[llvm] [VPlan] Implement cloning of VPlans. (PR #73158)

[via llvm-commits]

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@@ -615,6 +615,18 @@ void VPBasicBlock::print(raw_ostream &O, const Twine &Indent,
 }
 #endif
 
+VPBlockBase *VPRegionBlock::clone() {
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ayalz wrote:

Should Region::clone() deal only with cloning its blocks, recursively, w/o remapping any VPValues, similar to VPBB::clone()? To be followed by a single deep scan over all VPBB's of VPlan to map VPValues, fully, once. Otherwise a region nested within another will undergo multiple remappings of its VPValues.

https://github.com/llvm/llvm-project/pull/73158