From b2b0db0c470eba512d358dcf3d359488083e82a8 Mon Sep 17 00:00:00 2001
From: Mike McLaughlin <mikem@microsoft.com>
Date: Fri, 26 Jul 2024 15:17:41 -0700
Subject: [PATCH] Fix SOS !dumpmt -md command (#105575)

* Fix SOS !dumpmt -md command

The new virtual method slot enumerator failed if any of the Precode slot values were not in
the dump. There are usually 2 or so that are invalid/not in dump but that should not stop/fail
the new enumeration DAC API.

Part of this is to make MethodTable::GetMethodDescForSlot_NoThrow not throw a read exception and
return a null MD.

* Code review feedback - move CATCH to request.cpp
---
 src/coreclr/debug/daccess/request.cpp | 33 ++++++++++++++++++---------
 src/coreclr/vm/method.cpp             |  5 ++--
 2 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/src/coreclr/debug/daccess/request.cpp b/src/coreclr/debug/daccess/request.cpp
index b4de3332da23f7..33a8ad66354359 100644
--- a/src/coreclr/debug/daccess/request.cpp
+++ b/src/coreclr/debug/daccess/request.cpp
@@ -490,20 +490,31 @@ ClrDataAccess::GetMethodTableSlotEnumerator(CLRDATA_ADDRESS mt, ISOSMethodEnum *
 
 HRESULT DacMethodTableSlotEnumerator::Init(PTR_MethodTable mTable)
 {
-    unsigned int slot = 0;
-
     WORD numVtableSlots = mTable->GetNumVtableSlots();
-    while (slot < numVtableSlots)
+    for (WORD slot = 0; slot < numVtableSlots; slot++)
     {
-        MethodDesc* pMD = mTable->GetMethodDescForSlot_NoThrow(slot);
-        SOSMethodData methodData = {0};
-        methodData.MethodDesc = HOST_CDADDR(pMD);
-        methodData.Entrypoint = mTable->GetSlot(slot);
-        methodData.DefininingMethodTable = PTR_CDADDR(pMD->GetMethodTable());
-        methodData.DefiningModule = HOST_CDADDR(pMD->GetModule());
-        methodData.Token = pMD->GetMemberDef();
+        SOSMethodData methodData = {0, 0, 0, 0, 0, 0};
+        MethodDesc* pMD = nullptr;
+
+        EX_TRY
+        {
+            pMD = mTable->GetMethodDescForSlot_NoThrow(slot);
+        }
+        EX_CATCH
+        {
+        }
+        EX_END_CATCH(SwallowAllExceptions)
 
-        methodData.Slot = slot++;
+        if (pMD != nullptr)
+        {
+            methodData.MethodDesc = HOST_CDADDR(pMD);
+            methodData.DefininingMethodTable = PTR_CDADDR(pMD->GetMethodTable());
+            methodData.DefiningModule = HOST_CDADDR(pMD->GetModule());
+            methodData.Token = pMD->GetMemberDef();
+        }
+
+        methodData.Entrypoint = mTable->GetSlot(slot);
+        methodData.Slot = slot;
 
         if (!mMethods.Add(methodData))
             return E_OUTOFMEMORY;
diff --git a/src/coreclr/vm/method.cpp b/src/coreclr/vm/method.cpp
index 4f7e9d1cc825a9..d8313fdc965162 100644
--- a/src/coreclr/vm/method.cpp
+++ b/src/coreclr/vm/method.cpp
@@ -2624,7 +2624,7 @@ MethodDesc* MethodDesc::GetMethodDescFromStubAddr(PCODE addr, BOOL fSpeculative
     }
     CONTRACT_END;
 
-    MethodDesc *  pMD = NULL;
+    MethodDesc* pMD = NULL;
 
     // Otherwise this must be some kind of precode
     //
@@ -2633,10 +2633,9 @@ MethodDesc* MethodDesc::GetMethodDescFromStubAddr(PCODE addr, BOOL fSpeculative
     if (pPrecode != NULL)
     {
         pMD = pPrecode->GetMethodDesc(fSpeculative);
-        RETURN(pMD);
     }
 
-    RETURN(NULL); // Not found
+    RETURN(pMD);
 }
 
 //*******************************************************************************