[llvm] d84ca05 - Enhance peephole optimization.

Philip Reames via llvm-commits llvm-commits at lists.llvm.org
Tue May 10 13:55:34 PDT 2022


Thanks!

Philip

On 5/10/22 13:45, Mingming Liu wrote:
> Okay, working on it. Will update when it's complete.
>
> On Tue, May 10, 2022 at 1:43 PM Philip Reames 
> <listmail at philipreames.com> wrote:
>
>     Revert and recommit please.  The commit comment needs to contain
>     the information, not just the phab review.
>
>     Philip
>
>     On 5/10/22 13:27, Mingming Liu wrote:
>>     Hello Philip!
>>        A differential revision is attached in the commit message, and
>>     has more context of the commit.
>>
>>        Shall I just use differential revision or still revert and
>>     re-commit?
>>
>>     On Tue, May 10, 2022 at 1:17 PM Philip Reames
>>     <listmail at philipreames.com> wrote:
>>
>>         Please revert and reapply with a descriptive commit message.
>>
>>         Philip
>>
>>         On 5/10/22 12:39, Mingming Liu via llvm-commits wrote:
>>         > Author: Mingming Liu
>>         > Date: 2022-05-10T12:35:35-07:00
>>         > New Revision: d84ca05ef7f897fdd51900ea07e3c5344632130a
>>         >
>>         > URL:
>>         https://github.com/llvm/llvm-project/commit/d84ca05ef7f897fdd51900ea07e3c5344632130a
>>         > DIFF:
>>         https://github.com/llvm/llvm-project/commit/d84ca05ef7f897fdd51900ea07e3c5344632130a.diff
>>         >
>>         > LOG: Enhance peephole optimization.
>>         >
>>         > Differential Revision: https://reviews.llvm.org/D124118
>>         >
>>         > Added:
>>         > llvm/test/CodeGen/X86/peephole-test-after-add.mir
>>         >
>>         > Modified:
>>         >      llvm/lib/Target/X86/X86InstrInfo.cpp
>>         >
>>         > Removed:
>>         >
>>         >
>>         >
>>         >
>>         ################################################################################
>>         > diff  --git a/llvm/lib/Target/X86/X86InstrInfo.cpp
>>         b/llvm/lib/Target/X86/X86InstrInfo.cpp
>>         > index 0c45094b6e2f6..f4ffb42d9972d 100644
>>         > --- a/llvm/lib/Target/X86/X86InstrInfo.cpp
>>         > +++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
>>         > @@ -25,13 +25,16 @@
>>         >   #include "llvm/CodeGen/MachineConstantPool.h"
>>         >   #include "llvm/CodeGen/MachineDominators.h"
>>         >   #include "llvm/CodeGen/MachineFrameInfo.h"
>>         > +#include "llvm/CodeGen/MachineInstr.h"
>>         >   #include "llvm/CodeGen/MachineInstrBuilder.h"
>>         >   #include "llvm/CodeGen/MachineModuleInfo.h"
>>         > +#include "llvm/CodeGen/MachineOperand.h"
>>         >   #include "llvm/CodeGen/MachineRegisterInfo.h"
>>         >   #include "llvm/CodeGen/StackMaps.h"
>>         >   #include "llvm/IR/DebugInfoMetadata.h"
>>         >   #include "llvm/IR/DerivedTypes.h"
>>         >   #include "llvm/IR/Function.h"
>>         > +#include "llvm/IR/InstrTypes.h"
>>         >   #include "llvm/MC/MCAsmInfo.h"
>>         >   #include "llvm/MC/MCExpr.h"
>>         >   #include "llvm/MC/MCInst.h"
>>         > @@ -964,6 +967,101 @@ inline static bool
>>         isTruncatedShiftCountForLEA(unsigned ShAmt) {
>>         >     return ShAmt < 4 && ShAmt > 0;
>>         >   }
>>         >
>>         > +static bool findRedundantFlagInstr(MachineInstr &CmpInstr,
>>         > +                                   MachineInstr
>>         &CmpValDefInstr,
>>         > +                                   const
>>         MachineRegisterInfo *MRI,
>>         > +                                   MachineInstr **AndInstr,
>>         > +                                   const
>>         TargetRegisterInfo *TRI,
>>         > +                                   bool &NoSignFlag, bool
>>         &ClearsOverflowFlag) {
>>         > +  if (CmpValDefInstr.getOpcode() != X86::SUBREG_TO_REG)
>>         > +    return false;
>>         > +
>>         > +  if (CmpInstr.getOpcode() != X86::TEST64rr)
>>         > +    return false;
>>         > +
>>         > +  // CmpInstr is a TEST64rr instruction, and
>>         `X86InstrInfo::analyzeCompare`
>>         > +  // guarantees that it's analyzable only if two registers
>>         are identical.
