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1import subprocess2import re3import lit.util4 5 6def can_execute_generated_snippets(arch):7 is_host_arch = arch in config.root.host_triple8 # 'native' feature is defined as "host arch == default triple arch"9 is_native_codegen = "native" in config.available_features10 return is_host_arch and is_native_codegen11 12 13def can_use_perf_counters(mode, extra_options=[]):14 # We need libpfm to be installed and allow reading perf counters. We can15 # only know that at runtime, so we try to measure an empty code snippet16 # 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 False21 try:22 return_code = subprocess.call(23 [llvm_exegesis_exe, "-mode", mode, "-opcode-name=ADD64rr"]24 + extra_options,25 stdout=subprocess.DEVNULL,26 stderr=subprocess.DEVNULL,27 )28 return return_code == 029 except OSError:30 print("could not exec llvm-exegesis")31 return False32 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