[LoongArch] Support lowering frames larger than 2048 bytes

[SixWeining]

Had better to add some tests.

llvm/lib/Target/LoongArch/LoongArchRegisterInfo.cpp

138

[xen0n]

llvm/lib/Target/LoongArch/LoongArchRegisterInfo.cpp

138

No it's two sentences so the suggestion is wrong.

I'll add the trailing periods though (obviously the current expression can be interpreted ambiguously by non-native speakers judging from this). Thanks for the catch!

[SixWeining]

llvm/lib/Target/LoongArch/LoongArchRegisterInfo.cpp

138

Oh, my bad :) Thanks.

[xen0n]

cosmetic fixes and testcase addition

[SixWeining]

llvm/test/CodeGen/LoongArch/frame.ll

34–56

How about this IR which is simpler:

define void @test_large_frame_size_2032() {
; CHECK-LABEL: test_large_frame_size_2032:
; CHECK:       # %bb.0:
; CHECK-NEXT:    addi.d $sp, $sp, -2032
; CHECK-NEXT:    .cfi_def_cfa_offset 2032
; CHECK-NEXT:    addi.d $sp, $sp, 2032
; CHECK-NEXT:    ret
  %1 = alloca i8, i32 2032
  ret void
}

[xen0n]

simplify the test cases

[xen0n]

llvm/test/CodeGen/LoongArch/frame.ll

34–56

Thanks for the suggestion; I adapted CodeGen/Generic/2010-11-04-BigByval.ll which also happened to expose the suboptimal codegen. Your version is simpler and focuses solely on the frame size handling, which I'll take. Thanks.

[SixWeining]

LGTM. Thanks. Others may also have a look.

llvm/test/CodeGen/LoongArch/frame.ll

34–56

Thanks for the quick update. :)

[SixWeining]

Sorry. Forget to leave a LGTM.

llvm/lib/Target/LoongArch/LoongArchFrameLowering.cpp

 
 void LoongArchFrameLowering::adjustReg(MachineBasicBlock &MBB,
                                        MachineBasicBlock::iterator MBBI,
                                        const DebugLoc &DL, Register DestReg,
                                        Register SrcReg, int64_t Val,
                                        MachineInstr::MIFlag Flag) const {
   const LoongArchInstrInfo *TII = STI.getInstrInfo();
   bool IsLA64 = STI.is64Bit();
+  unsigned Addi = IsLA64 ? LoongArch::ADDI_D : LoongArch::ADDI_W;
 
   if (DestReg == SrcReg && Val == 0)
     return;
 
   if (isInt<12>(Val)) {
     // addi.w/d $DstReg, $SrcReg, Val
-    BuildMI(MBB, MBBI, DL,
-            TII->get(IsLA64 ? LoongArch::ADDI_D : LoongArch::ADDI_W), DestReg)
+    BuildMI(MBB, MBBI, DL, TII->get(Addi), DestReg)
         .addReg(SrcReg)
         .addImm(Val)
         .setMIFlag(Flag);
     return;
   }
 
-  report_fatal_error("adjustReg cannot yet handle adjustments >12 bits");
+  // Try to split the offset across two ADDIs. We need to keep the stack pointer
+  // aligned after each ADDI. We need to determine the maximum value we can put
+  // in each ADDI. In the negative direction, we can use -2048 which is always
+  // sufficiently aligned. In the positive direction, we need to find the
+  // largest 12-bit immediate that is aligned. Exclude -4096 since it can be
+  // created with LU12I.W.
+  assert(getStackAlign().value() < 2048 && "Stack alignment too large");
+  int64_t MaxPosAdjStep = 2048 - getStackAlign().value();
+  if (Val > -4096 && Val <= (2 * MaxPosAdjStep)) {
+    int64_t FirstAdj = Val < 0 ? -2048 : MaxPosAdjStep;
+    Val -= FirstAdj;
+    BuildMI(MBB, MBBI, DL, TII->get(Addi), DestReg)
+        .addReg(SrcReg)
+        .addImm(FirstAdj)
+        .setMIFlag(Flag);
+    BuildMI(MBB, MBBI, DL, TII->get(Addi), DestReg)
+        .addReg(DestReg, RegState::Kill)
+        .addImm(Val)
+        .setMIFlag(Flag);
+    return;
+  }
+
+  unsigned Opc = IsLA64 ? LoongArch::ADD_D : LoongArch::ADD_W;
+  if (Val < 0) {
+    Val = -Val;
+    Opc = IsLA64 ? LoongArch::SUB_D : LoongArch::SUB_W;
+  }
+
+  MachineRegisterInfo &MRI = MBB.getParent()->getRegInfo();
+  Register ScratchReg = MRI.createVirtualRegister(&LoongArch::GPRRegClass);
+  TII->movImm(MBB, MBBI, DL, ScratchReg, Val, Flag);
+  BuildMI(MBB, MBBI, DL, TII->get(Opc), DestReg)
+      .addReg(SrcReg)
+      .addReg(ScratchReg, RegState::Kill)
+      .setMIFlag(Flag);
 }
 
