|  | // Copyright 2022 The Dawn & Tint Authors | 
|  | // | 
|  | // Redistribution and use in source and binary forms, with or without | 
|  | // modification, are permitted provided that the following conditions are met: | 
|  | // | 
|  | // 1. Redistributions of source code must retain the above copyright notice, this | 
|  | //    list of conditions and the following disclaimer. | 
|  | // | 
|  | // 2. Redistributions in binary form must reproduce the above copyright notice, | 
|  | //    this list of conditions and the following disclaimer in the documentation | 
|  | //    and/or other materials provided with the distribution. | 
|  | // | 
|  | // 3. Neither the name of the copyright holder nor the names of its | 
|  | //    contributors may be used to endorse or promote products derived from | 
|  | //    this software without specific prior written permission. | 
|  | // | 
|  | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | 
|  | // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | 
|  | // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | 
|  | // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE | 
|  | // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | 
|  | // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | 
|  | // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | 
|  | // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, | 
|  | // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | 
|  | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | 
|  |  | 
|  | #include "src/tint/lang/wgsl/ast/transform/builtin_polyfill.h" | 
|  |  | 
|  | #include <algorithm> | 
|  | #include <tuple> | 
|  | #include <unordered_map> | 
|  | #include <utility> | 
|  |  | 
|  | #include "src/tint/lang/core/type/storage_texture.h" | 
|  | #include "src/tint/lang/core/type/texture_dimension.h" | 
|  | #include "src/tint/lang/wgsl/program/clone_context.h" | 
|  | #include "src/tint/lang/wgsl/program/program_builder.h" | 
|  | #include "src/tint/lang/wgsl/resolver/resolve.h" | 
|  | #include "src/tint/lang/wgsl/sem/builtin_fn.h" | 
|  | #include "src/tint/lang/wgsl/sem/call.h" | 
|  | #include "src/tint/lang/wgsl/sem/type_expression.h" | 
|  | #include "src/tint/lang/wgsl/sem/value_conversion.h" | 
|  | #include "src/tint/utils/containers/map.h" | 
|  | #include "src/tint/utils/rtti/switch.h" | 
|  |  | 
|  | using namespace tint::core::fluent_types;     // NOLINT | 
|  | using namespace tint::core::number_suffixes;  // NOLINT | 
|  |  | 
|  | TINT_INSTANTIATE_TYPEINFO(tint::ast::transform::BuiltinPolyfill); | 
|  | TINT_INSTANTIATE_TYPEINFO(tint::ast::transform::BuiltinPolyfill::Config); | 
|  |  | 
|  | namespace tint::ast::transform { | 
|  |  | 
|  | /// BinaryOpSignature is tuple of a binary op, LHS type and RHS type | 
|  | using BinaryOpSignature = | 
|  | std::tuple<core::BinaryOp, const core::type::Type*, const core::type::Type*>; | 
|  |  | 
|  | /// PIMPL state for the transform | 
|  | struct BuiltinPolyfill::State { | 
|  | /// Constructor | 
|  | /// @param program the source program | 
|  | /// @param config the transform config | 
|  | State(const Program& program, const Config& config) : src(program), cfg(config) {} | 
|  |  | 
|  | /// Runs the transform | 
|  | /// @returns the new program or SkipTransform if the transform is not required | 
|  | Transform::ApplyResult Run() { | 
|  | for (auto* node : src.ASTNodes().Objects()) { | 
|  | Switch( | 
|  | node,  // | 
|  | [&](const CallExpression* expr) { Call(expr); }, | 
|  | [&](const BinaryExpression* bin_op) { | 
|  | auto* s = src.Sem().Get(bin_op); | 
|  | if (!s || s->Stage() != core::EvaluationStage::kRuntime) { | 
|  | return;  // Only polyfill runtime expressions | 
|  | } | 
|  | switch (bin_op->op) { | 
|  | case core::BinaryOp::kShiftLeft: | 
|  | case core::BinaryOp::kShiftRight: { | 
|  | if (cfg.builtins.bitshift_modulo) { | 
|  | ctx.Replace(bin_op, | 
|  | [this, bin_op] { return BitshiftModulo(bin_op); }); | 
|  | made_changes = true; | 
|  | } | 
|  | break; | 
|  | } | 
|  | case core::BinaryOp::kDivide: { | 
|  | if (cfg.builtins.int_div_mod) { | 
|  | auto* lhs_ty = src.TypeOf(bin_op->lhs)->UnwrapRef(); | 
|  | if (lhs_ty->is_integer_scalar_or_vector()) { | 
|  | ctx.Replace(bin_op, | 
|  | [this, bin_op] { return IntDivMod(bin_op); }); | 
|  | made_changes = true; | 
|  | } | 
|  | } | 
|  | break; | 
|  | } | 
|  | case core::BinaryOp::kModulo: { | 
|  | if (cfg.builtins.int_div_mod) { | 
|  | auto* lhs_ty = src.TypeOf(bin_op->lhs)->UnwrapRef(); | 
|  | if (lhs_ty->is_integer_scalar_or_vector()) { | 
|  | ctx.Replace(bin_op, | 
|  | [this, bin_op] { return IntDivMod(bin_op); }); | 
|  | made_changes = true; | 
|  | } | 
|  | } | 
|  | if (cfg.builtins.precise_float_mod) { | 
|  | auto* lhs_ty = src.TypeOf(bin_op->lhs)->UnwrapRef(); | 
|  | if (lhs_ty->is_float_scalar_or_vector()) { | 
|  | ctx.Replace(bin_op, | 
|  | [this, bin_op] { return PreciseFloatMod(bin_op); }); | 
|  | made_changes = true; | 
|  | } | 
|  | } | 
|  | break; | 
|  | } | 
|  | default: | 
|  | break; | 
|  | } | 
|  | }, | 
|  | [&](const Expression* expr) { | 
|  | if (cfg.builtins.bgra8unorm) { | 
|  | if (auto* ty_expr = src.Sem().Get<sem::TypeExpression>(expr)) { | 
|  | if (auto* tex = ty_expr->Type()->As<core::type::StorageTexture>()) { | 
|  | if (tex->texel_format() == core::TexelFormat::kBgra8Unorm) { | 
|  | ctx.Replace(expr, [this, tex] { | 
|  | return ctx.dst->Expr(ctx.dst->ty.storage_texture( | 
|  | tex->dim(), core::TexelFormat::kRgba8Unorm, | 
|  | tex->access())); | 
|  | }); | 
|  | made_changes = true; | 
|  | } | 
|  | } | 
|  | } | 
|  | } | 
|  | }); | 
|  | } | 
|  |  | 
|  | if (!made_changes) { | 
|  | return SkipTransform; | 
|  | } | 
|  |  | 
|  | ctx.Clone(); | 
|  | return resolver::Resolve(b); | 
|  | } | 
|  |  | 
|  | private: | 
|  | /// The source program | 
|  | const Program& src; | 
|  | /// The transform config | 
|  | const Config& cfg; | 
|  | /// The destination program builder | 
|  | ProgramBuilder b; | 
|  | /// The clone context | 
|  | program::CloneContext ctx{&b, &src}; | 
|  | /// The source clone context | 
|  | const sem::Info& sem = src.Sem(); | 
|  | /// Polyfill functions for binary operators. | 
|  | Hashmap<BinaryOpSignature, Symbol, 8> binary_op_polyfills; | 
|  | /// Polyfill builtins. | 
|  | Hashmap<const sem::BuiltinFn*, Symbol, 8> builtin_polyfills; | 
|  | /// Polyfill f32 conversion to i32 or u32 (or vectors of) | 
|  | Hashmap<const core::type::Type*, Symbol, 2> f32_conv_polyfills; | 
|  | /// True if the transform has made changes (i.e. the program needs cloning) | 
|  | bool made_changes = false; | 
|  |  | 
|  | //////////////////////////////////////////////////////////////////////////// | 
