[llvm] [RISCV] Enable early if-conversion (PR #92959)

via llvm-commits llvm-commits at lists.llvm.org
Wed Jun 26 21:19:45 PDT 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Mikhail Gudim (mgudim)

<details>
<summary>Changes</summary>

Implements the necessary target methods (insertSelect, canInsertSelect) and adds early if-conversion to the RISCV pipeline. Doing if-conversion increases the number of executed instructions, so it only makes sense if there is enough ILP.

---

Patch is 27.41 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/92959.diff


7 Files Affected:

- (modified) llvm/lib/CodeGen/EarlyIfConversion.cpp (+1-1) 
- (modified) llvm/lib/Target/RISCV/RISCVInstrInfo.cpp (+193) 
- (modified) llvm/lib/Target/RISCV/RISCVInstrInfo.h (+12) 
- (modified) llvm/lib/Target/RISCV/RISCVSubtarget.cpp (+17) 
- (modified) llvm/lib/Target/RISCV/RISCVSubtarget.h (+2) 
- (modified) llvm/lib/Target/RISCV/RISCVTargetMachine.cpp (+8) 
- (added) llvm/test/CodeGen/RISCV/early-ifcvt.mir (+553) 


``````````diff
diff --git a/llvm/lib/CodeGen/EarlyIfConversion.cpp b/llvm/lib/CodeGen/EarlyIfConversion.cpp
index 2a7bee1618deb..2f8729fcbb945 100644
--- a/llvm/lib/CodeGen/EarlyIfConversion.cpp
+++ b/llvm/lib/CodeGen/EarlyIfConversion.cpp
@@ -879,7 +879,7 @@ bool EarlyIfConverter::shouldConvertIf() {
   // from a loop-invariant address predictable; we were unable to prove that it
   // doesn't alias any of the memory-writes in the loop, but it is likely to
   // read to same value multiple times.
-  if (CurrentLoop && any_of(IfConv.Cond, [&](MachineOperand &MO) {
+  if (CurrentLoop && all_of(IfConv.Cond, [&](MachineOperand &MO) {
         if (!MO.isReg() || !MO.isUse())
           return false;
         Register Reg = MO.getReg();
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index 444b9076005c2..748fc34cfe353 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -1446,6 +1446,199 @@ RISCVInstrInfo::optimizeSelect(MachineInstr &MI,
   return NewMI;
 }
 
+int RISCVInstrInfo::getICmpCost(unsigned CC,
+                                const TargetSchedModel &SchedModel) const {
+  switch (CC) {
+  default:
+    llvm_unreachable("Unknown condition code!");
+  case RISCVCC::COND_LT:
+    return SchedModel.computeInstrLatency(RISCV::SLT);
+  case RISCVCC::COND_LTU:
+    return SchedModel.computeInstrLatency(RISCV::SLTU);
+  case RISCVCC::COND_EQ:
+    return SchedModel.computeInstrLatency(RISCV::XOR) +
+           SchedModel.computeInstrLatency(RISCV::SLTIU);
+  case RISCVCC::COND_NE:
+    return SchedModel.computeInstrLatency(RISCV::XOR) +
+           SchedModel.computeInstrLatency(RISCV::SLTU);
+  case RISCVCC::COND_GE:
+    return SchedModel.computeInstrLatency(RISCV::XORI) +
+           SchedModel.computeInstrLatency(RISCV::SLT);
+  case RISCVCC::COND_GEU:
+    return SchedModel.computeInstrLatency(RISCV::XORI) +
+           SchedModel.computeInstrLatency(RISCV::SLTU);
+  }
+}
+
+void RISCVInstrInfo::insertICmp(MachineBasicBlock &MBB,
+                                MachineBasicBlock::iterator MI,
+                                const DebugLoc &DL, Register DstReg,
+                                unsigned CC, Register LHSReg,
+                                Register RHSReg) const {
+  MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
