[ARM][MachineOutliner] Fix costs model.

[yroux]

Summary

Fix candidates call costs model allocation and prepare stack fixup handling.

[samparker]

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5832

We were returning here previously, and now it's possible that there's a Candidate that hasn't been inserted into CandidatesWithoutStackFixups. When we update RepeatedSequences on line 5832, are we guaranteed to have not missed some candidates?

[yroux]

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5832

OK, in fact what I tried to do here is just to fix the costs given to the candidates which was wrongly set to Calldefault for all candidates when SP wasn't used and at least one of them was called with save/restore of LR into the stack.

We were returning here without outling these candidates, if the need of stack fixup was detected, but that wasn't necessary the instructions which migh need such a fixup were marked as illegal for outlining in the code lines 6055-6070

So, here we are just preparing the next step which will handle the fixups, it is the same logic which is used in the AArch64 implementation.

I'll renane and change the description of this revision

[samparker]

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5832

Okay, thanks for reminding me how this plugs together. So I'm sorry if I'm being dense... but couldn't this still mean we could outline an instruction that is dependent upon one that isn't outlined? If we're iterating through a sequence of instructions, effectively copying them back into RepeatedSequenceLocs, what is stopping us from skipping over an instruction which a following instruction maybe dependent upon?

[yroux]

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5832

Problematic instructions (like predicated ones, PIC related ones, etc...) are marked as illegal inside getOutliningType function, then the MachineOutliner algorithm search the repeated patterns of legal instructions, thus RepatedSequenceLocs only contain Candidates composed by safe instructions and here we are just adding info about their kind and costs. Hope it is clearer

[samparker]

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5832

I don't think that alleviates my concerns... From what I understand the machine outliner will pass a sequence of instructions here that could be outlined, safely, together. My concern is the 'together' part. As I understand it, this change would allow an instruction in the sequence to not be placed in the sequence for outlining. I'd be more than happy to be pointed to a test to show that I'm talking non-sense :)

[yroux]

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5832

hmm sorry if I was confusing with my explanations, but here RepeatedSequenceLocs is a vector of Candidates, a Candidate is indeed a sequence of instructions which can be outlined together, but we don't remove instructions in that sequence.

[samparker]

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5832

Yes, there's no removal here... but are all Candidates 'C' added into CandidatesWithoutStackFixups if line 5833 executes? Otherwise surely it is effectively removing a candidate. Looking again through this function, there are instructions being removed at 5742, so I now worried about that too.

[yroux]

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5832

right, we can remove a candidate if needed, it only means that instead of inserting a call to an outlined function three times we will only do two calls and don't touch the third occurence of the sequence if needed

Here ligne 5833 we only keep candidates whcih don't need a stack fixup (since we are not handling thjem yet) it means that if we have a sequence which sotre something on the stack, we wiull outline all the occurences which call that function without having to save/restore the link register into/from the stack.

At ligne 5742, we just remove the candidates where R12 and CPSR are lived accross them

[samparker]

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5832

Ah - okay! Thanks for your patience and explanation!

[yroux]

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

5832

No worries, thanks for the review :)

llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp

for (outliner::Candidate &C : RepeatedSequenceLocs) {
         CandidatesWithoutStackFixups.push_back(C);
       }
 
       // Is SP used in the sequence at all? If not, we don't have to modify
       // the stack, so we are guaranteed to get the same frame.
       else if (C.UsedInSequence.available(ARM::SP)) {
         NumBytesNoStackCalls += Costs.CallDefault;
         C.setCallInfo(MachineOutlinerDefault, Costs.CallDefault);
-        SetCandidateCallInfo(MachineOutlinerDefault, Costs.CallDefault);
         CandidatesWithoutStackFixups.push_back(C);
-      } else
-        return outliner::OutlinedFunction();
-    }
+      }
+
+      // If we outline this, we need to modify the stack. Pretend we don't
+      // outline this by saving all of its bytes.
+      else
+        NumBytesNoStackCalls += SequenceSize;
+    }
+
+    // If there are no places where we have to save LR, then note that we don't
+    // have to update the stack. Otherwise, give every candidate the default
+    // call type
+    if (NumBytesNoStackCalls <=
+        RepeatedSequenceLocs.size() * Costs.CallDefault) {
+      RepeatedSequenceLocs = CandidatesWithoutStackFixups;
+      FrameID = MachineOutlinerNoLRSave;
+      SetCandidateCallInfo(MachineOutlinerDefault, Costs.CallDefault);
 
