semantic-reasoning · justinjoy · Aug 24, 2026 · Aug 24, 2026
diff --git a/.github/workflows/ci-main.yml b/.github/workflows/ci-main.yml
@@ -131,64 +131,53 @@ jobs:
         if: runner.os == 'Linux' && matrix.compiler == 'gcc'
         continue-on-error: true
         run: |
-          rm -rf build-rel build-rel-o3
-          meson setup build-rel-o3 --buildtype=release \
-            -Doptimization=3 -Dcompact_release=false
-          meson compile -C build-rel-o3
+          rm -rf build-rel
           meson setup build-rel --buildtype=release
           meson compile -C build-rel
 
-          mapfile -t control_shared < <(find build-rel-o3 -maxdepth 1 -type f \
+          mapfile -t release_shared < <(find build-rel -maxdepth 1 -type f \
             -name 'libchronoid.so.*' -print)
-          mapfile -t compact_shared < <(find build-rel -maxdepth 1 -type f \
-            -name 'libchronoid.so.*' -print)
-          if [ "${#control_shared[@]}" -ne 1 ] \
-              || [ "${#compact_shared[@]}" -ne 1 ]; then
-            echo "Expected one versioned shared library per build." >&2
+          if [ "${#release_shared[@]}" -ne 1 ]; then
+            echo "Expected one versioned shared library." >&2
             exit 1
           fi
 
-          strip --strip-unneeded "${control_shared[0]}"
-          strip --strip-unneeded "${compact_shared[0]}"
+          strip --strip-unneeded "${release_shared[0]}"
 
           {
-            echo '## Footprint — ${{ matrix.os }} / GCC / x86_64'
+            echo '## Standard O3 footprint — ${{ matrix.os }} / GCC / ${{ runner.arch }}'
             echo ''
             echo 'Shared libraries are stripped with `strip --strip-unneeded`;'
             echo 'the static archive and CLI are measured as built.'
             echo ''
-            echo '| Artifact | O3 control | Compact O2 | Delta | Reduction |'
-            echo '|---|---:|---:|---:|---:|'
-            failed=0
+            echo '| Artifact | Bytes |'
+            echo '|---|---:|'
             for spec in \
-                "shared:${control_shared[0]}:${compact_shared[0]}" \
-                'static:build-rel-o3/libchronoid.a:build-rel/libchronoid.a' \
-                'chronoid-gen:build-rel-o3/chronoid-gen:build-rel/chronoid-gen'; do
-              IFS=: read -r label control_path compact_path <<< "$spec"
-              if [ ! -f "$control_path" ] || [ ! -f "$compact_path" ]; then
+                "shared:${release_shared[0]}" \
+                'static:build-rel/libchronoid.a' \
+                'chronoid-gen:build-rel/chronoid-gen'; do
+              IFS=: read -r label artifact_path <<< "$spec"
+              if [ ! -f "$artifact_path" ]; then
                 echo "Missing footprint artifact for $label." >&2
                 exit 1
               fi
-              control_bytes=$(stat -c '%s' "$control_path")
-              compact_bytes=$(stat -c '%s' "$compact_path")
-              case "$control_bytes:$compact_bytes" in
-                *[!0-9:]*|'':*|*:'')
+              artifact_bytes=$(stat -c '%s' "$artifact_path")
+              case "$artifact_bytes" in
+                *[!0-9]*|'')
                   echo "Invalid footprint size for $label." >&2
                   exit 1
                   ;;
               esac
-              delta=$((compact_bytes - control_bytes))
-              reduction=$(awk -v c="$control_bytes" -v n="$compact_bytes" \
-                'BEGIN { printf "%.1f%%", 100 * (c - n) / c }')
-              printf '| %s | %s | %s | %+d | %s |\n' \
-                "$label" "$control_bytes" "$compact_bytes" "$delta" "$reduction"
-              if [ "$compact_bytes" -ge "$control_bytes" ]; then
-                echo "Compact release did not shrink $label." >&2
-                failed=1
-              fi
+              printf '| %s | %s |\n' "$label" "$artifact_bytes"
             done
+            echo ''
+            echo '<details><summary>Shared-library sections</summary>'
+            echo ''
+            echo '```text'
+            size -A "${release_shared[0]}"
+            echo '```'
+            echo '</details>'
           } >> "$GITHUB_STEP_SUMMARY"
-          exit "$failed"
 
       - name: Publish results
         if: always()

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -11,16 +11,14 @@ every binary-incompatible change, and the major version bumps with it.
 
