[clang] [LLVM] Add new attribute `optdebug` to optimize for debugging (PR #66632)

[David Blaikie via cfe-commits]

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@@ -2028,6 +2030,8 @@ example:
     This attribute suggests that optimization passes and code generator passes
     should make choices that try to preserve debug info without significantly
     degrading runtime performance.
+    This attribute is incompatible with the ``minsize``, ``optsize``, and
+    ``optnone`` attributes.
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dwblaikie wrote:

Looks like this could be committed separately.

https://github.com/llvm/llvm-project/pull/66632