+
+  switch (CC) {
+  default:
+    llvm_unreachable("Unknown condition code!");
+  case RISCVCC::COND_LT:
+  case RISCVCC::COND_LTU: {
+    BuildMI(MBB, MI, DL, get(CC == RISCVCC::COND_LT ? RISCV::SLT : RISCV::SLTU),
+            DstReg)
+        .addReg(LHSReg)
+        .addReg(RHSReg);
+    return;
+  }
+  case RISCVCC::COND_EQ:
+  case RISCVCC::COND_NE: {
+    Register XorReg = LHSReg;
+    if (RHSReg != RISCV::X0) {
+      XorReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
+      BuildMI(MBB, MI, DL, get(RISCV::XOR), XorReg).addReg(LHSReg).addReg(RHSReg);
+    }
+    if (CC == RISCVCC::COND_EQ) {
+      BuildMI(MBB, MI, DL, get(RISCV::SLTIU), DstReg).addReg(XorReg).addImm(1);
+      return;
+    } else {
+      BuildMI(MBB, MI, DL, get(RISCV::SLTU), DstReg)
+          .addReg(RISCV::X0)
+          .addReg(XorReg);
+      return;
+    }
+  }
+  case RISCVCC::COND_GE:
+  case RISCVCC::COND_GEU: {
+    Register NotCCReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
+    BuildMI(MBB, MI, DL, get(CC == RISCVCC::COND_GE ? RISCV::SLT : RISCV::SLTU),
+            NotCCReg)
+        .addReg(LHSReg)
+        .addReg(RHSReg);
+    BuildMI(MBB, MI, DL, get(RISCV::XORI), DstReg).addReg(NotCCReg).addImm(1);
+    return;
+  }
+  }
+}
+
+void RISCVInstrInfo::insertSelect(MachineBasicBlock &MBB,
+                                  MachineBasicBlock::iterator MI,
+                                  const DebugLoc &DL, Register DstReg,
+                                  ArrayRef<MachineOperand> Cond,
+                                  Register TrueReg, Register FalseReg) const {
+  MachineFunction &MF = *MI->getParent()->getParent();
+  const RISCVSubtarget &ST = MF.getSubtarget<RISCVSubtarget>();
+  const TargetRegisterInfo &TRI = *ST.getRegisterInfo();
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+  Register CCReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
+
+  unsigned CC = Cond[0].getImm();
+  Register LHSReg = Cond[1].getReg();
+  Register RHSReg = Cond[2].getReg();
+
+  unsigned CondZeroEqzOpc =
+      ST.hasVendorXVentanaCondOps() ? RISCV::VT_MASKC : RISCV::CZERO_EQZ;
+  unsigned CondZeroNezOpc =
+      ST.hasVendorXVentanaCondOps() ? RISCV::VT_MASKCN : RISCV::CZERO_NEZ;
+
+  const TargetRegisterClass *DstRC = MRI.getRegClass(DstReg);
+  const TargetRegisterClass *CommonRC =
+      TRI.getCommonSubClass(DstRC, &RISCV::GPRRegClass);
+  bool NeedsRCCopies = (CommonRC != DstRC) && (CommonRC != &RISCV::GPRRegClass);
+
+  Register CondZeroEqzReg = TrueReg;
+  Register CondZeroNezReg = FalseReg;
+  if (NeedsRCCopies) {
+    CondZeroEqzReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
+    BuildMI(MBB, MI, DL, get(TargetOpcode::COPY), CondZeroEqzReg)
+        .addReg(TrueReg);
+    CondZeroNezReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
+    BuildMI(MBB, MI, DL, get(TargetOpcode::COPY), CondZeroNezReg)
+        .addReg(FalseReg);
+  }
+  if (CC == RISCVCC::COND_GE || CC == RISCVCC::COND_GEU) {
+    CC = (CC == RISCVCC::COND_GE) ? RISCVCC::COND_LT : RISCVCC::COND_LTU;
+    std::swap(CondZeroEqzReg, CondZeroNezReg);
+  }
+  insertICmp(MBB, MI, DL, CCReg, CC, LHSReg, RHSReg);
+
+  Register TrueValOrZeroReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
