[PATCH] D104440: [X86] Fix bug when X86 stackify pass handle one ArgFPRW.

[Craig Topper via Phabricator via llvm-commits]

craig.topper added a comment.

In D104440#2829198 <https://reviews.llvm.org/D104440#2829198>, @LuoYuanke wrote:

>> I don’t know what llvm-extract —recursive does. I’ve only used -func to extract a single function I knew caused a compiler crash.
>>
>> Converting IMPLICIT_DEF to undef flag is correct.
>>
>> IMPLICIT_DEF can get created from ISD::UNDEF but as far I could see ISD::UNDEF for fp80 is supposed to Expand to ConstantFP 0.
>>
>> I also think fneg of undef should be folded by getNode when it is created in SelectionDAGBuilder. Is this going through fast isel or something?
>
> In my small test case that is extracted by llvm-extract, the "fneg contract x86_fp80 undef" is lowered to "LD_Fp080". But in the big case which cause crash, it is lowered to "IMPLICIT_DEF" and "CHS_Fp80".
>
>   76:                                               ; preds = %74
>     %77 = call contract x86_fp80 @_ZN5boost4math8policies20raise_overflow_errorIeNS1_6policyINS1_13promote_floatILb0EEENS1_14promote_doubleILb0EEENS1_14default_policyES8_S8_S8_S8_S8_S8_S8_S8_S8_S8_EEEET_PKcSC_RKT0_(i8* getelementptr inbounds ([29 x i8], [29 x i8]* @.str.3.16422, i64 0, i64 0), i8* null, %"struct.std::__atomic_flag_base"* nonnull align 1 dereferenceable(1) %9)
>     %78 = fneg contract x86_fp80 undef
>     br label %121
>
>
>
>   CALL64pcrel32 @_ZN5boost4math8policies20raise_overflow_errorIeNS1_6policyINS1_13promote_floatILb0EEENS1_14promote_doubleILb0EEENS1_14default_policyES8_S8_S8_S8_S8_S8_S8_S8_S8_S8_EEEET_PKcSC_RKT0_, <regmask $bh $bl $bp $bph $bpl $bx $ebp $ebx $hbp $hbx $rbp $rbx $r12 $r13 $r14 $r15 $r12b $r13b $r14b $r15b $r12bh $r13bh $r14bh $r15bh $r12d $r13d $r14d $r15d $r12w $r13w $r14w $r15w $r12wh and 3 more...>, implicit $rsp, implicit $ssp, implicit $rdi, implicit $rsi, implicit $rdx, implicit-def $rsp, implicit-def $ssp, implicit-def $fp0
>   ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
>   %118:rfp80 = COPY $fp0
>   %13:rfp80 = nofpexcept LD_Fp080 implicit-def dead $fpsw, implicit $fpcw

Are you running the large and small cases the same way? Have looked at the SelectionDAG debug logs for the affected basic block in the large case?

I was able to trigger the error with llc -O2 -fast-isel on a simple test. So that is a path to create this but you haven’t answered if fast isel is being used in your case.


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https://reviews.llvm.org/D104440