-    // Does every candidate's MBB contain a call?  If so, then we might have a
-    // call in the range.
-    if (FlagsSetInAll & MachineOutlinerMBBFlags::HasCalls) {
-      // check if the range contains a call.  These require a save + restore of
-      // the link register.
-      if (std::any_of(FirstCand.front(), FirstCand.back(),
-                      [](const MachineInstr &MI) { return MI.isCall(); }))
-        NumBytesToCreateFrame += Costs.SaveRestoreLROnStack;
 
-      // Handle the last instruction separately.  If it is tail call, then the
-      // last instruction is a call, we don't want to save + restore in this
-      // case.  However, it could be possible that the last instruction is a
-      // call without it being valid to tail call this sequence.  We should
-      // consider this as well.
-      else if (FrameID != MachineOutlinerThunk &&
-               FrameID != MachineOutlinerTailCall && FirstCand.back()->isCall())
-        NumBytesToCreateFrame += Costs.SaveRestoreLROnStack;
-    }
-    RepeatedSequenceLocs = CandidatesWithoutStackFixups;
-  }
 
   return outliner::OutlinedFunction(RepeatedSequenceLocs, SequenceSize,
                                     NumBytesToCreateFrame, FrameID);
 }
 
 bool ARMBaseInstrInfo::isFunctionSafeToOutlineFrom(
     MachineFunction &MF, bool OutlineFromLinkOnceODRs) const {
   const Function &F = MF.getFunction();

llvm/test/CodeGen/ARM/machine-outliner-calls.mir

 body:             |
   ; CHECK-LABEL: name: outline_call_thumb
   ; CHECK: bb.0:
   ; CHECK:   liveins: $r7, $lr
   ; CHECK:   $sp = frame-setup t2STMDB_UPD $sp, 14 /* CC::al */, $noreg, killed $r7, killed $lr
   ; CHECK:   frame-setup CFI_INSTRUCTION def_cfa_offset 8
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $lr, -4
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $r7, -8
-  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_3
+  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_4
   ; CHECK: bb.1:
-  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_3
+  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_4
   ; CHECK: bb.2:
-  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_3
+  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_4
   ; CHECK: bb.3:
-  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_3
+  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_4
   ; CHECK: bb.4:
-  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_3
+  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_4
   ; CHECK: bb.5:
   ; CHECK:   $sp = frame-destroy t2LDMIA_RET $sp, 14 /* CC::al */, $noreg, def $r7, def $pc
   bb.0:
     tBL 14, $noreg, @bar, implicit-def dead $lr, implicit $sp
     $r0 = t2MOVi 1, 14, $noreg, $noreg
     $r1 = t2MOVi 1, 14, $noreg, $noreg
     $r2 = t2MOVi 1, 14, $noreg, $noreg
   bb.1:

