[llvm] [VPlan] Introduce scalar loop header in plan, remove VPLiveOut. (PR #109975)

[via llvm-commits]

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@@ -41,7 +41,11 @@ TEST(VPDominatorTreeTest, DominanceNoRegionsTest) {
   VPBlockUtils::connectBlocks(VPBB3, VPBB4);
 
   auto TC = std::make_unique<VPValue>();
-  VPlan Plan(VPPH, &*TC, VPBB0);
+  LLVMContext C;
+  auto ScalarHeader = std::make_unique<BasicBlock *>(BasicBlock::Create(C, ""));
+  VPIRBasicBlock *ScalarHeaderVPBB = new VPIRBasicBlock(*ScalarHeader);
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ayalz wrote:

Ah, right, ok.
Perhaps worth connecting ScalarHeaderVPBB to the other VPBB's and have it participate in dominance checks.

https://github.com/llvm/llvm-project/pull/109975