8 files changed, 693 insertions, 3 deletions

diff --git a/llvm/lib/Target/RISCV/CMakeLists.txt b/llvm/lib/Target/RISCV/CMakeLists.txt
index f8d4e2b9517..ee5ed625f12 100644
--- a/llvm/lib/Target/RISCV/CMakeLists.txt
+++ b/llvm/lib/Target/RISCV/CMakeLists.txt
@@ -15,6 +15,7 @@ add_public_tablegen_target(RISCVCommonTableGen)
 
 add_llvm_target(RISCVCodeGen
   RISCVAsmPrinter.cpp
+  RISCVExpandPseudoInsts.cpp
   RISCVFrameLowering.cpp
   RISCVInstrInfo.cpp
   RISCVISelDAGToDAG.cpp
diff --git a/llvm/lib/Target/RISCV/RISCV.h b/llvm/lib/Target/RISCV/RISCV.h
index 2e4f536aca3..b48a68f76eb 100644
--- a/llvm/lib/Target/RISCV/RISCV.h
+++ b/llvm/lib/Target/RISCV/RISCV.h
@@ -16,6 +16,7 @@
 #define LLVM_LIB_TARGET_RISCV_RISCV_H
 
 #include "MCTargetDesc/RISCVBaseInfo.h"
+#include "llvm/Target/TargetMachine.h"
 
 namespace llvm {
 class RISCVTargetMachine;
@@ -36,6 +37,9 @@ FunctionPass *createRISCVISelDag(RISCVTargetMachine &TM);
 
 FunctionPass *createRISCVMergeBaseOffsetOptPass();
 void initializeRISCVMergeBaseOffsetOptPass(PassRegistry &);
+
+FunctionPass *createRISCVExpandPseudoPass();
+void initializeRISCVExpandPseudoPass(PassRegistry &);
 }
 
