Fix MonoException

Add DebugHandler to be able to collect labels info on begin instruction

Author: radekdoulik

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -633,6 +633,8 @@ bool AsmPrinter::doInitialization(Module &M) {
   if (EnableMonoEH) {
       MonoException *mono_eh = new MonoException (this, DisableGNUEH);
       Handlers.push_back(std::unique_ptr<MonoException> (mono_eh));
+      MonoExceptionDebugHandler *mono_eh_dbg = new MonoExceptionDebugHandler(this, mono_eh);
+      addDebugHandler(std::unique_ptr<MonoExceptionDebugHandler> (mono_eh_dbg));
   }
 
   return false;

llvm/lib/CodeGen/AsmPrinter/MonoException.cpp

@@ -652,3 +652,27 @@ MonoException::endModule()
   streamer.emitLabel(tableEndSym);
   Asm->emitAlignment(llvm::Align(8));
 }
+
+MonoExceptionDebugHandler::MonoExceptionDebugHandler(AsmPrinter *A, MonoException *ME)
+  : DebugHandlerBase(A), me(ME)
+{
+}
+
+void
+MonoExceptionDebugHandler::beginInstruction(const MachineInstr *MI)
+{
+       if (MI->getOpcode() == TargetOpcode::CFI_INSTRUCTION) {
+               unsigned CFIIndex = MI->getOperand(0).getCFIIndex();
+
+               //outs () << "D: " << CFIIndex << " " << EHLabels.size() << "\n";
+
+               /* Emit a label and save the label-cfi index association */
+               if (CFIIndex != me->EHLabels.size())
+                       assert (0);
+
+               MCSymbol *Label = Asm->OutContext.createTempSymbol();
+               Asm->OutStreamer->emitLabel(Label);
+
+               me->EHLabels.push_back(Label);
+       }
+}

llvm/lib/CodeGen/AsmPrinter/MonoException.h

@@ -12,13 +12,12 @@
 
 #include "EHStreamer.h"
 #include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/DebugHandlerBase.h"
 
 namespace llvm {
 
 class TargetRegisterInfo;
 
-// TODO: we need to use DebugHandlerBase and addDebugHandler, so that beginInstruction is called
-// context https://github.com/llvm/llvm-project/pull/96785
 class MonoException : public EHStreamer {
 public:
   MonoException(AsmPrinter *A, bool disableGNUEH);
@@ -30,6 +29,8 @@ class MonoException : public EHStreamer {
 
   void endFunction(const MachineFunction *) override;
 
+  std::vector<MCSymbol*> EHLabels;
+
 private:
 
   struct MonoCallSiteEntry {
@@ -71,12 +72,28 @@ class MonoException : public EHStreamer {
   void EmitFnStart();
   void EmitFnEnd();
 
-  std::vector<MCSymbol*> EHLabels;
   std::vector<EHInfo> Frames;
   StringMap<int> FuncIndexes;
   const TargetRegisterInfo *RI;
   bool DisableGNUEH;
 };
+
+class MonoExceptionDebugHandler : public DebugHandlerBase {
+
+  public:
+
+    MonoExceptionDebugHandler(AsmPrinter *A, MonoException* ME);
+
+    void beginInstruction(const MachineInstr *MI) override;
+
+    void beginFunctionImpl(const MachineFunction *MF) override {}
+    void endFunctionImpl(const MachineFunction *MF) override {}
+    void endModule() override {}
+
+    private:
+      MonoException* me;
+};
+
 } // End of namespace llvm
 
 #endif