 body:             |
   ; CHECK-LABEL: name: outline_call_tailcall_arm
   ; CHECK: bb.0:
   ; CHECK:   liveins: $r4, $lr
   ; CHECK:   $sp = frame-setup STMDB_UPD $sp, 14 /* CC::al */, $noreg, killed $r4, killed $lr
   ; CHECK:   frame-setup CFI_INSTRUCTION def_cfa_offset 8
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $lr, -4
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $r4, -8
-  ; CHECK:   BL @OUTLINED_FUNCTION_2
+  ; CHECK:   BL @OUTLINED_FUNCTION_1
   ; CHECK: bb.1:
-  ; CHECK:   BL @OUTLINED_FUNCTION_2
+  ; CHECK:   BL @OUTLINED_FUNCTION_1
   ; CHECK: bb.2:
-  ; CHECK:   BL @OUTLINED_FUNCTION_2
+  ; CHECK:   BL @OUTLINED_FUNCTION_1
   ; CHECK: bb.3:
+  ; CHECK:   BL @OUTLINED_FUNCTION_1
+  ; CHECK: bb.4:
   ; CHECK:   $sp = frame-destroy LDMIA_UPD $sp, 14 /* CC::al */, $noreg, def $r4, def $lr
   ; CHECK:   BX_RET 14 /* CC::al */, $noreg
   bb.0:
     BL @bar, implicit-def dead $lr, implicit $sp
     $r0 = MOVi 2, 14, $noreg, $noreg
     $r1 = MOVi 2, 14, $noreg, $noreg
     $r2 = MOVi 2, 14, $noreg, $noreg
     $r3 = MOVi 2, 14, $noreg, $noreg
bb.2:
     BL @bar, implicit-def dead $lr, implicit $sp
     $r0 = MOVi 2, 14, $noreg, $noreg
     $r1 = MOVi 2, 14, $noreg, $noreg
     $r2 = MOVi 2, 14, $noreg, $noreg
     $r3 = MOVi 2, 14, $noreg, $noreg
     $r4 = MOVi 2, 14, $noreg, $noreg
     BL @bar, implicit-def dead $lr, implicit $sp
   bb.3:
+    BL @bar, implicit-def dead $lr, implicit $sp
+    $r0 = MOVi 2, 14, $noreg, $noreg
+    $r1 = MOVi 2, 14, $noreg, $noreg
+    $r2 = MOVi 2, 14, $noreg, $noreg
+    $r3 = MOVi 2, 14, $noreg, $noreg
+    $r4 = MOVi 2, 14, $noreg, $noreg
+    BL @bar, implicit-def dead $lr, implicit $sp
+  bb.4:
     BX_RET 14, $noreg
 ...
 ---
 
 name:           outline_call_tailcall_thumb
 tracksRegLiveness: true
 body:             |
   ; CHECK-LABEL: name: outline_call_tailcall_thumb
   ; CHECK: bb.0:
   ; CHECK:   liveins: $r7, $lr
   ; CHECK:   $sp = frame-setup t2STMDB_UPD $sp, 14 /* CC::al */, $noreg, killed $r7, killed $lr
   ; CHECK:   frame-setup CFI_INSTRUCTION def_cfa_offset 8
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $lr, -4
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $r7, -8
-  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_4
+  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_3
   ; CHECK: bb.1:
-  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_4
+  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_3
   ; CHECK: bb.2:
-  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_4
+  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_3
   ; CHECK: bb.3:
+  ; CHECK:   tBL 14 /* CC::al */, $noreg, @OUTLINED_FUNCTION_3
+  ; CHECK: bb.4:
   ; CHECK:   $sp = frame-destroy t2LDMIA_RET $sp, 14 /* CC::al */, $noreg, def $r7, def $pc
   bb.0:
     tBL 14, $noreg, @bar, implicit-def dead $lr, implicit $sp
     $r0 = t2MOVi 2, 14, $noreg, $noreg
     $r1 = t2MOVi 2, 14, $noreg, $noreg
     $r2 = t2MOVi 2, 14, $noreg, $noreg
     tBL 14, $noreg, @bar, implicit-def dead $lr, implicit $sp
   bb.1:
     tBL 14, $noreg, @bar, implicit-def dead $lr, implicit $sp
     $r0 = t2MOVi 2, 14, $noreg, $noreg
     $r1 = t2MOVi 2, 14, $noreg, $noreg
     $r2 = t2MOVi 2, 14, $noreg, $noreg
     tBL 14, $noreg, @bar, implicit-def dead $lr, implicit $sp
   bb.2:
     tBL 14, $noreg, @bar, implicit-def dead $lr, implicit $sp
     $r0 = t2MOVi 2, 14, $noreg, $noreg
     $r1 = t2MOVi 2, 14, $noreg, $noreg
     $r2 = t2MOVi 2, 14, $noreg, $noreg
     tBL 14, $noreg, @bar, implicit-def dead $lr, implicit $sp
   bb.3:
+    tBL 14, $noreg, @bar, implicit-def dead $lr, implicit $sp
+    $r0 = t2MOVi 2, 14, $noreg, $noreg
+    $r1 = t2MOVi 2, 14, $noreg, $noreg
+    $r2 = t2MOVi 2, 14, $noreg, $noreg
+    tBL 14, $noreg, @bar, implicit-def dead $lr, implicit $sp
+  bb.4:
     tBX_RET 14, $noreg
 ...
 ---
 
