| // Copyright 2022 The Tint Authors. |
| // |
| // 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 "src/tint/transform/builtin_polyfill.h" |
| |
| #include <unordered_map> |
| |
| #include "src/tint/program_builder.h" |
| #include "src/tint/sem/builtin.h" |
| #include "src/tint/sem/call.h" |
| #include "src/tint/utils/map.h" |
| |
| TINT_INSTANTIATE_TYPEINFO(tint::transform::BuiltinPolyfill); |
| TINT_INSTANTIATE_TYPEINFO(tint::transform::BuiltinPolyfill::Config); |
| |
| namespace tint::transform { |
| |
| /// The PIMPL state for the BuiltinPolyfill transform |
| struct BuiltinPolyfill::State { |
| /// Constructor |
| /// @param c the CloneContext |
| /// @param p the builtins to polyfill |
| State(CloneContext& c, Builtins p) : ctx(c), polyfill(p) {} |
| |
| /// The clone context |
| CloneContext& ctx; |
| /// The builtins to polyfill |
| Builtins polyfill; |
| /// The destination program builder |
| ProgramBuilder& b = *ctx.dst; |
| /// The source clone context |
| const sem::Info& sem = ctx.src->Sem(); |
| |
| /// Builds the polyfill function for the `countLeadingZeros` builtin |
| /// @param ty the parameter and return type for the function |
| /// @return the polyfill function name |
| Symbol countLeadingZeros(const sem::Type* ty) { |
| auto name = b.Symbols().New("tint_count_leading_zeros"); |
| uint32_t width = WidthOf(ty); |
| |
| // Returns either u32 or vecN<u32> |
| auto U = [&]() -> const ast::Type* { |
| if (width == 1) { |
| return b.ty.u32(); |
| } |
| return b.ty.vec<u32>(width); |
| }; |
| auto V = [&](uint32_t value) -> const ast::Expression* { |
| return ScalarOrVector(width, value); |
| }; |
| b.Func( |
| name, {b.Param("v", T(ty))}, T(ty), |
| { |
| // var x = U(v); |
| b.Decl(b.Var("x", nullptr, b.Construct(U(), b.Expr("v")))), |
| // let b16 = select(0, 16, x <= 0x0000ffff); |
| b.Decl(b.Let("b16", nullptr, |
| b.Call("select", V(0), V(16), b.LessThanEqual("x", V(0x0000ffff))))), |
| // x = x << b16; |
| b.Assign("x", b.Shl("x", "b16")), |
| // let b8 = select(0, 8, x <= 0x00ffffff); |
| b.Decl(b.Let("b8", nullptr, |
| b.Call("select", V(0), V(8), b.LessThanEqual("x", V(0x00ffffff))))), |
| // x = x << b8; |
| b.Assign("x", b.Shl("x", "b8")), |
| // let b4 = select(0, 4, x <= 0x0fffffff); |
| b.Decl(b.Let("b4", nullptr, |
| b.Call("select", V(0), V(4), b.LessThanEqual("x", V(0x0fffffff))))), |
| // x = x << b4; |
| b.Assign("x", b.Shl("x", "b4")), |
| // let b2 = select(0, 2, x <= 0x3fffffff); |
| b.Decl(b.Let("b2", nullptr, |
| b.Call("select", V(0), V(2), b.LessThanEqual("x", V(0x3fffffff))))), |
| // x = x << b2; |
| b.Assign("x", b.Shl("x", "b2")), |
| // let b1 = select(0, 1, x <= 0x7fffffff); |
| b.Decl(b.Let("b1", nullptr, |
| b.Call("select", V(0), V(1), b.LessThanEqual("x", V(0x7fffffff))))), |
| // let is_zero = select(0, 1, x == 0); |
| b.Decl(b.Let("is_zero", nullptr, b.Call("select", V(0), V(1), b.Equal("x", V(0))))), |
| // return R((b16 | b8 | b4 | b2 | b1) + zero); |
| b.Return(b.Construct( |
| T(ty), |
