[PATCH] D35974: AMDGPU: Add pass to replace out arguments

Matt Arsenault via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu Jul 27 22:50:13 PDT 2017

arsenm added inline comments.

Comment at: lib/Target/AMDGPU/AMDGPURewriteOutArguments.cpp:300
+  RetAttrs.addAttribute(Attribute::NoAlias);
+  NewFunc->removeAttributes(AttributeList::ReturnIndex, RetAttrs);
+  // TODO: How to preserve metadata?
rampitec wrote:
> arsenm wrote:
> > rampitec wrote:
> > > arsenm wrote:
> > > > rampitec wrote:
> > > > > Consider also marking it always inline.
> > > > The stub function is marked as always inline. The new function here steals the body of the old function, the original function is then marked always inline
> > > I mean stub gets original attributes. The new function gets original attributes + always inline. That way it will be always inlined into stub if otherwise not simplified. I.e. if at the end call to a stub will not be replaced with a call to the new function we will have no extra call.
> > > 
> > > You can also check the heuristic isWrapperOnlyCall() in the AMDInline.cpp from HSAIL, which basically implements the same logic: inline everything into a wrapper/stub.
> > This is what happens, it's just mechanically the original IR function becomes the stub
> If the original had no always inline, new will not get it either. In a worst case we can end up with two calls.
Line 367


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