 #endif
diff --git a/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp b/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
new file mode 100644
index 00000000000..1c23680abc1
--- /dev/null
+++ b/llvm/lib/Target/RISCV/RISCVExpandPseudoInsts.cpp
@@ -0,0 +1,452 @@
+//===-- RISCVExpandPseudoInsts.cpp - Expand pseudo instructions -----------===//
+//
+//                     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 expands pseudo instructions into target
+// instructions. This pass should be run after register allocation but before
+// the post-regalloc scheduling pass.
+//
+//===----------------------------------------------------------------------===//
+
+#include "RISCV.h"
+#include "RISCVInstrInfo.h"
+#include "RISCVTargetMachine.h"
+
+#include "llvm/CodeGen/LivePhysRegs.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+
+using namespace llvm;
+
+#define RISCV_EXPAND_PSEUDO_NAME "RISCV pseudo instruction expansion pass"
+
+namespace {
+
+class RISCVExpandPseudo : public MachineFunctionPass {
+public:
+  const RISCVInstrInfo *TII;
+  static char ID;
+
+  RISCVExpandPseudo() : MachineFunctionPass(ID) {
+    initializeRISCVExpandPseudoPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+
+  StringRef getPassName() const override { return RISCV_EXPAND_PSEUDO_NAME; }
+
+private:
+  bool expandMBB(MachineBasicBlock &MBB);
+  bool expandMI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
+                MachineBasicBlock::iterator &NextMBBI);
+  bool expandAtomicBinOp(MachineBasicBlock &MBB,
+                         MachineBasicBlock::iterator MBBI, AtomicRMWInst::BinOp,
+                         bool IsMasked, int Width,
+                         MachineBasicBlock::iterator &NextMBBI);
+  bool expandAtomicMinMaxOp(MachineBasicBlock &MBB,
+                            MachineBasicBlock::iterator MBBI,
+                            AtomicRMWInst::BinOp, bool IsMasked, int Width,
+                            MachineBasicBlock::iterator &NextMBBI);
+};
+
+char RISCVExpandPseudo::ID = 0;
+
+bool RISCVExpandPseudo::runOnMachineFunction(MachineFunction &MF) {
+  TII = static_cast<const RISCVInstrInfo *>(MF.getSubtarget().getInstrInfo());
+  bool Modified = false;
+  for (auto &MBB : MF)
+    Modified |= expandMBB(MBB);
+  return Modified;
+}
+
+bool RISCVExpandPseudo::expandMBB(MachineBasicBlock &MBB) {
+  bool Modified = false;
+
+  MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
+  while (MBBI != E) {
+    MachineBasicBlock::iterator NMBBI = std::next(MBBI);
+    Modified |= expandMI(MBB, MBBI, NMBBI);
+    MBBI = NMBBI;
+  }
+
+  return Modified;
+}
+
+bool RISCVExpandPseudo::expandMI(MachineBasicBlock &MBB,
+                                 MachineBasicBlock::iterator MBBI,
+                                 MachineBasicBlock::iterator &NextMBBI) {
+  switch (MBBI->getOpcode()) {
+  case RISCV::PseudoAtomicLoadNand32:
+    return expandAtomicBinOp(MBB, MBBI, AtomicRMWInst::Nand, false, 32,
+                             NextMBBI);
+  case RISCV::PseudoMaskedAtomicSwap32:
+    return expandAtomicBinOp(MBB, MBBI, AtomicRMWInst::Xchg, true, 32,
+                             NextMBBI);
+  case RISCV::PseudoMaskedAtomicLoadAdd32:
+    return expandAtomicBinOp(MBB, MBBI, AtomicRMWInst::Add, true, 32, NextMBBI);
+  case RISCV::PseudoMaskedAtomicLoadSub32:
+    return expandAtomicBinOp(MBB, MBBI, AtomicRMWInst::Sub, true, 32, NextMBBI);
+  case RISCV::PseudoMaskedAtomicLoadNand32:
+    return expandAtomicBinOp(MBB, MBBI, AtomicRMWInst::Nand, true, 32,
+                             NextMBBI);
+  case RISCV::PseudoMaskedAtomicLoadMax32:
+    return expandAtomicMinMaxOp(MBB, MBBI, AtomicRMWInst::Max, true, 32,
+                                NextMBBI);
+  case RISCV::PseudoMaskedAtomicLoadMin32:
+    return expandAtomicMinMaxOp(MBB, MBBI, AtomicRMWInst::Min, true, 32,
+                                NextMBBI);
+  case RISCV::PseudoMaskedAtomicLoadUMax32:
+    return expandAtomicMinMaxOp(MBB, MBBI, AtomicRMWInst::UMax, true, 32,
+                                NextMBBI);
+  case RISCV::PseudoMaskedAtomicLoadUMin32:
+    return expandAtomicMinMaxOp(MBB, MBBI, AtomicRMWInst::UMin, true, 32,
