[all-commits] [llvm/llvm-project] 62a967: [RISCV] Return nullptr for PHI defs in VSETVLIInfo...

[Luke Lau via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 62a967d5dc056875423351309aaa52e520984eed
      https://github.com/llvm/llvm-project/commit/62a967d5dc056875423351309aaa52e520984eed
  Author: Luke Lau <luke at igalia.com>
  Date:   2024-07-02 (Tue, 02 Jul 2024)

  Changed paths:
    M llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
    M llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.ll

  Log Message:
  -----------
  [RISCV] Return nullptr for PHI defs in VSETVLIInfo::getAVLDefMI (#97395)

When checking if a VSETVLIInfo is compatible, we call hasEquallyZeroAVL
if only the AVL-zeroness is demanded. This will try to lookup the
defining MachineInstr (to check if it's an ADDI immediate) via
getAVLDefMI, but in it we were asserting that the VSETVLIInfo's AVL
wouldn't come from a phi. It turns out this can happen in normal
circumstances.

This causes a crash when compiling highway, so this fixes it by relaxing
the assertion.



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