 name:           outline_call_KO_mcount
 tracksRegLiveness: true
 body:             |
   ; CHECK-LABEL: name: outline_call_KO_mcount
   ; CHECK: bb.0:
   ; CHECK:   liveins: $r4, $lr
   ; CHECK:   $sp = frame-setup STMDB_UPD $sp, 14 /* CC::al */, $noreg, killed $r4, killed $lr
   ; CHECK:   frame-setup CFI_INSTRUCTION def_cfa_offset 8
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $lr, -4
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $r4, -8
   ; CHECK:   BL @"\01mcount", csr_aapcs, implicit-def dead $lr, implicit $sp
-  ; CHECK:   BL @OUTLINED_FUNCTION_1
+  ; CHECK:   BL @OUTLINED_FUNCTION_2
   ; CHECK: bb.1:
   ; CHECK:   BL @"\01mcount", csr_aapcs, implicit-def dead $lr, implicit $sp
-  ; CHECK:   BL @OUTLINED_FUNCTION_1
+  ; CHECK:   BL @OUTLINED_FUNCTION_2
   ; CHECK: bb.2:
   ; CHECK:   BL @"\01mcount", csr_aapcs, implicit-def dead $lr, implicit $sp
-  ; CHECK:   BL @OUTLINED_FUNCTION_1
+  ; CHECK:   BL @OUTLINED_FUNCTION_2
   ; CHECK: bb.3:
   ; CHECK:   BL @"\01mcount", csr_aapcs, implicit-def dead $lr, implicit $sp
-  ; CHECK:   BL @OUTLINED_FUNCTION_1
+  ; CHECK:   BL @OUTLINED_FUNCTION_2
   ; CHECK: bb.4:
   ; CHECK:   BL @"\01mcount", csr_aapcs, implicit-def dead $lr, implicit $sp
-  ; CHECK:   BL @OUTLINED_FUNCTION_1
+  ; CHECK:   BL @OUTLINED_FUNCTION_2
   ; CHECK: bb.5:
   ; CHECK:   $sp = frame-destroy LDMIA_UPD $sp, 14 /* CC::al */, $noreg, def $r4, def $lr
   ; CHECK:   BX_RET 14 /* CC::al */, $noreg
   bb.0:
     BL @"\01mcount", csr_aapcs, implicit-def dead $lr, implicit $sp
     $r0 = MOVi 3, 14, $noreg, $noreg
     $r1 = MOVi 3, 14, $noreg, $noreg
     $r2 = MOVi 3, 14, $noreg, $noreg
body:             |
   ; CHECK:   $r2 = MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r3 = MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r4 = MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $lr, $sp = LDR_POST_IMM $sp, $noreg, 8, 14 /* CC::al */, $noreg
   ; CHECK:   MOVPCLR 14 /* CC::al */, $noreg
 
