From fa6e3c2737720e14194713767e45ebabb9e3c3ed Mon Sep 17 00:00:00 2001 From: David Neto Date: Wed, 3 Feb 2021 13:56:06 -0500 Subject: [PATCH] Add IntLog2 and use it Replace uses of floating point log2 when we want an integer result from an integer operand. This avoids concerns about accuracy of floating point library functions. --- glslang/Include/Common.h | 12 ++ glslang/MachineIndependent/ParseHelper.cpp | 9 +- gtests/CMakeLists.txt | 1 + gtests/Common.cpp | 165 +++++++++++++++++++++ 4 files changed, 179 insertions(+), 8 deletions(-) create mode 100644 gtests/Common.cpp diff --git a/glslang/Include/Common.h b/glslang/Include/Common.h index b628cdc2..89f0192c 100644 --- a/glslang/Include/Common.h +++ b/glslang/Include/Common.h @@ -286,6 +286,18 @@ template bool IsMultipleOfPow2(T number, int powerOf2) return ! (number & (powerOf2 - 1)); } +// Returns log2 of an integer power of 2. +// T should be integral. +template int IntLog2(T n) +{ + assert(IsPow2(n)); + int result = 0; + while ((T(1) << result) != n) { + result++; + } + return result; +} + } // end namespace glslang #endif // _COMMON_INCLUDED_ diff --git a/glslang/MachineIndependent/ParseHelper.cpp b/glslang/MachineIndependent/ParseHelper.cpp index 8927b823..ee7fa26b 100644 --- a/glslang/MachineIndependent/ParseHelper.cpp +++ b/glslang/MachineIndependent/ParseHelper.cpp @@ -5469,14 +5469,7 @@ void TParseContext::setLayoutQualifier(const TSourceLoc& loc, TPublicType& publi if (! IsPow2(value)) error(loc, "must be a power of 2", "buffer_reference_align", ""); else -#ifdef __ANDROID__ - // Android NDK r15c tageting ABI 15 doesn't have full support for C++11 - // (no std::exp2/log2). ::exp2 is available from C99 but ::log2 isn't - // available up until ABI 18 so we use the mathematical equivalent form - publicType.qualifier.layoutBufferReferenceAlign = (unsigned int)(std::log(value) / std::log(2.0)); -#else - publicType.qualifier.layoutBufferReferenceAlign = (unsigned int)std::log2(value); -#endif + publicType.qualifier.layoutBufferReferenceAlign = IntLog2(value); if (nonLiteral) error(loc, "needs a literal integer", "buffer_reference_align", ""); return; diff --git a/gtests/CMakeLists.txt b/gtests/CMakeLists.txt index 0617ff85..c0f2a9cd 100644 --- a/gtests/CMakeLists.txt +++ b/gtests/CMakeLists.txt @@ -47,6 +47,7 @@ if(BUILD_TESTING) # Test related source files ${CMAKE_CURRENT_SOURCE_DIR}/AST.FromFile.cpp ${CMAKE_CURRENT_SOURCE_DIR}/BuiltInResource.FromFile.cpp + ${CMAKE_CURRENT_SOURCE_DIR}/Common.cpp ${CMAKE_CURRENT_SOURCE_DIR}/Config.FromFile.cpp ${CMAKE_CURRENT_SOURCE_DIR}/HexFloat.cpp ${CMAKE_CURRENT_SOURCE_DIR}/Hlsl.FromFile.cpp diff --git a/gtests/Common.cpp b/gtests/Common.cpp new file mode 100644 index 00000000..0b70a83e --- /dev/null +++ b/gtests/Common.cpp @@ -0,0 +1,165 @@ +// Copyright (c) 2021 Google LLC +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include + +#include +#include "glslang/Include/Common.h" + +namespace { + +TEST(IsPow2, Int_Negative) { + EXPECT_EQ(false, glslang::IsPow2(-5)); + EXPECT_EQ(false, glslang::IsPow2(-1)); + EXPECT_EQ(false, glslang::IsPow2(INT_MIN)); + EXPECT_EQ(false, glslang::IsPow2(int64_t(-10))); +} + +TEST(IsPow2, Zero) { + EXPECT_EQ(false, glslang::IsPow2(0)); + EXPECT_EQ(false, glslang::IsPow2(0u)); + EXPECT_EQ(false, glslang::IsPow2(0)); + EXPECT_EQ(false, glslang::IsPow2(uint64_t(0))); + EXPECT_EQ(false, glslang::IsPow2(int64_t(0))); +} + +TEST(IsPow2, Int_Positive_PowersOf2) { + EXPECT_EQ(true, glslang::IsPow2(1)); + EXPECT_EQ(true, glslang::IsPow2(2)); + EXPECT_EQ(true, glslang::IsPow2(4)); + EXPECT_EQ(true, glslang::IsPow2(8)); + EXPECT_EQ(true, glslang::IsPow2(16)); + EXPECT_EQ(true, glslang::IsPow2(32768)); + EXPECT_EQ(true, glslang::IsPow2(65536)); + EXPECT_EQ(true, glslang::IsPow2(2147483648)); +} + +TEST(IsPow2, Int_Positive_NonPowersOf2) { + EXPECT_EQ(false, glslang::IsPow2(3)); + EXPECT_EQ(false, glslang::IsPow2(5)); + EXPECT_EQ(false, glslang::IsPow2(2147483647)); +} + +TEST(IsPow2, Uint_Positive_PowersOf2) { + EXPECT_EQ(true, glslang::IsPow2(1u)); + EXPECT_EQ(true, glslang::IsPow2(2u)); + EXPECT_EQ(true, glslang::IsPow2(4u)); + EXPECT_EQ(true, glslang::IsPow2(8u)); + EXPECT_EQ(true, glslang::IsPow2(16u)); + EXPECT_EQ(true, glslang::IsPow2(32768u)); + EXPECT_EQ(true, glslang::IsPow2(65536u)); + EXPECT_EQ(true, glslang::IsPow2(2147483648u)); +} + +TEST(IsPow2, Uint_Positive_NonPowersOf2) { + EXPECT_EQ(false, glslang::IsPow2(3u)); + EXPECT_EQ(false, glslang::IsPow2(5u)); + EXPECT_EQ(false, glslang::IsPow2(2147483647u)); +} + +TEST(IntLog2, Int) { + EXPECT_EQ(0, glslang::IntLog2(1)); + EXPECT_EQ(1, glslang::IntLog2(2)); + EXPECT_EQ(2, glslang::IntLog2(4)); + EXPECT_EQ(3, glslang::IntLog2(8)); + EXPECT_EQ(4, glslang::IntLog2(16)); + EXPECT_EQ(5, glslang::IntLog2(32)); + EXPECT_EQ(6, glslang::IntLog2(64)); + EXPECT_EQ(7, glslang::IntLog2(128)); + EXPECT_EQ(8, glslang::IntLog2(256)); + EXPECT_EQ(9, glslang::IntLog2(512)); + EXPECT_EQ(10, glslang::IntLog2(1024)); + EXPECT_EQ(11, glslang::IntLog2(2048)); + EXPECT_EQ(12, glslang::IntLog2(0x1000)); + EXPECT_EQ(13, glslang::IntLog2(0x2000)); + EXPECT_EQ(14, glslang::IntLog2(0x4000)); + EXPECT_EQ(15, glslang::IntLog2(0x8000)); + EXPECT_EQ(16, glslang::IntLog2(0x10000)); + EXPECT_EQ(17, glslang::IntLog2(0x20000)); + EXPECT_EQ(18, glslang::IntLog2(0x40000)); + EXPECT_EQ(19, glslang::IntLog2(0x80000)); + EXPECT_EQ(20, glslang::IntLog2(0x100000)); + EXPECT_EQ(21, glslang::IntLog2(0x200000)); + EXPECT_EQ(22, glslang::IntLog2(0x400000)); + EXPECT_EQ(23, glslang::IntLog2(0x800000)); + EXPECT_EQ(24, glslang::IntLog2(0x1000000)); + EXPECT_EQ(25, glslang::IntLog2(0x2000000)); + EXPECT_EQ(26, glslang::IntLog2(0x4000000)); + EXPECT_EQ(27, glslang::IntLog2(0x8000000)); + EXPECT_EQ(28, glslang::IntLog2(0x10000