[all-commits] [llvm/llvm-project] 156ba8: [SelectionDAG] Fix crash scalarizing `FLDEXP` with...

[Akash Manna via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 156ba8d3015afb36aa16831dfcac1ea229db85aa
      https://github.com/llvm/llvm-project/commit/156ba8d3015afb36aa16831dfcac1ea229db85aa
  Author: Akash Manna <akash.manna.mymail at gmail.com>
  Date:   2026-09-28 (Mon, 28 Sep 2026)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
    M llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
    M llvm/test/CodeGen/AArch64/ldexp.ll
    M llvm/test/CodeGen/X86/ldexp-avx512.ll
    M llvm/test/CodeGen/X86/ldexp.ll

  Log Message:
  -----------
  [SelectionDAG] Fix crash scalarizing `FLDEXP` with a legal `<1 x i1>` exponent (#224809)

Fixes #219695

When the result of an `FLDEXP` node is scalarized, we went through the
generic `ScalarizeVecRes_BinOp` handler, which asks for the scalarized
form of both operands. That only works when both operands share the
result's type action. `ldexp` is not a true binop: its exponent has its
own integer vector type, and under AVX-512 `<1 x i1>` is a legal mask
type. It was never scalarized, so it never made it into the table, and
the lookup hit `TableId should be non-zero`. It isn't specific to i1
either: on AArch64, `ldexp <1 x half>, <1 x i32>` hits the same assert
because `v1f16` is scalarized while `v1i32` is widened.

`FLDEXP` now has its own scalarization handler. The FP operand is
scalarized as before, while the exponent is legalized according to its
own type action: its scalarized value is used when one exists, otherwise
the single element is extracted from the vector. This is the same
approach `ScalarizeVecRes_UnaryOp` and `ScalarizeVecRes_SETCC` already
take for operands that don't need scalarizing, and mirrors what
`SplitVecRes_FPOp_MultiType` does for the split case.



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