 ### Changed (build)
 
-- Release builds now compile production targets at optimization level 2 by
-  default. On GCC 16.2.1 x86_64 this reduces the stripped shared library from
-  43,168 to 39,072 bytes (-9.5%), the as-built static archive from 56,142 to
-  52,358 bytes (-6.7%), and the as-built CLI from 37,312 to 33,328 bytes
-  (-10.7%) relative to an otherwise identical O3 build. Size optimization was
-  smaller but roughly halved KSUID CLI throughput, while LTO enlarged the
-  static archive more than threefold, so O2 is the size/performance compromise.
-  Pass `-Dcompact_release=false` to remove the per-target override and honor
-  the caller's global optimization setting. Public API, ABI, wire formats,
-  SIMD dispatch, and runtime dependencies are unchanged.
+- Release builds again honor Meson's standard optimization level 3. A private
+  RNG-state observation helper now uses its fixed test-buffer contract instead
+  of a variable-length copy, avoiding substantial compiler expansion. On GCC
+  16.2.1 x86_64 this reduces the stripped shared library from 43,168 to 39,072
+  bytes (-9.5%), the as-built static archive from 56,142 to 55,532 bytes
+  (-1.1%), and the as-built CLI from 37,312 to 37,248 bytes (-0.2%) versus the
+  same O3 build before the source change. Production RNG paths, public API,
+  ABI, wire formats, SIMD dispatch, and runtime dependencies are unchanged.
 