|  | // Function polyfills | 
|  | //////////////////////////////////////////////////////////////////////////// | 
|  |  | 
|  | /// Builds the polyfill function for the `acosh` builtin | 
|  | /// @param ty the parameter and return type for the function | 
|  | /// @return the polyfill function name | 
|  | Symbol acosh(const core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_acosh"); | 
|  | uint32_t width = WidthOf(ty); | 
|  |  | 
|  | auto V = [&](AFloat value) -> const Expression* { | 
|  | const Expression* expr = b.Expr(value); | 
|  | if (width == 1) { | 
|  | return expr; | 
|  | } | 
|  | return b.Call(T(ty), expr); | 
|  | }; | 
|  |  | 
|  | tint::Vector<const Statement*, 4> body; | 
|  | switch (cfg.builtins.acosh) { | 
|  | case Level::kFull: | 
|  | // return log(x + sqrt(x*x - 1)); | 
|  | body.Push(b.Return( | 
|  | b.Call("log", b.Add("x", b.Call("sqrt", b.Sub(b.Mul("x", "x"), 1_a)))))); | 
|  | break; | 
|  | case Level::kRangeCheck: { | 
|  | // return select(acosh(x), 0, x < 1); | 
|  | body.Push(b.Return( | 
|  | b.Call("select", b.Call("acosh", "x"), V(0.0_a), b.LessThan("x", V(1.0_a))))); | 
|  | break; | 
|  | } | 
|  | default: | 
|  | TINT_ICE() << "unhandled polyfill level: " << static_cast<int>(cfg.builtins.acosh); | 
|  | } | 
|  |  | 
|  | b.Func(name, tint::Vector{b.Param("x", T(ty))}, T(ty), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `asinh` builtin | 
|  | /// @param ty the parameter and return type for the function | 
|  | /// @return the polyfill function name | 
|  | Symbol asinh(const core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_sinh"); | 
|  |  | 
|  | // return log(x + sqrt(x*x + 1)); | 
|  | b.Func(name, tint::Vector{b.Param("x", T(ty))}, T(ty), | 
|  | tint::Vector{ | 
|  | b.Return(b.Call("log", b.Add("x", b.Call("sqrt", b.Add(b.Mul("x", "x"), 1_a))))), | 
|  | }); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `atanh` builtin | 
|  | /// @param ty the parameter and return type for the function | 
|  | /// @return the polyfill function name | 
|  | Symbol atanh(const core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_atanh"); | 
|  | uint32_t width = WidthOf(ty); | 
|  |  | 
|  | auto V = [&](AFloat value) -> const Expression* { | 
|  | const Expression* expr = b.Expr(value); | 
|  | if (width == 1) { | 
|  | return expr; | 
|  | } | 
|  | return b.Call(T(ty), expr); | 
|  | }; | 
|  |  | 
|  | tint::Vector<const Statement*, 1> body; | 
|  | switch (cfg.builtins.atanh) { | 
|  | case Level::kFull: | 
|  | // return log((1+x) / (1-x)) * 0.5 | 
|  | body.Push( | 
|  | b.Return(b.Mul(b.Call("log", b.Div(b.Add(1_a, "x"), b.Sub(1_a, "x"))), 0.5_a))); | 
|  | break; | 
|  | case Level::kRangeCheck: | 
|  | // return select(atanh(x), 0, x >= 1); | 
|  | body.Push(b.Return(b.Call("select", b.Call("atanh", "x"), V(0.0_a), | 
|  | b.GreaterThanEqual("x", V(1.0_a))))); | 
|  | break; | 
|  | default: | 
|  | TINT_ICE() << "unhandled polyfill level: " << static_cast<int>(cfg.builtins.acosh); | 
|  | } | 
|  |  | 
|  | b.Func(name, tint::Vector{b.Param("x", T(ty))}, T(ty), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `clamp` builtin when called with integer arguments | 
|  | /// (scalar or vector) | 
|  | /// @param ty the parameter and return type for the function | 
|  | /// @return the polyfill function name | 
|  | Symbol clampInteger(const core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_clamp"); | 
|  |  | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("e", T(ty)), | 
|  | b.Param("low", T(ty)), | 
|  | b.Param("high", T(ty)), | 
|  | }, | 
|  | T(ty), | 
|  | tint::Vector{ | 
|  | // return min(max(e, low), high); | 
|  | b.Return(b.Call("min", b.Call("max", "e", "low"), "high")), | 
|  | }); | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// 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 core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_count_leading_zeros"); | 
|  | uint32_t width = WidthOf(ty); | 
|  |  | 
|  | // Returns either u32 or vecN<u32> | 
|  | auto U = [&] { | 
|  | if (width == 1) { | 
|  | return b.ty.u32(); | 
|  | } | 
|  | return b.ty.vec<u32>(width); | 
|  | }; | 
|  | auto V = [&](uint32_t value) -> const Expression* { | 
|  | return ScalarOrVector(width, u32(value)); | 
|  | }; | 
|  | b.Func( | 
|  | name, | 
|  | tint::Vector{ | 
|  | b.Param("v", T(ty)), | 
|  | }, | 
|  | T(ty), | 
|  | tint::Vector{ | 
|  | // var x = U(v); | 
|  | b.Decl(b.Var("x", b.Call(U(), b.Expr("v")))), | 
|  | // let b16 = select(0, 16, x <= 0x0000ffff); | 
|  | b.Decl(b.Let("b16", | 
|  | 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", 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", 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", 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", 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", b.Call("select", V(0), V(1), b.Equal("x", V(0))))), | 
|  | // return R((b16 | b8 | b4 | b2 | b1) + zero); | 
|  | b.Return(b.Call(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 core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_count_trailing_zeros"); | 
|  | uint32_t width = WidthOf(ty); | 
|  |  | 
|  | // Returns either u32 or vecN<u32> | 
|  | auto U = [&] { | 
|  | if (width == 1) { | 
|  | return b.ty.u32(); | 
|  | } | 
|  | return b.ty.vec<u32>(width); | 
|  | }; | 
|  | auto V = [&](uint32_t value) -> const Expression* { | 
|  | return ScalarOrVector(width, u32(value)); | 
|  | }; | 
|  | auto B = [&](const Expression* value) -> const Expression* { | 
|  | if (width == 1) { | 
|  | return b.Call<bool>(value); | 
|  | } | 
|  | return b.Call(b.ty.vec<bool>(width), value); | 
|  | }; | 
|  | b.Func( | 
|  | name, | 
|  | tint::Vector{ | 
|  | b.Param("v", T(ty)), | 
|  | }, | 
|  | T(ty), | 
|  | tint::Vector{ | 
|  | // var x = U(v); | 
|  | b.Decl(b.Var("x", b.Call(U(), b.Expr("v")))), | 
|  | // let b16 = select(16, 0, bool(x & 0x0000ffff)); | 
|  | b.Decl(b.Let("b16", 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", 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", 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", 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", 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", b.Call("select", V(0), V(1), b.Equal("x", V(0))))), | 
|  | // return R((b16 | b8 | b4 | b2 | b1) + zero); | 
|  | b.Return(b.Call(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 core::type::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 Expression* value) -> const Expression* { | 
|  | if (width == 1) { | 
|  | return value; | 
|  | } | 
|  | return b.Call(b.ty.vec<u32>(width), value); | 
|  | }; | 
|  |  | 
|  | tint::Vector<const Statement*, 8> body{ | 
|  | b.Decl(b.Let("s", b.Call("min", "offset", u32(W)))), | 