000)); + EXPECT_EQ(29, glslang::IntLog2(0x20000000)); + EXPECT_EQ(30, glslang::IntLog2(0x40000000)); +} + +TEST(IntLog2, Uint) { + EXPECT_EQ(0, glslang::IntLog2(1u)); + EXPECT_EQ(1, glslang::IntLog2(2u)); + EXPECT_EQ(2, glslang::IntLog2(4u)); + EXPECT_EQ(3, glslang::IntLog2(8u)); + EXPECT_EQ(4, glslang::IntLog2(16u)); + EXPECT_EQ(5, glslang::IntLog2(32u)); + EXPECT_EQ(6, glslang::IntLog2(64u)); + EXPECT_EQ(7, glslang::IntLog2(128u)); + EXPECT_EQ(8, glslang::IntLog2(256u)); + EXPECT_EQ(9, glslang::IntLog2(512u)); + EXPECT_EQ(10, glslang::IntLog2(1024u)); + EXPECT_EQ(11, glslang::IntLog2(2048u)); + EXPECT_EQ(12, glslang::IntLog2(0x1000u)); + EXPECT_EQ(13, glslang::IntLog2(0x2000u)); + EXPECT_EQ(14, glslang::IntLog2(0x4000u)); + EXPECT_EQ(15, glslang::IntLog2(0x8000u)); + EXPECT_EQ(16, glslang::IntLog2(0x10000u)); + EXPECT_EQ(17, glslang::IntLog2(0x20000u)); + EXPECT_EQ(18, glslang::IntLog2(0x40000u)); + EXPECT_EQ(19, glslang::IntLog2(0x80000u)); + EXPECT_EQ(20, glslang::IntLog2(0x100000u)); + EXPECT_EQ(21, glslang::IntLog2(0x200000u)); + EXPECT_EQ(22, glslang::IntLog2(0x400000u)); + EXPECT_EQ(23, glslang::IntLog2(0x800000u)); + EXPECT_EQ(24, glslang::IntLog2(0x1000000u)); + EXPECT_EQ(25, glslang::IntLog2(0x2000000u)); + EXPECT_EQ(26, glslang::IntLog2(0x4000000u)); + EXPECT_EQ(27, glslang::IntLog2(0x8000000u)); + EXPECT_EQ(28, glslang::IntLog2(0x10000000u)); + EXPECT_EQ(29, glslang::IntLog2(0x20000000u)); + EXPECT_EQ(30, glslang::IntLog2(0x40000000u)); + EXPECT_EQ(31, glslang::IntLog2(0x80000000u)); +} + +TEST(IntLog2, Int64) { + EXPECT_EQ(0, glslang::IntLog2(int64_t(1))); + EXPECT_EQ(1, glslang::IntLog2(int64_t(2))); + EXPECT_EQ(2, glslang::IntLog2(int64_t(4))); + EXPECT_EQ(3, glslang::IntLog2(int64_t(8))); + EXPECT_EQ(30, glslang::IntLog2(int64_t(0x40000000u))); + EXPECT_EQ(31, glslang::IntLog2(int64_t(0x80000000u))); + EXPECT_EQ(32, glslang::IntLog2(int64_t(0x10000) * int64_t(0x10000))); + EXPECT_EQ(48, glslang::IntLog2(int64_t(0x10000) * int64_t(0x10000) * int64_t(0x10000))); + EXPECT_EQ(62, glslang::IntLog2(int64_t(0x10000) * int64_t(0x10000) * int64_t(0x10000) * int64_t(0x4000))); +} + +TEST(IntLog2, Uint64) { + EXPECT_EQ(0, glslang::IntLog2(uint64_t(1))); + EXPECT_EQ(1, glslang::IntLog2(uint64_t(2))); + EXPECT_EQ(2, glslang::IntLog2(uint64_t(4))); + EXPECT_EQ(3, glslang::IntLog2(uint64_t(8))); + EXPECT_EQ(30, glslang::IntLog2(uint64_t(0x40000000u))); + EXPECT_EQ(31, glslang::IntLog2(uint64_t(0x80000000u))); + EXPECT_EQ(32, glslang::IntLog2(uint64_t(0x10000) * uint64_t(0x10000))); + EXPECT_EQ(48, glslang::IntLog2(uint64_t(0x10000) * uint64_t(0x10000) * uint64_t(0x10000))); + EXPECT_EQ(62, glslang::IntLog2(uint64_t(0x10000) * uint64_t(0x10000) * uint64_t(0x10000) * uint64_t(0x4000))); + EXPECT_EQ(63, glslang::IntLog2(uint64_t(0x10000) * uint64_t(0x10000) * uint64_t(0x10000) * uint64_t(0x8000))); +} + +} // anonymous namespace