+                                NextMBBI);
+  }
+
+  return false;
+}
+
+static unsigned getLRForRMW32(AtomicOrdering Ordering) {
+  switch (Ordering) {
+  default:
+    llvm_unreachable("Unexpected AtomicOrdering");
+  case AtomicOrdering::Monotonic:
+    return RISCV::LR_W;
+  case AtomicOrdering::Acquire:
+    return RISCV::LR_W_AQ;
+  case AtomicOrdering::Release:
+    return RISCV::LR_W;
+  case AtomicOrdering::AcquireRelease:
+    return RISCV::LR_W_AQ;
+  case AtomicOrdering::SequentiallyConsistent:
+    return RISCV::LR_W_AQ_RL;
+  }
+}
+
+static unsigned getSCForRMW32(AtomicOrdering Ordering) {
+  switch (Ordering) {
+  default:
+    llvm_unreachable("Unexpected AtomicOrdering");
+  case AtomicOrdering::Monotonic:
+    return RISCV::SC_W;
+  case AtomicOrdering::Acquire:
+    return RISCV::SC_W;
+  case AtomicOrdering::Release:
+    return RISCV::SC_W_RL;
+  case AtomicOrdering::AcquireRelease:
+    return RISCV::SC_W_RL;
+  case AtomicOrdering::SequentiallyConsistent:
+    return RISCV::SC_W_AQ_RL;
+  }
+}
+
+static void doAtomicBinOpExpansion(const RISCVInstrInfo *TII, MachineInstr &MI,
+                                   DebugLoc DL, MachineBasicBlock *ThisMBB,
+                                   MachineBasicBlock *LoopMBB,
+                                   MachineBasicBlock *DoneMBB,
+                                   AtomicRMWInst::BinOp BinOp, int Width) {
+  assert(Width == 32 && "RV64 atomic expansion currently unsupported");
+  unsigned DestReg = MI.getOperand(0).getReg();
+  unsigned ScratchReg = MI.getOperand(1).getReg();
+  unsigned AddrReg = MI.getOperand(2).getReg();
+  unsigned IncrReg = MI.getOperand(3).getReg();
+  AtomicOrdering Ordering =
+      static_cast<AtomicOrdering>(MI.getOperand(4).getImm());
+
+  // .loop:
+  //   lr.w dest, (addr)
+  //   binop scratch, dest, val
+  //   sc.w scratch, scratch, (addr)
+  //   bnez scratch, loop
+  BuildMI(LoopMBB, DL, TII->get(getLRForRMW32(Ordering)), DestReg)
+      .addReg(AddrReg);
+  switch (BinOp) {
+  default:
+    llvm_unreachable("Unexpected AtomicRMW BinOp");
+  case AtomicRMWInst::Nand:
+    BuildMI(LoopMBB, DL, TII->get(RISCV::AND), ScratchReg)
+        .addReg(DestReg)
+        .addReg(IncrReg);
+    BuildMI(LoopMBB, DL, TII->get(RISCV::XORI), ScratchReg)
+        .addReg(ScratchReg)
+        .addImm(-1);
+    break;
+  }
+  BuildMI(LoopMBB, DL, TII->get(getSCForRMW32(Ordering)), ScratchReg)
+      .addReg(AddrReg)
+      .addReg(ScratchReg);
+  BuildMI(LoopMBB, DL, TII->get(RISCV::BNE))
+      .addReg(ScratchReg)
+      .addReg(RISCV::X0)
+      .addMBB(LoopMBB);
+}
+
+static void insertMaskedMerge(const RISCVInstrInfo *TII, DebugLoc DL,
+                              MachineBasicBlock *MBB, unsigned DestReg,
+                              unsigned OldValReg, unsigned NewValReg,
+                              unsigned MaskReg, unsigned ScratchReg) {
+  assert(OldValReg != ScratchReg && "OldValReg and ScratchReg must be unique");
+  assert(OldValReg != MaskReg && "OldValReg and MaskReg must be unique");
+  assert(ScratchReg != MaskReg && "ScratchReg and MaskReg must be unique");
+
+  // We select bits from newval and oldval using:
+  // https://graphics.stanford.edu/~seander/bithacks.html#MaskedMerge
+  // r = oldval ^ ((oldval ^ newval) & masktargetdata);
+  BuildMI(MBB, DL, TII->get(RISCV::XOR), ScratchReg)
+      .addReg(OldValReg)
+      .addReg(NewValReg);
+  BuildMI(MBB, DL, TII->get(RISCV::AND), ScratchReg)
+      .addReg(ScratchReg)
+      .addReg(MaskReg);
+  BuildMI(MBB, DL, TII->get(RISCV::XOR), DestReg)
+      .addReg(OldValReg)
+      .addReg(ScratchReg);
+}
+
+static void doMaskedAtomicBinOpExpansion(
+    const RISCVInstrInfo *TII, MachineInstr &MI, DebugLoc DL,
+    MachineBasicBlock *ThisMBB, MachineBasicBlock *LoopMBB,
+    MachineBasicBlock *DoneMBB, AtomicRMWInst::BinOp BinOp, int Width) {
+  assert(Width == 32 && "RV64 atomic expansion currently unsupported");
+  unsigned DestReg = MI.getOperand(0).getReg();
+  unsigned ScratchReg = MI.getOperand(1).getReg();
+  unsigned AddrReg = MI.getOperand(2).getReg();
+  unsigned IncrReg = MI.getOperand(3).getReg();