|  | b.Decl(b.Let("e", b.Call("min", u32(W), b.Add("s", "count")))), | 
|  | }; | 
|  |  | 
|  | switch (cfg.builtins.extract_bits) { | 
|  | case Level::kFull: | 
|  | body.Push(b.Decl(b.Let("shl", b.Sub(u32(W), "e")))); | 
|  | body.Push(b.Decl(b.Let("shr", b.Add("shl", "s")))); | 
|  | // Here we don't want the shl and shr modulos the rhs, so handle the `rhs >= 32u` | 
|  | // cases using `select`. In order to handle the signed shr `lhs >> rhs` corrently, | 
|  | // use `(lhs >> 31u) >> 1u` if `rhs >= 32u`. | 
|  | body.Push(b.Decl(b.Let("shl_result", b.Call("select", b.Call(T(ty)), | 
|  | b.Shl("v", vecN_u32(b.Expr("shl"))), | 
|  | b.LessThan("shl", 32_u))))); | 
|  | body.Push(b.Return(b.Call( | 
|  | "select", | 
|  | b.Shr(b.Shr("shl_result", vecN_u32(b.Expr(31_u))), vecN_u32(b.Expr(1_u))), | 
|  | b.Shr("shl_result", vecN_u32(b.Expr("shr"))), b.LessThan("shr", 32_u)) | 
|  |  | 
|  | )); | 
|  | break; | 
|  | case Level::kClampParameters: | 
|  | body.Push(b.Return(b.Call("extractBits", "v", "s", b.Sub("e", "s")))); | 
|  | break; | 
|  | default: | 
|  | TINT_ICE() << "unhandled polyfill level: " | 
|  | << static_cast<int>(cfg.builtins.extract_bits); | 
|  | } | 
|  |  | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("v", T(ty)), | 
|  | b.Param("offset", b.ty.u32()), | 
|  | b.Param("count", b.ty.u32()), | 
|  | }, | 
|  | T(ty), std::move(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 core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_first_leading_bit"); | 
|  | uint32_t width = WidthOf(ty); | 
|  |  | 
|  | // Returns either u32 or vecN<u32> | 
|  | auto U = [&] { | 
|  | if (width == 1) { | 
|  | return b.ty.u32(); | 
|  | } | 
|  | return b.ty.vec<u32>(width); | 
|  | }; | 
|  | auto V = [&](uint32_t value) -> const Expression* { | 
|  | return ScalarOrVector(width, u32(value)); | 
|  | }; | 
|  | auto B = [&](const Expression* value) -> const Expression* { | 
|  | if (width == 1) { | 
|  | return b.Call<bool>(value); | 
|  | } | 
|  | return b.Call(b.ty.vec<bool>(width), value); | 
|  | }; | 
|  |  | 
|  | const Expression* x = nullptr; | 
|  | if (ty->is_unsigned_integer_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.Call(U(), "v"),                // | 
|  | b.Call(U(), b.Complement("v")),  // | 
|  | b.LessThan("v", ScalarOrVector(width, 0_i))); | 
|  | } | 
|  |  | 
|  | b.Func( | 
|  | name, | 
|  | tint::Vector{ | 
|  | b.Param("v", T(ty)), | 
|  | }, | 
|  | T(ty), | 
|  | tint::Vector{ | 
|  | // var x = v;                          (unsigned) | 
|  | // var x = select(U(v), ~U(v), v < 0); (signed) | 
|  | b.Decl(b.Var("x", x)), | 
|  | // let b16 = select(0, 16, bool(x & 0xffff0000)); | 
|  | b.Decl(b.Let("b16", 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", 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", 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", 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", 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", b.Call("select", V(0), V(0xffffffff), b.Equal("x", V(0))))), | 
|  | // return R(b16 | b8 | b4 | b2 | b1 | zero); | 
|  | b.Return(b.Call( | 
|  | 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 core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_first_trailing_bit"); | 
|  | uint32_t width = WidthOf(ty); | 
|  |  | 
|  | // Returns either u32 or vecN<u32> | 
|  | auto U = [&] { | 
|  | if (width == 1) { | 
|  | return b.ty.u32(); | 
|  | } | 
|  | return b.ty.vec<u32>(width); | 
|  | }; | 
|  | auto V = [&](uint32_t value) -> const Expression* { | 
|  | return ScalarOrVector(width, u32(value)); | 
|  | }; | 
|  | auto B = [&](const Expression* value) -> const Expression* { | 
|  | if (width == 1) { | 
|  | return b.Call<bool>(value); | 
|  | } | 
|  | return b.Call(b.ty.vec<bool>(width), value); | 
|  | }; | 
|  | b.Func( | 
|  | name, | 
|  | tint::Vector{ | 
|  | b.Param("v", T(ty)), | 
|  | }, | 
|  | T(ty), | 
|  | tint::Vector{ | 
|  | // var x = U(v); | 
|  | b.Decl(b.Var("x", b.Call(U(), b.Expr("v")))), | 
|  | // let b16 = select(16, 0, bool(x & 0x0000ffff)); | 
|  | b.Decl(b.Let("b16", 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", 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", 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", 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", 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", b.Call("select", V(0), V(0xffffffff), b.Equal("x", V(0))))), | 
|  | // return R(b16 | b8 | b4 | b2 | b1 | is_zero); | 
|  | b.Return(b.Call( | 
|  | 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 `fwidthFine` builtin | 
|  | /// @param ty the parameter and return type for the function | 
|  | /// @return the polyfill function name | 
|  | Symbol fwidthFine(const core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_fwidth_fine"); | 
|  | // WGSL polyfill function: | 
|  | //      fn tint_fwidth_fine(v : T) -> T { | 
|  | //          return abs(dpdxFine(v)) + abs(dpdyFine(v)); | 
|  | //      } | 
|  | auto body = tint::Vector{ | 
|  | b.Return(b.Add(b.Call("abs", b.Call("dpdxFine", "v")), | 
|  | b.Call("abs", b.Call("dpdyFine", "v")))), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("v", T(ty)), | 
|  | }, | 
|  | T(ty), body); | 
|  | 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 core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_insert_bits"); | 
|  | uint32_t width = WidthOf(ty); | 
|  |  | 
|  | // Currently in WGSL parameters of insertBits must be i32, u32, vecN<i32> or vecN<u32> | 
|  | if (TINT_UNLIKELY(((!ty->DeepestElement()->IsAnyOf<core::type::I32, core::type::U32>())))) { | 
|  | TINT_ICE() | 
|  | << "insertBits polyfill only support i32, u32, and vector of i32 or u32, got " | 
|  | << ty->FriendlyName(); | 
|  | } | 
|  |  | 
|  | constexpr uint32_t W = 32u;  // 32-bit | 
|  |  | 
|  | auto V = [&](auto value) -> const Expression* { | 
|  | const Expression* expr = b.Expr(value); | 
|  | if (!ty->is_unsigned_integer_scalar_or_vector()) { | 
|  | expr = b.Call<i32>(expr); | 
|  | } | 
|  | if (ty->Is<core::type::Vector>()) { | 
|  | expr = b.Call(T(ty), expr); | 
|  | } | 
|  | return expr; | 
|  | }; | 
|  | auto U = [&](auto value) -> const Expression* { | 
|  | if (width == 1) { | 
|  | return b.Expr(value); | 
|  | } | 
|  | return b.vec(b.ty.u32(), width, value); | 
|  | }; | 
|  |  | 
|  | // Polyfill algorithm: | 
|  | //      s = min(offset, 32u); | 
|  | //      e = min(32u, (s + count)); | 
|  | //      mask = (((1u << s) - 1u) ^ ((1u << e) - 1u)); | 
|  | //      return (((n << s) & mask) | (v & ~(mask))); | 
|  | // Note that the algorithm above use the left-shifting in C++ manner, but in WGSL, HLSL, MSL | 
|  | // the rhs are modulo to bit-width of lhs (that is 32u in this case), and in GLSL the result | 
