[Alignment][NFC] Use llvm::Align for TargetLowering::getPrefLoopAlignment

[gchatelet]

Summary

This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

[courbet]

llvm/lib/CodeGen/MachineBlockPlacement.cpp

2810–2811

const

[gchatelet]

• rebase

llvm/include/llvm/CodeGen/MachineBasicBlock.h

using const_probability_iterator =
       std::vector<BranchProbability>::const_iterator;
 
   Optional<uint64_t> IrrLoopHeaderWeight;
 
   /// Keep track of the physical registers that are livein of the basicblock.
   using LiveInVector = std::vector<RegisterMaskPair>;
   LiveInVector LiveIns;
 
-  /// Alignment of the basic block. Zero if the basic block does not need to be
-  /// aligned. The alignment is specified as log2(bytes).
-  unsigned LogAlignment = 0;
+  /// Alignment of the basic block. One if the basic block does not need to be
+  /// aligned.
+  llvm::Align Alignment;
 
   /// Indicate that this basic block is entered via an exception handler.
   bool IsEHPad = false;
 
   /// Indicate that this basic block is potentially the target of an indirect
   /// branch.
   bool AddressTaken = false;
 
#endif
   const uint32_t *getBeginClobberMask(const TargetRegisterInfo *TRI) const;
 
   /// Get the clobber mask for the end of the basic block.
   /// \see getBeginClobberMask()
   const uint32_t *getEndClobberMask(const TargetRegisterInfo *TRI) const;
 
   /// Return alignment of the basic block. The alignment is specified as
   /// log2(bytes).
-  unsigned getLogAlignment() const { return LogAlignment; }
+  /// FIXME: Remove the Log versions once migration to llvm::Align is over.
+  unsigned getLogAlignment() const { return Log2(Alignment); }
+  llvm::Align getAlignment() const { return Alignment; }
 
   /// Set alignment of the basic block. The alignment is specified as
   /// log2(bytes).
-  void setLogAlignment(unsigned A) { LogAlignment = A; }
+  /// FIXME: Remove the Log versions once migration to llvm::Align is over.
+  void setLogAlignment(unsigned A) { Alignment = llvm::Align(1ULL << A); }
+  void setAlignment(llvm::Align A) { Alignment = A; }
 
   /// Returns true if the block is a landing pad. That is this basic block is
   /// entered via an exception handler.
   bool isEHPad() const { return IsEHPad; }
 
   /// Indicates the block is a landing pad.  That is this basic block is entered
   /// via an exception handler.
   void setIsEHPad(bool V = true) { IsEHPad = V; }

llvm/include/llvm/CodeGen/TargetLowering.h

   }
 
   /// Return the preferred function alignment.
   unsigned getPrefFunctionLogAlignment() const {
     return Log2(PrefFunctionAlignment);
   }
 
   /// Return the preferred loop alignment.
-  virtual unsigned getPrefLoopLogAlignment(MachineLoop *ML = nullptr) const {
-    return Log2(PrefLoopAlignment);
+  virtual llvm::Align getPrefLoopAlignment(MachineLoop *ML = nullptr) const {
+    return PrefLoopAlignment;
   }
 
   /// Should loops be aligned even when the function is marked OptSize (but not
   /// MinSize).
   virtual bool alignLoopsWithOptSize() const {
     return false;
   }
 

llvm/lib/CodeGen/MachineBlockPlacement.cpp

for (MachineBasicBlock *ChainBB : FunctionChain) {
     // Don't align non-looping basic blocks. These are unlikely to execute
     // enough times to matter in practice. Note that we'll still handle
     // unnatural CFGs inside of a natural outer loop (the common case) and
     // rotated loops.
     MachineLoop *L = MLI->getLoopFor(ChainBB);
     if (!L)
       continue;
 
-    unsigned LogAlign = TLI->getPrefLoopLogAlignment(L);
-    if (!LogAlign)
+    const llvm::Align Align = TLI->getPrefLoopAlignment(L);
+    if (Align == 1)
       continue; // Don't care about loop alignment.
 
     // If the block is cold relative to the function entry don't waste space
     // aligning it.
     BlockFrequency Freq = MBFI->getBlockFreq(ChainBB);
     if (Freq < WeightedEntryFreq)
       continue;
 
     // If the block is cold relative to its loop header, don't align it
     // regardless of what edges into the block exist.
     MachineBasicBlock *LoopHeader = L->getHeader();
     BlockFrequency LoopHeaderFreq = MBFI->getBlockFreq(LoopHeader);
     if (Freq < (LoopHeaderFreq * ColdProb))
       continue;
 
     // Check for the existence of a non-layout predecessor which would benefit
     // from aligning this block.
     MachineBasicBlock *LayoutPred =
         &*std::prev(MachineFunction::iterator(ChainBB));
 
     // Force alignment if all the predecessors are jumps. We already checked
     // that the block isn't cold above.
     if (!LayoutPred->isSuccessor(ChainBB)) {
-      ChainBB->setLogAlignment(LogAlign);
+      ChainBB->setLogAlignment(Log2(Align));
       continue;
     }
 
