Commit fc6fda90 authored by Jin Lin's avatar Jin Lin
Browse files

Fix incorrect logic in maintaining the side-effect of compiler generated outliner functions 

Summary: Fix incorrect logic in maintaining the side-effect of compiler generated outliner functions by adding the up-exposed uses.

Reviewers: paquette, tellenbach

Reviewed By: paquette

Subscribers: aemerson, lebedev.ri, hiraditya, llvm-commits, jinlin

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71217
parent 5dadf577

llvm/lib/CodeGen/MachineOutliner.cpp

+41 −18
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ 
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/MachineOutliner.h"

#include "llvm/ADT/DenseMap.h"

#include "llvm/ADT/SmallSet.h"

#include "llvm/ADT/Statistic.h"

#include "llvm/ADT/Twine.h"

#include "llvm/CodeGen/MachineFunction.h"
@@ -1245,31 +1246,53 @@ bool MachineOutliner::outline(Module &M, 
      // make sure that the ranges we yank things out of aren't wrong.

      if (MBB.getParent()->getProperties().hasProperty(

              MachineFunctionProperties::Property::TracksLiveness)) {

        // Helper lambda for adding implicit def operands to the call

        // The following code is to add implicit def operands to the call

        // instruction. It also updates call site information for moved

        // code.

        auto CopyDefsAndUpdateCalls = [&CallInst](MachineInstr &MI) {

          for (MachineOperand &MOP : MI.operands()) {

        SmallSet<Register, 2> UseRegs, DefRegs;

        // Copy over the defs in the outlined range.

        // First inst in outlined range <-- Anything that's defined in this

        // ...                           .. range has to be added as an

        // implicit Last inst in outlined range  <-- def to the call

        // instruction. Also remove call site information for outlined block

        // of code. The exposed uses need to be copied in the outlined range.

        for (MachineBasicBlock::reverse_iterator Iter = EndIt.getReverse(),

             Last = std::next(CallInst.getReverse());

             Iter != Last; Iter++) {

          MachineInstr *MI = &*Iter;

          for (MachineOperand &MOP : MI->operands()) {

            // Skip over anything that isn't a register.

            if (!MOP.isReg())

              continue;



            if (MOP.isDef()) {

              // Introduce DefRegs set to skip the redundant register.

              DefRegs.insert(MOP.getReg());

              if (UseRegs.count(MOP.getReg()))

                // Since the regiester is modeled as defined,

                // it is not necessary to be put in use register set.

                UseRegs.erase(MOP.getReg());

            } else if (!MOP.isUndef()) {

              // Any register which is not undefined should

              // be put in the use register set.

              UseRegs.insert(MOP.getReg());

            }

          }

          if (MI->isCandidateForCallSiteEntry())

            MI->getMF()->eraseCallSiteInfo(MI);

        }



        for (const Register &I : DefRegs)

           // If it's a def, add it to the call instruction.

            if (MOP.isDef())

          CallInst->addOperand(MachineOperand::CreateReg(

                  MOP.getReg(), true, /* isDef = true */

                  I, true, /* isDef = true */

                  true /* isImp = true */));



        for (const Register &I : UseRegs)

          // If it's a exposed use, add it to the call instruction.

          CallInst->addOperand(

              MachineOperand::CreateReg(I, false, /* isDef = false */

                                        true /* isImp = true */));

          }

          if (MI.shouldUpdateCallSiteInfo())

            MI.getMF()->eraseCallSiteInfo(&MI);

        };

        // Copy over the defs in the outlined range.