| b.Add(b.Or(b.Or(b.Or(b.Or("b16", "b8"), "b4"), "b2"), "b1"), "is_zero"))), |
| }); |
| return name; |
| } |
| |
| /// Builds the polyfill function for the `countTrailingZeros` builtin |
| /// @param ty the parameter and return type for the function |
| /// @return the polyfill function name |
| Symbol countTrailingZeros(const sem::Type* ty) { |
| auto name = b.Symbols().New("tint_count_trailing_zeros"); |
| uint32_t width = WidthOf(ty); |
| |
| // Returns either u32 or vecN<u32> |
| auto U = [&]() -> const ast::Type* { |
| if (width == 1) { |
| return b.ty.u32(); |
| } |
| return b.ty.vec<u32>(width); |
| }; |
| auto V = [&](uint32_t value) -> const ast::Expression* { |
| return ScalarOrVector(width, value); |
| }; |
| auto B = [&](const ast::Expression* value) -> const ast::Expression* { |
| if (width == 1) { |
| return b.Construct<bool>(value); |
| } |
| return b.Construct(b.ty.vec<bool>(width), value); |
| }; |
| b.Func( |
| name, {b.Param("v", T(ty))}, T(ty), |
| { |
| // var x = U(v); |
| b.Decl(b.Var("x", nullptr, b.Construct(U(), b.Expr("v")))), |
| // let b16 = select(16, 0, bool(x & 0x0000ffff)); |
| b.Decl(b.Let("b16", nullptr, |
| b.Call("select", V(16), V(0), B(b.And("x", V(0x0000ffff)))))), |
| // x = x >> b16; |
| b.Assign("x", b.Shr("x", "b16")), |
| // let b8 = select(8, 0, bool(x & 0x000000ff)); |
| b.Decl(b.Let("b8", nullptr, |
| b.Call("select", V(8), V(0), B(b.And("x", V(0x000000ff)))))), |
| // x = x >> b8; |
| b.Assign("x", b.Shr("x", "b8")), |
| // let b4 = select(4, 0, bool(x & 0x0000000f)); |
| b.Decl(b.Let("b4", nullptr, |
| b.Call("select", V(4), V(0), B(b.And("x", V(0x0000000f)))))), |
| // x = x >> b4; |
| b.Assign("x", b.Shr("x", "b4")), |
| // let b2 = select(2, 0, bool(x & 0x00000003)); |
| b.Decl(b.Let("b2", nullptr, |
| b.Call("select", V(2), V(0), B(b.And("x", V(0x00000003)))))), |
| // x = x >> b2; |
| b.Assign("x", b.Shr("x", "b2")), |
| // let b1 = select(1, 0, bool(x & 0x00000001)); |
| b.Decl(b.Let("b1", nullptr, |
| b.Call("select", V(1), V(0), B(b.And("x", V(0x00000001)))))), |
| // let is_zero = select(0, 1, x == 0); |
| b.Decl(b.Let("is_zero", nullptr, b.Call("select", V(0), V(1), b.Equal("x", V(0))))), |
| // return R((b16 | b8 | b4 | b2 | b1) + zero); |
| b.Return(b.Construct( |
| T(ty), |
| b.Add(b.Or(b.Or(b.Or(b.Or("b16", "b8"), "b4"), "b2"), "b1"), "is_zero"))), |
| }); |
| return name; |
| } |
| |
| /// Builds the polyfill function for the `extractBits` builtin |
| /// @param ty the parameter and return type for the function |
| /// @return the polyfill function name |
| Symbol extractBits(const sem::Type* ty) { |
| auto name = b.Symbols().New("tint_extract_bits"); |
| uint32_t width = WidthOf(ty); |
| |
| constexpr uint32_t W = 32u; // 32-bit |
| |
| auto vecN_u32 = [&](const ast::Expression* value) -> const ast::Expression* { |
| if (width == 1) { |
| return value; |
| } |
| return b.Construct(b.ty.vec<u32>(width), value); |
| }; |
| |
| ast::StatementList body = { |
| b.Decl(b.Let("s", nullptr, b.Call("min", "offset", W))), |
