Avoid clearing the whole build directory

bench-TriLMs.py

@@ -41,15 +41,19 @@ def gather_models(sizes: Sequence[str] = MODEL_SIZES):
 
 def build_llama_cpp(options: Sequence[str]):
     logger.info("Building llama.cpp")
-    os.chdir(LLAMA_CPP_PATH)
     builddir = LLAMA_CPP_PATH / "build"
     if builddir.exists():
-        logger.info("Removing %s", builddir)
-        os.system("rm -rf build")
-    builddir.mkdir()
+        # Clear previous config
+        cmake_cache = builddir / "CMakeCache.txt"
+        cmake_files = builddir / "CMakeFiles"
+        logger.info("Removing %s and %s", cmake_cache, cmake_files)
+        os.system(shlex.join(("rm", "-rf", str(cmake_cache), str(cmake_files))))
+    builddir.mkdir(exist_ok=True)
+    old_cwd = os.path.curdir
     os.chdir(builddir)
     os.system(shlex.join(("cmake", "..", *options)))
     os.system(f"make -j{os.cpu_count()} llama-bench llama-quantize test-backend-ops")
+    os.chdir(old_cwd)
 
 
 def quantize(types: Sequence[str] = ALL_TYPES, sizes: Sequence[str] = MODEL_SIZES):