Add a 'mono.this' custom metadata, this is used to mark an 'alloca' whose associated stack slot index will be saved in MachineFunction, and later can be saved in the mono specific EH tables.

3 files changed, 19 insertions, 0 deletions

diff --git a/llvm/include/llvm/CodeGen/MachineFunction.h b/llvm/include/llvm/CodeGen/MachineFunction.h
index 809c21dd26fc..4664d86e3f3e 100644
--- a/llvm/include/llvm/CodeGen/MachineFunction.h
+++ b/llvm/include/llvm/CodeGen/MachineFunction.h
@@ -371,6 +371,9 @@ class MachineFunction {
   /// \pre Fn, Target, MMI, and FunctionNumber are properly set.
   void init();
 
+  // Stack slot containing the this pointer for mono compiled functions
+  int MonoThisSlot;
+
 public:
   struct VariableDbgInfo {
     const DILocalVariable *Var;
@@ -476,6 +479,9 @@ public:
 
   PseudoSourceValueManager &getPSVManager() const { return *PSVManager; }
 
+  int getMonoThisSlot() const { return MonoThisSlot; }
+  void setMonoThisSlot(int Slot) { MonoThisSlot = Slot; }
+
   /// Return the DataLayout attached to the Module associated to this MF.
   const DataLayout &getDataLayout() const;
 
diff --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index 6d45f08804ed..e8248263b278 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -205,6 +205,8 @@ void MachineFunction::init() {
   PSVManager =
     std::make_unique<PseudoSourceValueManager>(*(getSubtarget().
                                                   getInstrInfo()));
+
+  MonoThisSlot = -1;
 }
 
 MachineFunction::~MachineFunction() {
diff --git a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index 5cf83cff3a90..f1d6de2de18c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -184,6 +184,17 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
             for (int *CatchObjPtr : Iter->second)
               *CatchObjPtr = FrameIndex;
           }
+
+          //
+          // The mono exception handling code needs to location of the 'this' pointer
+          // to handle stack traces containing generic shared methods.
+          // To implement this, it saves the this pointer to an alloca which is marked with
+          // the 'mono.this' custom metadata. We save the stack slot used by this alloca
+          // in MachineFunction, so the dwarf exception info emission code can use it to
+          // compute the reg+offset for it, and save it into the LSDA.
+          //
+          if (AI->getMetadata("mono.this"))
+            MF->setMonoThisSlot(StaticAllocaMap[AI]);
         } else {
           // FIXME: Overaligned static allocas should be grouped into
           // a single dynamic allocation instead of using a separate