[PATCH] D151883: [SDAG] Fix incorrect use of undef for boolean contents (PR63055)

[Nikita Popov via Phabricator via llvm-commits]

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FoldSetCC() returns UNDEF in a number of cases. However, the SetCC result must follow BooleanContents. Unless the type is a pre-legalization i1 or we have UndefinedBooleanContents, the use of UNDEF will not uphold the requirement that the top bits are either zero or match the low bit. In such cases, return zero instead.

Fixes https://github.com/llvm/llvm-project/issues/63055.


https://reviews.llvm.org/D151883

Files:
  llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  llvm/test/CodeGen/ARM/hoist-and-by-const-from-lshr-in-eqcmp-zero.ll
  llvm/test/CodeGen/ARM/hoist-and-by-const-from-shl-in-eqcmp-zero.ll
  llvm/test/CodeGen/X86/avx512-insert-extract.ll
  llvm/test/CodeGen/X86/setcc.ll

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