+  unsigned MaskReg = MI.getOperand(4).getReg();
+  AtomicOrdering Ordering =
+      static_cast<AtomicOrdering>(MI.getOperand(5).getImm());
+
+  // .loop:
+  //   lr.w destreg, (alignedaddr)
+  //   binop scratch, destreg, incr
+  //   xor scratch, destreg, scratch
+  //   and scratch, scratch, masktargetdata
+  //   xor scratch, destreg, scratch
+  //   sc.w scratch, scratch, (alignedaddr)
+  //   bnez scratch, loop
+  BuildMI(LoopMBB, DL, TII->get(getLRForRMW32(Ordering)), DestReg)
+      .addReg(AddrReg);
+  switch (BinOp) {
+  default:
+    llvm_unreachable("Unexpected AtomicRMW BinOp");
+  case AtomicRMWInst::Xchg:
+    BuildMI(LoopMBB, DL, TII->get(RISCV::ADD), ScratchReg)
+        .addReg(RISCV::X0)
+        .addReg(IncrReg);
+    break;
+  case AtomicRMWInst::Add:
+    BuildMI(LoopMBB, DL, TII->get(RISCV::ADD), ScratchReg)
+        .addReg(DestReg)
+        .addReg(IncrReg);
+    break;
+  case AtomicRMWInst::Sub:
+    BuildMI(LoopMBB, DL, TII->get(RISCV::SUB), ScratchReg)
+        .addReg(DestReg)
+        .addReg(IncrReg);
+    break;
+  case AtomicRMWInst::Nand:
+    BuildMI(LoopMBB, DL, TII->get(RISCV::AND), ScratchReg)
+        .addReg(DestReg)
+        .addReg(IncrReg);
+    BuildMI(LoopMBB, DL, TII->get(RISCV::XORI), ScratchReg)
+        .addReg(ScratchReg)
+        .addImm(-1);
+    break;
+  }
+
+  insertMaskedMerge(TII, DL, LoopMBB, ScratchReg, DestReg, ScratchReg, MaskReg,
+                    ScratchReg);
+
+  BuildMI(LoopMBB, DL, TII->get(getSCForRMW32(Ordering)), ScratchReg)
+      .addReg(AddrReg)
+      .addReg(ScratchReg);
+  BuildMI(LoopMBB, DL, TII->get(RISCV::BNE))
+      .addReg(ScratchReg)
+      .addReg(RISCV::X0)
+      .addMBB(LoopMBB);
+}
+
+bool RISCVExpandPseudo::expandAtomicBinOp(
+    MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
+    AtomicRMWInst::BinOp BinOp, bool IsMasked, int Width,
+    MachineBasicBlock::iterator &NextMBBI) {
+  MachineInstr &MI = *MBBI;
+  DebugLoc DL = MI.getDebugLoc();
+
+  MachineFunction *MF = MBB.getParent();
+  auto LoopMBB = MF->CreateMachineBasicBlock(MBB.getBasicBlock());
+  auto DoneMBB = MF->CreateMachineBasicBlock(MBB.getBasicBlock());
+
+  // Insert new MBBs.
+  MF->insert(++MBB.getIterator(), LoopMBB);
+  MF->insert(++LoopMBB->getIterator(), DoneMBB);
+
+  // Set up successors and transfer remaining instructions to DoneMBB.
+  LoopMBB->addSuccessor(LoopMBB);
+  LoopMBB->addSuccessor(DoneMBB);
+  DoneMBB->splice(DoneMBB->end(), &MBB, MI, MBB.end());
+  DoneMBB->transferSuccessors(&MBB);
+  MBB.addSuccessor(LoopMBB);
+
+  if (!IsMasked)
+    doAtomicBinOpExpansion(TII, MI, DL, &MBB, LoopMBB, DoneMBB, BinOp, Width);
+  else
+    doMaskedAtomicBinOpExpansion(TII, MI, DL, &MBB, LoopMBB, DoneMBB, BinOp,
+                                 Width);
+
+  NextMBBI = MBB.end();
+  MI.eraseFromParent();
+
+  LivePhysRegs LiveRegs;
+  computeAndAddLiveIns(LiveRegs, *LoopMBB);
+  computeAndAddLiveIns(LiveRegs, *DoneMBB);
+
+  return true;
+}
+
+static void insertSext(const RISCVInstrInfo *TII, DebugLoc DL,
+                       MachineBasicBlock *MBB, unsigned ValReg,
+                       unsigned ShamtReg) {
+  BuildMI(MBB, DL, TII->get(RISCV::SLL), ValReg)
+      .addReg(ValReg)
+      .addReg(ShamtReg);
+  BuildMI(MBB, DL, TII->get(RISCV::SRA), ValReg)
+      .addReg(ValReg)
+      .addReg(ShamtReg);
+}
+
+bool RISCVExpandPseudo::expandAtomicMinMaxOp(
+    MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
+    AtomicRMWInst::BinOp BinOp, bool IsMasked, int Width,
+    MachineBasicBlock::iterator &NextMBBI) {
+  assert(IsMasked == true &&
+         "Should only need to expand masked atomic max/min");
+  assert(Width == 32 && "RV64 atomic expansion currently unsupported");
+
+  MachineInstr &MI = *MBBI;
+  DebugLoc DL = MI.getDebugLoc();
+  MachineFunction *MF = MBB.getParent();
+  auto LoopHeadMBB = MF->CreateMachineBasicBlock(MBB.getBasicBlock());
+  auto LoopIfBodyMBB = MF->CreateMachineBasicBlock(MBB.getBasicBlock());
+  auto LoopTailMBB = MF->CreateMachineBasicBlock(MBB.getBasicBlock());
+  auto DoneMBB = MF->CreateMachineBasicBlock(MBB.getBasicBlock());
+
+  // Insert new MBBs.