|  | // is undefined if rhs is greater than or equal to bit-width of lhs. The results of `x << y` | 
|  | // in C++ and HLSL are different when `y >= 32u`, and the `s` and `e` defined above can be | 
|  | // 32u, which are cases we must handle specially. Replace all `(x << y)` to | 
|  | // `select(Tx(), x << y, y < 32u)`, in which `Tx` is the type of x, where y can be greater | 
|  | // than or equal to 32u. | 
|  | // WGSL polyfill function: | 
|  | //      fn tint_insert_bits(v : T, n : T, offset : u32, count : u32) -> T { | 
|  | //          let e = offset + count; | 
|  | //          let mask = ( | 
|  | //                        (select(0u, 1u << offset, offset < 32u) - 1u) ^ | 
|  | //                        (select(0u, 1u << e, e < 32u) - 1u) | 
|  | //                     ); | 
|  | //          return ((select(T(), n << offset, offset < 32u) & mask) | (v & ~(mask))); | 
|  | //      } | 
|  |  | 
|  | tint::Vector<const Statement*, 8> body; | 
|  |  | 
|  | switch (cfg.builtins.insert_bits) { | 
|  | case Level::kFull: | 
|  | // let e = offset + count; | 
|  | body.Push(b.Decl(b.Let("e", b.Add("offset", "count")))); | 
|  |  | 
|  | // let mask = ( | 
|  | //              (select(0u, 1u << offset, offset < 32u) - 1u) ^ | 
|  | //              (select(0u, 1u << e, e < 32u) - 1u) | 
|  | //            ); | 
|  | body.Push(b.Decl(b.Let( | 
|  | "mask", | 
|  | b.Xor(  // | 
|  | b.Sub( | 
|  | b.Call("select", 0_u, b.Shl(1_u, "offset"), b.LessThan("offset", 32_u)), | 
|  | 1_u), | 
|  | b.Sub(b.Call("select", 0_u, b.Shl(1_u, "e"), b.LessThan("e", 32_u)), | 
|  | 1_u)  // | 
|  | )))); | 
|  |  | 
|  | // return ((select(T(), n << offset, offset < 32u) & mask) | (v & ~(mask))); | 
|  | body.Push( | 
|  | b.Return(b.Or(b.And(b.Call("select", b.Call(T(ty)), b.Shl("n", U("offset")), | 
|  | b.LessThan("offset", 32_u)), | 
|  | V("mask")), | 
|  | b.And("v", V(b.Complement("mask")))))); | 
|  |  | 
|  | break; | 
|  | case Level::kClampParameters: | 
|  | body.Push(b.Decl(b.Let("s", b.Call("min", "offset", u32(W))))); | 
|  | body.Push(b.Decl(b.Let("e", b.Call("min", u32(W), b.Add("s", "count"))))); | 
|  | body.Push(b.Return(b.Call("insertBits", "v", "n", "s", b.Sub("e", "s")))); | 
|  | break; | 
|  | default: | 
|  | TINT_ICE() << "unhandled polyfill level: " | 
|  | << static_cast<int>(cfg.builtins.insert_bits); | 
|  | } | 
|  |  | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | 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; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `reflect` builtin | 
|  | /// @param ty the parameter and return type for the function | 
|  | /// @return the polyfill function name | 
|  | Symbol reflect(const core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_reflect"); | 
|  |  | 
|  | // WGSL polyfill function: | 
|  | //      fn tint_reflect(e1 : T, e2 : T) -> T { | 
|  | //          let factor = (-2.0 * dot(e1, e2)); | 
|  | //          return (e1 + (factor * e2)); | 
|  | //      } | 
|  | // Using -2.0 instead of 2.0 in factor to prevent the optimization that cause wrong result. | 
|  | // See https://crbug.com/tint/1798 for more details. | 
|  | auto body = tint::Vector{ | 
|  | b.Decl(b.Let("factor", b.Mul(-2.0_a, b.Call("dot", "e1", "e2")))), | 
|  | b.Return(b.Add("e1", b.Mul("factor", "e2"))), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("e1", T(ty)), | 
|  | b.Param("e2", T(ty)), | 
|  | }, | 
|  | T(ty), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `saturate` builtin | 
|  | /// @param ty the parameter and return type for the function | 
|  | /// @return the polyfill function name | 
|  | Symbol saturate(const core::type::Type* ty) { | 
|  | auto name = b.Symbols().New("tint_saturate"); | 
|  | auto body = tint::Vector{ | 
|  | b.Return(b.Call("clamp", "v", b.Call(T(ty), 0_a), b.Call(T(ty), 1_a))), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("v", T(ty)), | 
|  | }, | 
|  | T(ty), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `sign` builtin when the element type is integer | 
|  | /// @param ty the parameter and return type for the function | 
|  | /// @return the polyfill function name | 
|  | Symbol sign_int(const core::type::Type* ty) { | 
|  | const uint32_t width = WidthOf(ty); | 
|  | auto zero = [&] { return ScalarOrVector(width, 0_a); }; | 
|  |  | 
|  | // pos_or_neg_one = (v > 0) ? 1 : -1 | 
|  | auto pos_or_neg_one = b.Call("select",                     // | 
|  | ScalarOrVector(width, -1_a),  // | 
|  | ScalarOrVector(width, 1_a),   // | 
|  | b.GreaterThan("v", zero())); | 
|  |  | 
|  | auto name = b.Symbols().New("tint_sign"); | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("v", T(ty)), | 
|  | }, | 
|  | T(ty), | 
|  | tint::Vector{ | 
|  | b.Return(b.Call("select", pos_or_neg_one, zero(), b.Equal("v", zero()))), | 
|  | }); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `textureSampleBaseClampToEdge` builtin, when the | 
|  | /// texture type is texture_2d<f32>. | 
|  | /// @return the polyfill function name | 
|  | Symbol textureSampleBaseClampToEdge_2d_f32() { | 
|  | auto name = b.Symbols().New("tint_textureSampleBaseClampToEdge"); | 
|  | auto body = tint::Vector{ | 
|  | b.Decl(b.Let("dims", b.Call(b.ty.vec2<f32>(), b.Call("textureDimensions", "t", 0_a)))), | 
|  | b.Decl(b.Let("half_texel", b.Div(b.Call<vec2<f32>>(0.5_a), "dims"))), | 
|  | b.Decl( | 
|  | b.Let("clamped", b.Call("clamp", "coord", "half_texel", b.Sub(1_a, "half_texel")))), | 
|  | b.Return(b.Call("textureSampleLevel", "t", "s", "clamped", 0_a)), | 
|  | }; | 
|  | b.Func( | 
|  | name, | 
|  | tint::Vector{ | 
|  | b.Param("t", b.ty.sampled_texture(core::type::TextureDimension::k2d, b.ty.f32())), | 
|  | b.Param("s", b.ty.sampler(core::type::SamplerKind::kSampler)), | 
|  | b.Param("coord", b.ty.vec2<f32>()), | 
|  | }, | 
|  | b.ty.vec4<f32>(), body); | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `quantizeToF16` builtin, by replacing the vector form | 
|  | /// with scalar calls. | 
|  | /// @param vec the vector type | 
|  | /// @return the polyfill function name | 
|  | Symbol quantizeToF16(const core::type::Vector* vec) { | 
|  | auto name = b.Symbols().New("tint_quantizeToF16"); | 
|  | tint::Vector<const Expression*, 4> args; | 
|  | for (uint32_t i = 0; i < vec->Width(); i++) { | 
|  | args.Push(b.Call("quantizeToF16", b.IndexAccessor("v", u32(i)))); | 
|  | } | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("v", T(vec)), | 
|  | }, | 
|  | T(vec), | 
|  | tint::Vector{ | 
|  | b.Return(b.Call(T(vec), std::move(args))), | 
|  | }); | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `workgroupUniformLoad` builtin. | 
|  | /// @param type the type being loaded | 
|  | /// @return the polyfill function name | 
|  | Symbol workgroupUniformLoad(const core::type::Type* type) { | 
