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// Copyright 2020 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 <cstring>
#include "src/ast/override_decoration.h"
#include "src/writer/wgsl/test_helper.h"
namespace tint {
namespace writer {
namespace wgsl {
namespace {
// Makes an IEEE 754 binary32 floating point number with
// - 0 sign if sign is 0, 1 otherwise
// - 'exponent_bits' is placed in the exponent space.
// So, the exponent bias must already be included.
float MakeFloat(int sign, int biased_exponent, int mantissa) {
const uint32_t sign_bit = sign ? 0x80000000u : 0u;
// The binary32 exponent is 8 bits, just below the sign.
const uint32_t exponent_bits = (biased_exponent & 0xffu) << 23;
// The mantissa is the bottom 23 bits.
const uint32_t mantissa_bits = (mantissa & 0x7fffffu);
uint32_t bits = sign_bit | exponent_bits | mantissa_bits;
float result = 0.0f;
static_assert(sizeof(result) == sizeof(bits),
"expected float and uint32_t to be the same size");
std::memcpy(&result, &bits, sizeof(bits));
return result;
}
struct FloatData {
float value;
std::string expected;
};
inline std::ostream& operator<<(std::ostream& out, FloatData data) {
out << "{" << data.value << "," << data.expected << "}";
return out;
}
using WgslGenerator_FloatLiteralTest = TestParamHelper<FloatData>;
TEST_P(WgslGenerator_FloatLiteralTest, Emit) {
auto* v = Expr(GetParam().value);
SetResolveOnBuild(false);
GeneratorImpl& gen = Build();
std::stringstream out;
ASSERT_TRUE(gen.EmitScalarConstructor(out, v)) << gen.error();
EXPECT_EQ(out.str(), GetParam().expected);
}
INSTANTIATE_TEST_SUITE_P(Zero,
WgslGenerator_FloatLiteralTest,
::testing::ValuesIn(std::vector<FloatData>{
{0.0f, "0.0"},
{MakeFloat(0, 0, 0), "0.0"},
{MakeFloat(1, 0, 0), "-0.0"}}));
INSTANTIATE_TEST_SUITE_P(Normal,
WgslGenerator_FloatLiteralTest,
::testing::ValuesIn(std::vector<FloatData>{
{1.0f, "1.0"},
{-1.0f, "-1.0"},
{101.375, "101.375"}}));
INSTANTIATE_TEST_SUITE_P(
Subnormal,
WgslGenerator_FloatLiteralTest,
::testing::ValuesIn(std::vector<FloatData>{
{MakeFloat(0, 0, 1), "0x1p-149"}, // Smallest
{MakeFloat(1, 0, 1), "-0x1p-149"},
{MakeFloat(0, 0, 2), "0x1p-148"},
{MakeFloat(1, 0, 2), "-0x1p-148"},
{MakeFloat(0, 0, 0x7fffff), "0x1.fffffcp-127"}, // Largest
{MakeFloat(1, 0, 0x7fffff), "-0x1.fffffcp-127"}, // Largest
{MakeFloat(0, 0, 0xcafebe), "0x1.2bfaf8p-127"}, // Scattered bits
{MakeFloat(1, 0, 0xcafebe), "-0x1.2bfaf8p-127"}, // Scattered bits
{MakeFloat(0, 0, 0xaaaaa), "0x1.55554p-130"}, // Scattered bits
{MakeFloat(1, 0, 0xaaaaa), "-0x1.55554p-130"}, // Scattered bits
}));
INSTANTIATE_TEST_SUITE_P(Infinity,
WgslGenerator_FloatLiteralTest,
::testing::ValuesIn(std::vector<FloatData>{
{MakeFloat(0, 255, 0), "0x1p+128"},
{MakeFloat(1, 255, 0), "-0x1p+128"}}));
INSTANTIATE_TEST_SUITE_P(
// TODO(dneto): It's unclear how Infinity and NaN should be handled.
// https://github.com/gpuweb/gpuweb/issues/1769
// This test fails on Windows x86-64 because the machine sets the high
// mantissa bit on NaNs.
DISABLED_NaN,
// In the NaN case, the top bit in the mantissa is often used to encode
// whether the NaN is signalling or quiet, but no agreement between
// different machine architectures on whether 1 means signalling or
// if 1 means quiet.
WgslGenerator_FloatLiteralTest,
::testing::ValuesIn(std::vector<FloatData>{
// LSB only. Smallest mantissa.
{MakeFloat(0, 255, 1), "0x1.000002p+128"}, // Smallest mantissa
{MakeFloat(1, 255, 1), "-0x1.000002p+128"},
// MSB only.
{MakeFloat(0, 255, 0x400000), "0x1.8p+128"},
{MakeFloat(1, 255, 0x400000), "-0x1.8p+128"},
// All 1s in the mantissa.
{MakeFloat(0, 255, 0x7fffff), "0x1.fffffep+128"},
{MakeFloat(1, 255, 0x7fffff), "-0x1.fffffep+128"},
// Scattered bits, with 0 in top mantissa bit.
{MakeFloat(0, 255, 0x20101f), "0x1.40203ep+128"},
{MakeFloat(1, 255, 0x20101f), "-0x1.40203ep+128"},
// Scattered bits, with 1 in top mantissa bit.
{MakeFloat(0, 255, 0x40101f), "0x1.80203ep+128"},
{MakeFloat(1, 255, 0x40101f), "-0x1.80203ep+128"}}));
} // namespace
} // namespace wgsl
} // namespace writer
} // namespace tint