| b.Decl(b.Let("e", nullptr, b.Call("min", W, b.Add("s", "count")))), |
| }; |
| |
| switch (polyfill.extract_bits) { |
| case Level::kFull: |
| body.emplace_back(b.Decl(b.Let("shl", nullptr, b.Sub(W, "e")))); |
| body.emplace_back(b.Decl(b.Let("shr", nullptr, b.Add("shl", "s")))); |
| body.emplace_back( |
| b.Return(b.Shr(b.Shl("v", vecN_u32(b.Expr("shl"))), vecN_u32(b.Expr("shr"))))); |
| break; |
| case Level::kClampParameters: |
| body.emplace_back(b.Return(b.Call("extractBits", "v", "s", b.Sub("e", "s")))); |
| break; |
| default: |
| TINT_ICE(Transform, b.Diagnostics()) |
| << "unhandled polyfill level: " << static_cast<int>(polyfill.extract_bits); |
| return {}; |
| } |
| |
| b.Func(name, |
| { |
| b.Param("v", T(ty)), |
| b.Param("offset", b.ty.u32()), |
| b.Param("count", b.ty.u32()), |
| }, |
| T(ty), body); |
| |
| return name; |
| } |
| |
| /// Builds the polyfill function for the `firstLeadingBit` builtin |
| /// @param ty the parameter and return type for the function |
| /// @return the polyfill function name |
| Symbol firstLeadingBit(const sem::Type* ty) { |
| auto name = b.Symbols().New("tint_first_leading_bit"); |
| uint32_t width = WidthOf(ty); |
| |
| // Returns either u32 or vecN<u32> |
| auto U = [&]() -> const ast::Type* { |
| if (width == 1) { |
| return b.ty.u32(); |
| } |
| return b.ty.vec<u32>(width); |
| }; |
| auto V = [&](uint32_t value) -> const ast::Expression* { |
| return ScalarOrVector(width, value); |
| }; |
| auto B = [&](const ast::Expression* value) -> const ast::Expression* { |
| if (width == 1) { |
| return b.Construct<bool>(value); |
| } |
| return b.Construct(b.ty.vec<bool>(width), value); |
| }; |
| |
| const ast::Expression* x = nullptr; |
| if (ty->is_unsigned_scalar_or_vector()) { |
| x = b.Expr("v"); |
| } else { |
| // If ty is signed, then the value is inverted if the sign is negative |
| x = b.Call("select", // |
| b.Construct(U(), "v"), // |
| b.Construct(U(), b.Complement("v")), // |
| b.LessThan("v", ScalarOrVector(width, 0))); |
| } |
| |
| b.Func( |
| name, {b.Param("v", T(ty))}, T(ty), |
| { |
| // var x = v; (unsigned) |
| // var x = select(U(v), ~U(v), v < 0); (signed) |
| b.Decl(b.Var("x", nullptr, x)), |
| // let b16 = select(0, 16, bool(x & 0xffff0000)); |
| b.Decl(b.Let("b16", nullptr, |
| b.Call("select", V(0), V(16), B(b.And("x", V(0xffff0000)))))), |
| // x = x >> b16; |
| b.Assign("x", b.Shr("x", "b16")), |
| // let b8 = select(0, 8, bool(x & 0x0000ff00)); |
| b.Decl(b.Let("b8", nullptr, |
| b.Call("select", V(0), V(8), B(b.And("x", V(0x0000ff00)))))), |
| // x = x >> b8; |
| b.Assign("x", b.Shr("x", "b8")), |
| // let b4 = select(0, 4, bool(x & 0x000000f0)); |
| b.Decl(b.Let("b4", nullptr, |
| b.Call("select", V(0), V(4), B(b.And("x", V(0x000000f0)))))), |
| // x = x >> b4; |
| b.Assign("x", b.Shr("x", "b4")), |
| // let b2 = select(0, 2, bool(x & 0x0000000c)); |
| b.Decl(b.Let("b2", nullptr, |
| b.Call("select", V(0), V(2), B(b.And("x", V(0x0000000c)))))), |
| // x = x >> b2; |
| b.Assign("x", b.Shr("x", "b2")), |
