[Experimental][WIP] Pfor delta encoding

.gitignore

@@ -94,3 +94,6 @@ rat.txt
 
 # for ODBC DLL
 *.rc
+
+# Local out-of-tree benchmark build dir
+cpp/build-bench/

cpp/cmake_modules/SetupCxxFlags.cmake

@@ -633,21 +633,12 @@ endif()
 
 if(NOT MSVC)
   set(C_RELEASE_FLAGS "")
-  if(CMAKE_C_FLAGS_RELEASE MATCHES "-O3")
-    string(APPEND C_RELEASE_FLAGS " -O2")
-  endif()
+  # Local override: keep -O3 from CMake's default Release flags for the
+  # pfor benchmark — the bench is sensitive to inlining/unrolling that
+  # -O3 enables. Upstream Arrow downgrades to -O2 here; we skip that.
   set(CXX_RELEASE_FLAGS "")
-  if(CMAKE_CXX_FLAGS_RELEASE MATCHES "-O3")
-    string(APPEND CXX_RELEASE_FLAGS " -O2")
-  endif()
   set(C_RELWITHDEBINFO_FLAGS "")
-  if(CMAKE_C_FLAGS_RELWITHDEBINFO MATCHES "-O3")
-    string(APPEND C_RELWITHDEBINFO_FLAGS " -O2")
-  endif()
   set(CXX_RELWITHDEBINFO_FLAGS "")
-  if(CMAKE_CXX_FLAGS_RELWITHDEBINFO MATCHES "-O3")
-    string(APPEND CXX_RELWITHDEBINFO_FLAGS " -O2")
-  endif()
   if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     string(APPEND C_RELEASE_FLAGS " -ftree-vectorize")
     string(APPEND CXX_RELEASE_FLAGS " -ftree-vectorize")

cpp/src/arrow/CMakeLists.txt

@@ -566,6 +566,8 @@ set(ARROW_UTIL_SRCS
     util/math_internal.cc
     util/memory.cc
     util/mutex.cc
+    util/pfor/pfor.cc
+    util/pfor/pfor_wrapper.cc
     util/ree_util.cc
     util/secure_string.cc
     util/string.cc

cpp/src/arrow/meson.build

@@ -204,6 +204,8 @@ arrow_util_srcs = [
     'util/math_internal.cc',
     'util/memory.cc',
     'util/mutex.cc',
+    'util/pfor/pfor.cc',
+    'util/pfor/pfor_wrapper.cc',
     'util/ree_util.cc',
     'util/secure_string.cc',
     'util/string.cc',

cpp/src/arrow/util/CMakeLists.txt

@@ -118,6 +118,10 @@ add_arrow_test(threading-utility-test
                test_common.cc
                thread_pool_test.cc)
 
+add_arrow_test(pfor-test SOURCES pfor/pfor_test.cc)
+
+add_arrow_benchmark(pfor/pfor_benchmark)
+
 add_arrow_benchmark(bit_block_counter_benchmark)
 add_arrow_benchmark(bit_util_benchmark)
 add_arrow_benchmark(bitmap_reader_benchmark)

cpp/src/arrow/util/bpacking.cc

@@ -43,6 +43,23 @@ struct UnpackDynamicFunction {
   }
 };
 
+template <typename Uint>
+struct UnpackBiasDynamicFunction {
+  using FunctionType = decltype(&bpacking::unpack_bias_scalar<Uint>);
+
+  static constexpr auto targets() {
+    return std::array{
+        ARROW_DISPATCH_TARGET_NONE(&bpacking::unpack_bias_scalar<Uint>)    //
+        ARROW_DISPATCH_TARGET_NEON(&bpacking::unpack_bias_neon<Uint>)      //
+        ARROW_DISPATCH_TARGET_SVE128(&bpacking::unpack_bias_sve128<Uint>)  //
+        ARROW_DISPATCH_TARGET_SVE256(&bpacking::unpack_bias_sve256<Uint>)  //
+        ARROW_DISPATCH_TARGET_SSE4_2(&bpacking::unpack_bias_sse4_2<Uint>)  //
+        ARROW_DISPATCH_TARGET_AVX2(&bpacking::unpack_bias_avx2<Uint>)      //
+        ARROW_DISPATCH_TARGET_AVX512(&bpacking::unpack_bias_avx512<Uint>)  //
+    };
+  }
+};
+
 }  // namespace
 
 template <typename Uint>
@@ -57,4 +74,19 @@ template void unpack<uint16_t>(const uint8_t*, uint16_t*, const UnpackOptions&);
 template void unpack<uint32_t>(const uint8_t*, uint32_t*, const UnpackOptions&);
 template void unpack<uint64_t>(const uint8_t*, uint64_t*, const UnpackOptions&);
 
+template <typename Uint>
+void unpack_bias(const uint8_t* in, Uint* out, const UnpackOptions& opts, Uint bias) {
+  static const DynamicDispatch<UnpackBiasDynamicFunction<Uint>> dispatch;
+  return dispatch(in, out, opts, bias);
+}
+
+template void unpack_bias<uint8_t>(const uint8_t*, uint8_t*, const UnpackOptions&,
+                                   uint8_t);
+template void unpack_bias<uint16_t>(const uint8_t*, uint16_t*, const UnpackOptions&,
+                                    uint16_t);
+template void unpack_bias<uint32_t>(const uint8_t*, uint32_t*, const UnpackOptions&,
+                                    uint32_t);
+template void unpack_bias<uint64_t>(const uint8_t*, uint64_t*, const UnpackOptions&,
+                                    uint64_t);
+
 }  // namespace arrow::internal