>>         > +  assert(
>>         > +      (CmpInstr.getOperand(0).getReg() ==
>>         CmpInstr.getOperand(1).getReg()) &&
>>         > +      "CmpInstr is an analyzable TEST64rr, and
>>         `X86InstrInfo::analyzeCompare` "
>>         > +      "requires two reg operands are the same.");
>>         > +
>>         > +  // Caller (`X86InstrInfo::optimizeCompareInstr`)
>>         guarantees that
>>         > +  // `CmpValDefInstr` defines the value that's used by
>>         `CmpInstr`; in this case
>>         > +  // if `CmpValDefInstr` sets the EFLAGS, it is likely
>>         that `CmpInstr` is
>>         > +  // redundant.
>>         > +  assert(
>>         > + (MRI->getVRegDef(CmpInstr.getOperand(0).getReg()) ==
>>         &CmpValDefInstr) &&
>>         > +      "Caller guarantees that TEST64rr is a user of
>>         SUBREG_TO_REG.");
>>         > +
>>         > +  // As seen in X86 td files,
>>         CmpValDefInstr.getOperand(1).getImm() is typically
>>         > +  // 0.
>>         > +  if (CmpValDefInstr.getOperand(1).getImm() != 0)
>>         > +    return false;
>>         > +
>>         > +  // As seen in X86 td files, CmpValDefInstr.getOperand(3)
>>         is typically
>>         > +  // sub_32bit or sub_xmm.
>>         > +  if (CmpValDefInstr.getOperand(3).getImm() != X86::sub_32bit)
>>         > +    return false;
>>         > +
>>         > +  MachineInstr *VregDefInstr =
>>         > + MRI->getVRegDef(CmpValDefInstr.getOperand(2).getReg());
>>         > +
>>         > +  assert(VregDefInstr && "Must have a definition (SSA)");
>>         > +
>>         > +  // Requires `CmpValDefInstr` and `VregDefInstr` are from
>>         the same MBB
>>         > +  // to simplify the subsequent analysis.
>>         > +  //
>>         > +  // FIXME: If `VregDefInstr->getParent()` is the only
>>         predecessor of
>>         > +  // `CmpValDefInstr.getParent()`, this could be handled.
>>         > +  if (VregDefInstr->getParent() != CmpValDefInstr.getParent())
>>         > +    return false;
>>         > +
>>         > +  if (X86::isAND(VregDefInstr->getOpcode())) {
>>         > +    // Get a sequence of instructions like
>>         > +    //   %reg = and* ...                    // Set EFLAGS
>>         > +    //   ...                                // EFLAGS not
>>         changed
>>         > +    //   %extended_reg = subreg_to_reg 0, %reg,
>>         %subreg.sub_32bit
>>         > +    //   test64rr %extended_reg, %extended_reg,
>>         implicit-def $eflags
>>         > +    //
>>         > +    // If subsequent readers use a subset of bits that
>>         don't change
>>         > +    // after `and*` instructions, it's likely that the
>>         test64rr could
>>         > +    // be optimized away.
