[lld] [lld][InstrProf] Profile guided function order (PR #96268)

[Ellis Hoag via llvm-commits]

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@@ -147,6 +147,14 @@ def cs_profile_path: Joined<["--"], "cs-profile-path=">,
 defm pgo_warn_mismatch: BB<"pgo-warn-mismatch",
   "turn on warnings about profile cfg mismatch (default)",
   "turn off warnings about profile cfg mismatch">, Group<grp_lld>;
+def profile_guided_function_order: Joined<["--"], "profile-guided-function-order=">,
+    MetaVarName<"<profile>">, 
+    HelpText<"Read traces from <profile> to order functions to improve startup time">,
+    Group<grp_lld>;
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ellishg wrote:

I like `--irpgo-profile-sort` because it aligns better with `--call-graph-profile-sort`. Thanks for the suggestion! In the future we may order data sections to improve startup, so `function` is not in the flag. When that happens, we may need to add another flag like `-irpgo-profile-sort-type={function,data,both}`. For now I'll leave this out.

https://github.com/llvm/llvm-project/pull/96268