[clang] Reapply "[ubsan] Add -fsanitize-merge (and -fno-sanitize-merge) (#120…464)" (PR #120511)

[Thurston Dang via cfe-commits]

================
@@ -1,10 +1,26 @@
 // NOTE: Assertions have mostly been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 5
-// The most important assertion is the attributes at the end of the file, which
-// shows whether -ubsan-unique-traps attaches 'nomerge' to each ubsan call.
+// The most important assertions are the attributes at the end of the file, which
+// show whether -ubsan-unique-traps and -fno-sanitize-merge attach 'nomerge'
+// to each ubsan call.
 //
-// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 -mllvm -ubsan-unique-traps %s -o - -fsanitize-trap=signed-integer-overflow | FileCheck %s --check-prefix=TRAP
-// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 -mllvm -ubsan-unique-traps %s -o -                                         | FileCheck %s --check-prefix=HANDLER
-// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 -mllvm -ubsan-unique-traps %s -o - -fsanitize-minimal-runtime              | FileCheck %s --check-prefix=MINRT
+// N.B. although the clang driver defaults to -fsanitize-merge=undefined,
+// clang_cc1 defaults to non-merge. (This is similar to -fsanitize-recover, for
----------------
thurstond wrote:

I am planning to write a patch that will remove -ubsan-unique-traps and update the tests accordingly.

https://github.com/llvm/llvm-project/pull/120511