        // First inst in outlined range <-- Anything that's defined in this

        // ...                           .. range has to be added as an

        // implicit Last inst in outlined range  <-- def to the call

        // instruction. Also remove call site information for outlined block

        // of code.

        std::for_each(CallInst, std::next(EndIt), CopyDefsAndUpdateCalls);

      }



      // Erase from the point after where the call was inserted up to, and

llvm/test/CodeGen/AArch64/machine-outliner-noreturn-save-lr.mir

+4 −4
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ body: | 
    ; CHECK-LABEL: name: save_lr_1

    ; CHECK: liveins: $lr

    ; CHECK: $x0 = ORRXrs $xzr, $lr, 0

    ; CHECK: BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $lr, implicit-def $w3, implicit-def $w4, implicit-def $w5, implicit-def $w6

    ; CHECK: BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $w3, implicit-def $w4, implicit-def $w5, implicit-def $w6, implicit $sp, implicit $wzr, implicit $xzr, implicit $x0

    ; CHECK: $lr = ORRXrs $xzr, $x0, 0

    $w3 = ORRWri $wzr, 1

    $w4 = ORRWri $wzr, 1
@@ -49,7 +49,7 @@ body: | 
    ; CHECK-LABEL: name: save_lr_2

    ; CHECK: liveins: $lr

    ; CHECK: $x0 = ORRXrs $xzr, $lr, 0

    ; CHECK: BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $lr, implicit-def $w3, implicit-def $w4, implicit-def $w5, implicit-def $w6

    ; CHECK: BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $w3, implicit-def $w4, implicit-def $w5, implicit-def $w6, implicit $sp, implicit $wzr, implicit $xzr, implicit $x0

    ; CHECK: $lr = ORRXrs $xzr, $x0, 0

    $w3 = ORRWri $wzr, 1

    $w4 = ORRWri $wzr, 1
@@ -71,7 +71,7 @@ body: | 
    ; CHECK-LABEL: name: save_lr_3

    ; CHECK: liveins: $lr

    ; CHECK: $x0 = ORRXrs $xzr, $lr, 0

    ; CHECK: BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $lr, implicit-def $w3, implicit-def $w4, implicit-def $w5, implicit-def $w6

    ; CHECK: BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $w3, implicit-def $w4, implicit-def $w5, implicit-def $w6, implicit $sp, implicit $wzr, implicit $xzr, implicit $x0

    ; CHECK: $lr = ORRXrs $xzr, $x0, 0

    $w3 = ORRWri $wzr, 1

    $w4 = ORRWri $wzr, 1
@@ -93,7 +93,7 @@ body: | 
    ; CHECK-LABEL: name: save_lr_4

    ; CHECK: liveins: $lr

    ; CHECK: $x0 = ORRXrs $xzr, $lr, 0

    ; CHECK: BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $lr, implicit-def $w3, implicit-def $w4, implicit-def $w5, implicit-def $w6

    ; CHECK: BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $w3, implicit-def $w4, implicit-def $w5, implicit-def $w6, implicit $sp, implicit $wzr, implicit $xzr, implicit $x0

    ; CHECK: $lr = ORRXrs $xzr, $x0, 0

    $w3 = ORRWri $wzr, 1

    $w4 = ORRWri $wzr, 1

llvm/test/CodeGen/AArch64/machine-outliner-side-effect.mir

0 → 100644
+32 −0
Original line number Diff line number Diff line 
# RUN: llc -mtriple=aarch64 -run-pass=machine-outliner -verify-machineinstrs %s -o - | FileCheck %s



# The test checks whether the compiler updates the side effect of function @OUTLINED_FUNCTION_0 by adding the use of register x20.



--- |

  declare void @spam() local_unnamed_addr

  define void @baz() optsize minsize noredzone { ret void }

...

---

name:            baz

tracksRegLiveness: true

body:             |

  bb.0:

    liveins: $x0, $x20



    $x0 = COPY renamable $x20

    BL @spam, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit-def $sp, implicit-def $x0

    renamable $x21 = COPY $x0



    $x0 = COPY renamable $x20

    BL @spam, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit-def $sp, implicit-def $x0

    renamable $x22 = COPY $x0



    $x0 = COPY killed renamable $x20

    BL @spam, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp, implicit $x0, implicit-def $sp, implicit-def $x0

    renamable $x3 = COPY $x0



    RET_ReallyLR



...



# CHECK: BL @OUTLINED_FUNCTION_0, {{.*}}, implicit $x20, {{.*}}