|  | auto name = b.Symbols().New("tint_workgroupUniformLoad"); | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("p", b.ty.ptr<workgroup>(T(type))), | 
|  | }, | 
|  | T(type), | 
|  | tint::Vector{ | 
|  | b.CallStmt(b.Call("workgroupBarrier")), | 
|  | b.Decl(b.Let("result", b.Deref("p"))), | 
|  | b.CallStmt(b.Call("workgroupBarrier")), | 
|  | b.Return("result"), | 
|  | }); | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function to value convert a scalar or vector of f32 to an i32 or u32 (or | 
|  | /// vector of). | 
|  | /// @param source the type of the value being converted | 
|  | /// @param target the target conversion type | 
|  | /// @return the polyfill function name | 
|  | Symbol ConvF32ToIU32(const core::type::Type* source, const core::type::Type* target) { | 
|  | struct Limits { | 
|  | AFloat low_condition; | 
|  | AInt low_limit; | 
|  | AFloat high_condition; | 
|  | AInt high_limit; | 
|  | }; | 
|  | const bool is_signed = target->is_signed_integer_scalar_or_vector(); | 
|  | const Limits limits = is_signed ? Limits{ | 
|  | /* low_condition   */ -AFloat(0x80000000), | 
|  | /* low_limit  */ -AInt(0x80000000), | 
|  | /* high_condition  */ AFloat(0x7fffff80), | 
|  | /* high_limit */ AInt(0x7fffffff), | 
|  | } | 
|  | : Limits{ | 
|  | /* low_condition   */ AFloat(0), | 
|  | /* low_limit  */ AInt(0), | 
|  | /* high_condition  */ AFloat(0xffffff00), | 
|  | /* high_limit */ AInt(0xffffffff), | 
|  | }; | 
|  |  | 
|  | const uint32_t width = WidthOf(target); | 
|  |  | 
|  | // select(target(v), low_limit, v < low_condition) | 
|  | auto* select_low = b.Call(wgsl::BuiltinFn::kSelect,                 // | 
|  | b.Call(T(target), "v"),                   // | 
|  | ScalarOrVector(width, limits.low_limit),  // | 
|  | b.LessThan("v", ScalarOrVector(width, limits.low_condition))); | 
|  |  | 
|  | // select(high_limit, select_low, v < high_condition) | 
|  | auto* select_high = b.Call(wgsl::BuiltinFn::kSelect,                  // | 
|  | ScalarOrVector(width, limits.high_limit),  // | 
|  | select_low,                                // | 
|  | b.LessThan("v", ScalarOrVector(width, limits.high_condition))); | 
|  |  | 
|  | auto name = b.Symbols().New(is_signed ? "tint_ftoi" : "tint_ftou"); | 
|  | b.Func(name, tint::Vector{b.Param("v", T(source))}, T(target), | 
|  | tint::Vector{b.Return(select_high)}); | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `dot4I8Packed` builtin | 
|  | /// @return the polyfill function name | 
|  | Symbol Dot4I8Packed() { | 
|  | using vec4i = vec4<i32>; | 
|  | using vec4u = vec4<u32>; | 
|  |  | 
|  | auto name = b.Symbols().New("tint_dot4_i8_packed"); | 
|  |  | 
|  | auto body = tint::Vector{ | 
|  | // const n = vec4u(24, 16, 8, 0); | 
|  | // let a_i8 = bitcast<vec4i>(vec4u(a) << n) >> vec4u(24); | 
|  | // let b_i8 = bitcast<vec4i>(vec4u(b) << n) >> vec4u(24); | 
|  | // return dot(a_i8, b_i8); | 
|  | b.Decl(b.Const("n", b.Call<vec4u>(24_a, 16_a, 8_a, 0_a))), | 
|  | b.Decl(b.Let("a_i8", b.Shr(b.Bitcast<vec4i>(b.Shl(b.Call<vec4u>("a"), "n")), | 
|  | b.Call<vec4u>(24_a)))), | 
|  | b.Decl(b.Let("b_i8", b.Shr(b.Bitcast<vec4i>(b.Shl(b.Call<vec4u>("b"), "n")), | 
|  | b.Call<vec4u>(24_a)))), | 
|  | b.Return(b.Call("dot", "a_i8", "b_i8")), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("a", b.ty.u32()), | 
|  | b.Param("b", b.ty.u32()), | 
|  | }, | 
|  | b.ty.i32(), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `dot4U8Packed` builtin | 
|  | /// @return the polyfill function name | 
|  | Symbol Dot4U8Packed() { | 
|  | using vec4u = vec4<u32>; | 
|  | auto name = b.Symbols().New("tint_dot4_u8_packed"); | 
|  |  | 
|  | auto body = tint::Vector{ | 
|  | // const n = vec4u(24, 16, 8, 0); | 
|  | // let a_u8 = (vec4u(a) >> n) & vec4u(0xff); | 
|  | // let b_u8 = (vec4u(b) >> n) & vec4u(0xff); | 
|  | // return dot(a_u8, b_u8); | 
|  | b.Decl(b.Const("n", b.Call<vec4u>(24_a, 16_a, 8_a, 0_a))), | 
|  | b.Decl(b.Let("a_u8", b.And(b.Shr(b.Call<vec4u>("a"), "n"), b.Call<vec4u>(0xff_a)))), | 
|  | b.Decl(b.Let("b_u8", b.And(b.Shr(b.Call<vec4u>("b"), "n"), b.Call<vec4u>(0xff_a)))), | 
|  | b.Return(b.Call("dot", "a_u8", "b_u8")), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("a", b.ty.u32()), | 
|  | b.Param("b", b.ty.u32()), | 
|  | }, | 
|  | b.ty.u32(), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `pack4xI8` builtin | 
|  | /// @return the polyfill function name | 
|  | Symbol Pack4xI8() { | 
|  | using vec4u = vec4<u32>; | 
|  |  | 
|  | auto name = b.Symbols().New("tint_pack_4xi8"); | 
|  |  | 
|  | auto body = tint::Vector{ | 
|  | // const n = vec4u(0, 8, 16, 24); | 
|  | // let a_u32 = bitcast<vec4u>(a); | 
|  | // let a_u8 = (a_u32 & vec4u(0xff)) << n; | 
|  | // return dot(a_u8, vec4u(1)); | 
|  | b.Decl(b.Const("n", b.Call<vec4u>(0_a, 8_a, 16_a, 24_a))), | 
|  | b.Decl(b.Let("a_u32", b.Bitcast<vec4u>("a"))), | 
|  | b.Decl(b.Let("a_u8", b.Shl(b.And("a_u32", b.Call<vec4u>(0xff_a)), "n"))), | 
|  | b.Return(b.Call("dot", "a_u8", b.Call<vec4u>(1_a))), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("a", b.ty.vec4<i32>()), | 
|  | }, | 
|  | b.ty.u32(), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `pack4xU8` builtin | 
|  | /// @return the polyfill function name | 
|  | Symbol Pack4xU8() { | 
|  | using vec4u = vec4<u32>; | 
|  |  | 
|  | auto name = b.Symbols().New("tint_pack_4xu8"); | 
|  |  | 
|  | auto body = tint::Vector{ | 
|  | // const n = vec4u(0, 8, 16, 24); | 
|  | // let a_u8 = (a & vec4u(0xff)) << n; | 
|  | // return dot(a_u8, vec4u(1)); | 
|  | b.Decl(b.Const("n", b.Call<vec4u>(0_a, 8_a, 16_a, 24_a))), | 
|  | b.Decl(b.Let("a_u8", b.Shl(b.And("a", b.Call<vec4u>(0xff_a)), "n"))), | 
|  | b.Return(b.Call("dot", "a_u8", b.Call<vec4u>(1_a))), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("a", b.ty.vec4<u32>()), | 
|  | }, | 
|  | b.ty.u32(), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `pack4xI8Clamp` builtin | 
|  | /// @return the polyfill function name | 
|  | Symbol Pack4xI8Clamp() { | 
|  | using vec4i = vec4<i32>; | 
|  | using vec4u = vec4<u32>; | 
|  |  | 
|  | auto name = b.Symbols().New("tint_pack_4xi8_clamp"); | 
|  |  | 
|  | auto body = tint::Vector{ | 
|  | // const n = vec4u(0, 8, 16, 24); | 
|  | // let a_clamp = clamp(a, vec4i(-128), vec4i(127)); | 
|  | // let a_u32 = bitcast<vec4u>(a_clamp); | 
|  | // let a_u8 = (a_u32 & vec4u(0xff)) << n; | 
|  | // return dot(a_u8, vec4u(1)); | 
|  | b.Decl(b.Const("n", b.Call<vec4u>(0_a, 8_a, 16_a, 24_a))), | 
|  | b.Decl(b.Let("a_clamp", | 
|  | b.Call("clamp", "a", b.Call<vec4i>(-128_a), b.Call<vec4i>(127_a)))), | 
|  | b.Decl(b.Let("a_u32", b.Bitcast<vec4u>("a_clamp"))), | 
|  | b.Decl(b.Let("a_u8", b.Shl(b.And("a_u32", b.Call<vec4u>(0xff_a)), "n"))), | 
