Introduce ABIAnalyses2

Architecture-agnostic and ABI-independent data-flow analyses that
traverse the recovered functions in order to detect arguments and
return values registers.

lib/StackAnalysis/ABIAnalyses/UsedReturnValuesOfFunction.cpp

@@ -0,0 +1,61 @@
+//
+// This file is distributed under the MIT License. See LICENSE.md for details.
+//
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Support/Casting.h"
+
+#include "revng/MFP/MFP.h"
+#include "revng/Support/revng.h"
+
+#include "Analyses.h"
+
+namespace ABIAnalyses::UsedReturnValuesOfFunction {
+using namespace llvm;
+using namespace ABIAnalyses;
+
+std::map<const GlobalVariable *, State>
+analyze(const BasicBlock *ReturnBlock, const GeneratedCodeBasicInfo &GCBI) {
+  using MFI = MFIAnalysis<false, CoreLattice>;
+
+  MFI Instance{ { GCBI } };
+  MFI::LatticeElement InitialValue;
+  MFI::LatticeElement ExtremalValue(CoreLattice::ExtremalLatticeElement);
+
+  auto Res = MFP::getMaximalFixedPoint<MFI, MFI::GT, MFI::LGT>(Instance,
+                                                               ReturnBlock,
+                                                               InitialValue,
+                                                               ExtremalValue,
+                                                               { ReturnBlock },
+                                                               { ReturnBlock });
+
+  DenseSet<const GlobalVariable *> RegUnknown{};
+  std::map<const GlobalVariable *, State> RegYesOrDead{};
+
+  for (auto &[BB, Result] : Res) {
+    for (auto &[GV, RegState] : Result.OutValue) {
+      if (RegState == CoreLattice::Unknown) {
+        RegUnknown.insert(GV);
+      }
+    }
+  }
+
+  for (auto &[BB, Result] : Res) {
+    for (auto &[GV, RegState] : Result.OutValue) {
+      if (RegState == CoreLattice::YesOrDead && RegUnknown.count(GV) == 0) {
+        RegYesOrDead[GV] = State::YesOrDead;
+      }
+    }
+  }
+
+  return RegYesOrDead;
+}
+} // namespace ABIAnalyses::UsedReturnValuesOfFunction