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import subprocess
import lit.util
def can_execute_generated_snippets(arch):
is_host_arch = arch in config.root.host_triple
# 'native' feature is defined as "host arch == default triple arch"
is_native_codegen = 'native' in config.available_features
return is_host_arch and is_native_codegen
def can_use_perf_counters(mode, extra_options=[]):
# We need libpfm to be installed and allow reading perf counters. We can
# only know that at runtime, so we try to measure an empty code snippet
# and bail out on error.
llvm_exegesis_exe = lit.util.which('llvm-exegesis', config.llvm_tools_dir)
if llvm_exegesis_exe is None:
print('could not find llvm-exegesis')
return False
try:
return_code = subprocess.call(
[llvm_exegesis_exe, '-mode', mode, '-snippets-file', '/dev/null'] + extra_options,
stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
return return_code == 0
except OSError:
print('could not exec llvm-exegesis')
return False
for arch in ['aarch64', 'mips', 'powerpc', 'x86_64']:
if can_execute_generated_snippets(arch):
config.available_features.add('exegesis-can-execute-%s' % arch)
if can_use_perf_counters('latency'):
config.available_features.add('exegesis-can-measure-latency')
if can_use_perf_counters('uops'):
config.available_features.add('exegesis-can-measure-uops')
if can_execute_generated_snippets('x86_64'):
# Check for support of LBR format with cycles.
if can_use_perf_counters('latency', ['-x86-lbr-sample-period', '123', '-repetition-mode', 'loop']):
config.available_features.add('exegesis-can-measure-latency-lbr')
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