[clang] [Clang] Initialize bypassed variables w/ trivial-auto-var-init (PR #181937)

[Eli Friedman via cfe-commits]

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@@ -1544,8 +1544,12 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
       ShouldEmitLifetimeMarkers = true;
 
     // Initialize helper which will detect jumps which can cause invalid
-    // lifetime markers.
-    if (ShouldEmitLifetimeMarkers)
+    // lifetime markers or bypass trivial auto var init.
+    bool NeedsBypassDetection =
+        ShouldEmitLifetimeMarkers ||
+        (CGM.getLangOpts().getTrivialAutoVarInit() !=
+         LangOptions::TrivialAutoVarInitKind::Uninitialized);
+    if (NeedsBypassDetection)
       Bypasses.Init(CGM, Body);
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efriedma-quic wrote:

How expensive is just turning on bypass detection on its own, for code that rarely uses goto?  Maybe get an estimate from llvm-compile-time-tracker.com .

(This change will turn it on at -O0, which means it will basically always be on.)

https://github.com/llvm/llvm-project/pull/181937