+  MF->insert(++MBB.getIterator(), LoopHeadMBB);
+  MF->insert(++LoopHeadMBB->getIterator(), LoopIfBodyMBB);
+  MF->insert(++LoopIfBodyMBB->getIterator(), LoopTailMBB);
+  MF->insert(++LoopTailMBB->getIterator(), DoneMBB);
+
+  // Set up successors and transfer remaining instructions to DoneMBB.
+  LoopHeadMBB->addSuccessor(LoopIfBodyMBB);
+  LoopHeadMBB->addSuccessor(LoopTailMBB);
+  LoopIfBodyMBB->addSuccessor(LoopTailMBB);
+  LoopTailMBB->addSuccessor(LoopHeadMBB);
+  LoopTailMBB->addSuccessor(DoneMBB);
+  DoneMBB->splice(DoneMBB->end(), &MBB, MI, MBB.end());
+  DoneMBB->transferSuccessors(&MBB);
+  MBB.addSuccessor(LoopHeadMBB);
+
+  unsigned DestReg = MI.getOperand(0).getReg();
+  unsigned Scratch1Reg = MI.getOperand(1).getReg();
+  unsigned Scratch2Reg = MI.getOperand(2).getReg();
+  unsigned AddrReg = MI.getOperand(3).getReg();
+  unsigned IncrReg = MI.getOperand(4).getReg();
+  unsigned MaskReg = MI.getOperand(5).getReg();
+  bool IsSigned = BinOp == AtomicRMWInst::Min || BinOp == AtomicRMWInst::Max;
+  AtomicOrdering Ordering =
+      static_cast<AtomicOrdering>(MI.getOperand(IsSigned ? 7 : 6).getImm());
+
+  //
+  // .loophead:
+  //   lr.w destreg, (alignedaddr)
+  //   and scratch2, destreg, mask
+  //   mv scratch1, destreg
+  //   [sext scratch2 if signed min/max]
+  //   ifnochangeneeded scratch2, incr, .looptail
+  BuildMI(LoopHeadMBB, DL, TII->get(getLRForRMW32(Ordering)), DestReg)
+      .addReg(AddrReg);
+  BuildMI(LoopHeadMBB, DL, TII->get(RISCV::AND), Scratch2Reg)
+      .addReg(DestReg)
+      .addReg(MaskReg);
+  BuildMI(LoopHeadMBB, DL, TII->get(RISCV::ADDI), Scratch1Reg)
+      .addReg(DestReg)
+      .addImm(0);
+
+  switch (BinOp) {
+  default:
+    llvm_unreachable("Unexpected AtomicRMW BinOp");
+  case AtomicRMWInst::Max: {
+    insertSext(TII, DL, LoopHeadMBB, Scratch2Reg, MI.getOperand(6).getReg());
+    BuildMI(LoopHeadMBB, DL, TII->get(RISCV::BGE))
+        .addReg(Scratch2Reg)
+        .addReg(IncrReg)
+        .addMBB(LoopTailMBB);
+    break;
+  }
+  case AtomicRMWInst::Min: {
+    insertSext(TII, DL, LoopHeadMBB, Scratch2Reg, MI.getOperand(6).getReg());
+    BuildMI(LoopHeadMBB, DL, TII->get(RISCV::BGE))
+        .addReg(IncrReg)
+        .addReg(Scratch2Reg)
+        .addMBB(LoopTailMBB);
+    break;
+  }
+  case AtomicRMWInst::UMax:
+    BuildMI(LoopHeadMBB, DL, TII->get(RISCV::BGEU))
+        .addReg(Scratch2Reg)
+        .addReg(IncrReg)
+        .addMBB(LoopTailMBB);
+    break;
+  case AtomicRMWInst::UMin:
+    BuildMI(LoopHeadMBB, DL, TII->get(RISCV::BGEU))
+        .addReg(IncrReg)
+        .addReg(Scratch2Reg)
+        .addMBB(LoopTailMBB);
+    break;
+  }
+
+  // .loopifbody:
+  //   xor scratch1, destreg, incr
+  //   and scratch1, scratch1, mask
+  //   xor scratch1, destreg, scratch1
+  insertMaskedMerge(TII, DL, LoopIfBodyMBB, Scratch1Reg, DestReg, IncrReg,
+                    MaskReg, Scratch1Reg);
+
+  // .looptail:
+  //   sc.w scratch1, scratch1, (addr)
+  //   bnez scratch1, loop
+  BuildMI(LoopTailMBB, DL, TII->get(getSCForRMW32(Ordering)), Scratch1Reg)
+      .addReg(AddrReg)
+      .addReg(Scratch1Reg);
+  BuildMI(LoopTailMBB, DL, TII->get(RISCV::BNE))
+      .addReg(Scratch1Reg)
+      .addReg(RISCV::X0)
+      .addMBB(LoopHeadMBB);
+
+  NextMBBI = MBB.end();
+  MI.eraseFromParent();
+
+  LivePhysRegs LiveRegs;
+  computeAndAddLiveIns(LiveRegs, *LoopHeadMBB);
+  computeAndAddLiveIns(LiveRegs, *LoopIfBodyMBB);
+  computeAndAddLiveIns(LiveRegs, *LoopTailMBB);
+  computeAndAddLiveIns(LiveRegs, *DoneMBB);
+
+  return true;
+}
+
+} // end of anonymous namespace
+
+INITIALIZE_PASS(RISCVExpandPseudo, "riscv-expand-pseudo",
+                RISCV_EXPAND_PSEUDO_NAME, false, false)
+namespace llvm {
+
+FunctionPass *createRISCVExpandPseudoPass() { return new RISCVExpandPseudo(); }
+
+} // end of namespace llvm
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index 6f2e6b40038..44da49c23d5 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -137,10 +137,12 @@ RISCVTargetLowering::RISCVTargetLowering(const TargetMachine &TM,
   setOperationAction(ISD::BlockAddress, XLenVT, Custom);
   setOperationAction(ISD::ConstantPool, XLenVT, Custom);
 