 // Determine the size of the frame and maximum call frame size.
 void LoongArchFrameLowering::determineFrameLayout(MachineFunction &MF) const {
   MachineFrameInfo &MFI = MF.getFrameInfo();
 
   // Get the number of bytes to allocate from the FrameInfo.
   uint64_t FrameSize = MFI.getStackSize();

llvm/lib/Target/LoongArch/LoongArchInstrInfo.h

void storeRegToStackSlot(MachineBasicBlock &MBB,
                            bool IsKill, int FrameIndex,
                            const TargetRegisterClass *RC,
                            const TargetRegisterInfo *TRI) const override;
   void loadRegFromStackSlot(MachineBasicBlock &MBB,
                             MachineBasicBlock::iterator MBBI, Register DstReg,
                             int FrameIndex, const TargetRegisterClass *RC,
                             const TargetRegisterInfo *TRI) const override;
 
+  // Materializes the given integer Val into DstReg.
+  void movImm(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
+              const DebugLoc &DL, Register DstReg, uint64_t Val,
+              MachineInstr::MIFlag Flag = MachineInstr::NoFlags) const;
+
   unsigned getInstSizeInBytes(const MachineInstr &MI) const override;
 
   MachineBasicBlock *getBranchDestBlock(const MachineInstr &MI) const override;
 
   bool analyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                      MachineBasicBlock *&FBB,
                      SmallVectorImpl<MachineOperand> &Cond,
                      bool AllowModify) const override;
 
   unsigned removeBranch(MachineBasicBlock &MBB,
                         int *BytesRemoved = nullptr) const override;
 
   unsigned insertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
                         MachineBasicBlock *FBB, ArrayRef<MachineOperand> Cond,
                         const DebugLoc &dl,
                         int *BytesAdded = nullptr) const override;
 
   bool
   reverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const override;
+
+protected:
+  const LoongArchSubtarget &STI;
 };
 
 } // end namespace llvm
 #endif // LLVM_LIB_TARGET_LOONGARCH_LOONGARCHINSTRINFO_H

llvm/lib/Target/LoongArch/LoongArchInstrInfo.cpp

 //=- LoongArchInstrInfo.cpp - LoongArch Instruction Information -*- 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
 //
 //===----------------------------------------------------------------------===//
 //
 // This file contains the LoongArch implementation of the TargetInstrInfo class.
 //
 //===----------------------------------------------------------------------===//
 
 #include "LoongArchInstrInfo.h"
 #include "LoongArch.h"
 #include "LoongArchMachineFunctionInfo.h"
+#include "MCTargetDesc/LoongArchMatInt.h"
 
 using namespace llvm;
 
 #define GET_INSTRINFO_CTOR_DTOR
 #include "LoongArchGenInstrInfo.inc"
 
 LoongArchInstrInfo::LoongArchInstrInfo(LoongArchSubtarget &STI)
     : LoongArchGenInstrInfo(LoongArch::ADJCALLSTACKDOWN,
-                            LoongArch::ADJCALLSTACKUP) {}
+                            LoongArch::ADJCALLSTACKUP),
+      STI(STI) {}
 
 void LoongArchInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
                                      MachineBasicBlock::iterator MBBI,
                                      const DebugLoc &DL, MCRegister DstReg,
                                      MCRegister SrcReg, bool KillSrc) const {
   if (LoongArch::GPRRegClass.contains(DstReg, SrcReg)) {
     BuildMI(MBB, MBBI, DL, get(LoongArch::OR), DstReg)
         .addReg(SrcReg, getKillRegState(KillSrc))
MachineMemOperand *MMO = MF->getMachineMemOperand(
       MFI.getObjectSize(FI), MFI.getObjectAlign(FI));
 
   BuildMI(MBB, I, DL, get(Opcode), DstReg)
       .addFrameIndex(FI)
       .addImm(0)
       .addMemOperand(MMO);
 }
 
