[clang] Reland [Driver] Add support for crtbegin.o, crtend.o and libgloss lib to BareMetal toolchain object (PR #144649)

[Nico Weber via cfe-commits]

================
@@ -59,3 +118,39 @@
 
 // CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/include/c++/v1"
 // CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "-internal-isystem" "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/include"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../bin/aarch64-none-elf-ld"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "{{.*}}.o" "-Bstatic" "-EL"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/lib/crt0.o"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtbegin.o"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "-L{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/../../../../aarch64-none-elf/lib"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "-lc++" "-lm" "--start-group" "-lgcc_s" "-lgcc" "-lc" "-lgloss" "--end-group"
+// CXX-AARCH64-BAREMETAL-NOSYSROOT-LIBCXX: "{{.*}}/Inputs/basic_aarch64_gcc_tree/lib/gcc/aarch64-none-elf/8.2.1/crtend.o"
+
+// RUN: %clang -### %s -fuse-ld= \
+// RUN:   --target=aarch64-none-elf --rtlib=compiler-rt --unwindlib=platform \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_aarch64_gcc_tree \
+// RUN:   --sysroot=%S/Inputs/basic_aarch64_gcc_tree/aarch64-none-elf 2>&1 \
+// RUN:   | FileCheck -check-prefix=AARCH64-BAREMETAL-COMPILER-RT %s
+
+// AARCH64-BAREMETAL-COMPILER-RT: "{{.*}}crt0.o"
+// AARCH64-BAREMETAL-COMPILER-RT: "{{.*}}clang_rt.crtbegin.o"
+// AARCH64-BAREMETAL-COMPILER-RT: "--start-group" "{{.*}}libclang_rt.builtins.a" "-lc" "-lgloss" "--end-group"
----------------
nico wrote:

This line was failing on my bots like so: http://45.33.8.238/macm1/109605/step_6.txt

The other files touched in this commit are fine.

My bots use the GN build, which uses the old runtimes layout (what you get in the cmake build with `--DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF`). However, this does not reproduce for me locally, so maybe it's dependent on some incremental build state.

It looks like the problem is that clang prints `libclang_rt.builtins-aarch64.a` (with the `-aarch64` suffix).

https://github.com/llvm/llvm-project/commit/5220e4f2bfb6e01adcb7708dba44701c84016a4d fixed it.

Does that make sense to you?

Would this fail with `-DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=OFF` in CMake too? Is this the right fix? Is it needed in other tests too?

https://github.com/llvm/llvm-project/pull/144649