[llvm-branch-commits] [llvm] release/22.x: [MC] Try to fix ubsan bot (PR #177907)

[via llvm-branch-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-mc

Author: None (llvmbot)

<details>
<summary>Changes</summary>

Backport d064f395af7ac226dec3f8e90516a26e96e2acf1

Requested by: @<!-- -->nikic

---
Full diff: https://github.com/llvm/llvm-project/pull/177907.diff


1 Files Affected:

- (modified) llvm/lib/MC/MCObjectStreamer.cpp (+2-1) 


``````````diff
diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index 5fd30eccb45c5..0c64d89d7b491 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -111,7 +111,8 @@ void MCObjectStreamer::appendContents(ArrayRef<char> Contents) {
   assert(FragSpace >= Contents.size());
   // As this is performance-sensitive code, explicitly use std::memcpy.
   // Optimization of std::copy to memmove is unreliable.
-  std::memcpy(getCurFragEnd(), Contents.begin(), Contents.size());
+  if (!Contents.empty())
+    std::memcpy(getCurFragEnd(), Contents.begin(), Contents.size());
   CurFrag->FixedSize += Contents.size();
   FragSpace -= Contents.size();
 }

``````````

</details>


https://github.com/llvm/llvm-project/pull/177907