[clang] [llvm] Reland "[ORC] Track __emutls_t definitions in IRMaterializationUnit" (#207161) (PR #208413)

[Emery Conrad via cfe-commits]

conrade-ctc wrote:

> Is this related? Our CI suffered all the weekend like that:
> 
> ```
> 22:34:14  # executed command: cat /workspace/src/clang/test/Interpreter/emulated-tls.cpp
> 22:34:14  # executed command: /workspace/build/stage/product_build/bin/clang-repl
> 22:34:14  # .---command stderr------------
> 22:34:14  # | JIT session error: Symbols not found: [ __emutls_get_address ]
> 22:34:14  # | JIT session error: Failed to materialize symbols: { (main, { _Z6workerv }) }
> 22:34:14  # | error: Failed to materialize symbols: { (main, { __orc_init_func.incr_module_25 }) }
> 22:34:14  # `-----------------------------
> 22:34:14  # executed command: /workspace/build/stage/product_build/bin/FileCheck /workspace/src/clang/test/Interpreter/emulated-tls.cpp
> 22:34:14  # .---command stderr------------
> 22:34:14  # | /workspace/src/clang/test/Interpreter/emulated-tls.cpp:26:11: error: CHECK: expected string not found in input
> 22:34:14  # | // CHECK: tls = 2, 2
> 22:34:14  # |           ^
> 22:34:14  # | <stdin>:1:1: note: scanning from here
> 22:34:14  # | clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl> clang-repl>
> ```

@pawosm-arm, does your environment have a special build (non-default) for clang-repl? If not, it's probably that we scoped the triple check to Mach0, rather than more narrowly. I see it's now reverted, I'll put up a PR that more narrowly scopes the impact to avoid this. Sorry that this popped up for you! 

https://github.com/llvm/llvm-project/pull/208413