|  | b.Return(b.Call("dot", "a_u8", b.Call<vec4u>(1_a))), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("a", b.ty.vec4<i32>()), | 
|  | }, | 
|  | b.ty.u32(), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `pack4xU8Clamp` builtin | 
|  | /// @return the polyfill function name | 
|  | Symbol Pack4xU8Clamp() { | 
|  | using vec4u = vec4<u32>; | 
|  |  | 
|  | auto name = b.Symbols().New("tint_pack_4xu8_clamp"); | 
|  |  | 
|  | auto body = tint::Vector{ | 
|  | // const n = vec4u(0, 8, 16, 24); | 
|  | // let a_clamp = clamp(a, vec4u(0), vec4u(255)); | 
|  | // let a_u8 = a_clamp << n; | 
|  | // return dot(a_u8, vec4u(1)); | 
|  | b.Decl(b.Const("n", b.Call<vec4u>(0_a, 8_a, 16_a, 24_a))), | 
|  | b.Decl( | 
|  | b.Let("a_clamp", b.Call("clamp", "a", b.Call<vec4u>(0_a), b.Call<vec4u>(255_a)))), | 
|  | b.Decl(b.Let("a_u8", b.Call<vec4u>(b.Shl("a_clamp", "n")))), | 
|  | b.Return(b.Call("dot", "a_u8", b.Call<vec4u>(1_a))), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("a", b.ty.vec4<u32>()), | 
|  | }, | 
|  | b.ty.u32(), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `unpack4xI8` builtin | 
|  | /// @return the polyfill function name | 
|  | Symbol Unpack4xI8() { | 
|  | using vec4i = vec4<i32>; | 
|  | using vec4u = vec4<u32>; | 
|  |  | 
|  | auto name = b.Symbols().New("tint_unpack_4xi8"); | 
|  |  | 
|  | auto body = tint::Vector{ | 
|  | // const n = vec4u(24, 16, 8, 0); | 
|  | // let a_vec4u = vec4u(a); | 
|  | // let a_vec4i = bitcast<vec4i>(a_vec4u << n); | 
|  | // return a_vec4i >> vec4u(24); | 
|  | b.Decl(b.Const("n", b.Call<vec4u>(24_a, 16_a, 8_a, 0_a))), | 
|  | b.Decl(b.Let("a_vec4u", b.Call<vec4u>("a"))), | 
|  | b.Decl(b.Let("a_vec4i", b.Bitcast<vec4i>(b.Shl("a_vec4u", "n")))), | 
|  | b.Return(b.Shr("a_vec4i", b.Call<vec4u>(24_a))), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("a", b.ty.u32()), | 
|  | }, | 
|  | b.ty.vec4<i32>(), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill function for the `unpack4xU8` builtin | 
|  | /// @return the polyfill function name | 
|  | Symbol Unpack4xU8() { | 
|  | using vec4u = vec4<u32>; | 
|  |  | 
|  | auto name = b.Symbols().New("tint_unpack_4xu8"); | 
|  |  | 
|  | auto body = tint::Vector{ | 
|  | // const n = vec4u(0, 8, 16, 24); | 
|  | // const a_vec4u = vec4u(a) >> n; | 
|  | // return a_vec4u & vec4u(0xff); | 
|  | b.Decl(b.Const("n", b.Call<vec4u>(0_a, 8_a, 16_a, 24_a))), | 
|  | b.Decl(b.Let("a_vec4u", b.Shr(b.Call<vec4u>("a"), "n"))), | 
|  | b.Return(b.And("a_vec4u", b.Call<vec4u>(0xff_a))), | 
|  | }; | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("a", b.ty.u32()), | 
|  | }, | 
|  | b.ty.vec4<u32>(), body); | 
|  |  | 
|  | return name; | 
|  | } | 
|  |  | 
|  | //////////////////////////////////////////////////////////////////////////// | 
|  | // Inline polyfills | 
|  | //////////////////////////////////////////////////////////////////////////// | 
|  |  | 
|  | /// Builds the polyfill inline expression for a bitshift left or bitshift right, ensuring that | 
|  | /// the RHS is modulo the bit-width of the LHS. | 
|  | /// @param bin_op the original BinaryExpression | 
|  | /// @return the polyfill value for bitshift operation | 
|  | const Expression* BitshiftModulo(const BinaryExpression* bin_op) { | 
|  | auto* lhs_ty = src.TypeOf(bin_op->lhs)->UnwrapRef(); | 
|  | auto* rhs_ty = src.TypeOf(bin_op->rhs)->UnwrapRef(); | 
|  | auto* lhs_el_ty = lhs_ty->DeepestElement(); | 
|  | const Expression* mask = b.Expr(AInt(lhs_el_ty->Size() * 8 - 1)); | 
|  | if (rhs_ty->Is<core::type::Vector>()) { | 
|  | mask = b.Call(CreateASTTypeFor(ctx, rhs_ty), mask); | 
|  | } | 
|  | auto* lhs = ctx.Clone(bin_op->lhs); | 
|  | auto* rhs = b.And(ctx.Clone(bin_op->rhs), mask); | 
|  | return b.create<BinaryExpression>(ctx.Clone(bin_op->source), bin_op->op, lhs, rhs); | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill inline expression for a integer divide or modulo, preventing DBZs and | 
|  | /// integer overflows. | 
|  | /// @param bin_op the original BinaryExpression | 
|  | /// @return the polyfill divide or modulo | 
|  | const Expression* IntDivMod(const BinaryExpression* bin_op) { | 
|  | auto* lhs_ty = src.TypeOf(bin_op->lhs)->UnwrapRef(); | 
|  | auto* rhs_ty = src.TypeOf(bin_op->rhs)->UnwrapRef(); | 
|  | BinaryOpSignature sig{bin_op->op, lhs_ty, rhs_ty}; | 
|  | auto fn = binary_op_polyfills.GetOrAdd(sig, [&] { | 
|  | const bool is_div = bin_op->op == core::BinaryOp::kDivide; | 
|  |  | 
|  | const auto [lhs_el_ty, lhs_width] = lhs_ty->Elements(lhs_ty, 1); | 
|  | const auto [rhs_el_ty, rhs_width] = rhs_ty->Elements(rhs_ty, 1); | 
|  |  | 
|  | const uint32_t width = std::max(lhs_width, rhs_width); | 
|  |  | 
|  | const char* lhs = "lhs"; | 
|  | const char* rhs = "rhs"; | 
|  |  | 
|  | tint::Vector<const Statement*, 4> body; | 
|  |  | 
|  | if (lhs_width < width) { | 
|  | // lhs is scalar, rhs is vector. Convert lhs to vector. | 
|  | body.Push(b.Decl(b.Let("l", b.vec(T(lhs_el_ty), width, b.Expr(lhs))))); | 
|  | lhs = "l"; | 
|  | } | 
|  | if (rhs_width < width) { | 
|  | // lhs is vector, rhs is scalar. Convert rhs to vector. | 
|  | body.Push(b.Decl(b.Let("r", b.vec(T(rhs_el_ty), width, b.Expr(rhs))))); | 
|  | rhs = "r"; | 
|  | } | 
|  |  | 
|  | auto name = b.Symbols().New(is_div ? "tint_div" : "tint_mod"); | 
|  |  | 
|  | auto* rhs_is_zero = b.Equal(rhs, ScalarOrVector(width, 0_a)); | 
|  |  | 
|  | if (lhs_ty->is_signed_integer_scalar_or_vector()) { | 
|  | const auto bits = lhs_el_ty->Size() * 8; | 
|  | auto min_int = AInt(AInt::kLowestValue >> (AInt::kNumBits - bits)); | 
|  | const Expression* lhs_is_min = b.Equal(lhs, ScalarOrVector(width, min_int)); | 
|  | const Expression* rhs_is_minus_one = b.Equal(rhs, ScalarOrVector(width, -1_a)); | 
|  | // use_one = rhs_is_zero | ((lhs == MIN_INT) & (rhs == -1)) | 
|  | auto* use_one = b.Or(rhs_is_zero, b.And(lhs_is_min, rhs_is_minus_one)); | 
|  |  | 
|  | // Special handling for mod in case either operand is negative, as negative operands | 
|  | // for % is undefined behaviour for most backends (HLSL, MSL, GLSL, SPIR-V). | 
|  | if (!is_div) { | 
|  | const char* rhs_or_one = "rhs_or_one"; | 
|  | body.Push(b.Decl(b.Let( | 
|  | rhs_or_one, b.Call("select", rhs, ScalarOrVector(width, 1_a), use_one)))); | 
|  |  | 
|  | // Is either operand negative? | 
|  | // (lhs | rhs) & (1<<31) | 
|  | auto sign_bit_mask = ScalarOrVector(width, u32(1 << (bits - 1))); | 
|  | auto* lhs_or_rhs = CastScalarOrVector<u32>(width, b.Or(lhs, rhs_or_one)); | 
|  | auto* lhs_or_rhs_is_neg = | 
|  | b.NotEqual(b.And(lhs_or_rhs, sign_bit_mask), ScalarOrVector(width, 0_u)); | 
|  |  | 
|  | // lhs - trunc(lhs / rhs) * rhs (note: integral division truncates) | 
