Improve collided exception performance

With the new EH enabled, one exception handling performance test has
regressed while all other improved dramatically. I have investigated the
test case and it turned out that the regression is due to the way we
unwind during second pass when we have an exception that occured in a
catch or finally funclet call chain and escaped it.
What we do is that we unwind stack until we reach the parent stack frame
of the catch / finally and then continue searching for handlers.
The NativeAOT that the new EH is based on doesn't unwind stack though,
it just moves the current stack frame iterator to the position of the
previous exception's stack frame iterator by copying its state.
I have applied the same mechanism to the new EH in coreclr and it
improved the performance of that test 3-4 times on my machine.

src/coreclr/vm/exceptionhandling.cpp

@@ -8491,14 +8491,9 @@ extern "C" bool QCALLTYPE SfiNext(StackFrameIterator* pThis, uint* uExCollideCla
                             isCollided = true;
                             pExInfo->m_kind = (ExKind)((uint8_t)pExInfo->m_kind | (uint8_t)ExKind::SupersededFlag);
 
-                            // Unwind until we hit the frame of the prevExInfo
+                            // Unwind to the frame of the prevExInfo
                             ExInfo* pPrevExInfo = pThis->GetNextExInfo();
-                            do
-                            {
-                                retVal = MoveToNextNonSkippedFrame(pThis);
-                            }
-                            while ((retVal == SWA_CONTINUE) && !(pThis->GetFrameState() == StackFrameIterator::SFITER_FRAMELESS_METHOD && pThis->m_crawl.GetRegisterSet()->SP == pPrevExInfo->m_regDisplay.SP));
-                            _ASSERTE(retVal != SWA_FAILED);
+                            pThis->SkipTo(&pPrevExInfo->m_frameIter);
 
                             pThis->ResetNextExInfoForSP(pThis->m_crawl.GetRegisterSet()->SP);
                         }

src/coreclr/vm/stackwalk.cpp

@@ -1546,6 +1546,67 @@ BOOL StackFrameIterator::IsValid(void)
     return TRUE;
 } // StackFrameIterator::IsValid()
 
+#ifndef DACCESS_COMPILE
+//---------------------------------------------------------------------------------------
+//
+// Advance to the position that the other iterator is currently at.
+//
+void StackFrameIterator::SkipTo(StackFrameIterator *pOtherStackFrameIterator)
+{
+    // We copy the other stack frame iterator over the current one, but we need to
+    // keep a couple of members untouched. So we save them here and restore them
+    // after the copy.
+    ExInfo* pPrevExInfo = GetNextExInfo();
+    REGDISPLAY *pRD = m_crawl.GetRegisterSet();
+    GSCookie *pCurGSCookie = m_crawl.pCurGSCookie;
+    GSCookie *pFirstGSCookie = m_crawl.pFirstGSCookie;
+    Frame *pStartFrame = m_pStartFrame;
+#ifdef _DEBUG
+    Frame *pRealStartFrame = m_pRealStartFrame;
+#endif
+
+    *this = *pOtherStackFrameIterator;
+
+    m_pNextExInfo = pPrevExInfo;
+    m_crawl.pRD = pRD;
+    m_crawl.pCurGSCookie = pCurGSCookie;
+    m_crawl.pFirstGSCookie = pFirstGSCookie;
+    m_pStartFrame = pStartFrame;
+#ifdef _DEBUG
+    m_pRealStartFrame = pRealStartFrame;
+#endif
+
+    REGDISPLAY *pOtherRD = pOtherStackFrameIterator->m_crawl.GetRegisterSet();
+    *pRD->pCurrentContextPointers = *pOtherRD->pCurrentContextPointers;
+    SetIP(pRD->pCurrentContext, GetIP(pOtherRD->pCurrentContext));
+    SetSP(pRD->pCurrentContext, GetSP(pOtherRD->pCurrentContext));
+#if defined(TARGET_ARM) || defined(TARGET_ARM64)
+    SetLR(pRD->pCurrentContext, GetLR(pOtherRD->pCurrentContext));
+#elif defined(TARGET_RISCV64) || defined(TARGET_LOONGARCH64)
+    SetRA(pRD->pCurrentContext, GetRA(pOtherRD->pCurrentContext));
+#endif // TARGET_ARM || TARGET_ARM64
+#define CALLEE_SAVED_REGISTER(regname) pRD->pCurrentContext->regname = *pRD->pCurrentContextPointers->regname;
+    ENUM_CALLEE_SAVED_REGISTERS();
+#undef CALLEE_SAVED_REGISTER
+    pRD->IsCallerContextValid = pOtherRD->IsCallerContextValid;
+    if (pRD->IsCallerContextValid)
+    {
+        *pRD->pCallerContextPointers = *pOtherRD->pCallerContextPointers;
+        SetIP(pRD->pCallerContext, GetIP(pOtherRD->pCallerContext));
+        SetSP(pRD->pCallerContext, GetSP(pOtherRD->pCallerContext));
+#if defined(TARGET_ARM) || defined(TARGET_ARM64)
+        SetLR(pRD->pCallerContext, GetLR(pOtherRD->pCallerContext));
+#elif defined(TARGET_RISCV64) || defined(TARGET_LOONGARCH64)
+        SetRA(pRD->pCallerContext, GetRA(pOtherRD->pCallerContext));
+#endif // TARGET_ARM || TARGET_ARM64
+#define CALLEE_SAVED_REGISTER(regname) pRD->pCallerContext->regname = *pRD->pCallerContextPointers->regname;
+        ENUM_CALLEE_SAVED_REGISTERS();
+#undef CALLEE_SAVED_REGISTER
+    }
+    SyncRegDisplayToCurrentContext(pRD);
+}
+#endif // DACCESS_COMPILE
+
 //---------------------------------------------------------------------------------------
 //
 // Advance to the next frame according to the stackwalk flags.  If the iterator is stopped

src/coreclr/vm/stackwalk.h

@@ -599,6 +599,11 @@ class StackFrameIterator
     // advance to the next frame according to the stackwalk flags
     StackWalkAction Next(void);
 
+#ifndef DACCESS_COMPILE
+    // advance to the position that the other iterator is currently at
+    void SkipTo(StackFrameIterator *pOtherStackFrameIterator);
+#endif // DACCESS_COMPILE
+
 #ifdef FEATURE_EH_FUNCLETS
     void ResetNextExInfoForSP(TADDR SP);