AArch64: Move remaining target specific BranchRelaxation bits to TII

llvm-svn: 283458

llvm/include/llvm/Target/TargetInstrInfo.h

@@ -443,6 +443,18 @@ public:
                                 const MachineInstr &MI1,
                                 const MachineRegisterInfo *MRI = nullptr) const;
 
+  /// \returns true if a branch from an instruction with opcode \p BranchOpc
+  ///  bytes is capable of jumping to a position \p BrOffset bytes away.
+  virtual bool isBranchOffsetInRange(unsigned BranchOpc,
+                                     int64_t BrOffset) const {
+    llvm_unreachable("target did not implement");
+  }
+
+  /// \returns The block that branch instruction \p MI jumps to.
+  virtual MachineBasicBlock *getBranchDestBlock(const MachineInstr &MI) const {
+    llvm_unreachable("target did not implement");
+  }
+
   /// Analyze the branching code at the end of MBB, returning
   /// true if it cannot be understood (e.g. it's a switch dispatch or isn't
   /// implemented for a target).  Upon success, this returns false and returns

llvm/lib/Target/AArch64/AArch64BranchRelaxation.cpp

@@ -14,8 +14,6 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
-#include "llvm/CodeGen/MachineInstrBuilder.h"
-#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Format.h"
@@ -229,43 +227,23 @@ AArch64BranchRelaxation::splitBlockBeforeInstr(MachineInstr &MI) {
 /// specific BB can fit in MI's displacement field.
 bool AArch64BranchRelaxation::isBlockInRange(
   const MachineInstr &MI, const MachineBasicBlock &DestBB) const {
-  unsigned BrOffset = getInstrOffset(MI);
-  unsigned DestOffset = BlockInfo[DestBB.getNumber()].Offset;
+  int64_t BrOffset = getInstrOffset(MI);
+  int64_t DestOffset = BlockInfo[DestBB.getNumber()].Offset;
 
-  if (TII->isBranchInRange(MI.getOpcode(), BrOffset, DestOffset))
+  if (TII->isBranchOffsetInRange(MI.getOpcode(), DestOffset - BrOffset))
     return true;
 
   DEBUG(
     dbgs() << "Out of range branch to destination BB#" << DestBB.getNumber()
            << " from BB#" << MI.getParent()->getNumber()
            << " to " << DestOffset
-           << " offset " << static_cast<int>(DestOffset - BrOffset)
+           << " offset " << DestOffset - BrOffset
            << '\t' << MI
   );
 
   return false;
 }
 
-static MachineBasicBlock *getDestBlock(const MachineInstr &MI) {
-  switch (MI.getOpcode()) {
-  default:
-    llvm_unreachable("unexpected opcode!");
-  case AArch64::B:
-    return MI.getOperand(0).getMBB();
-  case AArch64::TBZW:
-  case AArch64::TBNZW:
-  case AArch64::TBZX:
-  case AArch64::TBNZX:
-    return MI.getOperand(2).getMBB();
-  case AArch64::CBZW:
-  case AArch64::CBNZW:
-  case AArch64::CBZX:
-  case AArch64::CBNZX:
-  case AArch64::Bcc:
-    return MI.getOperand(1).getMBB();
-  }
-}
-
 /// fixupConditionalBranch - Fix up a conditional branch whose destination is
 /// too far away to fit in its displacement field. It is converted to an inverse
 /// conditional branch + an unconditional branch to the destination.
@@ -368,7 +346,7 @@ bool AArch64BranchRelaxation::relaxBranchInstructions() {
       MachineInstr &MI = *J;
 
       if (MI.isConditionalBranch()) {
-        MachineBasicBlock *DestBB = getDestBlock(MI);
+        MachineBasicBlock *DestBB = TII->getBranchDestBlock(MI);
         if (!isBlockInRange(MI, *DestBB)) {
           if (Next != MBB.end() && Next->isConditionalBranch()) {
             // If there are multiple conditional branches, this isn't an

llvm/lib/Target/AArch64/AArch64InstrInfo.cpp

@@ -128,6 +128,8 @@ static unsigned getBranchDisplacementBits(unsigned Opc) {
   switch (Opc) {
   default:
     llvm_unreachable("unexpected opcode!");
+  case AArch64::B:
+    return 64;
   case AArch64::TBNZW:
   case AArch64::TBZW:
   case AArch64::TBNZX:
@@ -143,30 +145,33 @@ static unsigned getBranchDisplacementBits(unsigned Opc) {
   }
 }
 
-static unsigned getBranchMaxDisplacementBytes(unsigned Opc) {
-  if (Opc == AArch64::B)
-    return -1;
-
-  unsigned Bits = getBranchDisplacementBits(Opc);
-  unsigned MaxOffs = ((1 << (Bits - 1)) - 1) << 2;
-
-  // Verify the displacement bits options have sane values.
-  // XXX: Is there a better place for this?
-  assert(MaxOffs >= 8 &&
-         "max branch displacement must be enough to jump"
-         "over conditional branch expansion");
-
-  return MaxOffs;
+bool AArch64InstrInfo::isBranchOffsetInRange(unsigned BranchOp,
+                                             int64_t BrOffset) const {
+  unsigned Bits = getBranchDisplacementBits(BranchOp);
+  assert(Bits >= 3 && "max branch displacement must be enough to jump"
+                      "over conditional branch expansion");
+  return isIntN(Bits, BrOffset / 4);
 }
 
-bool AArch64InstrInfo::isBranchInRange(unsigned BranchOp, uint64_t BrOffset,
-                                       uint64_t DestOffset) const {
-  unsigned MaxOffs = getBranchMaxDisplacementBytes(BranchOp);
-
-  // Branch before the Dest.
-  if (BrOffset <= DestOffset)
-    return (DestOffset - BrOffset <= MaxOffs);
-  return (BrOffset - DestOffset <= MaxOffs);
+MachineBasicBlock *AArch64InstrInfo::getBranchDestBlock(
+  const MachineInstr &MI) const {
+  switch (MI.getOpcode()) {
+  default:
+    llvm_unreachable("unexpected opcode!");
+  case AArch64::B:
+    return MI.getOperand(0).getMBB();
+  case AArch64::TBZW:
+  case AArch64::TBNZW:
+  case AArch64::TBZX:
+  case AArch64::TBNZX:
+    return MI.getOperand(2).getMBB();
+  case AArch64::CBZW:
+  case AArch64::CBNZW:
+  case AArch64::CBZX:
+  case AArch64::CBNZX:
+  case AArch64::Bcc:
+    return MI.getOperand(1).getMBB();
+  }
 }
 
 // Branch analysis.

llvm/lib/Target/AArch64/AArch64InstrInfo.h

@@ -174,10 +174,11 @@ public:
                         LiveIntervals *LIS = nullptr) const override;
 
   /// \returns true if a branch from an instruction with opcode \p BranchOpc
-  /// located at \p BrOffset bytes is capable of jumping to a position at \p
-  /// DestOffset.
-  bool isBranchInRange(unsigned BranchOpc, uint64_t BrOffset,
-                       uint64_t DestOffset) const;
+  ///  bytes is capable of jumping to a position \p BrOffset bytes away.
+  bool isBranchOffsetInRange(unsigned BranchOpc,
+                             int64_t BrOffset) const override;
+
+  MachineBasicBlock *getBranchDestBlock(const MachineInstr &MI) const override;
 
   bool analyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                      MachineBasicBlock *&FBB,