Imported Upstream version 5.18.0.179

Former-commit-id: 67aa10e65b237e1c4537630979ee99ebe1374215

external/llvm/lib/CodeGen/GlobalISel/Legalizer.cpp

@@ -0,0 +1,186 @@
+//===-- llvm/CodeGen/GlobalISel/Legalizer.cpp -----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file This file implements the LegalizerHelper class to legalize individual
+/// instructions and the LegalizePass wrapper pass for the primary
+/// legalization.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/GlobalISel/Legalizer.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/CodeGen/GlobalISel/GISelWorkList.h"
+#include "llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h"
+#include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
+#include "llvm/CodeGen/GlobalISel/Utils.h"
+#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/TargetPassConfig.h"
+#include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/Support/Debug.h"
+
+#include <iterator>
+
+#define DEBUG_TYPE "legalizer"
+
+using namespace llvm;
+
+char Legalizer::ID = 0;
+INITIALIZE_PASS_BEGIN(Legalizer, DEBUG_TYPE,
+                      "Legalize the Machine IR a function's Machine IR", false,
+                      false)
+INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)
+INITIALIZE_PASS_END(Legalizer, DEBUG_TYPE,
+                    "Legalize the Machine IR a function's Machine IR", false,
+                    false)
+
+Legalizer::Legalizer() : MachineFunctionPass(ID) {
+  initializeLegalizerPass(*PassRegistry::getPassRegistry());
+}
+
+void Legalizer::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.addRequired<TargetPassConfig>();
+  MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+void Legalizer::init(MachineFunction &MF) {
+}
+
+static bool isArtifact(const MachineInstr &MI) {
+  switch (MI.getOpcode()) {
+  default:
+    return false;
+  case TargetOpcode::G_TRUNC:
+  case TargetOpcode::G_ZEXT:
+  case TargetOpcode::G_ANYEXT:
+  case TargetOpcode::G_SEXT:
+  case TargetOpcode::G_MERGE_VALUES:
+  case TargetOpcode::G_UNMERGE_VALUES:
+    return true;
+  }
+}
+
+bool Legalizer::runOnMachineFunction(MachineFunction &MF) {
+  // If the ISel pipeline failed, do not bother running that pass.
+  if (MF.getProperties().hasProperty(
+          MachineFunctionProperties::Property::FailedISel))
+    return false;
+  DEBUG(dbgs() << "Legalize Machine IR for: " << MF.getName() << '\n');
+  init(MF);
+  const TargetPassConfig &TPC = getAnalysis<TargetPassConfig>();
+  MachineOptimizationRemarkEmitter MORE(MF, /*MBFI=*/nullptr);
+  LegalizerHelper Helper(MF);
+
+  const size_t NumBlocks = MF.size();
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+
+  // Populate Insts
+  GISelWorkList<256> InstList;
+  GISelWorkList<128> ArtifactList;
+  ReversePostOrderTraversal<MachineFunction *> RPOT(&MF);
+  // Perform legalization bottom up so we can DCE as we legalize.
+  // Traverse BB in RPOT and within each basic block, add insts top down,
+  // so when we pop_back_val in the legalization process, we traverse bottom-up.
+  for (auto *MBB : RPOT) {
+    if (MBB->empty())
+      continue;
+    for (MachineInstr &MI : *MBB) {
+      // Only legalize pre-isel generic instructions: others don't have types
+      // and are assumed to be legal.
+      if (!isPreISelGenericOpcode(MI.getOpcode()))
+        continue;
+      if (isArtifact(MI))
+        ArtifactList.insert(&MI);
+      else
+        InstList.insert(&MI);
+    }
+  }
+  Helper.MIRBuilder.recordInsertions([&](MachineInstr *MI) {
+    // Only legalize pre-isel generic instructions.
+    // Legalization process could generate Target specific pseudo
+    // instructions with generic types. Don't record them
+    if (isPreISelGenericOpcode(MI->getOpcode())) {
+      if (isArtifact(*MI))
+        ArtifactList.insert(MI);
+      else
+        InstList.insert(MI);
+    }
+    DEBUG(dbgs() << ".. .. New MI: " << *MI;);
+  });
+  const LegalizerInfo &LInfo(Helper.getLegalizerInfo());
+  LegalizationArtifactCombiner ArtCombiner(Helper.MIRBuilder, MF.getRegInfo(), LInfo);
+  auto RemoveDeadInstFromLists = [&InstList,
+                                  &ArtifactList](MachineInstr *DeadMI) {
+    InstList.remove(DeadMI);
+    ArtifactList.remove(DeadMI);
+  };
+  bool Changed = false;
+  do {
+    while (!InstList.empty()) {
+      MachineInstr &MI = *InstList.pop_back_val();
+      assert(isPreISelGenericOpcode(MI.getOpcode()) && "Expecting generic opcode");
+      if (isTriviallyDead(MI, MRI)) {
+        DEBUG(dbgs() << MI << "Is dead; erasing.\n");
+        MI.eraseFromParentAndMarkDBGValuesForRemoval();
+        continue;
+      }
+
+      // Do the legalization for this instruction.
+      auto Res = Helper.legalizeInstrStep(MI);
+      // Error out if we couldn't legalize this instruction. We may want to
+      // fall back to DAG ISel instead in the future.
+      if (Res == LegalizerHelper::UnableToLegalize) {
+        Helper.MIRBuilder.stopRecordingInsertions();
+        reportGISelFailure(MF, TPC, MORE, "gisel-legalize",
+                           "unable to legalize instruction", MI);
+        return false;
+      }
+      Changed |= Res == LegalizerHelper::Legalized;
+    }
+    while (!ArtifactList.empty()) {
+      MachineInstr &MI = *ArtifactList.pop_back_val();
+      assert(isPreISelGenericOpcode(MI.getOpcode()) && "Expecting generic opcode");
+      if (isTriviallyDead(MI, MRI)) {
+        DEBUG(dbgs() << MI << "Is dead; erasing.\n");
+        RemoveDeadInstFromLists(&MI);
+        MI.eraseFromParentAndMarkDBGValuesForRemoval();
+        continue;
+      }
+      SmallVector<MachineInstr *, 4> DeadInstructions;
+      if (ArtCombiner.tryCombineInstruction(MI, DeadInstructions)) {
+        for (auto *DeadMI : DeadInstructions) {
+          DEBUG(dbgs() << ".. Erasing Dead Instruction " << *DeadMI);
+          RemoveDeadInstFromLists(DeadMI);
+          DeadMI->eraseFromParentAndMarkDBGValuesForRemoval();
+        }
+        Changed = true;
+        continue;
+      }
+      // If this was not an artifact (that could be combined away), this might
+      // need special handling. Add it to InstList, so when it's processed
+      // there, it has to be legal or specially handled.
+      else
+        InstList.insert(&MI);
+    }
+  } while (!InstList.empty());
+
+  // For now don't support if new blocks are inserted - we would need to fix the
+  // outerloop for that.
+  if (MF.size() != NumBlocks) {
+    MachineOptimizationRemarkMissed R("gisel-legalize", "GISelFailure",
+                                      MF.getFunction().getSubprogram(),
+                                      /*MBB=*/nullptr);
+    R << "inserting blocks is not supported yet";
+    reportGISelFailure(MF, TPC, MORE, R);
+    return false;
+  }
+
+  return Changed;
+}