[llvm] [AMDGPU][SplitModule] Handle !callees metadata (PR #108802)

[Juan Manuel Martinez Caamaño via llvm-commits]

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@@ -476,12 +486,36 @@ void SplitGraph::Node::visitAllDependencies(
   }
 }
 
+/// Checks if \p I has MD_callees and if it does, parse it and put the function
+/// in \p Callees.
+///
+/// \returns true if there was metadata and it was parsed correctly. false if
+/// there was no MD or if it contained unknown entries.
+static bool handleCalleesMD(const Instruction &I,
+                            SmallVector<Function *> &Callees) {
+  auto *MD = I.getMetadata(LLVMContext::MD_callees);
+  if (!MD)
+    return false;
+
+  for (const auto &Op : MD->operands()) {
+    Function *Callee = mdconst::extract_or_null<Function>(Op);
+    if (!Callee)
+      return false;
+    Callees.push_back(Callee);
+  }
+
+  return true;
+}
+
 void SplitGraph::buildGraph(CallGraph &CG) {
   SplitModuleTimer SMT("buildGraph", "graph construction");
   LLVM_DEBUG(
       dbgs()
       << "[build graph] constructing graph representation of the input\n");
 
+  // FIXME(?): Is the callgraph really worth using if we have to iterate the
+  // function again whenever it fails to give us enough information?
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jmmartinez wrote:

> You're giving the callgraph a bit too much credit :)

:*(

https://github.com/llvm/llvm-project/pull/108802