 ### Fixed (build)
 

diff --git a/README.md b/README.md
@@ -91,24 +91,27 @@ meson compile -C build-release
 strip --strip-unneeded build-release/libchronoid.so.*
 ```
 
-Release builds use Meson optimization level 2 by default. This keeps the
-installed artifacts compact without the substantial KSUID throughput loss
-observed with size optimization. To honor Meson's or the caller's global
-release optimization level instead, configure with
-`-Dcompact_release=false` (Meson's standard release default is level 3).
+Release builds use Meson's standard optimization level 3. Binary footprint is
+reduced in the source rather than by overriding the caller's optimization
+policy.
 
 ## Footprint
 
-A GCC 16.2.1 release build on x86_64 produces the following paired result.
+A GCC 16.2.1 O3 release build on x86_64 produces the following paired result.
 The shared library is measured after `strip --strip-unneeded`; the static
-archive and CLI are measured as built. Both columns use the same compiler and
-linker invocation, with only `compact_release` changed:
-
-| Artifact              | Compact O2 | O3 control | Reduction |
-| :-------------------- | ---------: | ---------: | --------: |
-| libchronoid.so.1.1.0  |     39 072 |     43 168 |      9.5% |
-| libchronoid.a         |     52 358 |     56 142 |      6.7% |
-| chronoid-gen (CLI)    |     33 328 |     37 312 |     10.7% |
+archive and CLI are measured as built. Both columns use the same compiler,
+linker, build options, and optimization level:
+
+| Artifact              | O3 before | O3 source-optimized | Reduction |
+| :-------------------- | --------: | ------------------: | --------: |
+| libchronoid.so.1.1.0  |    43 168 |              39 072 |      9.5% |
+| libchronoid.a         |    56 142 |              55 532 |      1.1% |
+| chronoid-gen (CLI)    |    37 312 |              37 248 |      0.2% |
+
+The source change compacts a private RNG-state observation helper used only by
+the test suite. Its documented fixed-capacity contract avoids the compiler's
+large variable-length `memcpy` expansion without changing production RNG hot
+paths, public API, or wire formats.
 
 The bulk-encode AVX2 kernel from `chronoid/ksuid/encode_avx2.c` accounts for
 roughly 8 KB of the shared-library size, and the UUIDv7 hex AVX2

diff --git a/chronoid/rand.h b/chronoid/rand.h
@@ -88,15 +88,12 @@ extern _Atomic int chronoid_thread_exit_wipes_observed;
  * erase. Must be called before any draw on the same thread. */
 void chronoid_random_thread_state_set_sentinel_for_testing (void);
 
-/* Copy the calling thread's TLS RNG state bytes into |out| (which
- * must be at least sizeof(chronoid_tls_rng_t) -- the test is allowed to
- * over-allocate). Used to assert the wipe actually zeroed the
- * region. */
-void chronoid_random_thread_state_peek_for_testing (uint8_t * out,
-    size_t out_len);
+/* Capacity for the private TLS-state observation buffer. The helper
+ * returns the actual bytes copied; any unused tail stays untouched. */
+#define CHRONOID_RANDOM_THREAD_STATE_PEEK_CAPACITY 256u
 
-/* Size in bytes that a peek buffer must accommodate. */
-size_t chronoid_random_thread_state_size_for_testing (void);
+size_t chronoid_random_thread_state_peek_for_testing (uint8_t
+    out[CHRONOID_RANDOM_THREAD_STATE_PEEK_CAPACITY]);
 
 /* Test-only: replace the wall-clock source used by chronoid_uuidv7_*
  * generation. Pass a non-NULL fn to install; pass NULL to restore the

diff --git a/chronoid/rand_tls.c b/chronoid/rand_tls.c
@@ -78,6 +78,10 @@ typedef struct
   bool destructor_registered;   /* thread-exit wipe registered yet?      */
 } chronoid_tls_rng_t;
 
+_Static_assert (sizeof (chronoid_tls_rng_t)
+    <= CHRONOID_RANDOM_THREAD_STATE_PEEK_CAPACITY,
+    "test observation capacity must hold the complete TLS RNG state");
+
 static _Thread_local chronoid_tls_rng_t chronoid_tls_rng_;
 
 /* Re-entry guard for chronoid_random_thread_state_wipe. A future change
@@ -120,18 +124,11 @@ chronoid_random_thread_state_set_sentinel_for_testing (void)
   chronoid_tls_rng_.destructor_registered = registered;
 }
 
-void
-chronoid_random_thread_state_peek_for_testing (uint8_t *out, size_t out_len)
-{
-  size_t n = sizeof chronoid_tls_rng_;
-  if (out_len < n)
-    n = out_len;
-  memcpy (out, &chronoid_tls_rng_, n);
-}
-
 size_t
-chronoid_random_thread_state_size_for_testing (void)
+chronoid_random_thread_state_peek_for_testing (uint8_t
+    out[CHRONOID_RANDOM_THREAD_STATE_PEEK_CAPACITY])
 {
+  memcpy (out, &chronoid_tls_rng_, sizeof chronoid_tls_rng_);
   return sizeof chronoid_tls_rng_;
 }
 

diff --git a/meson.build b/meson.build
@@ -13,17 +13,6 @@ project('libchronoid', 'c',
 cc = meson.get_compiler('c')
