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lib/Algorithm/Classifier/IsolationForest.pm  view on Meta::CPAN

				warn "Algorithm::Classifier::IsolationForest: ignoring invalid " . "IF_ARCH value '$ENV{IF_ARCH}'\n";
			}
		} elsif ( $ENV{IF_NATIVE} ) {
			$arch = 'native';
		}
		# -ffp-contract=off rides along with any -march: once the target
		# has FMA (x86-64-v3, most -march=native hosts), the compiler may
		# otherwise contract a*b+c expressions into fused multiply-adds
		# whose different rounding breaks the documented guarantee that
		# use_c => 1 and use_c => 0 build bit-identical trees (one ulp in a
		# split value cascades into a structurally different tree).  The
		# -march speedup comes from AVX2 vectorization, not contraction,
		# so this costs little (verified against the fit-determinism and
		# scoring-parity tests).
		my $opt_level = $opt;
		$opt_level .= " -march=$arch -ffp-contract=off" if length $arch;

		# IF_NO_OPENMP=1 forces the serial C build: the OpenMP compile attempt
		# is skipped, so the object has no libgomp linkage and never starts an
		# OpenMP runtime in the process.  Distinct from OMP_NUM_THREADS=1,
		# which runs the parallel code on a single thread but still loads