..28bd0ec
--- /dev/null
+++ b/lib/Target/BPF/BPFInstrInfo.cpp
@@ -0,0 +1,168 @@
+//===-- BPFInstrInfo.cpp - BPF Instruction Information ----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the BPF implementation of the TargetInstrInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "BPF.h"
+#include "BPFInstrInfo.h"
+#include "BPFSubtarget.h"
+#include "BPFTargetMachine.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+
+#define GET_INSTRINFO_CTOR_DTOR
+#include "BPFGenInstrInfo.inc"
+
+using namespace llvm;
+
+BPFInstrInfo::BPFInstrInfo()
+    : BPFGenInstrInfo(BPF::ADJCALLSTACKDOWN, BPF::ADJCALLSTACKUP) {}
+
+void BPFInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
+                               MachineBasicBlock::iterator I, DebugLoc DL,
+                               unsigned DestReg, unsigned SrcReg,
+                               bool KillSrc) const {
+  if (BPF::GPRRegClass.contains(DestReg, SrcReg))
+    BuildMI(MBB, I, DL, get(BPF::MOV_rr), DestReg)
+        .addReg(SrcReg, getKillRegState(KillSrc));
+  else
+    llvm_unreachable("Impossible reg-to-reg copy");
+}
+
+void BPFInstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
+                                       MachineBasicBlock::iterator I,
+                                       unsigned SrcReg, bool IsKill, int FI,
+                                       const TargetRegisterClass *RC,
+                                       const TargetRegisterInfo *TRI) const {
+  DebugLoc DL;
+  if (I != MBB.end())
+    DL = I->getDebugLoc();
+
+  if (RC == &BPF::GPRRegClass)
+    BuildMI(MBB, I, DL, get(BPF::STD))
+        .addReg(SrcReg, getKillRegState(IsKill))
+        .addFrameIndex(FI)
+        .addImm(0);
+  else
+    llvm_unreachable("Can't store this register to stack slot");
+}
+
+void BPFInstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
+                                        MachineBasicBlock::iterator I,
+                                        unsigned DestReg, int FI,
+                                        const TargetRegisterClass *RC,
+                                        const TargetRegisterInfo *TRI) const {
+  DebugLoc DL;
+  if (I != MBB.end())
+    DL = I->getDebugLoc();
+
+  if (RC == &BPF::GPRRegClass)
+    BuildMI(MBB, I, DL, get(BPF::LDD), DestReg).addFrameIndex(FI).addImm(0);
+  else
+    llvm_unreachable("Can't load this register from stack slot");
+}
+
+bool BPFInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
+                                 MachineBasicBlock *&TBB,
+                                 MachineBasicBlock *&FBB,
+                                 SmallVectorImpl<MachineOperand> &Cond,
+                                 bool AllowModify) const {
+  // Start from the bottom of the block and work up, examining the
+  // terminator instructions.
+  MachineBasicBlock::iterator I = MBB.end();
+  while (I != MBB.begin()) {
+    --I;
+    if (I->isDebugValue())
+      continue;
+
+    // Working from the bottom, when we see a non-terminator
+    // instruction, we're done.
+    if (!isUnpredicatedTerminator(I))
+      break;
+
+    // A terminator that isn't a branch can't easily be handled
+    // by this analysis.
+    if (!I->isBranch())
+      return true;
+
+    // Handle unconditional branches.
+    if (I->getOpcode() == BPF::JMP) {
+      if (!AllowModify) {
+        TBB = I->getOperand(0).getMBB();
+        continue;
+      }
+
+      // If the block has any instructions after a J, delete them.
+      while (std::next(I) != MBB.end())
+        std::next(I)->eraseFromParent();
+      Cond.clear();
+      FBB = 0;
+
+      // Delete the J if it's equivalent to a fall-through.
+      if (MBB.isLayoutSuccessor(I->getOperand(0).getMBB())) {
+        TBB = 0;
+        I->eraseFromParent();
+        I = MBB.end();
+        continue;
+      }
+
+      // TBB is used to indicate the unconditinal destination.
+      TBB = I->getOperand(0).getMBB();
+      continue;
+    }
+    // Cannot handle conditional branches
+    return true;
+  }
+
+  return false;
+}
+
+unsigned BPFInstrInfo::InsertBranch(MachineBasicBlock &MBB,
+                                    MachineBasicBlock *TBB,
+                                    MachineBasicBlock *FBB,
+                                    const SmallVectorImpl<MachineOperand> &Cond,
+                                    DebugLoc DL) const {
+  // Shouldn't be a fall through.
+  assert(TBB && "InsertBranch must not be told to insert a fallthrough");
+
+  if (Cond.empty()) {
+    // Unconditional branch
+    assert(!FBB && "Unconditional branch with multiple successors!");
+    BuildMI(&MBB, DL, get(BPF::JMP)).addMBB(TBB);
+    return 1;
+  }
+
+  llvm_unreachable("Unexpected conditional branch");
+}
+
+unsigned BPFInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
+  MachineBasicBlock::iterator I = MBB.end();
+  unsigned Count = 0;
+
+  while (I != MBB.begin()) {
+    --I;
+    if (I->isDebugValue())
+      continue;
+    if (I->getOpcode() != BPF::JMP)
+      break;
+    // Remove the branch.
+    I->eraseFromParent();
+    I = MBB.end();
+    ++Count;
+  }
+
+  return Count;
+}