Revert "[AVR] Add the branch selection pass from the GitHub repository"

This reverts commit 602ef067c1d58ecb425d061f35f2bc4c7e92f4f3.

llvm-svn: 307111

3 files changed, 0 insertions, 269 deletions

diff --git a/llvm/lib/Target/AVR/AVRBranchSelector.cpp b/llvm/lib/Target/AVR/AVRBranchSelector.cpp
deleted file mode 100644
index bbc15916963..00000000000
--- a/llvm/lib/Target/AVR/AVRBranchSelector.cpp
+++ /dev/null
@@ -1,262 +0,0 @@
-//===-- AVRBranchSelector.cpp - Emit long conditional branches ------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file contains a pass that scans a machine function to determine which
-// conditional branches need more than 8 bits of displacement to reach their
-// target basic block.  It does this in two passes; a calculation of basic block
-// positions pass, and a branch pseudo op to machine branch opcode pass.  This
-// pass should be run last, just before the assembly printer.
-//
-//===----------------------------------------------------------------------===//
-
-#include "AVR.h"
-
-#include "llvm/ADT/Statistic.h"
-#include "llvm/CodeGen/MachineFunctionPass.h"
-#include "llvm/CodeGen/MachineInstrBuilder.h"
-
-#include "AVRInstrInfo.h"
-#include "AVRTargetMachine.h"
-#include "MCTargetDesc/AVRMCTargetDesc.h"
-
-#define DEBUG_TYPE "avr-branch-select"
-
-STATISTIC(NumExpanded, "Number of branches expanded to long format");
-
-namespace llvm {
-
-/// Ensures branch targets can fit inside the instruction
-/// they reside in.
-///
-/// If a branch target is too large for the instruction it
-/// is being used with, this pass replaces it with a larger,
-/// equivalent instruction which can fit the target.
-class AVRBSel : public MachineFunctionPass {
-public:
-  static char ID;
-
-  explicit AVRBSel() : MachineFunctionPass(ID) {}
-
-  bool runOnMachineFunction(MachineFunction &MF) override;
-
-  StringRef getPassName() const override { return "AVR Branch Selector"; }
-
-protected:
-
-  /// Measure and sum the size of all basic blocks in a function.
-  unsigned calculateFunctionSize(const MachineFunction &MF);
-
-private:
-  /// The sizes of the basic blocks in the function.
-  std::vector<unsigned> BlockSizes;
-};
-
-char AVRBSel::ID = 0;
-
-/// Checks whether the passed opcode is a conditional branch.
-static bool isConditionalBranch(int Opcode) {
-  switch (Opcode) {
-  default:
-    return false;
-  case AVR::BREQk:
-  case AVR::BRNEk:
-  case AVR::BRSHk:
-  case AVR::BRLOk:
-  case AVR::BRMIk:
-  case AVR::BRPLk:
-  case AVR::BRGEk:
-  case AVR::BRLTk:
-    return true;
-  }
-}
-
-unsigned AVRBSel::calculateFunctionSize(const MachineFunction &MF) {
-  const AVRSubtarget &STI = MF.getSubtarget<AVRSubtarget>();
-  const AVRInstrInfo &TII = *STI.getInstrInfo();
-
-  unsigned FuncSize = 0;
-
-  for (const MachineBasicBlock &MBB : MF) {
-    unsigned BlockSize = 0;
-
-    for (const MachineInstr &MI : MBB) {
-      BlockSize += TII.getInstSizeInBytes(MI);
-    }
-
-    BlockSizes[MBB.getNumber()] = BlockSize;
-    FuncSize += BlockSize;
-  }
-
-  assert(FuncSize % 2 == 0 && "function should have an even number of bytes");
-
-  return FuncSize;
-}
-
-bool AVRBSel::runOnMachineFunction(MachineFunction &MF) {
-  const AVRSubtarget &STI = MF.getSubtarget<AVRSubtarget>();
-  const AVRInstrInfo &TII = *STI.getInstrInfo();
-
-  // Give the blocks of the function a dense, in-order, numbering.
-  MF.RenumberBlocks();
-  BlockSizes.resize(MF.getNumBlockIDs());
-
-  unsigned FuncSize = calculateFunctionSize(MF);
-
-  // If the entire function is smaller than the displacement of a branch field,
-  // we know we don't need to shrink any branches in this function.  This is a
-  // common case.
-  if (isUInt<7>(FuncSize)) {
-    BlockSizes.clear();
-    return false;
-  }
-
-  // For each conditional branch, if the offset to its destination is larger
-  // than the offset field allows, transform it into a long or a huge branch
-  // sequence like this:
-  //  -short branch:
-  //     brCC MBB
-  //  -long branch:
-  //     br!CC $PC+2
-  //     rjmp MBB
-  //  -huge branch:
-  //     br!CC $PC+4
-  //     jmp MBB
-  bool MadeChange = true;
-  while (MadeChange) {
-    // Iteratively expand branches until we reach a fixed point.
-    MadeChange = false;
-
-    for (MachineBasicBlock &MBB : MF) {
-      unsigned MBBStartOffset = 0;
-
-      for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E;
-           ++I) {
-        int Opc = I->getOpcode();
-        if ((!isConditionalBranch(Opc) || I->getOperand(0).isImm()) &&
-            (Opc != AVR::RJMPk)) {
-          MBBStartOffset += TII.getInstSizeInBytes(*I);
-          continue;
-        }
-
-        // Determine the offset from the current branch to the destination
-        // block.
-        MachineBasicBlock &Dest = *I->getOperand(0).getMBB();
-
-        assert(Dest.getNumber() >= 0 &&
-            "Destination basic block isn't in a function");
-
