chore: pipp review

barretenberg/cpp/CMakePresets.json

@@ -405,6 +405,7 @@
       "generator": "Ninja",
       "toolchainFile": "cmake/toolchains/wasm32-wasi.cmake",
       "environment": {
+        "WASI_SDK_PREFIX": "/opt/wasi-sdk",
         "CC": "$env{WASI_SDK_PREFIX}/bin/clang",
         "CXX": "$env{WASI_SDK_PREFIX}/bin/clang++",
         "CXXFLAGS": "-DBB_VERBOSE -fvisibility=hidden",

barretenberg/cpp/src/barretenberg/commitment_schemes/commitment_key.hpp

@@ -11,13 +11,17 @@
  */
 
 #include "barretenberg/common/bb_bench.hpp"
+#include "barretenberg/common/log.hpp"
 #include "barretenberg/common/ref_span.hpp"
 #include "barretenberg/ecc/scalar_multiplication/scalar_multiplication.hpp"
 #include "barretenberg/polynomials/polynomial.hpp"
 #include "barretenberg/srs/factories/crs_factory.hpp"
 #include "barretenberg/srs/global_crs.hpp"
 
+#include <algorithm>
+#include <array>
 #include <cstddef>
+#include <cstdint>
 #include <cstdlib>
 #include <limits>
 #include <memory>

barretenberg/cpp/src/barretenberg/commitment_schemes/ipa/ipa.hpp

@@ -10,6 +10,7 @@
 #include "barretenberg/common/assert.hpp"
 #include "barretenberg/common/bb_bench.hpp"
 #include "barretenberg/common/container.hpp"
+#include "barretenberg/common/log.hpp"
 #include "barretenberg/common/thread.hpp"
 #include "barretenberg/common/throw_or_abort.hpp"
 #include "barretenberg/constants.hpp"
@@ -19,6 +20,7 @@
 #include "barretenberg/stdlib/primitives/circuit_builders/circuit_builders_fwd.hpp"
 #include "barretenberg/transcript/transcript.hpp"
 #include <cstddef>
+#include <cstdlib>
 #include <numeric>
 #include <string>
 #include <utility>

barretenberg/cpp/src/barretenberg/common/thread.cpp

@@ -81,9 +81,11 @@ namespace bb::detail {
  * for it to reach num_workers_ before returning, guaranteeing no worker is
  * still inside do_iterations() when the next generation is published.
  *
- * Idle wait is yield-spin then 100 us sleep_for fallback. Neither path
- * lowers to i32.atomic.wait, so the V8 wasi-threads lost-wakeup race that
- * affects condition_variable-based pools does not apply here.
+ * Idle wait is yield-spin then 100 us sleep_for fallback on native. Browser WASM
+ * keeps yielding because std::this_thread::sleep_for lowers to WASI poll_oneoff,
+ * which is intentionally stubbed out in this build. Neither path lowers to
+ * i32.atomic.wait, so the V8 wasi-threads lost-wakeup race that affects
+ * condition_variable-based pools does not apply here.
  *
  * This is the same design as the round-parallel MSM's local pool — the MSM
  * dispatches parallel_for hundreds of times per proof, and per-call overhead
@@ -151,7 +153,11 @@ class ParallelForPool {
             std::this_thread::yield();
         }
         while (!pred()) {
+#ifdef __wasm__
+            std::this_thread::yield();
+#else
             std::this_thread::sleep_for(std::chrono::microseconds(100));
+#endif
         }
     }
 };
@@ -191,7 +197,11 @@ void ParallelForPool::worker_loop()
             ++idle_spins;
             std::this_thread::yield();
         } else {
+#ifdef __wasm__
+            std::this_thread::yield();
+#else
             std::this_thread::sleep_for(std::chrono::microseconds(100));
+#endif
         }
     }
 }

barretenberg/cpp/src/barretenberg/ecc/scalar_multiplication/scalar_multiplication.hpp

@@ -178,8 +178,21 @@ extern template class MSM<curve::BN254>;
 // and bench targets can pin behaviour at the boundary.
 inline constexpr size_t MIN_PTS_PER_THREAD_FOR_PIPPENGER = 24;
 
+// Per-MSM arena sizer. Returns 0 for shapes that fall back to the Jacobian-fast path
+// (no affine arena). Mirrors the inline budget calc inside `pippenger_round_parallel`;
+// declared here so the test suite can exercise the same sizer.
+template <typename Curve>
+size_t compute_arena_bytes_for_msm(size_t n_input, bool external_glv_provided, bool dedup_active = false) noexcept;
+
 namespace round_parallel_detail {
 
+// Above this N, GLV's 2x point-count cost outweighs the windows-halved benefit.
+#ifdef __wasm__
+inline constexpr size_t GLV_SMALL_N_THRESHOLD = size_t{ 1 } << 16;
+#else
+inline constexpr size_t GLV_SMALL_N_THRESHOLD = size_t{ 1 } << 13;
+#endif
+
 /**
  * @brief Single-MSM, no-affine-trick Pippenger over window_bits-wide windows.
  *