[llvm] [llvm-exegesis] Error instead of aborting on verification failure (PR #137581)

[Min-Yih Hsu via llvm-commits]

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@@ -323,10 +324,8 @@ Error assembleToStream(const ExegesisTarget &ET,
   TPC->printAndVerify("After ExegesisTarget::addTargetSpecificPasses");
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mshockwave wrote:

Right, I was thinking about replacing `TPC->printAndVerify(...)` with manual MachineFunction verification like you did in line 340. But I don't have a strong opinion on this.

> and the checks need to be explicitly enabled by the user on the command line

Just FYI I think `LLVM_ENABLE_EXPENSIVE_CHECKS` will also enable those by default. 

https://github.com/llvm/llvm-project/pull/137581