-  if (Subtarget.hasStdExtA())
+  if (Subtarget.hasStdExtA()) {
     setMaxAtomicSizeInBitsSupported(Subtarget.getXLen());
-  else
+    setMinCmpXchgSizeInBits(32);
+  } else {
     setMaxAtomicSizeInBitsSupported(0);
+  }
 
   setBooleanContents(ZeroOrOneBooleanContent);
 
@@ -160,6 +162,33 @@ EVT RISCVTargetLowering::getSetCCResultType(const DataLayout &DL, LLVMContext &,
   return VT.changeVectorElementTypeToInteger();
 }
 
+bool RISCVTargetLowering::getTgtMemIntrinsic(IntrinsicInfo &Info,
+                                             const CallInst &I,
+                                             MachineFunction &MF,
+                                             unsigned Intrinsic) const {
+  switch (Intrinsic) {
+  default:
+    return false;
+  case Intrinsic::riscv_masked_atomicrmw_xchg_i32:
+  case Intrinsic::riscv_masked_atomicrmw_add_i32:
+  case Intrinsic::riscv_masked_atomicrmw_sub_i32:
+  case Intrinsic::riscv_masked_atomicrmw_nand_i32:
+  case Intrinsic::riscv_masked_atomicrmw_max_i32:
+  case Intrinsic::riscv_masked_atomicrmw_min_i32:
+  case Intrinsic::riscv_masked_atomicrmw_umax_i32:
+  case Intrinsic::riscv_masked_atomicrmw_umin_i32:
+    PointerType *PtrTy = cast<PointerType>(I.getArgOperand(0)->getType());
+    Info.opc = ISD::INTRINSIC_W_CHAIN;
+    Info.memVT = MVT::getVT(PtrTy->getElementType());
+    Info.ptrVal = I.getArgOperand(0);
+    Info.offset = 0;
+    Info.align = 4;
+    Info.flags = MachineMemOperand::MOLoad | MachineMemOperand::MOStore |
+                 MachineMemOperand::MOVolatile;
+    return true;
+  }
+}
+
 bool RISCVTargetLowering::isLegalAddressingMode(const DataLayout &DL,
                                                 const AddrMode &AM, Type *Ty,
                                                 unsigned AS,
@@ -1596,3 +1625,63 @@ Instruction *RISCVTargetLowering::emitTrailingFence(IRBuilder<> &Builder,
     return Builder.CreateFence(AtomicOrdering::Acquire);
   return nullptr;
 }
+
+TargetLowering::AtomicExpansionKind
+RISCVTargetLowering::shouldExpandAtomicRMWInIR(AtomicRMWInst *AI) const {
+  unsigned Size = AI->getType()->getPrimitiveSizeInBits();
+  if (Size == 8 || Size == 16)
+    return AtomicExpansionKind::MaskedIntrinsic;
+  return AtomicExpansionKind::None;
+}
+
+static Intrinsic::ID
+getIntrinsicForMaskedAtomicRMWBinOp32(AtomicRMWInst::BinOp BinOp) {
+  switch (BinOp) {
+  default:
+    llvm_unreachable("Unexpected AtomicRMW BinOp");
+  case AtomicRMWInst::Xchg:
+    return Intrinsic::riscv_masked_atomicrmw_xchg_i32;
+  case AtomicRMWInst::Add:
+    return Intrinsic::riscv_masked_atomicrmw_add_i32;
+  case AtomicRMWInst::Sub:
+    return Intrinsic::riscv_masked_atomicrmw_sub_i32;
+  case AtomicRMWInst::Nand:
+    return Intrinsic::riscv_masked_atomicrmw_nand_i32;
+  case AtomicRMWInst::Max:
+    return Intrinsic::riscv_masked_atomicrmw_max_i32;
+  case AtomicRMWInst::Min:
+    return Intrinsic::riscv_masked_atomicrmw_min_i32;
+  case AtomicRMWInst::UMax:
+    return Intrinsic::riscv_masked_atomicrmw_umax_i32;
+  case AtomicRMWInst::UMin:
+    return Intrinsic::riscv_masked_atomicrmw_umin_i32;
+  }
+}
+
+Value *RISCVTargetLowering::emitMaskedAtomicRMWIntrinsic(
+    IRBuilder<> &Builder, AtomicRMWInst *AI, Value *AlignedAddr, Value *Incr,
+    Value *Mask, Value *ShiftAmt, AtomicOrdering Ord) const {
+  Value *Ordering = Builder.getInt32(static_cast<uint32_t>(AI->getOrdering()));
+  Type *Tys[] = {AlignedAddr->getType()};
+  Function *LrwOpScwLoop = Intrinsic::getDeclaration(
+      AI->getModule(),
+      getIntrinsicForMaskedAtomicRMWBinOp32(AI->getOperation()), Tys);
+
+  // Must pass the shift amount needed to sign extend the loaded value prior
+  // to performing a signed comparison for min/max. ShiftAmt is the number of
+  // bits to shift the value into position. Pass XLen-ShiftAmt-ValWidth, which
+  // is the number of bits to left+right shift the value in order to
+  // sign-extend.
+  if (AI->getOperation() == AtomicRMWInst::Min ||
+      AI->getOperation() == AtomicRMWInst::Max) {
+    const DataLayout &DL = AI->getModule()->getDataLayout();
+    unsigned ValWidth =
+        DL.getTypeStoreSizeInBits(AI->getValOperand()->getType());
+    Value *SextShamt = Builder.CreateSub(
+        Builder.getInt32(Subtarget.getXLen() - ValWidth), ShiftAmt);
+    return Builder.CreateCall(LrwOpScwLoop,
+                              {AlignedAddr, Incr, Mask, SextShamt, Ordering});
+  }
+
+  return Builder.CreateCall(LrwOpScwLoop, {AlignedAddr, Incr, Mask, Ordering});
+}
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.h b/llvm/lib/Target/RISCV/RISCVISelLowering.h
index 3e3e67b9188..e21951140b3 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.h
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.h
@@ -43,6 +43,9 @@ public:
   explicit RISCVTargetLowering(const TargetMachine &TM,
                                const RISCVSubtarget &STI);
 
+  bool getTgtMemIntrinsic(IntrinsicInfo &Info, const CallInst &I,
+                          MachineFunction &MF,
+                          unsigned Intrinsic) const override;
   bool isLegalAddressingMode(const DataLayout &DL, const AddrMode &AM, Type *Ty,
                              unsigned AS,
                              Instruction *I = nullptr) const override;
@@ -115,6 +118,12 @@ private:
   bool IsEligibleForTailCallOptimization(CCState &CCInfo,
     CallLoweringInfo &CLI, MachineFunction &MF,
     const SmallVector<CCValAssign, 16> &ArgLocs) const;
+
+  TargetLowering::AtomicExpansionKind
+  shouldExpandAtomicRMWInIR(AtomicRMWInst *AI) const override;
+  virtual Value *emitMaskedAtomicRMWIntrinsic(
+      IRBuilder<> &Builder, AtomicRMWInst *AI, Value *AlignedAddr, Value *Incr,
+      Value *Mask, Value *ShiftAmt, AtomicOrdering Ord) const override;
 };
 }
 
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.td b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
index 720dd78c4ac..dd739f03f9b 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
@@ -603,7 +603,7 @@ def : MnemonicAlias<"sbreak", "ebreak">;
 
