1 files changed, 220 insertions, 0 deletions
diff --git a/contrib/llvm-project/llvm/lib/CodeGen/GlobalISel/Localizer.cpp b/contrib/llvm-project/llvm/lib/CodeGen/GlobalISel/Localizer.cpp
new file mode 100644
index 000000000000..55984423e5bc
--- /dev/null
+++ b/contrib/llvm-project/llvm/lib/CodeGen/GlobalISel/Localizer.cpp
@@ -0,0 +1,220 @@
+//===- Localizer.cpp ---------------------- Localize some instrs -*- C++ -*-==//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file implements the Localizer class.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/GlobalISel/Localizer.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/CodeGen/GlobalISel/Utils.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/TargetLowering.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "localizer"
+
+using namespace llvm;
+
+char Localizer::ID = 0;
+INITIALIZE_PASS_BEGIN(Localizer, DEBUG_TYPE,
+                      "Move/duplicate certain instructions close to their use",
+                      false, false)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_END(Localizer, DEBUG_TYPE,
+                    "Move/duplicate certain instructions close to their use",
+                    false, false)
+
+Localizer::Localizer(std::function<bool(const MachineFunction &)> F)
+    : MachineFunctionPass(ID), DoNotRunPass(F) {}
+
+Localizer::Localizer()
+    : Localizer([](const MachineFunction &) { return false; }) {}
+
+void Localizer::init(MachineFunction &MF) {
+  MRI = &MF.getRegInfo();
+  TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(MF.getFunction());
+}
+
+void Localizer::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.addRequired<TargetTransformInfoWrapperPass>();
+  getSelectionDAGFallbackAnalysisUsage(AU);
+  MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+bool Localizer::isLocalUse(MachineOperand &MOUse, const MachineInstr &Def,
+                           MachineBasicBlock *&InsertMBB) {
+  MachineInstr &MIUse = *MOUse.getParent();
+  InsertMBB = MIUse.getParent();
+  if (MIUse.isPHI())
+    InsertMBB = MIUse.getOperand(MOUse.getOperandNo() + 1).getMBB();
+  return InsertMBB == Def.getParent();
+}
+
+bool Localizer::isNonUniquePhiValue(MachineOperand &Op) const {
+  MachineInstr *MI = Op.getParent();
+  if (!MI->isPHI())
+    return false;
+
+  Register SrcReg = Op.getReg();
+  for (unsigned Idx = 1; Idx < MI->getNumOperands(); Idx += 2) {
+    auto &MO = MI->getOperand(Idx);
+    if (&MO != &Op && MO.isReg() && MO.getReg() == SrcReg)
+      return true;
+  }
+  return false;
+}
+
+bool Localizer::localizeInterBlock(MachineFunction &MF,
+                                   LocalizedSetVecT &LocalizedInstrs) {
+  bool Changed = false;
+  DenseMap<std::pair<MachineBasicBlock *, unsigned>, unsigned> MBBWithLocalDef;
+
+  // Since the IRTranslator only emits constants into the entry block, and the
+  // rest of the GISel pipeline generally emits constants close to their users,
+  // we only localize instructions in the entry block here. This might change if
+  // we start doing CSE across blocks.
+  auto &MBB = MF.front();
+  auto &TL = *MF.getSubtarget().getTargetLowering();
+  for (MachineInstr &MI : llvm::reverse(MBB)) {
+    if (!TL.shouldLocalize(MI, TTI))
+      continue;
+    LLVM_DEBUG(dbgs() << "Should localize: " << MI);
+    assert(MI.getDesc().getNumDefs() == 1 &&
+           "More than one definition not supported yet");
+    Register Reg = MI.getOperand(0).getReg();
+    // Check if all the users of MI are local.
+    // We are going to invalidation the list of use operands, so we
+    // can't use range iterator.
+    for (MachineOperand &MOUse :
+         llvm::make_early_inc_range(MRI->use_operands(Reg))) {
+      // Check if the use is already local.
+      MachineBasicBlock *InsertMBB;
+      LLVM_DEBUG(MachineInstr &MIUse = *MOUse.getParent();
+                 dbgs() << "Checking use: " << MIUse
+                        << " #Opd: " << MOUse.getOperandNo() << '\n');
+      if (isLocalUse(MOUse, MI, InsertMBB)) {
+        // Even if we're in the same block, if the block is very large we could
+        // still have many long live ranges. Try to do intra-block localization
+        // too.
+        LocalizedInstrs.insert(&MI);
+        continue;
+      }
+
+      // If the use is a phi operand that's not unique, don't try to localize.
