[llvm] [update_mir_test_checks] Precommit test for multiple defs of vreg (PR #66482)

[Nikita Popov via llvm-commits]

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+## Check that update_mir_test_checks handles multiple definitions of the same
+## virtual register (after coming out of SSA form).
+
+# RUN: cp -f %S/Inputs/multiple-defs.mir %t.mir && %update_mir_test_checks %t.mir
+# RUN: FileCheck %t.mir < %t.mir
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nikic wrote:

We normally check the expected generated check lines using diff instead.

https://github.com/llvm/llvm-project/pull/66482