     // Align this block if the layout predecessor's edge into this block is
     // cold relative to the block. When this is true, other predecessors make up
     // all of the hot entries into the block and thus alignment is likely to be
     // important.
     BranchProbability LayoutProb =
         MBPI->getEdgeProbability(LayoutPred, ChainBB);
     BlockFrequency LayoutEdgeFreq = MBFI->getBlockFreq(LayoutPred) * LayoutProb;
     if (LayoutEdgeFreq <= (Freq * ColdProb))
-      ChainBB->setLogAlignment(LogAlign);
+      ChainBB->setLogAlignment(Log2(Align));
   }
 }
 
 /// Tail duplicate \p BB into (some) predecessors if profitable, repeating if
 /// it was duplicated into its chain predecessor and removed.
 /// \p BB    - Basic block that may be duplicated.
 ///
 /// \p LPred - Chosen layout predecessor of \p BB.

llvm/lib/Target/AMDGPU/SIISelLowering.h

public:
   bool denormalsEnabledForType(EVT VT) const;
 
   bool isKnownNeverNaNForTargetNode(SDValue Op,
                                     const SelectionDAG &DAG,
                                     bool SNaN = false,
                                     unsigned Depth = 0) const override;
   AtomicExpansionKind shouldExpandAtomicRMWInIR(AtomicRMWInst *) const override;
 
-  unsigned getPrefLoopLogAlignment(MachineLoop *ML) const override;
+  llvm::Align getPrefLoopAlignment(MachineLoop *ML) const override;
 
   void allocateHSAUserSGPRs(CCState &CCInfo,
                             MachineFunction &MF,
                             const SIRegisterInfo &TRI,
                             SIMachineFunctionInfo &Info) const;
 
   void allocateSystemSGPRs(CCState &CCInfo,
                            MachineFunction &MF,

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

TargetLowering::computeKnownBitsForFrameIndex(Op, Known, DemandedElts,
                                                 DAG, Depth);
 
   // Set the high bits to zero based on the maximum allowed scratch size per
   // wave. We can't use vaddr in MUBUF instructions if we don't know the address
   // calculation won't overflow, so assume the sign bit is never set.
   Known.Zero.setHighBits(getSubtarget()->getKnownHighZeroBitsForFrameIndex());
 }
 
-unsigned SITargetLowering::getPrefLoopLogAlignment(MachineLoop *ML) const {
-  const unsigned PrefLogAlign = TargetLowering::getPrefLoopLogAlignment(ML);
-  const unsigned CacheLineLogAlign = 6; // log2(64)
+llvm::Align SITargetLowering::getPrefLoopAlignment(MachineLoop *ML) const {
+  const llvm::Align PrefAlign = TargetLowering::getPrefLoopAlignment(ML);
+  const llvm::Align CacheLineAlign = llvm::Align(64);
 
   // Pre-GFX10 target did not benefit from loop alignment
   if (!ML || DisableLoopAlignment ||
       (getSubtarget()->getGeneration() < AMDGPUSubtarget::GFX10) ||
       getSubtarget()->hasInstFwdPrefetchBug())
-    return PrefLogAlign;
+    return PrefAlign;
 
   // On GFX10 I$ is 4 x 64 bytes cache lines.
   // By default prefetcher keeps one cache line behind and reads two ahead.
   // We can modify it with S_INST_PREFETCH for larger loops to have two lines
   // behind and one ahead.
   // Therefor we can benefit from aligning loop headers if loop fits 192 bytes.
   // If loop fits 64 bytes it always spans no more than two cache lines and
   // does not need an alignment.
   // Else if loop is less or equal 128 bytes we do not need to modify prefetch,
   // Else if loop is less or equal 192 bytes we need two lines behind.
 
   const SIInstrInfo *TII = getSubtarget()->getInstrInfo();
   const MachineBasicBlock *Header = ML->getHeader();
-  if (Header->getLogAlignment() != PrefLogAlign)
-    return Header->getLogAlignment(); // Already processed.
+  if (Header->getAlignment() != PrefAlign)
+    return Header->getAlignment(); // Already processed.
 
   unsigned LoopSize = 0;
   for (const MachineBasicBlock *MBB : ML->blocks()) {
     // If inner loop block is aligned assume in average half of the alignment
     // size to be added as nops.
     if (MBB != Header)
       LoopSize += (1 << MBB->getLogAlignment()) / 2;
 
     for (const MachineInstr &MI : *MBB) {
       LoopSize += TII->getInstSizeInBytes(MI);
       if (LoopSize > 192)
-        return PrefLogAlign;
+        return PrefAlign;
     }
   }
 
   if (LoopSize <= 64)
-    return PrefLogAlign;
+    return PrefAlign;
 
   if (LoopSize <= 128)
-    return CacheLineLogAlign;
+    return CacheLineAlign;
 