| // let b1 = select(0, 1, bool(x & 0x00000002)); |
| b.Decl(b.Let("b1", nullptr, |
| b.Call("select", V(0), V(1), B(b.And("x", V(0x00000002)))))), |
| // let is_zero = select(0, 0xffffffff, x == 0); |
| b.Decl(b.Let("is_zero", nullptr, |
| b.Call("select", V(0), V(0xffffffff), b.Equal("x", V(0))))), |
| // return R(b16 | b8 | b4 | b2 | b1 | zero); |
| b.Return(b.Construct( |
| T(ty), b.Or(b.Or(b.Or(b.Or(b.Or("b16", "b8"), "b4"), "b2"), "b1"), "is_zero"))), |
| }); |
| return name; |
| } |
| |
| /// Builds the polyfill function for the `firstTrailingBit` builtin |
| /// @param ty the parameter and return type for the function |
| /// @return the polyfill function name |
| Symbol firstTrailingBit(const sem::Type* ty) { |
| auto name = b.Symbols().New("tint_first_trailing_bit"); |
| uint32_t width = WidthOf(ty); |
| |
| // Returns either u32 or vecN<u32> |
| auto U = [&]() -> const ast::Type* { |
| if (width == 1) { |
| return b.ty.u32(); |
| } |
| return b.ty.vec<u32>(width); |
| }; |
| auto V = [&](uint32_t value) -> const ast::Expression* { |
| return ScalarOrVector(width, value); |
| }; |
| auto B = [&](const ast::Expression* value) -> const ast::Expression* { |
| if (width == 1) { |
| return b.Construct<bool>(value); |
| } |
| return b.Construct(b.ty.vec<bool>(width), value); |
| }; |
| b.Func( |
| name, {b.Param("v", T(ty))}, T(ty), |
| { |
| // var x = U(v); |
| b.Decl(b.Var("x", nullptr, b.Construct(U(), b.Expr("v")))), |
| // let b16 = select(16, 0, bool(x & 0x0000ffff)); |
| b.Decl(b.Let("b16", nullptr, |
| b.Call("select", V(16), V(0), B(b.And("x", V(0x0000ffff)))))), |
| // x = x >> b16; |
| b.Assign("x", b.Shr("x", "b16")), |
| // let b8 = select(8, 0, bool(x & 0x000000ff)); |
| b.Decl(b.Let("b8", nullptr, |
| b.Call("select", V(8), V(0), B(b.And("x", V(0x000000ff)))))), |
| // x = x >> b8; |
| b.Assign("x", b.Shr("x", "b8")), |
| // let b4 = select(4, 0, bool(x & 0x0000000f)); |
| b.Decl(b.Let("b4", nullptr, |
| b.Call("select", V(4), V(0), B(b.And("x", V(0x0000000f)))))), |
| // x = x >> b4; |
| b.Assign("x", b.Shr("x", "b4")), |
| // let b2 = select(2, 0, bool(x & 0x00000003)); |
| b.Decl(b.Let("b2", nullptr, |
| b.Call("select", V(2), V(0), B(b.And("x", V(0x00000003)))))), |
| // x = x >> b2; |
| b.Assign("x", b.Shr("x", "b2")), |
| // let b1 = select(1, 0, bool(x & 0x00000001)); |
| b.Decl(b.Let("b1", nullptr, |
| b.Call("select", V(1), V(0), B(b.And("x", V(0x00000001)))))), |
| // let is_zero = select(0, 0xffffffff, x == 0); |
| b.Decl(b.Let("is_zero", nullptr, |
| b.Call("select", V(0), V(0xffffffff), b.Equal("x", V(0))))), |
| // return R(b16 | b8 | b4 | b2 | b1 | is_zero); |
| b.Return(b.Construct( |
| T(ty), b.Or(b.Or(b.Or(b.Or(b.Or("b16", "b8"), "b4"), "b2"), "b1"), "is_zero"))), |
| }); |
| return name; |
| } |
| |
| /// Builds the polyfill function for the `insertBits` builtin |
| /// @param ty the parameter and return type for the function |
| /// @return the polyfill function name |
| Symbol insertBits(const sem::Type* ty) { |
| auto name = b.Symbols().New("tint_insert_bits"); |
