[PATCH] D100118: [clang] RFC Support new builtin __arithmetic_fence to control floating point optimization, and new clang option fprotect-parens

[Kevin P. Neal via Phabricator via cfe-commits]

kpn added inline comments.


================
Comment at: clang/lib/CodeGen/CGBuiltin.cpp:2844
+      return RValue::get(
+          Builder.CreateArithmeticFence(ArgValue, ConvertType(ArgType)));
+    return RValue::get(ArgValue);
----------------
Does this say that the fence will be silently dropped if any of the fast math flags are disabled? Silently dropping something used for correctness makes me nervous. Is there a case where all of these flags are required for correct behavior of the fence?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D100118/new/

https://reviews.llvm.org/D100118