[clang] [compiler-rt] [compiler-rt] Support `-shared-libsan` for Offload UBSan (PR #226551)

[Yaxun Liu via llvm-commits]

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@@ -1744,8 +1744,9 @@ collectSanitizerRuntimes(Compilation &C, const ToolChain &TC,
   if (SanArgs.needsAsanRt())
     HelperStaticRuntimes.push_back("asan_static");
 
-  // Offloading images can live in DSOs, the host interceptors must follow.
-  if (NeedsOffloadRt) {
+  // Offloading images can live in DSOs, the host interceptors must follow. The
+  // shared UBSan runtime already contains them.
+  if (NeedsOffloadRt && !SanArgs.needsSharedRt()) {
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yxsamliu wrote:

Could we make sure shared UBSan stays in the finished program when only device code uses UBSan? The host may have no UBSan references, so `--as-needed` can drop the library even though it appears on the link command. Device reports would then have no host handler. Could we test this by checking the final binary’s `DT_NEEDED` entries and ensure the library is retained?

https://github.com/llvm/llvm-project/pull/226551