[PATCH] D66942: [DebugInfo] LiveDebugValues: locations with different exprs should compare differently

Mon Sep 2 07:14:50 PDT 2019

jmorse marked an inline comment as done.
jmorse added inline comments.

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Comment at: lib/CodeGen/LiveDebugValues.cpp:196
+    /// The (potentially complex) expression applied to this location.
+    const DIExpression *Expr;
+
----------------
jmorse wrote:
> aprantl wrote:
> > Do you need to store this here, or could you derive it from MI below?
> It could be either; the comment on line 211 indicates past concern about repeatedly accessing MI when comparing VarLocs. I'll give both options a spin through an asan build of clang-3.4 to see if there's any real difference.
There are only fractional performance differences between {unpatched, this patch, expr-derived-from-MI} clang-trunk when building clang-3.4 with asan. Typically <0.5%, which is more or less the margin of error on my machines. So, it could be either.

Repository:
  rL LLVM

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  https://reviews.llvm.org/D66942/new/

https://reviews.llvm.org/D66942