 /// Generic pattern classes
 
-class PatGprGpr<SDPatternOperator OpNode, RVInstR Inst>
+class PatGprGpr<SDPatternOperator OpNode, RVInst Inst>
     : Pat<(OpNode GPR:$rs1, GPR:$rs2), (Inst GPR:$rs1, GPR:$rs2)>;
 class PatGprSimm12<SDPatternOperator OpNode, RVInstI Inst>
     : Pat<(OpNode GPR:$rs1, simm12:$imm12), (Inst GPR:$rs1, simm12:$imm12)>;
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoA.td b/llvm/lib/Target/RISCV/RISCVInstrInfoA.td
index ef46892b9ff..bf8c835918a 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoA.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoA.td
@@ -105,4 +105,129 @@ defm : LdPat<atomic_load_32, LW>;
 defm : AtomicStPat<atomic_store_8,  SB, GPR>;
 defm : AtomicStPat<atomic_store_16, SH, GPR>;
 defm : AtomicStPat<atomic_store_32, SW, GPR>;
+
+/// AMOs
+
+multiclass AMOPat<string AtomicOp, string BaseInst> {
+  def : PatGprGpr<!cast<PatFrag>(AtomicOp#"_monotonic"),
+                  !cast<RVInst>(BaseInst)>;
+  def : PatGprGpr<!cast<PatFrag>(AtomicOp#"_acquire"),
+                  !cast<RVInst>(BaseInst#"_AQ")>;
+  def : PatGprGpr<!cast<PatFrag>(AtomicOp#"_release"),
+                  !cast<RVInst>(BaseInst#"_RL")>;
+  def : PatGprGpr<!cast<PatFrag>(AtomicOp#"_acq_rel"),
+                  !cast<RVInst>(BaseInst#"_AQ_RL")>;
+  def : PatGprGpr<!cast<PatFrag>(AtomicOp#"_seq_cst"),
+                  !cast<RVInst>(BaseInst#"_AQ_RL")>;
+}
+
+defm : AMOPat<"atomic_swap_32", "AMOSWAP_W">;
+defm : AMOPat<"atomic_load_add_32", "AMOADD_W">;
+defm : AMOPat<"atomic_load_and_32", "AMOAND_W">;
+defm : AMOPat<"atomic_load_or_32", "AMOOR_W">;
+defm : AMOPat<"atomic_load_xor_32", "AMOXOR_W">;
+defm : AMOPat<"atomic_load_max_32", "AMOMAX_W">;
+defm : AMOPat<"atomic_load_min_32", "AMOMIN_W">;
+defm : AMOPat<"atomic_load_umax_32", "AMOMAXU_W">;
+defm : AMOPat<"atomic_load_umin_32", "AMOMINU_W">;
+
+def : Pat<(atomic_load_sub_32_monotonic GPR:$addr, GPR:$incr),
+          (AMOADD_W GPR:$addr, (SUB X0, GPR:$incr))>;
+def : Pat<(atomic_load_sub_32_acquire GPR:$addr, GPR:$incr),
+          (AMOADD_W_AQ GPR:$addr, (SUB X0, GPR:$incr))>;
+def : Pat<(atomic_load_sub_32_release GPR:$addr, GPR:$incr),
+          (AMOADD_W_RL GPR:$addr, (SUB X0, GPR:$incr))>;
+def : Pat<(atomic_load_sub_32_acq_rel GPR:$addr, GPR:$incr),
+          (AMOADD_W_AQ_RL GPR:$addr, (SUB X0, GPR:$incr))>;
+def : Pat<(atomic_load_sub_32_seq_cst GPR:$addr, GPR:$incr),
+          (AMOADD_W_AQ_RL GPR:$addr, (SUB X0, GPR:$incr))>;
+
+/// Pseudo AMOs
+
+class PseudoAMO : Pseudo<(outs GPR:$res, GPR:$scratch),
+                         (ins GPR:$addr, GPR:$incr, i32imm:$ordering), []> {
+  let Constraints = "@earlyclobber $res,@earlyclobber $scratch";
+  let mayLoad = 1;
+  let mayStore = 1;
+  let hasSideEffects = 0;
+}
+
+def PseudoAtomicLoadNand32 : PseudoAMO;
+// Ordering constants must be kept in sync with the AtomicOrdering enum in 
+// AtomicOrdering.h.
+def : Pat<(atomic_load_nand_32_monotonic GPR:$addr, GPR:$incr),
+          (PseudoAtomicLoadNand32 GPR:$addr, GPR:$incr, 2)>;
+def : Pat<(atomic_load_nand_32_acquire GPR:$addr, GPR:$incr),
+          (PseudoAtomicLoadNand32 GPR:$addr, GPR:$incr, 4)>;
+def : Pat<(atomic_load_nand_32_release GPR:$addr, GPR:$incr),
+          (PseudoAtomicLoadNand32 GPR:$addr, GPR:$incr, 5)>;
+def : Pat<(atomic_load_nand_32_acq_rel GPR:$addr, GPR:$incr),
+          (PseudoAtomicLoadNand32 GPR:$addr, GPR:$incr, 6)>;
+def : Pat<(atomic_load_nand_32_seq_cst GPR:$addr, GPR:$incr),
+          (PseudoAtomicLoadNand32 GPR:$addr, GPR:$incr, 7)>;
+
+class PseudoMaskedAMO
+    : Pseudo<(outs GPR:$res, GPR:$scratch),
+             (ins GPR:$addr, GPR:$incr, GPR:$mask, i32imm:$ordering), []> {
+  let Constraints = "@earlyclobber $res,@earlyclobber $scratch";
+  let mayLoad = 1;
+  let mayStore = 1;
+  let hasSideEffects = 0;
+}
+
+class PseudoMaskedAMOMinMax
