[compiler-rt] [llvm] [msan] Add experimental '-mllvm -msan-embed-faulting-instruction' and MSAN_OPTIONS=print_faulting_instruction (PR #136539)

[Thurston Dang via llvm-commits]

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@@ -352,10 +352,44 @@ void __sanitizer::BufferedStackTrace::UnwindImpl(
 
 using namespace __msan;
 
+#define PRINT_FAULTING_INSTRUCTION(instname)                            \
+  if (__msan::flags()->print_faulting_instruction) {                    \
+    Printf("Instruction that failed the shadow check: %s\n", instname); \
+    Printf("\n");                                                       \
+  }
+
+#define WARN_IF_PRINT_FAULTING_INSTRUCTION_REQUESTED                    \
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thurstond wrote:

Good point, fixed in https://github.com/llvm/llvm-project/pull/136539/commits/56791cfa8ec7c4d739d3dd34a861a7770437180b

https://github.com/llvm/llvm-project/pull/136539