[llvm] [MemProf] Add assert to make sure ContextIterBegin isn't at StackContext.end() (PR #81004)

[via llvm-commits]

https://github.com/lifengxiang1025 created https://github.com/llvm/llvm-project/pull/81004

None

>From 2e8d586d45b5d2fe2de54d70eb5edb97befba960 Mon Sep 17 00:00:00 2001
From: lifengxiang <lifengxiang.1025 at bytedance.com>
Date: Wed, 7 Feb 2024 23:34:39 +0800
Subject: [PATCH] [MemProf] Add assert to make sure ContextIterBegin isn't at
 StackContext.end()

---
 llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp b/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp
index d81239dd49e4cc..6705c2337f04a6 100644
--- a/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp
+++ b/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp
@@ -3474,6 +3474,7 @@ bool MemProfContextDisambiguation::applyImport(Module &M) {
             CallStack<MDNode, MDNode::op_iterator> StackContext(StackMDNode);
             auto ContextIterBegin =
                 StackContext.beginAfterSharedPrefix(CallsiteContext);
+            assert(ContextIterBegin != StackContext.end());
             // Skip the checking on the first iteration.
             uint64_t LastStackContextId = *ContextIterBegin == 0 ? 1 : 0;
             for (auto ContextIter = ContextIterBegin;