[PATCH] D40864: [Darwin] Add a new -mstack-probe option and enable by default

[Akira Hatanaka via Phabricator via cfe-commits]

ahatanak added inline comments.


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Comment at: lib/CodeGen/BackendUtil.cpp:442
   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
+  Options.EnableStackProbe = CodeGenOpts.StackProbe;
 
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aemerson wrote:
> ahatanak wrote:
> > Is there a reason you can't use function attributes "probe-stack"="___chkstk_darwin" and "stack-probe-size"=4096 instead of setting a TargetOptions flag here? If you intend to use stack probing with LTO, I think you need function attributes. Also, it looks like that would simplify the changes made to X86 backend.
> I don't think there's any reason not to. Is it worth specifying the probe size itself given that it'll be a known fixed value? It could be misleading to give a probe size which only has a single valid value for Darwin.
If 4096B is the only valid size for Darwin and the default size is 4096B in the backend, you can just add attribute "probe-stack"="___chkstk_darwin" to the function.  The backend can check the existence of the attribute and decide whether to enable stack-probing.


Repository:
  rC Clang

https://reviews.llvm.org/D40864