+void LoongArchInstrInfo::movImm(MachineBasicBlock &MBB,
+                                MachineBasicBlock::iterator MBBI,
+                                const DebugLoc &DL, Register DstReg,
+                                uint64_t Val, MachineInstr::MIFlag Flag) const {
+  Register SrcReg = LoongArch::R0;
+
+  if (!STI.is64Bit() && !isInt<32>(Val))
+    report_fatal_error("Should only materialize 32-bit constants for LA32");
+
+  auto Seq = LoongArchMatInt::generateInstSeq(Val);
+  assert(!Seq.empty());
+
+  for (auto &Inst : Seq) {
+    switch (Inst.Opc) {
+    case LoongArch::LU12I_W:
+      BuildMI(MBB, MBBI, DL, get(Inst.Opc), DstReg)
+          .addImm(Inst.Imm)
+          .setMIFlag(Flag);
+      break;
+    case LoongArch::ADDI_W:
+    case LoongArch::ORI:
+    case LoongArch::LU32I_D: // "rj" is needed due to InstrInfo pattern
+    case LoongArch::LU52I_D:
+      BuildMI(MBB, MBBI, DL, get(Inst.Opc), DstReg)
+          .addReg(SrcReg, RegState::Kill)
+          .addImm(Inst.Imm)
+          .setMIFlag(Flag);
+      break;
+    default:
+      assert(false && "Unknown insn emitted by LoongArchMatInt");
+    }
+
+    // Only the first instruction has $zero as its source.
+    SrcReg = DstReg;
+  }
+}
+
 unsigned LoongArchInstrInfo::getInstSizeInBytes(const MachineInstr &MI) const {
   return MI.getDesc().getSize();
 }
 
 MachineBasicBlock *
 LoongArchInstrInfo::getBranchDestBlock(const MachineInstr &MI) const {
   assert(MI.getDesc().isBranch() && "Unexpected opcode!");
   // The branch target is always the last operand.

llvm/lib/Target/LoongArch/LoongArchRegisterInfo.h

getPointerRegClass(const MachineFunction &MF,
     return &LoongArch::GPRRegClass;
   }
 
   void eliminateFrameIndex(MachineBasicBlock::iterator MI, int SPAdj,
                            unsigned FIOperandNum,
                            RegScavenger *RS = nullptr) const override;
 
   Register getFrameRegister(const MachineFunction &MF) const override;
+
+  bool requiresRegisterScavenging(const MachineFunction &MF) const override {
+    return true;
+  }
+
+  bool requiresFrameIndexScavenging(const MachineFunction &MF) const override {
+    return true;
+  }
 };
 } // end namespace llvm
 
 #endif // LLVM_LIB_TARGET_LOONGARCH_LOONGARCHREGISTERINFO_H

llvm/lib/Target/LoongArch/LoongArchRegisterInfo.cpp

 //===- LoongArchRegisterInfo.cpp - LoongArch Register Information -*- 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
 //
 //===----------------------------------------------------------------------===//
 //
 // This file contains the LoongArch implementation of the TargetRegisterInfo
 // class.
 //
 //===----------------------------------------------------------------------===//
 
 #include "LoongArchRegisterInfo.h"
 #include "LoongArch.h"
+#include "LoongArchInstrInfo.h"
 #include "LoongArchSubtarget.h"
+#include "MCTargetDesc/LoongArchMCTargetDesc.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/RegisterScavenging.h"
 #include "llvm/CodeGen/TargetFrameLowering.h"
 #include "llvm/CodeGen/TargetInstrInfo.h"
 #include "llvm/Support/ErrorHandling.h"
 
void LoongArchRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
                                                 unsigned FIOperandNum,
                                                 RegScavenger *RS) const {
   // TODO: this implementation is a temporary placeholder which does just
   // enough to allow other aspects of code generation to be tested.
 
   assert(SPAdj == 0 && "Unexpected non-zero SPAdj value");
 
   MachineInstr &MI = *II;
+  MachineBasicBlock &MBB = *MI.getParent();
   MachineFunction &MF = *MI.getParent()->getParent();
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+  const LoongArchSubtarget &STI = MF.getSubtarget<LoongArchSubtarget>();
+  const LoongArchInstrInfo *TII = STI.getInstrInfo();
   const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
   DebugLoc DL = MI.getDebugLoc();
 
   int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
   Register FrameReg;
   StackOffset Offset =
       TFI->getFrameIndexReference(MF, FrameIndex, FrameReg) +
       StackOffset::getFixed(MI.getOperand(FIOperandNum + 1).getImm());
 
-  // Offsets must be encodable with a 12-bit immediate field.
+  bool FrameRegIsKill = false;
+
   if (!isInt<12>(Offset.getFixed())) {
-    report_fatal_error("Frame offsets outside of the signed 12-bit range is "
-                       "not supported currently");
+    unsigned Addi = STI.is64Bit() ? LoongArch::ADDI_D : LoongArch::ADDI_W;
+    unsigned Add = STI.is64Bit() ? LoongArch::ADD_D : LoongArch::ADD_W;
+
+    // The offset won't fit in an immediate, so use a scratch register instead.
+    // Modify Offset and FrameReg appropriately.
+    Register ScratchReg = MRI.createVirtualRegister(&LoongArch::GPRRegClass);
+    TII->movImm(MBB, II, DL, ScratchReg, Offset.getFixed());
+    if (MI.getOpcode() == Addi) {
+      BuildMI(MBB, II, DL, TII->get(Add), MI.getOperand(0).getReg())
+          .addReg(FrameReg)
+          .addReg(ScratchReg, RegState::Kill);
+      MI.eraseFromParent();
+      return;
+    }
+    BuildMI(MBB, II, DL, TII->get(Add), ScratchReg)
+        .addReg(FrameReg)
+        .addReg(ScratchReg, RegState::Kill);
+    Offset = StackOffset::getFixed(0);
+    FrameReg = ScratchReg;
+    FrameRegIsKill = true;
   }
 
