[clang] [Clang][Driver] Add new flags to control IR verification (PR #68172)

[Matheus Izvekov via cfe-commits]

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@@ -146,6 +146,13 @@ Non-comprehensive list of changes in this release
 
 New Compiler Flags
 ------------------
+* ``-fverify-intermediate-code`` and it's complement ``-fno-verify-intermediate-code``.
+  Enables or disables verification of the generated LLVM IR.
+  It's strongly encouraged to enable this verification, as it can catch hard to
+  find code generation bugs.
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mizvekov wrote:

FWIW, I am proposing this recommendation based on these numbers: https://llvm-compile-time-tracker.com/compare.php?from=634c0f8ea4acd0694d89c3e2d278e6bcb78b923f&to=49da7e1de6348f1c67a952e9cfea93abe920c4d5&stat=instructions:u

It 'feels' to me like to me that cost is high enough that we shouldn't force enable it for simplicity, not even make it opt-out, because will take folks by surprise, but it's not really high enough that I wouldn't feel comfortable strongly recommending they try it.

https://github.com/llvm/llvm-project/pull/68172