[PATCH] D39210: Add default calling convention support for regcall.

Elizabeth Andrews via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Wed Oct 25 11:00:49 PDT 2017

eandrews added inline comments.

Comment at: lib/Sema/SemaType.cpp:3269-3273
+  bool IsMain = false;
+  if (D.getIdentifier() && D.getIdentifier()->isStr("main") &&
+      S.CurContext->getRedeclContext()->isTranslationUnit() &&
+      !S.getLangOpts().Freestanding)
+    IsMain = true;
erichkeane wrote:
> rnk wrote:
> > erichkeane wrote:
> > > rnk wrote:
> > > > I highly doubt this is correct. I have a feeling there are all kinds of ways you can get this to fire on things that aren't a function declaration. It's also inefficient to check the identifier string every time we make a function type. Please find somewhere else to add this. I'd suggest adjusting the function type in CheckMain, or some time before then, whereever we make main implicitly extern "C".
> > > I believe the logic here was pulled from FunctionDecl's "isMain" function: https://clang.llvm.org/doxygen/classclang_1_1FunctionDecl.html#aa2b31caf653741632b16cce1ae2061cc
> > > 
> > > As this is so early in the process (at Declarator), I didn't see a good place to recommend extracting this, besides pulling it into the Declarator.  
> > > 
> > > CheckMain is also run at the Decl stage, isn't it?  Is your suggestion be to simply let this go through with the wrong calling-convention here, then revert it it in "CheckMain"?
> > Yep. You can look at how we use FunctionTypeUnwrapper and ASTContext::adjustFunctionType in various places to fix up function types that were built with the wrong calling convention without losing type source info.
> Perfect, thanks for the examples!  I am sure @eandrews can use those to track down the right place to fix this up.
Thanks for the review! I've updated the patch. Please take a look.


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