[PATCH] D61970: [CodeGen][ObjC] Call objc_autoreleaseReturnValue and objc_retainAutoreleasedReturnValue instead of objc_autorelease and objc_retain in MRR

[Akira Hatanaka via Phabricator via cfe-commits]

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


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Comment at: lib/CodeGen/CGObjC.cpp:2611
+  if (!CGM.getCodeGenOpts().ObjCNoBuiltinRetainRelease && !getInvokeDest())
+    return EmitARCRetainAutoreleasedReturnValue(value, returnType);
   return emitObjCValueOperation(
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rjmccall wrote:
> Same question: won't this make it significantly more difficult to detect when we're generating bad code?  And the overhead here (on every retain in MRC!) is pretty significant; shouldn't this at least be restricted to situations where it's plausible that it might be reclaiming something, like when the receiver expression is a function call of some sort?
As I mentioned in my response to David's question, I was thinking the ARC optimizer would be able to convert an `objc_retainAutoreleasedReturnValue` call to an `objc_retain` call. However, after reading your comment in https://reviews.llvm.org/D61970, I don't think it's okay to use the ARC optimizer to transform code that was compiled in MRR mode.


Repository:
  rC Clang

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D61970/new/

https://reviews.llvm.org/D61970