[PATCH] Fix crash in MachineLICM.cpp

[zan jyu Wong via llvm-commits]

I've tried the following example on Thumb backend with the flags, it's ok?

RUN: llc licm.ll -sink-insts-to-avoid-spills

========== example ===========
; ModuleID = 'licm.c'
source_filename = "licm.c"
target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "armv4t--"

; Function Attrs: nounwind readonly
define arm_aapcscc i32 @sum(i32* noalias nocapture readonly %arr, i32 %c)
#0 {
entry:
  %cmp7 = icmp sgt i32 %c, 0
  br i1 %cmp7, label %for.body.preheader, label %for.cond.cleanup

for.body.preheader:                               ; preds = %entry
  %sp = tail call i32 asm "mov $0, sp", "=r"() #1, !srcloc !3
  br label %for.body

for.cond.cleanup.loopexit:                        ; preds = %for.body
  br label %for.cond.cleanup

for.cond.cleanup:                                 ; preds =
%for.cond.cleanup.loopexit, %entry
  %sum.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.cond.cleanup.loopexit ]
  ret i32 %sum.0.lcssa

for.body:                                         ; preds =
%for.body.preheader, %for.body
  %i.09 = phi i32 [ %inc, %for.body ], [ 0, %for.body.preheader ]
  %sum.08 = phi i32 [ %add, %for.body ], [ 0, %for.body.preheader ]
  %arrayidx = getelementptr inbounds i32, i32* %arr, i32 %i.09
  %0 = load i32, i32* %arrayidx, align 4, !tbaa !4
  %mul = mul nsw i32 %0, %sp
  %add = add nsw i32 %mul, %sum.08
  %inc = add nuw nsw i32 %i.09, 1
  %exitcond = icmp eq i32 %inc, %c
  br i1 %exitcond, label %for.cond.cleanup.loopexit, label %for.body
}

attributes #0 = { nounwind readonly "disable-tail-calls"="false"
"less-precise-fpmad"="false" "no-frame-pointer-elim"="true"
"no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false"
"no-jump-tables"="false" "no-nans-fp-math"="false"
"stack-protector-buffer-size"="8" "target-cpu"="arm7tdmi"
"target-features"="+soft-float,+strict-align,-crypto,-neon"
"unsafe-fp-math"="false" "use-soft-float"="true" }
attributes #1 = { nounwind readnone }

!llvm.module.flags = !{!0, !1}
!llvm.ident = !{!2}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 1, !"min_enum_size", i32 4}
!2 = !{!"clang version 3.9.0 (http://llvm.org/git/clang.git
e8204bf8264d6d52aab4e8ac84328654d3ef28bd) (http://llvm.org/git/llvm.git
d75f887d2fcccc1f0dbf7809c2638e2ff3448462)"}
!3 = !{i32 76}
!4 = !{!5, !5, i64 0}
!5 = !{!"long", !6, i64 0}
!6 = !{!"omnipotent char", !7, i64 0}
!7 = !{!"Simple C/C++ TBAA"}

On Wed, Jun 8, 2016 at 8:50 AM, Quentin Colombet <qcolombet at apple.com>
wrote:

> Could you try a simple example with that flag on x86_64 to produce a test
> case?
>
> Thanks,
> Q.
>
> On Jun 7, 2016, at 5:38 PM, zan jyu Wong <zyfwong at gmail.com> wrote:
>
> No. Since I'm working on a custom backend, unless I upload the backend.
> But there is an assertion in isDef(), so I think it can be reproduced on
> other backend when compile with -sink-insts-to-avoid-spills=true.
>
> On Wed, Jun 8, 2016 at 12:03 AM, Quentin Colombet <qcolombet at apple.com>
> wrote:
>
>> Hi Zan Jyu,
>>
>> Yep.
>>
>> Do you have a test case to put with that?
>>
>> Thanks,
>> -Quentin
>>
>> On Jun 7, 2016, at 12:25 AM, zan jyu Wong via llvm-commits <
>> llvm-commits at lists.llvm.org> wrote:
>>
>> We should test isReg() before isDef()
>>
>> diff --git a/lib/CodeGen/MachineLICM.cpp b/lib/CodeGen/MachineLICM.cpp
>> index 00dec82..4ea0c56 100644
>> --- a/lib/CodeGen/MachineLICM.cpp
>> +++ b/lib/CodeGen/MachineLICM.cpp
>> @@ -716,7 +716,7 @@ void MachineLICM::SinkIntoLoop() {
>>
>>    for (MachineInstr *I : Candidates) {
>>      const MachineOperand &MO = I->getOperand(0);
>> -    if (!MO.isDef() || !MO.isReg() || !MO.getReg())
>> +    if (!MO.isReg() || !MO.isDef() || !MO.getReg())
>>        continue;
>>      if (!MRI->hasOneDef(MO.getReg()))
>>        continue;
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at lists.llvm.org
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>>
>>
>>
>
>
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