Add a 'mono.this' custom metadata, this is used to mark an 'alloca' w…

…hose associated stack slot index will be saved in MachineFunction, and later can be saved in the mono specific EH tables.
directhex · Mar 26, 2022 · d8126bd · d8126bd
1 parent 8d01bed
commit d8126bd
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diff --git a/llvm/include/llvm/CodeGen/MachineFunction.h b/llvm/include/llvm/CodeGen/MachineFunction.h
@@ -390,6 +390,9 @@ class LLVM_EXTERNAL_VISIBILITY 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;
@@ -600,6 +603,9 @@ class LLVM_EXTERNAL_VISIBILITY MachineFunction {
 
   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
@@ -211,6 +211,8 @@ 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
@@ -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