>>         > +    for (const MachineInstr &Instr :
>>         > +
>>          make_range(std::next(MachineBasicBlock::iterator(VregDefInstr)),
>>         > + MachineBasicBlock::iterator(CmpValDefInstr))) {
>>         > +      // There are instructions between 'VregDefInstr' and
>>         > +      // 'CmpValDefInstr' that modifies EFLAGS.
>>         > +      if (Instr.modifiesRegister(X86::EFLAGS, TRI))
>>         > +        return false;
>>         > +    }
>>         > +
>>         > +    *AndInstr = VregDefInstr;
>>         > +
>>         > +    // AND instruction will essentially update SF and
>>         clear OF, so
>>         > +    // NoSignFlag should be false in the sense that SF is
>>         modified by `AND`.
>>         > +    //
>>         > +    // However, the implementation artifically sets
>>         `NoSignFlag` to true
>>         > +    // to poison the SF bit; that is to say, if SF is
>>         looked at later, the
>>         > +    // optimization (to erase TEST64rr) will be disabled.
>>         > +    //
>>         > +    // The reason to poison SF bit is that SF bit value
>>         could be
>>         > diff erent
>>         > +    // in the `AND` and `TEST` operation; signed bit is
>>         not known for `AND`,
>>         > +    // and is known to be 0 as a result of `TEST64rr`.
>>         > +    //
>>         > +    // FIXME: As opposed to poisoning the SF bit direclty,
>>         consider peeking into
>>         > +    // the AND instruction and using the static
>>         information to guide peephole optimization if possible.
>>         > +    // For example, it's possible to fold a conditional
>>         move into a copy
>>         > +    // if the relevant EFLAG bits could be deduced from an
>>         immediate operand of and operation.
>>         > +    //
>>         > +    NoSignFlag = true;
>>         > +    // ClearsOverflowFlag is true for AND operation (no
>>         surprise).
>>         > +    ClearsOverflowFlag = true;
>>         > +    return true;
>>         > +  }
>>         > +  return false;
>>         > +}
>>         > +
>>         >   bool X86InstrInfo::classifyLEAReg(MachineInstr &MI, const
>>         MachineOperand &Src,
>>         >                                     unsigned Opc, bool
>>         AllowSP, Register &NewSrc,
>>         >                                     bool &isKill,
>>         MachineOperand &ImplicitOp,
>>         > @@ -4226,6 +4324,23 @@ bool
>>         X86InstrInfo::optimizeCompareInstr(MachineInstr &CmpInstr,
>>         Register SrcReg,
>>         >             MI = &Inst;
>>         >             break;
>>         >           }
>>         > +
>>         > +        // Look back for the following pattern, in which
>>         case the test64rr
>>         > +        // instruction could be erased.
>>         > +        //
>>         > +        // Example:
>>         > +        //  %reg = and32ri %in_reg, 5
>>         > +        //  ...                         // EFLAGS not changed.
>>         > +        //  %src_reg = subreg_to_reg 0, %reg,
>>         %subreg.sub_index
>>         > +        //  test64rr %src_reg, %src_reg, implicit-def $eflags
>>         > +        MachineInstr *AndInstr = nullptr;
>>         > +        if (IsCmpZero &&
>>         > +            findRedundantFlagInstr(CmpInstr, Inst, MRI,
>>         &AndInstr, TRI,
>>         > +                                   NoSignFlag,
>>         ClearsOverflowFlag)) {
>>         > +          assert(AndInstr != nullptr &&
>>         X86::isAND(AndInstr->getOpcode()));
>>         > +          MI = AndInstr;
>>         > +          break;
>>         > +        }
>>         >           // Cannot find other candidates before definition
>>         of SrcReg.
