[llvm] [VPlan] Model first memory runtime checks as VPlan recipes. (PR #221483)

[Florian Hahn via llvm-commits]

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@@ -1541,13 +1494,55 @@ void VPlanTransforms::attachCheckBlock(VPlan &Plan, Value *Cond,
   attachVPCheckBlock(Plan, CondVPV, CheckBlockVPBB, AddBranchWeights);
 }
 
+void VPlanTransforms::addMemoryRuntimeChecks(
+    VPlan &Plan, ArrayRef<RuntimePointerCheck> Checks, ScalarEvolution &SE,
+    DebugLoc DL, bool AddBranchWeights) {
+  assert(!Checks.empty() && "no checks to replace the pre-built block with");
+
+  auto *MemCheckVPBB = Plan.createVPBasicBlock("vector.memcheck");
+  VPBuilder Builder(MemCheckVPBB);
+  insertCheckBlockBeforeVectorLoop(Plan, MemCheckVPBB);
+  VPSCEVExpander Expander(Builder, SE, DL);
+
+  // Expand each group's bounds once and up front.
+  SmallDenseMap<const RuntimeCheckingPtrGroup *,
+                std::pair<VPValue *, VPValue *>>
+      GroupToBounds;
+  for (const auto &[A, B] : Checks)
+    for (const RuntimeCheckingPtrGroup *CG : {A, B}) {
+      if (GroupToBounds.contains(CG))
+        continue;
+      VPValue *Start = Expander.expand(CG->Low);
+      VPValue *End = Expander.expand(CG->High);
+      if (CG->NeedsFreeze) {
+        Start = Builder.createFreeze(Start, DL);
+        End = Builder.createFreeze(End, DL);
+      }
+      GroupToBounds.try_emplace(CG, Start, End);
+    }
+
+  VPValue *Cond = nullptr;
+  for (const auto &[A, B] : Checks) {
+    auto [AStart, AEnd] = GroupToBounds.at(A);
+    auto [BStart, BEnd] = GroupToBounds.at(B);
+    VPValue *Bound0 =
+        Builder.createICmp(CmpInst::ICMP_ULT, AStart, BEnd, DL, "bound0");
+    VPValue *Bound1 =
+        Builder.createICmp(CmpInst::ICMP_ULT, BStart, AEnd, DL, "bound1");
+    VPValue *IsConflict =
+        Builder.createAnd(Bound0, Bound1, DL, "found.conflict");
+    Cond = Cond ? Builder.createOr(Cond, IsConflict, DL, "conflict.rdx")
+                : IsConflict;
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fhahn wrote:

updated, thanks

https://github.com/llvm/llvm-project/pull/221483