Performance-portable, length-agnostic SIMD with runtime dispatch
This report presents the forensic synthetic code analysis of google/highway, a C++ project with 5,674 GitHub stars. SynthScan v2.0 examined 149,513 lines of code across 116 source files, recording 598 pattern matches distributed across 6 syntactic categories. The overall adjusted score of 3.8 places this repository in the Likely human-written band.
The scanner applied 160+ deterministic lexical heuristics, multi-line block detectors, abstract syntax tree depth profilers, and a cross-file Jaccard similarity matrix to construct a statistically normalised synthetic code estimate. All matches are individually weighted by severity coefficient and contextual multiplier before summation, and the resulting headline score is temporally discounted to account for the repository's development history relative to the commercial emergence of large language model coding tooling (November 2022 onward).
This chart maps the temporal evolution of the adjusted synthetic code score across successive scan runs. An upward trajectory indicates ongoing incorporation of AI-generated code or expanding LLM-assisted scaffolding; a stable or declining trajectory may reflect active human refactoring, code removal, or the adoption of stricter authorship policies. The dashed secondary line (right axis) independently tracks total raw pattern hit count, which can diverge from the normalised score when codebase size changes significantly between scans.
Classifies detected patterns by their diagnostic confidence and structural impact. CRITICAL patterns (coefficient 10) represent definitive synthetic signatures — hallucinated imports, explicit LLM attribution metadata — virtually never produced by human authors. HIGH (5) indicates strong structural tells such as cross-file repetition or cross-linguistic idioms. MEDIUM (2) covers recognisable conversational padding and AI-specific vocabulary. LOW (1) captures subtle indicators like tautological comments and generic boilerplate that require density to carry independent signal.
This horizontal bar chart decomposes the repository's raw synthetic code score by top-level directory, allowing you to pinpoint precisely which modules or components carry the highest AI authorship density. Directories with disproportionately high scores relative to their size warrant targeted manual review: concentrated AI signatures often trace back to mass-generated configuration layers, auto-ported test suites, LLM-scaffolded boilerplate classes, or entire subsystems authored under heavy copilot assistance. Use this view to prioritise your human code-review effort.
The scanner identified 598 distinct pattern matches across 6 syntactic categories. Each entry below represents a discrete location in the source code where the engine recorded a statistically significant AI authorship indicator. Expand any category row to inspect the individual file paths, line numbers, code snippets, and the lexical context (CODE, COMMENT, or STRING) in which each match was detected.
Reading the findings table: The Severity column indicates the diagnostic confidence level (CRITICAL / HIGH / MEDIUM / LOW). The Context column identifies whether the match occurred inside executable code, an inline comment, or a string literal — comment-context matches receive a ×1.5 weight because LLMs systematically over-annotate. The ⚡ bolt icon marks clustered matches: three or more patterns within a 10-line window, each receiving an additional ×1.5 density multiplier as dense clusters constitute far stronger evidence of synthetic authorship than isolated hits.
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | CMakeLists.txt | 1 | # Copyright 2019 Google LLC | COMMENT |
| LOW | hwy/highway.h | 1 | // Copyright 2020 Google LLC | COMMENT |
| LOW | hwy/highway.h | 21 | #include "hwy/detect_targets.h" | COMMENT |
| LOW | hwy/highway.h | 41 | // Shorthand for tags (defined in shared-inl.h) used to select overloads. | COMMENT |
| LOW | hwy/highway.h | 61 | //------------------------------------------------------------------------------ | COMMENT |
| LOW | hwy/highway.h | 81 | #define HWY_STATIC_NAMESPACE N_WASM | COMMENT |
| LOW | hwy/highway.h | 101 | #define HWY_STATIC_NAMESPACE N_NEON_WITHOUT_AES | COMMENT |
| LOW | hwy/highway.h | 121 | #define HWY_STATIC_NAMESPACE N_AVX2 | COMMENT |
| LOW | hwy/highway.h | 141 | // that target was not compiled. | COMMENT |
| LOW | hwy/highway.h | 161 | #define HWY_VISIT_WASM(VISITOR) | COMMENT |
| LOW | hwy/highway.h | 181 | #define HWY_CHOOSE_Z15(FUNC_NAME) &N_Z15::FUNC_NAME | COMMENT |
| LOW | hwy/highway.h | 201 | #define HWY_VISIT_PPC9(VISITOR) | COMMENT |
| LOW | hwy/highway.h | 221 | #define HWY_CHOOSE_PPC10(FUNC_NAME) &N_PPC10::FUNC_NAME | COMMENT |
| LOW | hwy/highway.h | 241 | #define HWY_CHOOSE_NEON_WITHOUT_AES(FUNC_NAME) nullptr | COMMENT |
| LOW | hwy/highway.h | 261 | #if HWY_TARGETS & HWY_SVE | COMMENT |
| LOW | hwy/highway.h | 281 | #define HWY_CHOOSE_SVE_256(FUNC_NAME) nullptr | COMMENT |
| LOW | hwy/highway.h | 301 | #if HWY_TARGETS & HWY_SSSE3 | COMMENT |
| LOW | hwy/highway.h | 321 | #define HWY_CHOOSE_AVX2(FUNC_NAME) nullptr | COMMENT |
