[PATCH] D123799: [RISCV] Mark FSIN and other math functions as Expand for scalable vectors.

[Liao Chunyu via Phabricator via llvm-commits]

liaolucy added a comment.
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In D123799#3457920 <https://reviews.llvm.org/D123799#3457920>, @craig.topper wrote:

> In D123799#3457909 <https://reviews.llvm.org/D123799#3457909>, @liaolucy wrote:
>
>> I would like to ask a question:
>>
>> What are the benefits of illegal costs?  Is there a problem that illegal costs are trying to solve?
>
> It prevents the vectorizer from creating llvm.sin, etc. with scalable vector types since they will crash in the backend.

Thank Craig , I get the crash today.

This patch fix tsvc s451 crash.

  fatal error: error in backend: Cannot select: t12: nxv2f32 = fsin nnan ninf nsz arcp contract afn reassoc t7
    t7: nxv2f32,ch = load<(load unknown-size from %ir.uglygep51, align 16, !tbaa !4)> t0, t4, undef:i64
      t4: i64 = add t3, t81
        t3: i64,ch = CopyFromReg t0, Register:i64 %12
          t2: i64 = Register %12
        t81: i64 = ADDI t80, TargetGlobalAddress:i64<ptr @b> 0 [TF=3]
          t80: i64 = LUI TargetGlobalAddress:i64<ptr @b> 0 [TF=4]
            t78: i64 = TargetGlobalAddress<ptr @b> 0 [TF=4]
          t79: i64 = TargetGlobalAddress<ptr @b> 0 [TF=3]
      t6: i64 = undef
  In function: s451


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