+  Register FalseValOrZeroReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
+  BuildMI(MBB, MI, DL, get(CondZeroEqzOpc), TrueValOrZeroReg)
+      .addReg(CondZeroEqzReg)
+      .addReg(CCReg);
+  BuildMI(MBB, MI, DL, get(CondZeroNezOpc), FalseValOrZeroReg)
+      .addReg(CondZeroNezReg)
+      .addReg(CCReg);
+
+  Register SelectOutReg = DstReg;
+  if (NeedsRCCopies) {
+    SelectOutReg = MRI.createVirtualRegister(&RISCV::GPRRegClass);
+  }
+  BuildMI(MBB, MI, DL, get(RISCV::OR), SelectOutReg)
+      .addReg(TrueValOrZeroReg)
+      .addReg(FalseValOrZeroReg);
+  if (NeedsRCCopies) {
+    BuildMI(MBB, MI, DL, get(TargetOpcode::COPY), DstReg).addReg(SelectOutReg);
+  }
+
+  return;
+}
+
+bool RISCVInstrInfo::canInsertSelect(const MachineBasicBlock &MBB,
+                                     ArrayRef<MachineOperand> Cond,
+                                     Register DstReg, Register TrueReg,
+                                     Register FalseReg, int &CondCycles,
+                                     int &TrueCycles, int &FalseCycles) const {
+  const MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
+  const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
+  const TargetRegisterClass *TrueRC = MRI.getRegClass(TrueReg);
+  const TargetRegisterClass *DstRC = MRI.getRegClass(DstReg);
+  const TargetRegisterClass *CommonRC =
+      TRI.getCommonSubClass(DstRC, &RISCV::GPRRegClass);
+  bool NeedsRCCopies = (CommonRC != DstRC) && (CommonRC != &RISCV::GPRRegClass);
+
+  TargetSchedModel SchedModel;
+  SchedModel.init(&STI);
+
+  // this is used for testing only.
+  if (!SchedModel.hasInstrSchedModelOrItineraries())
+    return true;
+
+  CondCycles = getICmpCost(Cond[0].getImm(), SchedModel);
+  TrueCycles = SchedModel.computeInstrLatency(RISCV::OR) +
+               SchedModel.computeInstrLatency(STI.hasVendorXVentanaCondOps()
+                                                  ? RISCV::VT_MASKC
+                                                  : RISCV::CZERO_EQZ);
+  FalseCycles = SchedModel.computeInstrLatency(RISCV::OR) +
+                SchedModel.computeInstrLatency(STI.hasVendorXVentanaCondOps()
+                                                   ? RISCV::VT_MASKCN
+                                                   : RISCV::CZERO_NEZ);
+
+  if (NeedsRCCopies) {
+    unsigned CopyIntoGPROpc = 0;
+    if (TrueRC == &RISCV::FPR32RegClass) {
+      CopyIntoGPROpc = RISCV::FMV_X_W;
+    } else if (TrueRC == &RISCV::FPR64RegClass) {
+      CopyIntoGPROpc = RISCV::FMV_X_D;
+    } else {
+      llvm_unreachable("Unknown register class");
+    }
+    int CopyIntoGPRCycles = SchedModel.computeInstrLatency(CopyIntoGPROpc);
+
+    unsigned CopyFromGPROpc = 0;
+    if (DstRC == &RISCV::FPR32RegClass) {
+      CopyIntoGPROpc = RISCV::FMV_W_X;
+    } else if (DstRC == &RISCV::FPR64RegClass) {
+      CopyIntoGPROpc = RISCV::FMV_D_X;
+    } else {
+      llvm_unreachable("Unknown register class");
+    }
+    int CopyFromGPRCycles = SchedModel.computeInstrLatency(CopyFromGPROpc);
+
+    TrueCycles += (CopyIntoGPRCycles + CopyFromGPRCycles);
+    FalseCycles += (CopyIntoGPRCycles + CopyFromGPRCycles);
+  }
+  return true;
+}
+
 unsigned RISCVInstrInfo::getInstSizeInBytes(const MachineInstr &MI) const {
   if (MI.isMetaInstruction())
