[clang] [CIR] Minimize dependencies of check-clang-cir (PR #227957)

[Andy Kaylor via cfe-commits]

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@@ -238,11 +238,54 @@ add_lit_testsuite(check-clang "Running the Clang regression tests"
   ARGS ${CLANG_TEST_EXTRA_ARGS}
   )
 
+# Skip CIR here. check-clang above still runs these tests. The check-clang-cir
+# target is created explicitly below so that it (and its subdirectory-based
+# sub-targets) depend only on the tools those tests invoke and the tools
+# required to load clang/test/lit.cfg.py.
 add_lit_testsuites(CLANG ${CMAKE_CURRENT_SOURCE_DIR}
   DEPENDS ${CLANG_TEST_DEPS}
   FOLDER "Clang tests/Suites"
+  SKIP "^CIR"
 )
 
+# These tools are resolved while loading clang/test/lit.cfg.py, or invoked
+# directly by tests under clang/test/CIR.
+set(CLANG_CIR_TEST_DEPS
+  clang
+  )
+if(CLANG_ENABLE_CIR)
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andykaylor wrote:

It could be. The lit config makes the target a noop if CIR isn't enabled, and the targets were added implicitly before this change. The way it's organized here preserves the old behavior, but it's probably better to have the target undefined if CIR isn't enabled.

https://github.com/llvm/llvm-project/pull/227957