 pkg = import('pkgconfig')
 
-# Meson's release build type selects optimization level 3. GCC and Clang
-# expand several of our fixed-trip-count codec loops aggressively at that
-# level, increasing all three installed artifacts without a measurable CLI
-# throughput benefit. Keep the public release recipe compact by overriding
-# production targets to level 2. Setting -Dcompact_release=false removes the
-# target override and honors the caller's global optimization choice.
-compact_release_options = []
-if get_option('compact_release') and get_option('buildtype') == 'release'
-  compact_release_options = ['optimization=2']
-endif
-
 # Hardening / portability flags applied to all our TUs. Compiler-
 # specific defaults split between gcc/clang and MSVC: visibility
 # control + POSIX feature macros only mean anything on the GCC-style
@@ -302,7 +291,6 @@ if have_hex_ssse3
     'chronoid/uuidv7/hex_ssse3.c',
     include_directories : inc,
     c_args              : ssse3_arg != '' ? [ssse3_arg] : [],
-    override_options    : compact_release_options,
     pic                 : true,
     install             : false,
   )
@@ -317,7 +305,6 @@ if have_avx2_batch
     'chronoid/ksuid/encode_avx2.c',
     include_directories : inc,
     c_args              : [avx2_arg],
-    override_options    : compact_release_options,
     pic                 : true,
     install             : false,
   )
@@ -341,7 +328,6 @@ if have_hex_avx2
     'chronoid/uuidv7/hex_avx2.c',
     include_directories : inc,
     c_args              : [avx2_arg],
-    override_options    : compact_release_options,
     pic                 : true,
     install             : false,
   )
@@ -352,7 +338,6 @@ chronoid_lib = both_libraries('chronoid', core_sources,
   include_directories : inc,
   dependencies        : extra_link_deps,
   link_whole          : hex_ssse3_lib_dep + avx2_lib_dep + hex_avx2_lib_dep,
-  override_options    : compact_release_options,
   version             : meson.project_version(),
   # soversion tracks semver major: a major bump means a binary-
   # incompatible ABI break and the SONAME flips with it. 1.0 is the
@@ -386,7 +371,6 @@ if get_option('cli')
     'examples/chronoid-gen.c',
     include_directories : inc,
     link_with : chronoid_lib.get_static_lib(),
-    override_options : compact_release_options,
     install : true,
   )
 endif

diff --git a/meson.options b/meson.options
@@ -2,8 +2,6 @@ option('tests', type : 'boolean', value : true,
        description : 'Build the unit test suite')
 option('cli', type : 'boolean', value : true,
        description : 'Build the chronoid-gen CLI tool')
-option('compact_release', type : 'boolean', value : true,
-       description : 'Use optimization level 2 for smaller release artifacts; disable to honor the global release optimization level')
 option('simd', type : 'combo', choices : ['auto', 'none'], value : 'auto',
        description : 'Enable SIMD/NEON acceleration (auto-detected per host arch)')
 option('avx2_batch', type : 'feature', value : 'auto',

diff --git a/tests/test_rand_tls.c b/tests/test_rand_tls.c
@@ -118,17 +118,30 @@ sentinel_thread_body (void *opaque)
    * registered destructor still fires at thread exit and wipes
    * whatever is in the slot. */
   chronoid_random_thread_state_set_sentinel_for_testing ();
-  /* Sanity check: the sentinel landed in the slot. */
-  size_t n = chronoid_random_thread_state_size_for_testing ();
-  uint8_t *peek = malloc (n);
-  if (peek == NULL)
-    return -1;
-  chronoid_random_thread_state_peek_for_testing (peek, n);
+  /* Sanity check: the sentinel landed in the slot. Guard bytes and
+   * the unused capacity tail prove that the observation helper copies
+   * exactly the private state size it reports. */
+  enum
+  { guard_size = 16 };
+  uint8_t guarded[guard_size + CHRONOID_RANDOM_THREAD_STATE_PEEK_CAPACITY
+      + guard_size];
+  memset (guarded, 0x3c, sizeof guarded);
+  uint8_t *peek = guarded + guard_size;
+  size_t n = chronoid_random_thread_state_peek_for_testing (peek);
+  if (n == 0 || n > CHRONOID_RANDOM_THREAD_STATE_PEEK_CAPACITY)
+    return -3;
   size_t a5_count = 0;
   for (size_t i = 0; i < n; ++i)
     if (peek[i] == 0xa5)
       ++a5_count;
-  free (peek);
+  for (size_t i = 0; i < guard_size; ++i) {
+    if (guarded[i] != 0x3c
+        || peek[CHRONOID_RANDOM_THREAD_STATE_PEEK_CAPACITY + i] != 0x3c)
+      return -3;
+  }
+  for (size_t i = n; i < CHRONOID_RANDOM_THREAD_STATE_PEEK_CAPACITY; ++i)
+    if (peek[i] != 0x3c)
+      return -3;
   /* At least 64 bytes of state[16] plus 64 bytes of buf must be
    * the sentinel (the bool flags read as 1, not 0xa5, but everything
    * else does). Use a conservative lower bound. */