   // If any of parent loops is surrounded by prefetch instructions do not
   // insert new for inner loop, which would reset parent's settings.
   for (MachineLoop *P = ML->getParentLoop(); P; P = P->getParentLoop()) {
     if (MachineBasicBlock *Exit = P->getExitBlock()) {
       auto I = Exit->getFirstNonDebugInstr();
       if (I != Exit->end() && I->getOpcode() == AMDGPU::S_INST_PREFETCH)
-        return CacheLineLogAlign;
+        return CacheLineAlign;
     }
   }
 
   MachineBasicBlock *Pre = ML->getLoopPreheader();
   MachineBasicBlock *Exit = ML->getExitBlock();
 
   if (Pre && Exit) {
     BuildMI(*Pre, Pre->getFirstTerminator(), DebugLoc(),
             TII->get(AMDGPU::S_INST_PREFETCH))
       .addImm(1); // prefetch 2 lines behind PC
 
     BuildMI(*Exit, Exit->getFirstNonDebugInstr(), DebugLoc(),
             TII->get(AMDGPU::S_INST_PREFETCH))
       .addImm(2); // prefetch 1 line behind PC
   }
 
-  return CacheLineLogAlign;
+  return CacheLineAlign;
 }
 
 LLVM_ATTRIBUTE_UNUSED
 static bool isCopyFromRegOfInlineAsm(const SDNode *N) {
   assert(N->getOpcode() == ISD::CopyFromReg);
   do {
     // Follow the chain until we find an INLINEASM node.
     N = N->getOperand(0).getNode();

llvm/lib/Target/PowerPC/PPCISelLowering.h

unsigned getRegisterByName(const char* RegName, EVT VT,
                                SelectionDAG &DAG) const override;
 
     void computeKnownBitsForTargetNode(const SDValue Op,
                                        KnownBits &Known,
                                        const APInt &DemandedElts,
                                        const SelectionDAG &DAG,
                                        unsigned Depth = 0) const override;
 
-    unsigned getPrefLoopLogAlignment(MachineLoop *ML) const override;
+    llvm::Align getPrefLoopAlignment(MachineLoop *ML) const override;
 
     bool shouldInsertFencesForAtomic(const Instruction *I) const override {
       return true;
     }
 
     Instruction *emitLeadingFence(IRBuilder<> &Builder, Instruction *Inst,
                                   AtomicOrdering Ord) const override;
     Instruction *emitTrailingFence(IRBuilder<> &Builder, Instruction *Inst,

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

case ISD::INTRINSIC_WO_CHAIN: {
     case Intrinsic::ppc_altivec_vcmpgtud_p:
       Known.Zero = ~1U;  // All bits but the low one are known to be zero.
       break;
     }
   }
   }
 }
 
-unsigned PPCTargetLowering::getPrefLoopLogAlignment(MachineLoop *ML) const {
+llvm::Align PPCTargetLowering::getPrefLoopAlignment(MachineLoop *ML) const {
   switch (Subtarget.getDarwinDirective()) {
   default: break;
   case PPC::DIR_970:
   case PPC::DIR_PWR4:
   case PPC::DIR_PWR5:
   case PPC::DIR_PWR5X:
   case PPC::DIR_PWR6:
   case PPC::DIR_PWR6X:
   case PPC::DIR_PWR7:
   case PPC::DIR_PWR8:
   case PPC::DIR_PWR9: {
     if (!ML)
       break;
 
     if (!DisableInnermostLoopAlign32) {
       // If the nested loop is an innermost loop, prefer to a 32-byte alignment,
       // so that we can decrease cache misses and branch-prediction misses.
       // Actual alignment of the loop will depend on the hotness check and other
       // logic in alignBlocks.
       if (ML->getLoopDepth() > 1 && ML->getSubLoops().empty())
-        return 5;
+        return llvm::Align(32);
     }
 
     const PPCInstrInfo *TII = Subtarget.getInstrInfo();
 
     // For small loops (between 5 and 8 instructions), align to a 32-byte
     // boundary so that the entire loop fits in one instruction-cache line.
     uint64_t LoopSize = 0;
     for (auto I = ML->block_begin(), IE = ML->block_end(); I != IE; ++I)
       for (auto J = (*I)->begin(), JE = (*I)->end(); J != JE; ++J) {
         LoopSize += TII->getInstSizeInBytes(*J);
         if (LoopSize > 32)
           break;
       }
 
     if (LoopSize > 16 && LoopSize <= 32)
-      return 5;
+      return llvm::Align(32);
 
     break;
   }
   }
 
-  return TargetLowering::getPrefLoopLogAlignment(ML);
+  return TargetLowering::getPrefLoopAlignment(ML);
 }
 
 /// getConstraintType - Given a constraint, return the type of
 /// constraint it is for this target.
 PPCTargetLowering::ConstraintType
 PPCTargetLowering::getConstraintType(StringRef Constraint) const {
   if (Constraint.size() == 1) {
     switch (Constraint[0]) {