[PATCH] D57931: [GISel]: While constructing the GISelWorklist make sure we reserve at least the required size to the underlying dense map.

[Aditya Nandakumar via Phabricator via llvm-commits]

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


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Comment at: include/llvm/CodeGen/GlobalISel/GISelWorkList.h:32
 class GISelWorkList {
   SmallVector<MachineInstr *, N> Worklist;
   DenseMap<MachineInstr *, unsigned> WorklistMap;
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arsenm wrote:
> aditya_nandakumar wrote:
> > arsenm wrote:
> > > If this matters, should this even be a SmallVector?
> > Could you elaborate? Are you implying we replace this with something else (std::vector) or implying that the template parameter is probably not needed and we can always runtime reserve the size once..
> Yes, if this is is big, there's no reason for the reserved small size so std::vector
I thought I'd run some numbers just to be sure (the 512 number we use in most places is quite arbitrary) - however we do use the GISelWorkList in some passes (out of tree) for collecting some intermediate instructions, and it's set to 16 (and we avoid heap).
Either way, I can change that (and add the interface to reserve) in a subsequent patch.


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