From 38729a7086ae28e1bdd4f13b9500741c5a9920de Mon Sep 17 00:00:00 2001
From: Valentijn van de Beek <valentijn.vandebeek@amd.com>
Date: Mon, 13 May 2024 16:18:33 +0100
Subject: [PATCH] [GISel][CombinerHelper] Add a function that chains a list of
 generators together

---
 llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
index 102460631379..4cdd3d553eb4 100644
--- a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -399,6 +399,21 @@ adderGenerator(const int32_t From, const int32_t To, const int32_t StepSize) {
   };
 }
 
+// Move to the next generator if it is exhausted allowing to chain generators
+CombinerHelper::GeneratorType
+concatGenerators(SmallVector<CombinerHelper::GeneratorType> &Generators) {
+  auto *GeneratorIterator = Generators.begin();
+
+  return [GeneratorIterator, Generators]() mutable {
+    std::optional<int32_t> GenValue = (*GeneratorIterator)();
+    if (!GenValue.has_value() && GeneratorIterator != Generators.end()) {
+      GeneratorIterator++;
+      GenValue = (*GeneratorIterator)();
+    }
+    return GenValue;
+  };
+}
+
 Register CombinerHelper::createUnmergeValue(
     MachineInstr &MI, const Register SrcReg, const Register DstReg,
     const uint8_t DestinationIndex, const uint32_t Start, const uint32_t End) {