| uint32_t width = WidthOf(ty); |
| |
| constexpr uint32_t W = 32u; // 32-bit |
| |
| auto V = [&](auto value) -> const ast::Expression* { |
| const ast::Expression* expr = b.Expr(value); |
| if (!ty->is_unsigned_scalar_or_vector()) { |
| expr = b.Construct<i32>(expr); |
| } |
| if (ty->Is<sem::Vector>()) { |
| expr = b.Construct(T(ty), expr); |
| } |
| return expr; |
| }; |
| auto U = [&](auto value) -> const ast::Expression* { |
| if (width == 1) { |
| return b.Expr(value); |
| } |
| return b.vec(b.ty.u32(), width, value); |
| }; |
| |
| ast::StatementList body = { |
| b.Decl(b.Let("s", nullptr, b.Call("min", "offset", W))), |
| b.Decl(b.Let("e", nullptr, b.Call("min", W, b.Add("s", "count")))), |
| }; |
| |
| switch (polyfill.insert_bits) { |
| case Level::kFull: |
| // let mask = ((1 << s) - 1) ^ ((1 << e) - 1) |
| body.emplace_back(b.Decl(b.Let( |
| "mask", nullptr, b.Xor(b.Sub(b.Shl(1u, "s"), 1u), b.Sub(b.Shl(1u, "e"), 1u))))); |
| // return ((n << s) & mask) | (v & ~mask) |
| body.emplace_back(b.Return(b.Or(b.And(b.Shl("n", U("s")), V("mask")), |
| b.And("v", V(b.Complement("mask")))))); |
| break; |
| case Level::kClampParameters: |
| body.emplace_back(b.Return(b.Call("insertBits", "v", "n", "s", b.Sub("e", "s")))); |
| break; |
| default: |
| TINT_ICE(Transform, b.Diagnostics()) |
| << "unhandled polyfill level: " << static_cast<int>(polyfill.insert_bits); |
| return {}; |
| } |
| |
| b.Func(name, |
| { |
| b.Param("v", T(ty)), |
| b.Param("n", T(ty)), |
| b.Param("offset", b.ty.u32()), |
| b.Param("count", b.ty.u32()), |
| }, |
| T(ty), body); |
| |
| return name; |
| } |
| |
| private: |
| /// Aliases |
| using u32 = ProgramBuilder::u32; |
| using i32 = ProgramBuilder::i32; |
| |
| /// @returns the AST type for the given sem type |
| const ast::Type* T(const sem::Type* ty) const { return CreateASTTypeFor(ctx, ty); } |
| |
| /// @returns 1 if `ty` is not a vector, otherwise the vector width |
| uint32_t WidthOf(const sem::Type* ty) const { |
| if (auto* v = ty->As<sem::Vector>()) { |
| return v->Width(); |
| } |
| return 1; |
| } |
| |
| /// @returns a scalar or vector with the given width, with each element with |
| /// the given value. |
| template <typename T> |
| const ast::Expression* ScalarOrVector(uint32_t width, T value) const { |
| if (width == 1) { |
| return b.Expr(value); |
| } |
| return b.Construct(b.ty.vec<T>(width), value); |
| } |
| }; |
| |
| BuiltinPolyfill::BuiltinPolyfill() = default; |
| |
| BuiltinPolyfill::~BuiltinPolyfill() = default; |
| |
| bool BuiltinPolyfill::ShouldRun(const Program* program, const DataMap& data) const { |
| if (auto* cfg = data.Get<Config>()) { |
| auto builtins = cfg->builtins; |
| auto& sem = program->Sem(); |
| for (auto* node : program->ASTNodes().Objects()) { |
| if (auto* call = sem.Get<sem::Call>(node)) { |
| if (auto* builtin = call->Target()->As<sem::Builtin>()) { |
| switch (builtin->Type()) { |
| case sem::BuiltinType::kCountLeadingZeros: |
| if (builtins.count_leading_zeros) { |
| return true; |
| } |
