[llvm] Improve compiler-rt build structure and export compilation info (PR #190088)

[Jordan Rupprecht via llvm-commits]

================
@@ -288,10 +317,13 @@ AARCH64_OUTLINE_ATOMICS_FMT = "lib/builtins/aarch64/outline_atomic_{0}{1}_{2}.S"
 
 # Source files for the AArch64 architecture-specific builtins.
 filegroup(
-    name = "builtins_aarch64_srcs",
+    name = "builtins_unfiltered_aarch64_srcs",
     srcs = [
         "lib/builtins/cpu_model/aarch64.c",
         "lib/builtins/cpu_model/aarch64.h",
+        ":builtins_bf16_srcs",
----------------
rupprecht wrote:

Tangent to this PR: it might be more readable if we had more consistent/structured names for these filegroups. Given a name `builtins_<something>_srcs`, it's not immediately obvious what `<something>` is -- it could be an arch (aarch64) or a general grouping (generic, bf16).

We have `builtins_x86_arch_srcs`, and this PR adds `builtins_arm_arch_srcs`, but the other rules like `builtins_riscv_srcs` don't have that `_arch_srcs` suffix. And a prefix might be better to, so that a sorted deps list will show which deps are from other arches and which deps are general deps.

Anyway, bikeshed over.

https://github.com/llvm/llvm-project/pull/190088