|  | auto* slow_mod = b.Sub(lhs, b.Mul(b.Div(lhs, rhs_or_one), rhs_or_one)); | 
|  |  | 
|  | // lhs % rhs | 
|  | auto* fast_mod = b.Mod(lhs, rhs_or_one); | 
|  |  | 
|  | auto* use_slow = b.Call("any", lhs_or_rhs_is_neg); | 
|  |  | 
|  | body.Push(b.If(use_slow, b.Block(b.Return(slow_mod)), | 
|  | b.Else(b.Block(b.Return(fast_mod))))); | 
|  |  | 
|  | } else { | 
|  | auto* rhs_or_one = b.Call("select", rhs, ScalarOrVector(width, 1_a), use_one); | 
|  | body.Push(b.Return(is_div ? b.Div(lhs, rhs_or_one) : b.Mod(lhs, rhs_or_one))); | 
|  | } | 
|  |  | 
|  | } else { | 
|  | auto* rhs_or_one = b.Call("select", rhs, ScalarOrVector(width, 1_a), rhs_is_zero); | 
|  | body.Push(b.Return(is_div ? b.Div(lhs, rhs_or_one) : b.Mod(lhs, rhs_or_one))); | 
|  | } | 
|  |  | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("lhs", T(lhs_ty)), | 
|  | b.Param("rhs", T(rhs_ty)), | 
|  | }, | 
|  | width == 1 ? T(lhs_ty) : b.ty.vec(T(lhs_el_ty), width),  // return type | 
|  | std::move(body)); | 
|  |  | 
|  | return name; | 
|  | }); | 
|  | auto* lhs = ctx.Clone(bin_op->lhs); | 
|  | auto* rhs = ctx.Clone(bin_op->rhs); | 
|  | return b.Call(fn, lhs, rhs); | 
|  | } | 
|  |  | 
|  | /// Builds the polyfill inline expression for a precise float modulo, as defined in the spec. | 
|  | /// @param bin_op the original BinaryExpression | 
|  | /// @return the polyfill divide or modulo | 
|  | const Expression* PreciseFloatMod(const BinaryExpression* bin_op) { | 
|  | auto* lhs_ty = src.TypeOf(bin_op->lhs)->UnwrapRef(); | 
|  | auto* rhs_ty = src.TypeOf(bin_op->rhs)->UnwrapRef(); | 
|  | BinaryOpSignature sig{bin_op->op, lhs_ty, rhs_ty}; | 
|  | auto fn = binary_op_polyfills.GetOrAdd(sig, [&] { | 
|  | const auto [lhs_el_ty, lhs_width] = lhs_ty->Elements(lhs_ty, 1); | 
|  | const auto [rhs_el_ty, rhs_width] = rhs_ty->Elements(rhs_ty, 1); | 
|  |  | 
|  | const uint32_t width = std::max(lhs_width, rhs_width); | 
|  |  | 
|  | const char* lhs = "lhs"; | 
|  | const char* rhs = "rhs"; | 
|  |  | 
|  | tint::Vector<const Statement*, 4> body; | 
|  |  | 
|  | if (lhs_width < width) { | 
|  | // lhs is scalar, rhs is vector. Convert lhs to vector. | 
|  | body.Push(b.Decl(b.Let("l", b.vec(T(lhs_el_ty), width, b.Expr(lhs))))); | 
|  | lhs = "l"; | 
|  | } | 
|  | if (rhs_width < width) { | 
|  | // lhs is vector, rhs is scalar. Convert rhs to vector. | 
|  | body.Push(b.Decl(b.Let("r", b.vec(T(rhs_el_ty), width, b.Expr(rhs))))); | 
|  | rhs = "r"; | 
|  | } | 
|  |  | 
|  | auto name = b.Symbols().New("tint_float_mod"); | 
|  |  | 
|  | // lhs - trunc(lhs / rhs) * rhs | 
|  | auto* precise_mod = b.Sub(lhs, b.Mul(b.Call("trunc", b.Div(lhs, rhs)), rhs)); | 
|  | body.Push(b.Return(precise_mod)); | 
|  |  | 
|  | b.Func(name, | 
|  | tint::Vector{ | 
|  | b.Param("lhs", T(lhs_ty)), | 
|  | b.Param("rhs", T(rhs_ty)), | 
|  | }, | 
|  | width == 1 ? T(lhs_ty) : b.ty.vec(T(lhs_el_ty), width),  // return type | 
|  | std::move(body)); | 
|  |  | 
|  | return name; | 
|  | }); | 
|  | auto* lhs = ctx.Clone(bin_op->lhs); | 
|  | auto* rhs = ctx.Clone(bin_op->rhs); | 
|  | return b.Call(fn, lhs, rhs); | 
|  | } | 
|  |  | 
|  | /// @returns the AST type for the given sem type | 
|  | Type T(const core::type::Type* ty) { return CreateASTTypeFor(ctx, ty); } | 
|  |  | 
|  | /// @returns 1 if `ty` is not a vector, otherwise the vector width | 
|  | uint32_t WidthOf(const core::type::Type* ty) const { | 
|  | if (auto* v = ty->As<core::type::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 Expression* ScalarOrVector(uint32_t width, T value) { | 
|  | if (width == 1) { | 
|  | return b.Expr(value); | 
|  | } | 
|  | return b.Call(b.ty.vec<T>(width), value); | 
|  | } | 
|  |  | 
|  | template <typename To> | 
|  | const Expression* CastScalarOrVector(uint32_t width, const Expression* e) { | 
|  | if (width == 1) { | 
|  | return b.Call(b.ty.Of<To>(), e); | 
|  | } | 
|  | return b.Call(b.ty.vec<To>(width), e); | 
|  | } | 
|  |  | 
|  | /// Examines the call expression @p expr, applying any necessary polyfill transforms | 
|  | void Call(const CallExpression* expr) { | 
|  | auto* call = src.Sem().Get(expr)->UnwrapMaterialize()->As<sem::Call>(); | 
|  | if (!call || call->Stage() != core::EvaluationStage::kRuntime) { | 
|  | return;  // Only polyfill runtime expressions | 
|  | } | 
|  | Symbol fn = Switch( | 
|  | call->Target(),  // | 
|  | [&](const sem::BuiltinFn* builtin) { | 
|  | switch (builtin->Fn()) { | 
|  | case wgsl::BuiltinFn::kAcosh: | 
|  | if (cfg.builtins.acosh != Level::kNone) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return acosh(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kAsinh: | 
|  | if (cfg.builtins.asinh) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return asinh(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kAtanh: | 
|  | if (cfg.builtins.atanh != Level::kNone) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return atanh(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kClamp: | 
|  | if (cfg.builtins.clamp_int) { | 
|  | auto& sig = builtin->Signature(); | 
|  | if (sig.parameters[0]->Type()->is_integer_scalar_or_vector()) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return clampInteger(builtin->ReturnType()); }); | 
|  | } | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kCountLeadingZeros: | 
|  | if (cfg.builtins.count_leading_zeros) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return countLeadingZeros(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kCountTrailingZeros: | 
|  | if (cfg.builtins.count_trailing_zeros) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return countTrailingZeros(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kExtractBits: | 
|  | if (cfg.builtins.extract_bits != Level::kNone) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return extractBits(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kFirstLeadingBit: | 
|  | if (cfg.builtins.first_leading_bit) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return firstLeadingBit(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kFirstTrailingBit: | 
|  | if (cfg.builtins.first_trailing_bit) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return firstTrailingBit(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kFwidthFine: | 
|  | if (cfg.builtins.fwidth_fine) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return fwidthFine(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kInsertBits: | 
|  | if (cfg.builtins.insert_bits != Level::kNone) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return insertBits(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kReflect: | 
|  | // Only polyfill for vec2<f32>. See https://crbug.com/tint/1798 for | 
|  | // more details. | 
|  | if (cfg.builtins.reflect_vec2_f32) { | 