| LOW | hwy/highway.h | 341 | #if HWY_TARGETS & HWY_AVX3_ZEN4 | COMMENT |
| LOW | hwy/highway.h | 361 | #define HWY_CHOOSE_AVX10_2(FUNC_NAME) nullptr | COMMENT |
| LOW | hwy/highway.h | 441 | COMMENT | |
| LOW | hwy/highway.h | 461 | // HWY_EXPORT(MyFunction); // Defines the dispatch table in this scope. | COMMENT |
| LOW | hwy/highway.h | 481 | // Note that HWY_EXPORT_T must be invoked inside a template (in the above | COMMENT |
| LOW | hwy/highway.h | 501 | COMMENT | |
| LOW | hwy/highway.h | 521 | // user-visible function signature. | COMMENT |
| LOW | hwy/highway.h | 641 | COMMENT | |
| LOW | hwy/highway.h | 661 | #define HWY_CAP_FLOAT16 HWY_HAVE_FLOAT16 | COMMENT |
| LOW | hwy/highway.h | 681 | #if HWY_ENABLED_BASELINE == 0 | COMMENT |
| LOW | hwy/highway.h | 701 | #include "hwy/ops/x86_avx3-inl.h" | COMMENT |
| LOW | hwy/highway.h | 721 | #elif HWY_TARGET == HWY_SCALAR | COMMENT |
| LOW | hwy/print-inl.h | 1 | // Copyright 2022 Google LLC | COMMENT |
| LOW | hwy/print-inl.h | 21 | #include "hwy/print.h" | COMMENT |
| LOW | hwy/highway_export.h | 1 | // Pseudo-generated file to handle both cmake & bazel build system. | COMMENT |
| LOW | hwy/highway_export.h | 21 | #ifdef _WIN32 | COMMENT |
| LOW | hwy/highway_export.h | 41 | #else | COMMENT |
| LOW | hwy/highway_export.h | 61 | #endif | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 1 | // Copyright 2020 Google LLC | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 21 | COMMENT | |
| LOW | hwy/detect_compiler_arch.h | 41 | #if defined(_MSC_VER) && !defined(__clang__) | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 61 | #else | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 81 | #if __has_builtin(__builtin_elementwise_fshl) | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 101 | #elif __has_warning("-Wreserved-identifier") | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 121 | #else // Anything older than 7.0 is not recommended for Highway. | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 141 | !HWY_COMPILER_ICX | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 161 | // Compiler features and C++ version | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 181 | #ifdef __has_feature | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 201 | #else | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 221 | #define HWY_IF_CONSTEXPR if | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 241 | #define HWY_IS_MSAN 1 | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 261 | defined(__SANITIZE_THREAD__) | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 281 | COMMENT | |
| LOW | hwy/detect_compiler_arch.h | 301 | #endif | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 321 | #if defined(__powerpc64__) || defined(__PPC64__) || defined(__ppc64__) || \ | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 341 | #if HWY_ARCH_ARM_A64 && HWY_ARCH_ARM_V7 | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 361 | #else | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 381 | #if __riscv_xlen == 64 | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 401 | COMMENT | |
| LOW | hwy/detect_compiler_arch.h | 421 | #if defined(__hexagon__) || defined(__HEXAGON_ARCH__) | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 441 | #elif HWY_ARCH_X86 | COMMENT |
| LOW | hwy/detect_compiler_arch.h | 461 | #define HWY_OS_LINUX 1 | COMMENT |
| 524 more matches not shown… | ||||
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| MEDIUM | hwy/nanobenchmark.h | 20 | // prediction hit rates. Uses a robust estimator to summarize the measurements. | COMMENT |
| MEDIUM | hwy/nanobenchmark.h | 46 | // which is more robust to outliers and skewed data than the mean or median. | COMMENT |
| MEDIUM | hwy/auto_tune.h | 78 | // - The minimum is not a robust estimator because there are also "lucky | COMMENT |
| MEDIUM | hwy/auto_tune.h | 96 | // - Trim the initial sample via MAD or skewness for a robust estimate of the | COMMENT |
| MEDIUM | hwy/auto_tune.h | 153 | // deviation, which is robust to almost half of the sample being outliers. | COMMENT |
| MEDIUM | hwy/robust_statistics.h | 82 | // Half Sample Mode estimator proposed by Bickel in "On a fast, robust | COMMENT |
| MEDIUM | hwy/robust_statistics.h | 132 | // Returns a robust measure of variability. | COMMENT |
| MEDIUM | hwy/contrib/hash/phast-inl.h | 94 | // Two vectors have higher throughput because they utilize all 16-bit lanes | COMMENT |
| MEDIUM | hwy/ops/rvv-inl.h | 5229 | // Definitely at least 128 bit: match x86 semantics (independent blocks). Using | COMMENT |
| MEDIUM | hwy/ops/rvv-inl.h | 5289 | // Definitely less than 128-bit only if there is a small cap; fractional LMUL | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| MEDIUM | CMakeLists.txt | 663 | # -------------------------------------------------------- | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | docs/conf.py | 14 | CODE |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | docs/mm-converter.py | 44 | CODE |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | docs/mm-converter.py | 77 | CODE |