+    : Pseudo<(outs GPR:$res, GPR:$scratch1, GPR:$scratch2),
+             (ins GPR:$addr, GPR:$incr, GPR:$mask, i32imm:$sextshamt,
+              i32imm:$ordering), []> {
+  let Constraints = "@earlyclobber $res,@earlyclobber $scratch1,"
+                    "@earlyclobber $scratch2";
+  let mayLoad = 1;
+  let mayStore = 1;
+  let hasSideEffects = 0;
+}
+
+class PseudoMaskedAMOUMinUMax
+    : Pseudo<(outs GPR:$res, GPR:$scratch1, GPR:$scratch2),
+             (ins GPR:$addr, GPR:$incr, GPR:$mask, i32imm:$ordering), []> {
+  let Constraints = "@earlyclobber $res,@earlyclobber $scratch1,"
+                    "@earlyclobber $scratch2";
+  let mayLoad = 1;
+  let mayStore = 1;
+  let hasSideEffects = 0;
+}
+
+class PseudoMaskedAMOPat<Intrinsic intrin, Pseudo AMOInst>
+    : Pat<(intrin GPR:$addr, GPR:$incr, GPR:$mask, imm:$ordering),
+          (AMOInst GPR:$addr, GPR:$incr, GPR:$mask, imm:$ordering)>;
+
+class PseudoMaskedAMOMinMaxPat<Intrinsic intrin, Pseudo AMOInst>
+    : Pat<(intrin GPR:$addr, GPR:$incr, GPR:$mask, GPR:$shiftamt,
+           imm:$ordering),
+          (AMOInst GPR:$addr, GPR:$incr, GPR:$mask, GPR:$shiftamt,
+           imm:$ordering)>;
+
+def PseudoMaskedAtomicSwap32 : PseudoMaskedAMO;
+def : PseudoMaskedAMOPat<int_riscv_masked_atomicrmw_xchg_i32,
+                         PseudoMaskedAtomicSwap32>;
+def PseudoMaskedAtomicLoadAdd32 : PseudoMaskedAMO;
+def : PseudoMaskedAMOPat<int_riscv_masked_atomicrmw_add_i32,
+                         PseudoMaskedAtomicLoadAdd32>;
+def PseudoMaskedAtomicLoadSub32 : PseudoMaskedAMO;
+def : PseudoMaskedAMOPat<int_riscv_masked_atomicrmw_sub_i32,
+                         PseudoMaskedAtomicLoadSub32>;
+def PseudoMaskedAtomicLoadNand32 : PseudoMaskedAMO;
+def : PseudoMaskedAMOPat<int_riscv_masked_atomicrmw_nand_i32,
+                         PseudoMaskedAtomicLoadNand32>;
+def PseudoMaskedAtomicLoadMax32 : PseudoMaskedAMOMinMax;
+def : PseudoMaskedAMOMinMaxPat<int_riscv_masked_atomicrmw_max_i32,
+                               PseudoMaskedAtomicLoadMax32>;
+def PseudoMaskedAtomicLoadMin32 : PseudoMaskedAMOMinMax;
+def : PseudoMaskedAMOMinMaxPat<int_riscv_masked_atomicrmw_min_i32,
+                               PseudoMaskedAtomicLoadMin32>;
+def PseudoMaskedAtomicLoadUMax32 : PseudoMaskedAMOUMinUMax;
+def : PseudoMaskedAMOPat<int_riscv_masked_atomicrmw_umax_i32,
+                         PseudoMaskedAtomicLoadUMax32>;
+def PseudoMaskedAtomicLoadUMin32 : PseudoMaskedAMOUMinUMax;
+def : PseudoMaskedAMOPat<int_riscv_masked_atomicrmw_umin_i32,
+                         PseudoMaskedAtomicLoadUMin32>;
 } // Predicates = [HasStdExtA]
diff --git a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
index a2ebf5bf3e6..e75da768ee2 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -27,6 +27,8 @@ using namespace llvm;
 extern "C" void LLVMInitializeRISCVTarget() {
   RegisterTargetMachine<RISCVTargetMachine> X(getTheRISCV32Target());
   RegisterTargetMachine<RISCVTargetMachine> Y(getTheRISCV64Target());
+  auto PR = PassRegistry::getPassRegistry();
+  initializeRISCVExpandPseudoPass(*PR);
 }
 
 static std::string computeDataLayout(const Triple &TT) {
@@ -78,6 +80,7 @@ public:
   void addIRPasses() override;
   bool addInstSelector() override;
   void addPreEmitPass() override;
+  void addPreEmitPass2() override;
   void addPreRegAlloc() override;
 };
 }
@@ -99,6 +102,13 @@ bool RISCVPassConfig::addInstSelector() {
 
 void RISCVPassConfig::addPreEmitPass() { addPass(&BranchRelaxationPassID); }
 
+void RISCVPassConfig::addPreEmitPass2() {
+  // Schedule the expansion of AMOs at the last possible moment, avoiding the
+  // possibility for other passes to break the requirements for forward
+  // progress in the LR/SC block.
+  addPass(createRISCVExpandPseudoPass());
+}
+
 void RISCVPassConfig::addPreRegAlloc() {
   addPass(createRISCVMergeBaseOffsetOptPass());
 }