[clang] [llvm] [llvm][clang] Allocate a new stack instead of spawning a new thread to get more stack space (PR #133173)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-x86_64-linux-abi-test` running on `sie-linux-worker2` while building `clang,llvm` at step 6 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/8/builds/14018

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (build-unified-tree) failure: build (failure)
...
In member function ‘void llvm::ContextAndReplaceableUses::makeReplaceable(std::unique_ptr<llvm::ReplaceableMetadataImpl>)’,
    inlined from ‘virtual void {anonymous}::ContextAndReplaceableUsesTest_makeReplaceable_Test::TestBody()’ at /home/buildbot/buildbot-root/abi-test/llvm/llvm/unittests/IR/MetadataTest.cpp:49:22:
/home/buildbot/buildbot-root/abi-test/llvm/llvm/include/llvm/IR/Metadata.h:1025:31: warning: ‘void operator delete(void*, std::size_t)’ called on unallocated object ‘Context’ [-Wfree-nonheap-object]
 1025 |     delete getReplaceableUses();
      |                               ^
/home/buildbot/buildbot-root/abi-test/llvm/llvm/unittests/IR/MetadataTest.cpp: In member function ‘virtual void {anonymous}::ContextAndReplaceableUsesTest_makeReplaceable_Test::TestBody()’:
/home/buildbot/buildbot-root/abi-test/llvm/llvm/unittests/IR/MetadataTest.cpp:47:15: note: declared here
   47 |   LLVMContext Context;
      |               ^~~~~~~
279.205 [147/10/7017] Building CXX object unittests/Support/CMakeFiles/SupportTests.dir/ProgramStackTest.cpp.o
FAILED: unittests/Support/CMakeFiles/SupportTests.dir/ProgramStackTest.cpp.o 
/opt/ccache/bin/g++ -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_STATIC -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbot/buildbot-root/abi-test/build/unittests/Support -I/home/buildbot/buildbot-root/abi-test/llvm/llvm/unittests/Support -I/home/buildbot/buildbot-root/abi-test/build/include -I/home/buildbot/buildbot-root/abi-test/llvm/llvm/include -I/home/buildbot/buildbot-root/abi-test/llvm/third-party/unittest/googletest/include -I/home/buildbot/buildbot-root/abi-test/llvm/third-party/unittest/googlemock/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -Wno-dangling-else -Wno-variadic-macros -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -Wno-suggest-override -std=c++17 -MD -MT unittests/Support/CMakeFiles/SupportTests.dir/ProgramStackTest.cpp.o -MF unittests/Support/CMakeFiles/SupportTests.dir/ProgramStackTest.cpp.o.d -o unittests/Support/CMakeFiles/SupportTests.dir/ProgramStackTest.cpp.o -c /home/buildbot/buildbot-root/abi-test/llvm/llvm/unittests/Support/ProgramStackTest.cpp
/home/buildbot/buildbot-root/abi-test/llvm/llvm/unittests/Support/ProgramStackTest.cpp: In member function ‘virtual void ProgramStackTest_runOnNewStack_Test::TestBody()’:
/home/buildbot/buildbot-root/abi-test/llvm/llvm/unittests/Support/ProgramStackTest.cpp:33:16: error: call of overloaded ‘runOnNewStack(int, llvm::function_ref<void(int&)>, int&)’ is ambiguous
   33 |   runOnNewStack(0, function_ref<void(int &)>(func2), A);
      |   ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /home/buildbot/buildbot-root/abi-test/llvm/llvm/unittests/Support/ProgramStackTest.cpp:9:
/home/buildbot/buildbot-root/abi-test/llvm/llvm/include/llvm/Support/ProgramStack.h:48:3: note: candidate: ‘R llvm::runOnNewStack(unsigned int, llvm::function_ref<Ret(Params ...)>, Ts&& ...) [with R = void; Ts = {int&}]’
   48 | R runOnNewStack(unsigned StackSize, function_ref<R(Ts...)> Fn, Ts &&...Args) {
      |   ^~~~~~~~~~~~~
/home/buildbot/buildbot-root/abi-test/llvm/llvm/include/llvm/Support/ProgramStack.h:55:6: note: candidate: ‘void llvm::runOnNewStack(unsigned int, llvm::function_ref<void(Ts ...)>, Ts&& ...) [with Ts = {int&}]’
   55 | void runOnNewStack(unsigned StackSize, function_ref<void(Ts...)> Fn,
      |      ^~~~~~~~~~~~~
282.563 [147/2/7025] Building CXX object unittests/Target/AMDGPU/CMakeFiles/AMDGPUTests.dir/CSETest.cpp.o
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/133173