   ; CHECK-LABEL: name: OUTLINED_FUNCTION_1
   ; CHECK: bb.0:
-  ; CHECK:   liveins: $r11, $r10, $r9, $r8, $r7, $r6, $r5, $d15, $d14, $d13, $d12, $d11, $d10, $d9, $d8
-  ; CHECK:   $r0 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r1 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r2 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r3 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r4 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   MOVPCLR 14 /* CC::al */, $noreg
-
-  ; CHECK-LABEL: name: OUTLINED_FUNCTION_2
-  ; CHECK: bb.0:
   ; CHECK:   liveins: $r11, $r10, $r9, $r8, $r7, $r6, $r5, $d15, $d14, $d13, $d12, $d11, $d10, $d9, $d8, $lr
   ; CHECK:   early-clobber $sp = STR_PRE_IMM killed $lr, $sp, -8, 14 /* CC::al */, $noreg
   ; CHECK:   frame-setup CFI_INSTRUCTION def_cfa_offset 8
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $lr, -8
   ; CHECK:   BL @bar, implicit-def dead $lr, implicit $sp
   ; CHECK:   $r0 = MOVi 2, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r1 = MOVi 2, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r2 = MOVi 2, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r3 = MOVi 2, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $r4 = MOVi 2, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $lr, $sp = LDR_POST_IMM $sp, $noreg, 8, 14 /* CC::al */, $noreg
   ; CHECK:   TAILJMPd @bar, implicit $sp
 
+  ; CHECK-LABEL: name: OUTLINED_FUNCTION_2
+  ; CHECK: bb.0:
+  ; CHECK:   liveins: $r11, $r10, $r9, $r8, $r7, $r6, $r5, $d15, $d14, $d13, $d12, $d11, $d10, $d9, $d8
+  ; CHECK:   $r0 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   $r1 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   $r2 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   $r3 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   $r4 = MOVi 3, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   MOVPCLR 14 /* CC::al */, $noreg
+
   ; CHECK-LABEL: name: OUTLINED_FUNCTION_3
   ; CHECK: bb.0:
   ; CHECK:   liveins: $r11, $r10, $r9, $r8, $r6, $r5, $r4, $d15, $d14, $d13, $d12, $d11, $d10, $d9, $d8, $lr
   ; CHECK:   early-clobber $sp = t2STR_PRE killed $lr, $sp, -8, 14 /* CC::al */, $noreg
   ; CHECK:   frame-setup CFI_INSTRUCTION def_cfa_offset 8
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $lr, -8
   ; CHECK:   tBL 14 /* CC::al */, $noreg, @bar, implicit-def dead $lr, implicit $sp
-  ; CHECK:   $r0 = t2MOVi 1, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r1 = t2MOVi 1, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r2 = t2MOVi 1, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   $r0 = t2MOVi 2, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   $r1 = t2MOVi 2, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   $r2 = t2MOVi 2, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $lr, $sp = t2LDR_POST $sp, 8, 14 /* CC::al */, $noreg
-  ; CHECK:   tBX_RET 14 /* CC::al */, $noreg
+  ; CHECK:   tTAILJMPdND @bar, 14 /* CC::al */, $noreg, implicit $sp
 