>>         >           return false;
>>         >         }
>>         >
>>         > diff  --git
>>         a/llvm/test/CodeGen/X86/peephole-test-after-add.mir
>>         b/llvm/test/CodeGen/X86/peephole-test-after-add.mir
>>         > new file mode 100644
>>         > index 0000000000000..65a90fafa655c
>>         > --- /dev/null
>>         > +++ b/llvm/test/CodeGen/X86/peephole-test-after-add.mir
>>         > @@ -0,0 +1,196 @@
>>         > +# NOTE: Assertions have been autogenerated by
>>         utils/update_mir_test_checks.py
>>         > +# RUN: llc -o - %s -mtriple=x86_64-unknown-linux-gnu
>>         --run-pass=peephole-opt | FileCheck %s
>>         > +
>>         > +# Test that TEST64rr is erased in `test_erased`, and kept
>>         in `test_not_erased_when_sf_used`
>>         > +# and `test_not_erased_when_eflags_change`.
>>         > +
>>         > +--- |
>>         > +  ; ModuleID = 'tmp.ll'
>>         > +  source_filename = "tmp.ll"
>>         > +  target datalayout =
>>         "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
>>         > +
>>         > +  define i64 @test_erased(ptr %0, i64 %1, i64 %2) {
>>         > +    %4 = load i64, ptr %0, align 8
>>         > +    %5 = and i64 %4, 3
>>         > +    %6 = icmp eq i64 %5, 0
>>         > +    %7 = select i1 %6, i64 %1, i64 %5
>>         > +    store i64 %7, ptr %0, align 8
>>         > +    ret i64 %5
>>         > +  }
>>         > +
>>         > +  define i64 @test_not_erased_when_sf_used(ptr %0, i64 %1,
>>         i64 %2, i64 %3) {
>>         > +    %5 = load i64, ptr %0, align 8
>>         > +    %6 = and i64 %5, 3
>>         > +    %7 = icmp slt i64 %6, 0
>>         > +    %8 = select i1 %7, i64 %1, i64 %6
>>         > +    store i64 %8, ptr %0, align 8
>>         > +    ret i64 %5
>>         > +  }
>>         > +
>>         > +  define void @test_not_erased_when_eflags_change(ptr %0,
>>         i64 %1, i64 %2, i64 %3, ptr %4) {
>>         > +    %6 = load i64, ptr %0, align 8
>>         > +    %7 = and i64 %6, 3
>>         > +    %8 = xor i64 %3, 5
>>         > +    %9 = icmp eq i64 %7, 0
>>         > +    %10 = select i1 %9, i64 %1, i64 %7
>>         > +    store i64 %10, ptr %0, align 8
>>         > +    store i64 %8, ptr %4, align 8
>>         > +    ret void
>>         > +  }
>>         > +
>>         > +...
>>         > +---
>>         > +name:            test_erased
>>         > +alignment:       16
>>         > +tracksDebugUserValues: false
>>         > +registers:
>>         > +  - { id: 0, class: gr64, preferred-register: '' }
>>         > +  - { id: 1, class: gr64, preferred-register: '' }
>>         > +  - { id: 2, class: gr64, preferred-register: '' }
>>         > +  - { id: 3, class: gr64, preferred-register: '' }
>>         > +  - { id: 4, class: gr32, preferred-register: '' }
>>         > +  - { id: 5, class: gr32, preferred-register: '' }
>>         > +  - { id: 6, class: gr64, preferred-register: '' }
>>         > +  - { id: 7, class: gr64, preferred-register: '' }
>>         > +liveins:
>>         > +  - { reg: '$rdi', virtual-reg: '%0' }