     return 0;
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.h b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
index e069717aaef23..a331f1e2af9db 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.h
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.h
@@ -149,6 +149,18 @@ class RISCVInstrInfo : public RISCVGenInstrInfo {
                                SmallPtrSetImpl<MachineInstr *> &SeenMIs,
                                bool) const override;
 
+  int getICmpCost(unsigned CC, const TargetSchedModel &SchedModel) const;
+  void insertICmp(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
+                  const DebugLoc &DL, Register DstReg, unsigned CC,
+                  Register LHSReg, Register RHSReg) const;
+  bool canInsertSelect(const MachineBasicBlock &, ArrayRef<MachineOperand> Cond,
+                       Register, Register, Register, int &, int &,
+                       int &) const override;
+  void insertSelect(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
+                    const DebugLoc &DL, Register DstReg,
+                    ArrayRef<MachineOperand> Cond, Register TrueReg,
+                    Register FalseReg) const override;
+
   bool isAsCheapAsAMove(const MachineInstr &MI) const override;
 
   std::optional<DestSourcePair>
diff --git a/llvm/lib/Target/RISCV/RISCVSubtarget.cpp b/llvm/lib/Target/RISCV/RISCVSubtarget.cpp
index d3236bb07d56d..0b0347003f0d4 100644
--- a/llvm/lib/Target/RISCV/RISCVSubtarget.cpp
+++ b/llvm/lib/Target/RISCV/RISCVSubtarget.cpp
@@ -65,6 +65,14 @@ static cl::opt<unsigned> RISCVMinimumJumpTableEntries(
     "riscv-min-jump-table-entries", cl::Hidden,
     cl::desc("Set minimum number of entries to use a jump table on RISCV"));
 
+static cl::opt<bool>
+    RISCVDisableEarlyIfcvt("riscv-disable-early-ifcvt", cl::Hidden,
+                           cl::desc("Disable early if-conversion"),
+                           cl::init(true), cl::Hidden);
+
+static cl::opt<bool> RISCVForceEalyIfcvt("riscv-force-early-ifcvt", cl::Hidden,
+                                         cl::desc("Force early if-conversion"),
+                                         cl::init(false), cl::Hidden);
 void RISCVSubtarget::anchor() {}
 
 RISCVSubtarget &
@@ -203,3 +211,12 @@ unsigned RISCVSubtarget::getMinimumJumpTableEntries() const {
              ? RISCVMinimumJumpTableEntries
              : TuneInfo->MinimumJumpTableEntries;
 }
+
+bool RISCVSubtarget::enableEarlyIfConversion() const {
+  TargetSchedModel SchedModel;
+  SchedModel.init(this);
+  return RISCVForceEalyIfcvt ||
+         (!RISCVDisableEarlyIfcvt &&
+          (hasStdExtZicond() || hasVendorXVentanaCondOps()) &&
+          SchedModel.hasInstrSchedModelOrItineraries());
+}
diff --git a/llvm/lib/Target/RISCV/RISCVSubtarget.h b/llvm/lib/Target/RISCV/RISCVSubtarget.h
index c880c9e921e0e..fe8143942e938 100644
--- a/llvm/lib/Target/RISCV/RISCVSubtarget.h
+++ b/llvm/lib/Target/RISCV/RISCVSubtarget.h
@@ -303,6 +303,8 @@ class RISCVSubtarget : public RISCVGenSubtargetInfo {
   unsigned getMinimumJumpTableEntries() const;
 
   bool supportsInitUndef() const override { return hasVInstructions(); }
+
+  bool enableEarlyIfConversion() const override;
 };
 } // End llvm namespace
 
