[PATCH] D109441: [FuncSpec] Don't specialise call sites that have the MinSize attribute set

[Chuanqi Xu via Phabricator via llvm-commits]

ChuanqiXu added inline comments.


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Comment at: llvm/lib/Transforms/IPO/FunctionSpecialization.cpp:659
       auto &CS = *cast<CallBase>(U);
+      if (CS.hasFnAttr(Attribute::MinSize))
+        continue;
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snehasish wrote:
> If I understand correctly this should only disallow specialization of this callsite as opposed to the function if any callsite is marked minsize. This is aligned with the intent of minsize applied at the callsite. Do we need to add a similar check to rewriteCallSites?
It is an interesting question that if the attribute marked on callsite should be applied to callee function. Since it is possible that there is an attribute in callsite only. So here is the decision point:
- if the attribute marked on callsite should be applied to callee function. We should decide to not specialize the function once we found that there is callsite of it marked as `MinSize`.
- if the attribute marked on callsite could not be applied to callee function. I think current implementation is right. A question is that should we add a similar check in `rewriteCallSites `. I think we can omit it. Since once the function get specialized, replace the corresponding callsite wouldn't enlarge the size any more.

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Another funny question is that if the attribute marked on callsite should be applied to callee function. How should we consider indirect call. I mean, once we found an indirect call with specific attribute, should we do alias analysis to check how many functions should this indirect call could be?


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  https://reviews.llvm.org/D109441/new/

https://reviews.llvm.org/D109441