+      // If we do, we can cause unnecessary instruction bloat by duplicating
+      // into each predecessor block, when the existing one is sufficient and
+      // allows for easier optimization later.
+      if (isNonUniquePhiValue(MOUse))
+        continue;
+
+      LLVM_DEBUG(dbgs() << "Fixing non-local use\n");
+      Changed = true;
+      auto MBBAndReg = std::make_pair(InsertMBB, Reg);
+      auto NewVRegIt = MBBWithLocalDef.find(MBBAndReg);
+      if (NewVRegIt == MBBWithLocalDef.end()) {
+        // Create the localized instruction.
+        MachineInstr *LocalizedMI = MF.CloneMachineInstr(&MI);
+        LocalizedInstrs.insert(LocalizedMI);
+        MachineInstr &UseMI = *MOUse.getParent();
+        if (MRI->hasOneUse(Reg) && !UseMI.isPHI())
+          InsertMBB->insert(UseMI, LocalizedMI);
+        else
+          InsertMBB->insert(InsertMBB->SkipPHIsAndLabels(InsertMBB->begin()),
+                            LocalizedMI);
+
+        // Set a new register for the definition.
+        Register NewReg = MRI->cloneVirtualRegister(Reg);
+        LocalizedMI->getOperand(0).setReg(NewReg);
+        NewVRegIt =
+            MBBWithLocalDef.insert(std::make_pair(MBBAndReg, NewReg)).first;
+        LLVM_DEBUG(dbgs() << "Inserted: " << *LocalizedMI);
+      }
+      LLVM_DEBUG(dbgs() << "Update use with: " << printReg(NewVRegIt->second)
+                        << '\n');
+      // Update the user reg.
+      MOUse.setReg(NewVRegIt->second);
+    }
+  }
+  return Changed;
+}
+
+bool Localizer::localizeIntraBlock(LocalizedSetVecT &LocalizedInstrs) {
+  bool Changed = false;
+
+  // For each already-localized instruction which has multiple users, then we
+  // scan the block top down from the current position until we hit one of them.
+
+  // FIXME: Consider doing inst duplication if live ranges are very long due to
+  // many users, but this case may be better served by regalloc improvements.
+
+  for (MachineInstr *MI : LocalizedInstrs) {
+    Register Reg = MI->getOperand(0).getReg();
+    MachineBasicBlock &MBB = *MI->getParent();
+    // All of the user MIs of this reg.
+    SmallPtrSet<MachineInstr *, 32> Users;
+    for (MachineInstr &UseMI : MRI->use_nodbg_instructions(Reg)) {
+      if (!UseMI.isPHI())
+        Users.insert(&UseMI);
+    }
+    // If all the users were PHIs then they're not going to be in our block,
+    // don't try to move this instruction.
+    if (Users.empty())
+      continue;
+
+    MachineBasicBlock::iterator II(MI);
+    ++II;
+    while (II != MBB.end() && !Users.count(&*II))
+      ++II;
+
+    assert(II != MBB.end() && "Didn't find the user in the MBB");
+    LLVM_DEBUG(dbgs() << "Intra-block: moving " << *MI << " before " << *II
+                      << '\n');
+
+    MI->removeFromParent();
+    MBB.insert(II, MI);
+    Changed = true;
+
+    // If the instruction (constant) being localized has single user, we can
+    // propagate debug location from user.
+    if (Users.size() == 1) {
+      const auto &DefDL = MI->getDebugLoc();
+      const auto &UserDL = (*Users.begin())->getDebugLoc();
+
+      if ((!DefDL || DefDL.getLine() == 0) && UserDL && UserDL.getLine() != 0) {
+        MI->setDebugLoc(UserDL);
+      }
+    }
+  }
+  return Changed;
+}
+
+bool Localizer::runOnMachineFunction(MachineFunction &MF) {
+  // If the ISel pipeline failed, do not bother running that pass.
+  if (MF.getProperties().hasProperty(
+          MachineFunctionProperties::Property::FailedISel))
+    return false;
+
+  // Don't run the pass if the target asked so.
+  if (DoNotRunPass(MF))
+    return false;
+
+  LLVM_DEBUG(dbgs() << "Localize instructions for: " << MF.getName() << '\n');
+
+  init(MF);
+
+  // Keep track of the instructions we localized. We'll do a second pass of
+  // intra-block localization to further reduce live ranges.
+  LocalizedSetVecT LocalizedInstrs;
+
+  bool Changed = localizeInterBlock(MF, LocalizedInstrs);
+  Changed |= localizeIntraBlock(LocalizedInstrs);
+  return Changed;
+}