-  MI.getOperand(FIOperandNum).ChangeToRegister(FrameReg, false);
+  MI.getOperand(FIOperandNum)
+      .ChangeToRegister(FrameReg, false, false, FrameRegIsKill);
   MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset.getFixed());
 }

llvm/test/CodeGen/LoongArch/frame.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc --mtriple=loongarch64 < %s | FileCheck %s
 
 %struct.key_t = type { i32, [16 x i8] }
 
+declare void @llvm.memset.p0i8.i64(ptr, i8, i64, i1)
+declare void @test1(ptr)
+
 define i32 @test() nounwind {
 ; CHECK-LABEL: test:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    addi.d $sp, $sp, -32
 ; CHECK-NEXT:    st.d $ra, $sp, 24 # 8-byte Folded Spill
 ; CHECK-NEXT:    st.w $zero, $sp, 16
 ; CHECK-NEXT:    st.d $zero, $sp, 8
 ; CHECK-NEXT:    st.d $zero, $sp, 0
 ; CHECK-NEXT:    addi.d $a0, $sp, 4
 ; CHECK-NEXT:    bl %plt(test1)
 ; CHECK-NEXT:    move $a0, $zero
 ; CHECK-NEXT:    ld.d $ra, $sp, 24 # 8-byte Folded Reload
 ; CHECK-NEXT:    addi.d $sp, $sp, 32
 ; CHECK-NEXT:    ret
   %key = alloca %struct.key_t, align 4
   call void @llvm.memset.p0i8.i64(ptr %key, i8 0, i64 20, i1 false)
   %1 = getelementptr inbounds %struct.key_t, ptr %key, i64 0, i32 1, i64 0
   call void @test1(ptr %1)
   ret i32 0
 }
 
-declare void @llvm.memset.p0i8.i64(ptr, i8, i64, i1)
+;; Should involve only one SP-adjusting addi per adjustment.
+define void @test_large_frame_size_2032() {
+; CHECK-LABEL: test_large_frame_size_2032:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addi.d $sp, $sp, -2032
+; CHECK-NEXT:    .cfi_def_cfa_offset 2032
+; CHECK-NEXT:    addi.d $sp, $sp, 2032
+; CHECK-NEXT:    ret
+  %1 = alloca i8, i32 2032
+  ret void
+}
 
-declare void @test1(ptr)
+;; Should involve two SP-adjusting addi's when adjusting SP up, but only one
+;; when adjusting down.
+define void @test_large_frame_size_2048() {
+; CHECK-LABEL: test_large_frame_size_2048:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addi.d $sp, $sp, -2048
+; CHECK-NEXT:    .cfi_def_cfa_offset 2048
+; CHECK-NEXT:    addi.d $sp, $sp, 2032
+; CHECK-NEXT:    addi.d $sp, $sp, 16
+; CHECK-NEXT:    ret
+  %1 = alloca i8, i32 2048
+  ret void
+}
+
+;; Should involve two SP-adjusting addi's per adjustment.
+define void @test_large_frame_size_2064() {
+; CHECK-LABEL: test_large_frame_size_2064:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    addi.d $sp, $sp, -2048
+; CHECK-NEXT:    addi.d $sp, $sp, -16
+; CHECK-NEXT:    .cfi_def_cfa_offset 2064
+; CHECK-NEXT:    addi.d $sp, $sp, 2032
+; CHECK-NEXT:    addi.d $sp, $sp, 32
+; CHECK-NEXT:    ret
+  %1 = alloca i8, i32 2064
+  ret void
+}
+
+;; SP should be adjusted with help of a scratch register.
+define void @test_large_frame_size_1234576() {
+; CHECK-LABEL: test_large_frame_size_1234576:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    lu12i.w $a0, 301
+; CHECK-NEXT:    ori $a0, $a0, 1680
+; CHECK-NEXT:    sub.d $sp, $sp, $a0
+; CHECK-NEXT:    .cfi_def_cfa_offset 1234576
+; CHECK-NEXT:    lu12i.w $a0, 301
+; CHECK-NEXT:    ori $a0, $a0, 1680
+; CHECK-NEXT:    add.d $sp, $sp, $a0
+; CHECK-NEXT:    ret
+  %1 = alloca i8, i32 1234567
+  ret void
+}