>>         > +  - { reg: '$rsi', virtual-reg: '%1' }
>>         > +frameInfo:
>>         > +  maxAlignment:    1
>>         > +machineFunctionInfo: {}
>>         > +body:             |
>>         > +  bb.0 (%ir-block.3):
>>         > +    liveins: $rdi, $rsi
>>         > +
>>         > +    ; CHECK-LABEL: name: test_erased
>>         > +    ; CHECK: [[COPY:%[0-9]+]]:gr64 = COPY $rsi
>>         > +    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gr64 = COPY $rdi
>>         > +    ; CHECK-NEXT: [[MOV64rm:%[0-9]+]]:gr64 = MOV64rm
>>         [[COPY1]], 1, $noreg, 0, $noreg :: (load (s64) from %ir.0)
>>         > +    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gr32 = COPY
>>         [[MOV64rm]].sub_32bit
>>         > +    ; CHECK-NEXT: [[AND32ri8_:%[0-9]+]]:gr32 = AND32ri8
>>         [[COPY2]], 3, implicit-def $eflags
>>         > +    ; CHECK-NEXT: [[SUBREG_TO_REG:%[0-9]+]]:gr64 =
>>         SUBREG_TO_REG 0, killed [[AND32ri8_]], %subreg.sub_32bit
>>         > +    ; CHECK-NEXT: [[CMOV64rr:%[0-9]+]]:gr64 = CMOV64rr
>>         [[SUBREG_TO_REG]], [[COPY]], 4, implicit $eflags
>>         > +    ; CHECK-NEXT: MOV64mr [[COPY1]], 1, $noreg, 0, $noreg,
>>         killed [[CMOV64rr]] :: (store (s64) into %ir.0)
>>         > +    ; CHECK-NEXT: $rax = COPY [[SUBREG_TO_REG]]
>>         > +    ; CHECK-NEXT: RET 0, $rax
>>         > +    %1:gr64 = COPY $rsi
>>         > +    %0:gr64 = COPY $rdi
>>         > +    %3:gr64 = MOV64rm %0, 1, $noreg, 0, $noreg :: (load
>>         (s64) from %ir.0)
>>         > +    %4:gr32 = COPY %3.sub_32bit
>>         > +    %5:gr32 = AND32ri8 %4, 3, implicit-def dead $eflags
>>         > +    %6:gr64 = SUBREG_TO_REG 0, killed %5, %subreg.sub_32bit
>>         > +    TEST64rr %6, %6, implicit-def $eflags
>>         > +    %7:gr64 = CMOV64rr %6, %1, 4, implicit $eflags
>>         > +    MOV64mr %0, 1, $noreg, 0, $noreg, killed %7 :: (store
>>         (s64) into %ir.0)
>>         > +    $rax = COPY %6
>>         > +    RET 0, $rax
>>         > +
>>         > +...
>>         > +---
>>         > +name:            test_not_erased_when_sf_used
>>         > +alignment:       16
>>         > +tracksDebugUserValues: false
>>         > +registers:
>>         > +  - { id: 0, class: gr64, preferred-register: '' }
>>         > +  - { id: 1, class: gr64, preferred-register: '' }
>>         > +  - { id: 2, class: gr64, preferred-register: '' }
>>         > +  - { id: 3, class: gr64, preferred-register: '' }
>>         > +  - { id: 4, class: gr64, preferred-register: '' }
>>         > +  - { id: 5, class: gr32, preferred-register: '' }
>>         > +  - { id: 6, class: gr32, preferred-register: '' }
>>         > +  - { id: 7, class: gr64, preferred-register: '' }
>>         > +  - { id: 8, class: gr64, preferred-register: '' }
>>         > +liveins:
>>         > +  - { reg: '$rdi', virtual-reg: '%0' }
>>         > +  - { reg: '$rsi', virtual-reg: '%1' }
>>         > +frameInfo:
>>         > +  maxAlignment:    1
>>         > +machineFunctionInfo: {}
>>         > +body:             |
