Use stack peeling instead of PCTAddr check; re-add optimization for EECodeManager::UnwindStackFrame

Author: filipnavara

src/coreclr/vm/eetwain.cpp

@@ -1189,6 +1189,30 @@ bool EECodeManager::UnwindStackFrame(PREGDISPLAY     pContext,
         SUPPORTS_DAC;
     } CONTRACTL_END;
 
+#ifdef FEATURE_EH_FUNCLETS
+    if (pContext->IsCallerContextValid)
+    {
+        // We already have the caller's frame context
+        // We just switch the pointers
+        PT_CONTEXT temp           = pContext->pCurrentContext;
+        pContext->pCurrentContext = pContext->pCallerContext;
+        pContext->pCallerContext  = temp;
+
+        PT_KNONVOLATILE_CONTEXT_POINTERS tempPtrs = pContext->pCurrentContextPointers;
+        pContext->pCurrentContextPointers         = pContext->pCallerContextPointers;
+        pContext->pCallerContextPointers          = tempPtrs;
+
+        SyncRegDisplayToCurrentContext(pContext);
+
+        pContext->PCTAddr = pContext->SP - GetStackParameterSize(pCodeInfo) - sizeof(DWORD);
+
+        pContext->IsCallerContextValid = FALSE;
+        pContext->IsCallerSPValid      = FALSE;        // Don't add usage of this field.  This is only temporary.
+
+        return true;
+    }
+#endif
+
     bool updateAllRegs = flags & UpdateAllRegs;
 
     // Address where the method has been interrupted

src/coreclr/vm/threadsuspend.cpp

@@ -4783,16 +4783,9 @@ StackWalkAction SWCB_GetExecutionState(CrawlFrame *pCF, VOID *pData)
 #endif
                         }
 #elif defined(TARGET_X86)
-                        if (pRDT->PCTAddr == 0)
-                        {
-                            // Initial context doesn't have PCTAddr so we have to compute it
-                            EECodeInfo codeInfo(pRDT->ControlPC);
-                            pES->m_ppvRetAddrPtr = (void **) (EECodeManager::GetCallerSp(pRDT) - codeInfo.GetCodeManager()->GetStackParameterSize(&codeInfo) - sizeof(void*));
-                        }
-                        else
-                        {
-                            pES->m_ppvRetAddrPtr = (void **) pRDT->PCTAddr;
-                        }
+                        // peel off the next frame to expose the return address on the stack
+                        pES->m_FirstPass = FALSE;
+                        action = SWA_CONTINUE;
 #elif defined(TARGET_AMD64)
                         pES->m_ppvRetAddrPtr = (void **) (EECodeManager::GetCallerSp(pRDT) - sizeof(void*));
 #else // TARGET_X86 || TARGET_AMD64