1import subprocess 2import re 3import lit.util 4 5 6def can_execute_generated_snippets(arch): 7 is_host_arch = arch in config.root.host_triple 8 # 'native' feature is defined as "host arch == default triple arch" 9 is_native_codegen = "native" in config.available_features 10 return is_host_arch and is_native_codegen 11 12 13def can_use_perf_counters(mode, extra_options=[]): 14 # We need libpfm to be installed and allow reading perf counters. We can 15 # only know that at runtime, so we try to measure an empty code snippet 16 # and bail out on error. 17 llvm_exegesis_exe = lit.util.which("llvm-exegesis", config.llvm_tools_dir) 18 if llvm_exegesis_exe is None: 19 print("could not find llvm-exegesis") 20 return False 21 try: 22 return_code = subprocess.call( 23 [llvm_exegesis_exe, "-mode", mode, "-snippets-file", "/dev/null"] 24 + extra_options, 25 stdout=subprocess.DEVNULL, 26 stderr=subprocess.DEVNULL, 27 ) 28 return return_code == 0 29 except OSError: 30 print("could not exec llvm-exegesis") 31 return False 32 33 34for arch in ["aarch64", "mips", "powerpc", "x86_64"]: 35 if can_execute_generated_snippets(arch): 36 config.available_features.add("exegesis-can-execute-%s" % arch) 37 38if can_use_perf_counters("latency"): 39 config.available_features.add("exegesis-can-measure-latency") 40 41if can_use_perf_counters("uops"): 42 config.available_features.add("exegesis-can-measure-uops") 43 44if can_execute_generated_snippets("x86_64"): 45 # Check for support of LBR format with cycles. 46 if can_use_perf_counters( 47 "latency", ["-x86-lbr-sample-period", "123", "-repetition-mode", "loop"] 48 ): 49 config.available_features.add("exegesis-can-measure-latency-lbr") 50 51