>>         > +  bb.0 (%ir-block.4):
>>         > +    liveins: $rdi, $rsi
>>         > +
>>         > +    ; CHECK-LABEL: name: test_not_erased_when_sf_used
>>         > +    ; CHECK: [[COPY:%[0-9]+]]:gr64 = COPY $rsi
>>         > +    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gr64 = COPY $rdi
>>         > +    ; CHECK-NEXT: [[MOV64rm:%[0-9]+]]:gr64 = MOV64rm
>>         [[COPY1]], 1, $noreg, 0, $noreg :: (load (s64) from %ir.0)
>>         > +    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gr32 = COPY
>>         [[MOV64rm]].sub_32bit
>>         > +    ; CHECK-NEXT: [[AND32ri8_:%[0-9]+]]:gr32 = AND32ri8
>>         [[COPY2]], 3, implicit-def dead $eflags
>>         > +    ; CHECK-NEXT: [[SUBREG_TO_REG:%[0-9]+]]:gr64 =
>>         SUBREG_TO_REG 0, killed [[AND32ri8_]], %subreg.sub_32bit
>>         > +    ; CHECK-NEXT: TEST64rr [[SUBREG_TO_REG]],
>>         [[SUBREG_TO_REG]], implicit-def $eflags
>>         > +    ; CHECK-NEXT: [[CMOV64rr:%[0-9]+]]:gr64 = CMOV64rr
>>         [[SUBREG_TO_REG]], [[COPY]], 8, implicit $eflags
>>         > +    ; CHECK-NEXT: MOV64mr [[COPY1]], 1, $noreg, 0, $noreg,
>>         killed [[CMOV64rr]] :: (store (s64) into %ir.0)
>>         > +    ; CHECK-NEXT: $rax = COPY [[MOV64rm]]
>>         > +    ; CHECK-NEXT: RET 0, $rax
>>         > +    %1:gr64 = COPY $rsi
>>         > +    %0:gr64 = COPY $rdi
>>         > +    %4:gr64 = MOV64rm %0, 1, $noreg, 0, $noreg :: (load
>>         (s64) from %ir.0)
>>         > +    %5:gr32 = COPY %4.sub_32bit
>>         > +    %6:gr32 = AND32ri8 %5, 3, implicit-def dead $eflags
>>         > +    %7:gr64 = SUBREG_TO_REG 0, killed %6, %subreg.sub_32bit
>>         > +    TEST64rr %7, %7, implicit-def $eflags
>>         > +    %8:gr64 = CMOV64rr %7, %1, 8, implicit $eflags
>>         > +    MOV64mr %0, 1, $noreg, 0, $noreg, killed %8 :: (store
>>         (s64) into %ir.0)
>>         > +    $rax = COPY %4
>>         > +    RET 0, $rax
>>         > +
>>         > +...
>>         > +---
>>         > +name: test_not_erased_when_eflags_change
>>         > +alignment:       16
>>         > +tracksDebugUserValues: false
>>         > +registers:
>>         > +  - { id: 0, class: gr64, preferred-register: '' }
>>         > +  - { id: 1, class: gr64, preferred-register: '' }
>>         > +  - { id: 2, class: gr64, preferred-register: '' }
>>         > +  - { id: 3, class: gr64, preferred-register: '' }
>>         > +  - { id: 4, class: gr64, preferred-register: '' }
>>         > +  - { id: 5, class: gr64, preferred-register: '' }
>>         > +  - { id: 6, class: gr32, preferred-register: '' }
>>         > +  - { id: 7, class: gr32, preferred-register: '' }
>>         > +  - { id: 8, class: gr64, preferred-register: '' }
>>         > +  - { id: 9, class: gr64, preferred-register: '' }
>>         > +  - { id: 10, class: gr64, preferred-register: '' }
>>         > +liveins:
>>         > +  - { reg: '$rdi', virtual-reg: '%0' }
>>         > +  - { reg: '$rsi', virtual-reg: '%1' }
>>         > +  - { reg: '$rcx', virtual-reg: '%3' }