diff --git a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
index 5aab138dae408..a205738eeebd9 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -349,6 +349,7 @@ class RISCVPassConfig : public TargetPassConfig {
   bool addPreISel() override;
   void addCodeGenPrepare() override;
   bool addInstSelector() override;
+  bool addILPOpts() override;
   bool addIRTranslator() override;
   void addPreLegalizeMachineIR() override;
   bool addLegalizeMachineIR() override;
@@ -450,6 +451,13 @@ bool RISCVPassConfig::addInstSelector() {
   return false;
 }
 
+bool RISCVPassConfig::addILPOpts() {
+  if (getOptLevel() != CodeGenOptLevel::None) {
+    addPass(&EarlyIfConverterID);
+  }
+  return true;
+}
+
 bool RISCVPassConfig::addIRTranslator() {
   addPass(new IRTranslator(getOptLevel()));
   return false;
diff --git a/llvm/test/CodeGen/RISCV/early-ifcvt.mir b/llvm/test/CodeGen/RISCV/early-ifcvt.mir
new file mode 100644
index 0000000000000..f4acd2e3a38ec
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/early-ifcvt.mir
@@ -0,0 +1,553 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=riscv64 -mcpu=veyron-v1 -riscv-disable-early-ifcvt=false -riscv-force-early-ifcvt=true -stress-early-ifcvt=true \
+# RUN: -run-pass=early-ifcvt -simplify-mir  -o - %s | FileCheck %s
+
+---
+name: blt
+tracksRegLiveness: true
+body: |
+  ; CHECK-LABEL: name: blt
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   liveins: $x10, $x11, $x12
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   %x:gpr = COPY $x10
+  ; CHECK-NEXT:   %n:gpr = COPY $x11
+  ; CHECK-NEXT:   %k:gpr = COPY $x12
+  ; CHECK-NEXT:   %zero:gpr = COPY $x0
+  ; CHECK-NEXT:   PseudoBR %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   successors: %bb.1, %bb.5
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   %i:gpr = PHI %zero, %bb.0, %i_inc, %bb.1
+  ; CHECK-NEXT:   %x_i_addr:gpr = ADD %x, %i
+  ; CHECK-NEXT:   %x_i:gpr = LD %x_i_addr, 0
+  ; CHECK-NEXT:   %add1:gpr = ADDI %x_i, 1
+  ; CHECK-NEXT:   %add2:gpr = ADDI %x_i, 2
+  ; CHECK-NEXT:   [[SLT:%[0-9]+]]:gpr = SLT %x_i, %k
+  ; CHECK-NEXT:   [[VT_MASKC:%[0-9]+]]:gpr = VT_MASKC %add1, [[SLT]]
+  ; CHECK-NEXT:   [[VT_MASKCN:%[0-9]+]]:gpr = VT_MASKCN %add2, [[SLT]]
+  ; CHECK-NEXT:   %res:gpr = OR [[VT_MASKC]], [[VT_MASKCN]]
+  ; CHECK-NEXT:   SD %res, %x_i, 0
+  ; CHECK-NEXT:   %i_inc:gpr = ADDI %i, 1
+  ; CHECK-NEXT:   BEQ %i_inc, %n, %bb.5
+  ; CHECK-NEXT:   PseudoBR %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.5:
+  ; CHECK-NEXT:   PseudoRET
+  bb.0:
+    successors: %bb.1
+    liveins: $x10, $x11, $x12
+
+    %x:gpr = COPY $x10
+    %n:gpr = COPY $x11
+    %k:gpr = COPY $x12
+    %zero:gpr = COPY $x0
+    PseudoBR %bb.1
+
+  bb.1:
+    successors: %bb.2, %bb.3
+
+    %i:gpr = PHI %zero, %bb.0, %i_inc, %bb.4
+    %x_i_addr:gpr = ADD %x, %i
+    %x_i:gpr = LD %x_i_addr, 0
+    BLT %x_i, %k, %bb.2
+    PseudoBR %bb.3
+
+  bb.2:
+    successors: %bb.4
+
+    %add1:gpr = ADDI %x_i, 1
+    PseudoBR %bb.4
+
+  bb.3:
+    successors: %bb.4
+
+    %add2:gpr = ADDI %x_i, 2
+    PseudoBR %bb.4
+
+  bb.4:
+    successors: %bb.1, %bb.5
+
+    %res:gpr = PHI %add1, %bb.2, %add2, %bb.3
+    SD %res, %x_i, 0
+    %i_inc:gpr = ADDI %i, 1
+    BEQ %i_inc, %n, %bb.5
+    PseudoBR %bb.1
+
+  bb.5:
+    PseudoRET
+...
