[clang] [Clang] Enable -fextend-lifetimes at -Og (PR #118026)

[Jeremy Morse via cfe-commits]

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@@ -4298,6 +4298,26 @@ def stack_usage_file : Separate<["-"], "stack-usage-file">,
   Visibility<[CC1Option]>,
   HelpText<"Filename (or -) to write stack usage output to">,
   MarshallingInfoString<CodeGenOpts<"StackUsageOutput">>;
+def fextend_variable_liveness_EQ : Joined<["-"], "fextend-variable-liveness=">,
+  Group<f_Group>, Visibility<[ClangOption, CC1Option]>,
+  HelpText<"Extend the liveness of user variables through optimizations to "
+           "prevent stale or optimized-out variable values when debugging. Can "
+           "be applied to all user variables, or just to the C++ 'this' ptr. "
+           "May choose not to extend the liveness of some variables, such as "
+           "non-scalars larger than 4 unsigned ints, or variables in any "
+           "inlined functions.">,
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jmorse wrote:

Are there other compiler flags which have such long help-text? IIRC this is a super-short summary that appears on the command line with --help, and thus conciseness is key. Developers looking for more information will go to the full docs.

https://github.com/llvm/llvm-project/pull/118026