   ; CHECK-LABEL: name: OUTLINED_FUNCTION_4
   ; CHECK: bb.0:
   ; CHECK:   liveins: $r11, $r10, $r9, $r8, $r6, $r5, $r4, $d15, $d14, $d13, $d12, $d11, $d10, $d9, $d8, $lr
   ; CHECK:   early-clobber $sp = t2STR_PRE killed $lr, $sp, -8, 14 /* CC::al */, $noreg
   ; CHECK:   frame-setup CFI_INSTRUCTION def_cfa_offset 8
   ; CHECK:   frame-setup CFI_INSTRUCTION offset $lr, -8
   ; CHECK:   tBL 14 /* CC::al */, $noreg, @bar, implicit-def dead $lr, implicit $sp
-  ; CHECK:   $r0 = t2MOVi 2, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r1 = t2MOVi 2, 14 /* CC::al */, $noreg, $noreg
-  ; CHECK:   $r2 = t2MOVi 2, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   $r0 = t2MOVi 1, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   $r1 = t2MOVi 1, 14 /* CC::al */, $noreg, $noreg
+  ; CHECK:   $r2 = t2MOVi 1, 14 /* CC::al */, $noreg, $noreg
   ; CHECK:   $lr, $sp = t2LDR_POST $sp, 8, 14 /* CC::al */, $noreg
-  ; CHECK:   tTAILJMPdND @bar, 14 /* CC::al */, $noreg, implicit $sp
+  ; CHECK:   tBX_RET 14 /* CC::al */, $noreg
 
 
 

llvm/test/CodeGen/ARM/machine-outliner-stack-use.mir

+# RUN: llc -mtriple=arm-- -run-pass=machine-outliner -verify-machineinstrs \
+# RUN: %s -o - | FileCheck %s
+
+--- |
+  define void @stack_use_no_lr_save_1() #0 { ret void }
+  define void @stack_use_no_lr_save_2() #0 { ret void }
+
+  attributes #0 = { minsize optsize }
+...
+---
+
+name:           stack_use_no_lr_save_1
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    ; CHECK-LABEL: name:           stack_use_no_lr_save_1
+    ; CHECK: BL @OUTLINED_FUNCTION_0
+    $r0 = MOVi 1, 14, $noreg, $noreg
+    $r0 = MOVi 1, 14, $noreg, $noreg
+    $r0 = LDRi12 $sp, 0, 14, $noreg
+    $r0 = LDRi12 $sp, 0, 14, $noreg
+    $r0 = LDRi12 $sp, 0, 14, $noreg
+    $r0 = MOVi 1, 14, $noreg, $noreg
+    $r0 = LDRi12 $sp, 0, 14, $noreg
+    $r0 = MOVi 1, 14, $noreg, $noreg
+  bb.1:
+    liveins: $r0, $r1, $r2, $r3, $r4, $r5, $r6, $r7, $r8, $r9, $r10, $r11
+    BX_RET 14, $noreg
+...
+---
+
+name:           stack_use_no_lr_save_2
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    ; CHECK-LABEL: name:           stack_use_no_lr_save_2
+    ; CHECK: BL @OUTLINED_FUNCTION_0
+    $r0 = MOVi 1, 14, $noreg, $noreg
+    $r0 = MOVi 1, 14, $noreg, $noreg
+    $r0 = LDRi12 $sp, 0, 14, $noreg
+    $r0 = LDRi12 $sp, 0, 14, $noreg
+    $r0 = LDRi12 $sp, 0, 14, $noreg
+    $r0 = MOVi 1, 14, $noreg, $noreg
+    $r0 = LDRi12 $sp, 0, 14, $noreg
+    $r0 = MOVi 1, 14, $noreg, $noreg
+  bb.1:
+    BX_RET 14, $noreg
+
+    ;CHECK: name:           OUTLINED_FUNCTION_0
+    ;CHECK: $r0 = MOVi 1, 14 /* CC::al */, $noreg, $noreg
+    ;CHECK-NEXT: $r0 = MOVi 1, 14 /* CC::al */, $noreg, $noreg
+    ;CHECK-NEXT: $r0 = LDRi12 $sp, 0, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r0 = LDRi12 $sp, 0, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r0 = LDRi12 $sp, 0, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r0 = MOVi 1, 14 /* CC::al */, $noreg, $noreg
+    ;CHECK-NEXT: $r0 = LDRi12 $sp, 0, 14 /* CC::al */, $noreg
+    ;CHECK-NEXT: $r0 = MOVi 1, 14 /* CC::al */, $noreg, $noreg
+    ;CHECK-NEXT: MOVPCLR 14 /* CC::al */, $noreg