+
+---
+name: bltu
+tracksRegLiveness: true
+body: |
+  ; CHECK-LABEL: name: bltu
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   liveins: $x10, $x11, $x12
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   %x:gpr = COPY $x10
+  ; CHECK-NEXT:   %n:gpr = COPY $x11
+  ; CHECK-NEXT:   %k:gpr = COPY $x12
+  ; CHECK-NEXT:   %zero:gpr = COPY $x0
+  ; CHECK-NEXT:   PseudoBR %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   successors: %bb.1, %bb.5
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   %i:gpr = PHI %zero, %bb.0, %i_inc, %bb.1
+  ; CHECK-NEXT:   %x_i_addr:gpr = ADD %x, %i
+  ; CHECK-NEXT:   %x_i:gpr = LD %x_i_addr, 0
+  ; CHECK-NEXT:   %add1:gpr = ADDI %x_i, 1
+  ; CHECK-NEXT:   %add2:gpr = ADDI %x_i, 2
+  ; CHECK-NEXT:   [[SLTU:%[0-9]+]]:gpr = SLTU %x_i, %k
+  ; CHECK-NEXT:   [[VT_MASKC:%[0-9]+]]:gpr = VT_MASKC %add1, [[SLTU]]
+  ; CHECK-NEXT:   [[VT_MASKCN:%[0-9]+]]:gpr = VT_MASKCN %add2, [[SLTU]]
+  ; CHECK-NEXT:   %res:gpr = OR [[VT_MASKC]], [[VT_MASKCN]]
+  ; CHECK-NEXT:   SD %res, %x_i, 0
+  ; CHECK-NEXT:   %i_inc:gpr = ADDI %i, 1
+  ; CHECK-NEXT:   BEQ %i_inc, %n, %bb.5
+  ; CHECK-NEXT:   PseudoBR %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.5:
+  ; CHECK-NEXT:   PseudoRET
+  bb.0:
+    successors: %bb.1
+    liveins: $x10, $x11, $x12
+
+    %x:gpr = COPY $x10
+    %n:gpr = COPY $x11
+    %k:gpr = COPY $x12
+    %zero:gpr = COPY $x0
+    PseudoBR %bb.1
+
+  bb.1:
+    successors: %bb.2, %bb.3
+
+    %i:gpr = PHI %zero, %bb.0, %i_inc, %bb.4
+    %x_i_addr:gpr = ADD %x, %i
+    %x_i:gpr = LD %x_i_addr, 0
+    BLTU %x_i, %k, %bb.2
+    PseudoBR %bb.3
+
+  bb.2:
+    successors: %bb.4
+
+    %add1:gpr = ADDI %x_i, 1
+    PseudoBR %bb.4
+
+  bb.3:
+    successors: %bb.4
+
+    %add2:gpr = ADDI %x_i, 2
+    PseudoBR %bb.4
+
+  bb.4:
+    successors: %bb.1, %bb.5
+
+    %res:gpr = PHI %add1, %bb.2, %add2, %bb.3
+    SD %res, %x_i, 0
+    %i_inc:gpr = ADDI %i, 1
+    BEQ %i_inc, %n, %bb.5
+    PseudoBR %bb.1
+
+  bb.5:
+    PseudoRET
+...