| break; |
| case sem::BuiltinType::kCountTrailingZeros: |
| if (builtins.count_trailing_zeros) { |
| return true; |
| } |
| break; |
| case sem::BuiltinType::kExtractBits: |
| if (builtins.extract_bits != Level::kNone) { |
| return true; |
| } |
| break; |
| case sem::BuiltinType::kFirstLeadingBit: |
| if (builtins.first_leading_bit) { |
| return true; |
| } |
| break; |
| case sem::BuiltinType::kFirstTrailingBit: |
| if (builtins.first_trailing_bit) { |
| return true; |
| } |
| break; |
| case sem::BuiltinType::kInsertBits: |
| if (builtins.insert_bits != Level::kNone) { |
| return true; |
| } |
| break; |
| default: |
| break; |
| } |
| } |
| } |
| } |
| } |
| return false; |
| } |
| |
| void BuiltinPolyfill::Run(CloneContext& ctx, const DataMap& data, DataMap&) const { |
| auto* cfg = data.Get<Config>(); |
| if (!cfg) { |
| ctx.Clone(); |
| return; |
| } |
| |
| std::unordered_map<const sem::Builtin*, Symbol> polyfills; |
| |
| ctx.ReplaceAll([&](const ast::CallExpression* expr) -> const ast::CallExpression* { |
| auto builtins = cfg->builtins; |
| State s{ctx, builtins}; |
| if (auto* call = s.sem.Get<sem::Call>(expr)) { |
| if (auto* builtin = call->Target()->As<sem::Builtin>()) { |
| Symbol polyfill; |
| switch (builtin->Type()) { |
| case sem::BuiltinType::kCountLeadingZeros: |
| if (builtins.count_leading_zeros) { |
| polyfill = utils::GetOrCreate(polyfills, builtin, [&] { |
| return s.countLeadingZeros(builtin->ReturnType()); |
| }); |
| } |
| break; |
| case sem::BuiltinType::kCountTrailingZeros: |
| if (builtins.count_trailing_zeros) { |
| polyfill = utils::GetOrCreate(polyfills, builtin, [&] { |
| return s.countTrailingZeros(builtin->ReturnType()); |
| }); |
| } |
| break; |
| case sem::BuiltinType::kExtractBits: |
| if (builtins.extract_bits != Level::kNone) { |
| polyfill = utils::GetOrCreate(polyfills, builtin, [&] { |
| return s.extractBits(builtin->ReturnType()); |
| }); |
| } |
| break; |
| case sem::BuiltinType::kFirstLeadingBit: |
| if (builtins.first_leading_bit) { |
| polyfill = utils::GetOrCreate(polyfills, builtin, [&] { |
| return s.firstLeadingBit(builtin->ReturnType()); |
| }); |
| } |
| break; |
| case sem::BuiltinType::kFirstTrailingBit: |
| if (builtins.first_trailing_bit) { |
| polyfill = utils::GetOrCreate(polyfills, builtin, [&] { |
| return s.firstTrailingBit(builtin->ReturnType()); |
| }); |
| } |
| break; |
| case sem::BuiltinType::kInsertBits: |
| if (builtins.insert_bits != Level::kNone) { |
| polyfill = utils::GetOrCreate(polyfills, builtin, [&] { |
| return s.insertBits(builtin->ReturnType()); |
| }); |
| } |
| break; |
| default: |
| break; |
| } |
| if (polyfill.IsValid()) { |
| return s.b.Call(polyfill, ctx.Clone(call->Declaration()->args)); |
| } |
| } |
| } |
| return nullptr; |
| }); |
| |
| ctx.Clone(); |
| } |
| |
| BuiltinPolyfill::Config::Config(const Builtins& b) : builtins(b) {} |
| BuiltinPolyfill::Config::Config(const Config&) = default; |
| BuiltinPolyfill::Config::~Config() = default; |
| |
| } // namespace tint::transform |
