[all-commits] [llvm/llvm-project] 6fcb1c: [LoongArch] Fix assertion failure for annotate tab...

[hev via All-commits]

  Branch: refs/heads/release/20.x
  Home:   https://github.com/llvm/llvm-project
  Commit: 6fcb1c127b407cd6cb731bcc39efb360643b8d25
      https://github.com/llvm/llvm-project/commit/6fcb1c127b407cd6cb731bcc39efb360643b8d25
  Author: hev <wangrui at loongson.cn>
  Date:   2025-05-23 (Fri, 23 May 2025)

  Changed paths:
    M llvm/lib/Target/LoongArch/LoongArchAsmPrinter.cpp
    M llvm/lib/Target/LoongArch/LoongArchExpandPseudoInsts.cpp
    M llvm/lib/Target/LoongArch/LoongArchMachineFunctionInfo.h

  Log Message:
  -----------
  [LoongArch] Fix assertion failure for annotate tablejump (#140907)

Fix a use-after-free issue related to annotateTableJump in the LoongArch
target.

Previously, `LoongArchPreRAExpandPseudo::annotateTableJump()` recorded a
reference to a MachineOperand representing a jump table index. However,
later optimizations such as the `BranchFolder` pass may delete the
instruction containing this operand, leaving a dangling reference.

This led to an assertion failure in
`LoongArchAsmPrinter::emitJumpTableInfo()` when trying to access a freed
MachineOperand via `getIndex()`.

The fix avoids holding a reference to the MachineOperand. Instead, we
extract and store the jump table index at the time of annotation. During
`emitJumpTableInfo()`, we verify whether the recorded index still exists
in the MachineFunction's jump table. If not, we skip emission for that
entry.

Fixes #140904

(cherry picked from commit 4e186f20e2f2be2fbf95d9713341a0b6507e707d)



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