>>         > +  - { reg: '$r8', virtual-reg: '%4' }
>>         > +frameInfo:
>>         > +  maxAlignment:    1
>>         > +machineFunctionInfo: {}
>>         > +body:             |
>>         > +  bb.0 (%ir-block.5):
>>         > +    liveins: $rdi, $rsi, $rcx, $r8
>>         > +
>>         > +    ; CHECK-LABEL: name: test_not_erased_when_eflags_change
>>         > +    ; CHECK: [[COPY:%[0-9]+]]:gr64 = COPY $r8
>>         > +    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gr64 = COPY $rcx
>>         > +    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:gr64 = COPY $rsi
>>         > +    ; CHECK-NEXT: [[COPY3:%[0-9]+]]:gr64 = COPY $rdi
>>         > +    ; CHECK-NEXT: [[MOV64rm:%[0-9]+]]:gr64 = MOV64rm
>>         [[COPY3]], 1, $noreg, 0, $noreg :: (load (s64) from %ir.0)
>>         > +    ; CHECK-NEXT: [[COPY4:%[0-9]+]]:gr32 = COPY
>>         [[MOV64rm]].sub_32bit
>>         > +    ; CHECK-NEXT: [[AND32ri8_:%[0-9]+]]:gr32 = AND32ri8
>>         [[COPY4]], 3, implicit-def dead $eflags
>>         > +    ; CHECK-NEXT: [[SUBREG_TO_REG:%[0-9]+]]:gr64 =
>>         SUBREG_TO_REG 0, killed [[AND32ri8_]], %subreg.sub_32bit
>>         > +    ; CHECK-NEXT: [[XOR64ri8_:%[0-9]+]]:gr64 = XOR64ri8
>>         [[COPY1]], 5, implicit-def dead $eflags
>>         > +    ; CHECK-NEXT: TEST64rr [[SUBREG_TO_REG]],
>>         [[SUBREG_TO_REG]], implicit-def $eflags
>>         > +    ; CHECK-NEXT: [[CMOV64rr:%[0-9]+]]:gr64 = CMOV64rr
>>         [[SUBREG_TO_REG]], [[COPY2]], 4, implicit $eflags
>>         > +    ; CHECK-NEXT: MOV64mr [[COPY3]], 1, $noreg, 0, $noreg,
>>         killed [[CMOV64rr]] :: (store (s64) into %ir.0)
>>         > +    ; CHECK-NEXT: MOV64mr [[COPY]], 1, $noreg, 0, $noreg,
>>         killed [[XOR64ri8_]] :: (store (s64) into %ir.4)
>>         > +    ; CHECK-NEXT: RET 0
>>         > +    %4:gr64 = COPY $r8
>>         > +    %3:gr64 = COPY $rcx
>>         > +    %1:gr64 = COPY $rsi
>>         > +    %0:gr64 = COPY $rdi
>>         > +    %5:gr64 = MOV64rm %0, 1, $noreg, 0, $noreg :: (load
>>         (s64) from %ir.0)
>>         > +    %6:gr32 = COPY %5.sub_32bit
>>         > +    %7:gr32 = AND32ri8 %6, 3, implicit-def dead $eflags
>>         > +    %8:gr64 = SUBREG_TO_REG 0, killed %7, %subreg.sub_32bit
>>         > +    %9:gr64 = XOR64ri8 %3, 5, implicit-def dead $eflags
>>         > +    TEST64rr %8, %8, implicit-def $eflags
>>         > +    %10:gr64 = CMOV64rr %8, %1, 4, implicit $eflags
>>         > +    MOV64mr %0, 1, $noreg, 0, $noreg, killed %10 :: (store
>>         (s64) into %ir.0)
>>         > +    MOV64mr %4, 1, $noreg, 0, $noreg, killed %9 :: (store
>>         (s64) into %ir.4)
>>         > +    RET 0
>>         > +
>>         > +...
>>         >
>>         >
>>         >
>>         > _______________________________________________
>>         > llvm-commits mailing list
>>         > llvm-commits at lists.llvm.org
>>         > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>
>>
>>
>>     -- 
>>     Thanks,
>>     Mingming
>
>
>
> -- 
> Thanks,
> Mingming
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