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

Sat Jun 19 22:37:24 PDT 2021

LuoYuanke added a comment.

> 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

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D104440/new/

https://reviews.llvm.org/D104440