-        int BranchSize;
-        if (Dest.getNumber() <= MBB.getNumber()) {
-          // If this is a backwards branch, the delta is the offset from the
-          // start of this block to this branch, plus the sizes of all blocks
-          // from this block to the dest.
-          BranchSize = MBBStartOffset;
-
-          for (unsigned i = Dest.getNumber(), e = MBB.getNumber(); i != e;
-               ++i) {
-            BranchSize += BlockSizes[i];
-          }
-
-          // Set the size of backwards branches to a negative value.
-          BranchSize = -BranchSize;
-        } else {
-          // Otherwise, add the size of the blocks between this block and the
-          // dest to the number of bytes left in this block.
-          BranchSize = -MBBStartOffset;
-
-          for (unsigned i = MBB.getNumber(), e = Dest.getNumber(); i != e;
-               ++i) {
-            BranchSize += BlockSizes[i];
-          }
-        }
-
-        if (isConditionalBranch(Opc))
-          BranchSize -= 2; // take the size of the current instruction.
-
-        assert(BranchSize % 2 == 0 &&
-               "BranchSize should have an even number of bytes");
-
-        // If this branch is in range, ignore it.
-        if ((isConditionalBranch(Opc) && isInt<8>(BranchSize)) ||
-            (Opc == AVR::RJMPk && isInt<13>(BranchSize))) {
-          MBBStartOffset += 2;
-          continue;
-        }
-
-        // Otherwise, we have to expand it to a long branch.
-        unsigned NewSize;
-        int UncondOpc;
-        MachineInstr &OldBranch = *I;
-        DebugLoc DL = OldBranch.getDebugLoc();
-
-        if (Opc == AVR::RJMPk) {
-          // Replace this instruction with a jmp which has a size of 4 bytes.
-          NewSize = 4;
-          UncondOpc = AVR::JMPk;
-
-          // We may be converting a conditional long jump to a huge one, if this
-          // is the case, update the $PC+2 operand in brCC to $PC+4.
-          // Skip the check when this instruction is the first inside the BB.
-          if (I != MBB.begin()) {
-            MachineInstr &PI = *std::prev(I);
-
-            if (isConditionalBranch(PI.getOpcode()) &&
-                PI.getOperand(0).isImm() &&
-                PI.getOperand(0).getImm() == 2) {
-              PI.getOperand(0).setImm(4);
-            }
-          }
-        } else {
-          assert(isConditionalBranch(Opc) &&
-              "opcode should be a conditional branch");
-
-          unsigned BrCCOffs;
-          // Determine if we can reach the destination block with a rjmp,
-          // otherwise a jmp instruction is needed.
-          if (isInt<13>(BranchSize)) {
-            NewSize = 4;
-            BrCCOffs = 2;
-            UncondOpc = AVR::RJMPk;
-          } else {
-            NewSize = 6;
-            BrCCOffs = 4;
-            UncondOpc = AVR::JMPk;
-          }
-
-          AVRCC::CondCodes OCC =
-              TII.getOppositeCondition(TII.getCondFromBranchOpc(Opc));
-          // Jump over the uncond branch inst (i.e. $+2) on opposite condition.
-          BuildMI(MBB, I, DL, TII.getBrCond(OCC)).addImm(BrCCOffs);
-        }
-
-        // Uncond branch to the real destination.
-        I = BuildMI(MBB, I, DL, TII.get(UncondOpc)).addMBB(&Dest);
-
-        // Remove the old branch from the function.
-        OldBranch.eraseFromParent();
-
-        // Remember that this instruction is NewSize bytes, increase the size of
-        // the block by NewSize-2, remember to iterate.
-        BlockSizes[MBB.getNumber()] += NewSize - 2;
-        MBBStartOffset += NewSize;
-
-        ++NumExpanded;
-        MadeChange = true;
-      }
-    }
-  }
-
-  BlockSizes.clear();
-  return true;
-}
-
-FunctionPass *createAVRBranchSelectionPass() { return new AVRBSel(); }
-
-} // end of namespace llvm
-
diff --git a/llvm/lib/Target/AVR/AVRTargetMachine.cpp b/llvm/lib/Target/AVR/AVRTargetMachine.cpp
index f620668215a..91d2a8737b8 100644
--- a/llvm/lib/Target/AVR/AVRTargetMachine.cpp
+++ b/llvm/lib/Target/AVR/AVRTargetMachine.cpp
@@ -67,7 +67,6 @@ public:
   bool addInstSelector() override;
   void addPreSched2() override;
   void addPreRegAlloc() override;
-  void addPreEmitPass() override;
 };
 } // namespace
 
@@ -116,9 +115,4 @@ void AVRPassConfig::addPreSched2() {
   addPass(createAVRExpandPseudoPass());
 }
 
-void AVRPassConfig::addPreEmitPass() {
-  // Must run branch selection immediately preceding the asm printer.
-  addPass(createAVRBranchSelectionPass());
-}
-
 } // end of namespace llvm
diff --git a/llvm/lib/Target/AVR/CMakeLists.txt b/llvm/lib/Target/AVR/CMakeLists.txt
index 2e335509804..e103a60fa6f 100644
--- a/llvm/lib/Target/AVR/CMakeLists.txt
+++ b/llvm/lib/Target/AVR/CMakeLists.txt
@@ -18,7 +18,6 @@ add_public_tablegen_target(AVRCommonTableGen)
 
 add_llvm_target(AVRCodeGen
   AVRAsmPrinter.cpp
-  AVRBranchSelector.cpp
   AVRExpandPseudoInsts.cpp
   AVRFrameLowering.cpp
   AVRInstrInfo.cpp