+
+---
+name: beq
+tracksRegLiveness: true
+body: |
+  ; CHECK-LABEL: name: beq
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   liveins: $x10, $x11, $x12
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   %x:gpr = COPY $x10
+  ; CHECK-NEXT:   %n:gpr = COPY $x11
+  ; CHECK-NEXT:   %k:gpr = COPY $x12
+  ; CHECK-NEXT:   %zero:gpr = COPY $x0
+  ; CHECK-NEXT:   PseudoBR %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   successors: %bb.1, %bb.5
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   %i:gpr = PHI %zero, %bb.0, %i_inc, %bb.1
+  ; CHECK-NEXT:   %x_i_addr:gpr = ADD %x, %i
+  ; CHECK-NEXT:   %x_i:gpr = LD %x_i_addr, 0
+  ; CHECK-NEXT:   %add1:gpr = ADDI %x_i, 1
+  ; CHECK-NEXT:   %add2:gpr = ADDI %x_i, 2
+  ; CHECK-NEXT:   [[XOR:%[0-9]+]]:gpr = XOR %x_i, %k
+  ; CHECK-NEXT:   [[SLTIU:%[0-9]+]]:gpr = SLTIU [[XOR]], 1
+  ; CHECK-NEXT:   [[VT_MASKC:%[0-9]+]]:gpr = VT_MASKC %add1, [[SLTIU]]
+  ; CHECK-NEXT:   [[VT_MASKCN:%[0-9]+]]:gpr = VT_MASKCN %add2, [[SLTIU]]
+  ; CHECK-NEXT:   %res:gpr = OR [[VT_MASKC]], [[VT_MASKCN]]
+  ; CHECK-NEXT:   SD %res, %x_i, 0
+  ; CHECK-NEXT:   %i_inc:gpr = ADDI %i, 1
+  ; CHECK-NEXT:   BEQ %i_inc, %n, %bb.5
+  ; CHECK-NEXT:   PseudoBR %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.5:
+  ; CHECK-NEXT:   PseudoRET
+  bb.0:
+    successors: %bb.1
+    liveins: $x10, $x11, $x12
+
+    %x:gpr = COPY $x10
+    %n:gpr = COPY $x11
+    %k:gpr = COPY $x12
+    %zero:gpr = COPY $x0
+    PseudoBR %bb.1
+
+  bb.1:
+    successors: %bb.2, %bb.3
+
+    %i:gpr = PHI %zero, %bb.0, %i_inc, %bb.4
+    %x_i_addr:gpr = ADD %x, %i
+    %x_i:gpr = LD %x_i_addr, 0
+    BEQ %x_i, %k, %bb.2
+    PseudoBR %bb.3
+
+  bb.2:
+    successors: %bb.4
+
+    %add1:gpr = ADDI %x_i, 1
+    PseudoBR %bb.4
+
+  bb.3:
+    successors: %bb.4
+
+    %add2:gpr = ADDI %x_i, 2
+    PseudoBR %bb.4
+
+  bb.4:
+    successors: %bb.1, %bb.5
+
+    %res:gpr = PHI %add1, %bb.2, %add2, %bb.3
+    SD %res, %x_i, 0
+    %i_inc:gpr = ADDI %i, 1
+    BEQ %i_inc, %n, %bb.5
+    PseudoBR %bb.1
+
+  bb.5:
+    PseudoRET
+...
+
+---
+name: bne
+tracksRegLiveness: true
+body: |
+  ; CHECK-LABEL: name: bne
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   liveins: $x10, $x11, $x12
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   %x:gpr = COPY $x10
+  ; CHECK-NEXT:   %n:gpr = COPY $x11
+  ; CHECK-NEXT:   %k:gpr = COPY $x12
+  ; CHECK-NEXT:   %zero:gpr = COPY $x0
+  ; CHECK-NEXT:   PseudoBR %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   successors: %bb.1, %bb.5
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   %i:gpr = PHI %zero, %bb.0, %i_inc, %bb.1
+  ; CHECK-NEXT:   %x_i_addr:gpr = ADD %x, %i
+  ; CHECK-NEXT:   %x_i:gpr = LD %x_i_addr, 0
+  ; CHECK-NEXT:   %add1:gpr = ADDI %x_i, 1
+  ; CHECK-NEXT:   %add2:gpr = ADDI %x_i, 2
+  ; CHECK-NEXT:   [[XOR:%[0-9]+]]:gpr = XOR %x_i, %k
+  ; CHECK-NEXT:   [[SLTU:%[0-9]+]]:gpr = SLTU $x0, [[XOR]]
+  ; CHECK-NEXT:   [[VT_MASKC:%[0-9]+]]:gpr = VT_MASKC %add1, [[SLTU]]
+  ; CHECK-NEXT:   ...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/92959


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