|  | auto& sig = builtin->Signature(); | 
|  | auto* vec = sig.return_type->As<core::type::Vector>(); | 
|  | if (vec && vec->Width() == 2 && vec->type()->Is<core::type::F32>()) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return reflect(builtin->ReturnType()); }); | 
|  | } | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kSaturate: | 
|  | if (cfg.builtins.saturate) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return saturate(builtin->ReturnType()); }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kSign: | 
|  | if (cfg.builtins.sign_int) { | 
|  | auto* ty = builtin->ReturnType(); | 
|  | if (ty->is_signed_integer_scalar_or_vector()) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, | 
|  | [&] { return sign_int(ty); }); | 
|  | } | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kTextureLoad: | 
|  | if (cfg.builtins.bgra8unorm) { | 
|  | auto& sig = builtin->Signature(); | 
|  | auto* tex = sig.Parameter(core::ParameterUsage::kTexture); | 
|  | if (auto* stex = tex->Type()->As<core::type::StorageTexture>()) { | 
|  | if (stex->texel_format() == core::TexelFormat::kBgra8Unorm) { | 
|  | ctx.Replace(expr, [this, expr] { | 
|  | return ctx.dst->MemberAccessor( | 
|  | ctx.CloneWithoutTransform(expr), "bgra"); | 
|  | }); | 
|  | made_changes = true; | 
|  | } | 
|  | } | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kTextureSampleBaseClampToEdge: | 
|  | if (cfg.builtins.texture_sample_base_clamp_to_edge_2d_f32) { | 
|  | auto& sig = builtin->Signature(); | 
|  | auto* tex = sig.Parameter(core::ParameterUsage::kTexture); | 
|  | if (auto* stex = tex->Type()->As<core::type::SampledTexture>()) { | 
|  | if (stex->type()->Is<core::type::F32>()) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, [&] { | 
|  | return textureSampleBaseClampToEdge_2d_f32(); | 
|  | }); | 
|  | } | 
|  | } | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kTextureStore: | 
|  | if (cfg.builtins.bgra8unorm) { | 
|  | auto& sig = builtin->Signature(); | 
|  | auto* tex = sig.Parameter(core::ParameterUsage::kTexture); | 
|  | if (auto* stex = tex->Type()->As<core::type::StorageTexture>()) { | 
|  | if (stex->texel_format() == core::TexelFormat::kBgra8Unorm) { | 
|  | size_t value_idx = static_cast<size_t>( | 
|  | sig.IndexOf(core::ParameterUsage::kValue)); | 
|  | ctx.Replace(expr, [this, expr, value_idx] { | 
|  | tint::Vector<const Expression*, 3> args; | 
|  | for (auto* arg : expr->args) { | 
|  | arg = ctx.Clone(arg); | 
|  | if (args.Length() == value_idx) {  // value | 
|  | arg = ctx.dst->MemberAccessor(arg, "bgra"); | 
|  | } | 
|  | args.Push(arg); | 
|  | } | 
|  | return ctx.dst->Call( | 
|  | tint::ToString(wgsl::BuiltinFn::kTextureStore), | 
|  | std::move(args)); | 
|  | }); | 
|  | made_changes = true; | 
|  | } | 
|  | } | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kQuantizeToF16: | 
|  | if (cfg.builtins.quantize_to_vec_f16) { | 
|  | if (auto* vec = builtin->ReturnType()->As<core::type::Vector>()) { | 
|  | return builtin_polyfills.GetOrAdd( | 
|  | builtin, [&] { return quantizeToF16(vec); }); | 
|  | } | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kWorkgroupUniformLoad: | 
|  | if (cfg.builtins.workgroup_uniform_load) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, [&] { | 
|  | return workgroupUniformLoad(builtin->ReturnType()); | 
|  | }); | 
|  | } | 
|  | return Symbol{}; | 
|  |  | 
|  | case wgsl::BuiltinFn::kDot4I8Packed: { | 
|  | if (cfg.builtins.dot_4x8_packed) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, | 
|  | [&] { return Dot4I8Packed(); }); | 
|  | } | 
|  | return Symbol{}; | 
|  | } | 
|  |  | 
|  | case wgsl::BuiltinFn::kDot4U8Packed: { | 
|  | if (cfg.builtins.dot_4x8_packed) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, | 
|  | [&] { return Dot4U8Packed(); }); | 
|  | } | 
|  | return Symbol{}; | 
|  | } | 
|  |  | 
|  | case wgsl::BuiltinFn::kPack4XI8: { | 
|  | if (cfg.builtins.pack_unpack_4x8) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, [&] { return Pack4xI8(); }); | 
|  | } | 
|  | return Symbol{}; | 
|  | } | 
|  |  | 
|  | case wgsl::BuiltinFn::kPack4XU8: { | 
|  | if (cfg.builtins.pack_unpack_4x8) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, [&] { return Pack4xU8(); }); | 
|  | } | 
|  | return Symbol{}; | 
|  | } | 
|  |  | 
|  | case wgsl::BuiltinFn::kPack4XI8Clamp: { | 
|  | if (cfg.builtins.pack_unpack_4x8) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, | 
|  | [&] { return Pack4xI8Clamp(); }); | 
|  | } | 
|  | return Symbol{}; | 
|  | } | 
|  |  | 
|  | case wgsl::BuiltinFn::kPack4XU8Clamp: { | 
|  | if (cfg.builtins.pack_4xu8_clamp) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, | 
|  | [&] { return Pack4xU8Clamp(); }); | 
|  | } | 
|  | return Symbol{}; | 
|  | } | 
|  |  | 
|  | case wgsl::BuiltinFn::kUnpack4XI8: { | 
|  | if (cfg.builtins.pack_unpack_4x8) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, | 
|  | [&] { return Unpack4xI8(); }); | 
|  | } | 
|  | return Symbol{}; | 
|  | } | 
|  |  | 
|  | case wgsl::BuiltinFn::kUnpack4XU8: { | 
|  | if (cfg.builtins.pack_unpack_4x8) { | 
|  | return builtin_polyfills.GetOrAdd(builtin, | 
|  | [&] { return Unpack4xU8(); }); | 
|  | } | 
|  | return Symbol{}; | 
|  | } | 
|  |  | 
|  | default: | 
|  | return Symbol{}; | 
|  | } | 
|  | }, | 
|  | [&](const sem::ValueConversion* conv) { | 
|  | if (cfg.builtins.conv_f32_to_iu32) { | 
|  | auto* src_ty = conv->Source(); | 
|  | if (tint::Is<core::type::F32>(src_ty->Elements(src_ty).type)) { | 
|  | auto* dst_ty = conv->Target(); | 
|  | if (tint::IsAnyOf<core::type::I32, core::type::U32>( | 
|  | dst_ty->Elements(dst_ty).type)) { | 
|  | return f32_conv_polyfills.GetOrAdd(dst_ty, [&] {  // | 
|  | return ConvF32ToIU32(src_ty, dst_ty); | 
|  | }); | 
|  | } | 
|  | } | 
|  | } | 
|  | return Symbol{}; | 
|  | }); | 
|  |  | 
|  | if (fn.IsValid()) { | 
|  | ctx.Replace(call->Declaration(), | 
|  | [this, fn, expr] { return ctx.dst->Call(fn, ctx.Clone(expr->args)); }); | 
|  | made_changes = true; | 
|  | } | 
|  | } | 
|  | }; | 
|  |  | 
|  | BuiltinPolyfill::BuiltinPolyfill() = default; | 
|  |  | 
|  | BuiltinPolyfill::~BuiltinPolyfill() = default; | 
|  |  | 
|  | Transform::ApplyResult BuiltinPolyfill::Apply(const Program& src, | 
|  | const DataMap& data, | 
|  | DataMap&) const { | 
|  | auto* cfg = data.Get<Config>(); | 
|  | if (!cfg) { | 
|  | return SkipTransform; | 
|  | } | 
|  | return State{src, *cfg}.Run(); | 
|  | } | 
|  |  | 
|  | BuiltinPolyfill::Config::Config() = default; | 
|  | BuiltinPolyfill::Config::Config(const Builtins& b) : builtins(b) {} | 
|  | BuiltinPolyfill::Config::Config(const Config&) = default; | 
|  | BuiltinPolyfill::Config::~Config() = default; | 
|  |  | 
|  | }  // namespace tint::ast::transform |