shader: encode 11/10-bit float formatted buffer stores as truncated unsigned floats

This commit is contained in:
nmzik
2026-10-25 01:39:01 +02:00
parent 9a20c6f738
commit 59d8256b36
4 changed files with 49 additions and 25 deletions
@@ -54,9 +54,30 @@ uint32_t EmitExt(EmitterState& state, uint32_t type, uint32_t opcode,
return result;
}
uint32_t EmitF32ToF16RtzBits(EmitterState& state, uint32_t value) {
uint32_t EmitF32ToU32(EmitterState& state, uint32_t src, bool signed_value) {
// Clamping first keeps the truncating conversion defined; NaN and values past the largest
// float below the integer limit are selected afterwards.
const auto clamped =
EmitExt(state, TypeF32(state), GLSLstd450NClamp,
{src, ConstantF32(state, signed_value ? 0xcf000000u : 0u),
ConstantF32(state, signed_value ? 0x4effffffu : 0x4f7fffffu)});
const auto converted = signed_value
? Unary(state, spv::OpBitcast, TypeU32(state),
Unary(state, spv::OpConvertFToS, TypeI32(state), clamped))
: Unary(state, spv::OpConvertFToU, TypeU32(state), clamped);
const auto above = Binary(state, spv::OpFOrdGreaterThanEqual, TypeBool(state), src,
ConstantF32(state, signed_value ? 0x4f000000u : 0x4f800000u));
const auto high =
Select(state, TypeU32(state), above,
ConstantU32(state, signed_value ? 0x7fffffffu : 0xffffffffu), converted);
return Select(state, TypeU32(state), Unary(state, spv::OpIsNan, TypeBool(state), src),
ConstantU32(state, 0), high);
}
} // namespace
uint32_t EmitF32BitsToF16RtzBits(EmitterState& state, uint32_t bits) {
// Native half conversion causes regressions; use compact integer RTZ conversion.
const auto bits = EmitBitcastF32ToU32(state, value);
const auto abs = EmitAndConstant(state, bits, 0x7fffffffu);
const auto sign = EmitAndConstant(
state, Binary(state, spv::OpShiftRightLogical, TypeU32(state), bits, ConstantU32(state, 16)),
@@ -92,28 +113,6 @@ uint32_t EmitF32ToF16RtzBits(EmitterState& state, uint32_t value) {
return EmitOrU32(state, sign, magnitude);
}
uint32_t EmitF32ToU32(EmitterState& state, uint32_t src, bool signed_value) {
// Clamping first keeps the truncating conversion defined; NaN and values past the largest
// float below the integer limit are selected afterwards.
const auto clamped =
EmitExt(state, TypeF32(state), GLSLstd450NClamp,
{src, ConstantF32(state, signed_value ? 0xcf000000u : 0u),
ConstantF32(state, signed_value ? 0x4effffffu : 0x4f7fffffu)});
const auto converted = signed_value
? Unary(state, spv::OpBitcast, TypeU32(state),
Unary(state, spv::OpConvertFToS, TypeI32(state), clamped))
: Unary(state, spv::OpConvertFToU, TypeU32(state), clamped);
const auto above = Binary(state, spv::OpFOrdGreaterThanEqual, TypeBool(state), src,
ConstantF32(state, signed_value ? 0x4f000000u : 0x4f800000u));
const auto high =
Select(state, TypeU32(state), above,
ConstantU32(state, signed_value ? 0x7fffffffu : 0xffffffffu), converted);
return Select(state, TypeU32(state), Unary(state, spv::OpIsNan, TypeBool(state), src),
ConstantU32(state, 0), high);
}
} // namespace
uint32_t EmitFPFma32(EmitterState& state, uint32_t a, uint32_t b, uint32_t c) {
const auto result = EmitGlsl<GLSLstd450Fma, IR::Type::F32>(state, a, b, c);
state.builder.AddAnnotation(spv::OpDecorate, result, spv::DecorationNoContraction);
@@ -199,7 +198,8 @@ uint32_t EmitCompositeExtractU32x2(EmitterState& state, uint32_t arg0, IR::Value
uint32_t EmitPackFloat2x16Rtz(EmitterState& state, uint32_t arg0, uint32_t arg1) {
return EmitNative<spv::OpBitFieldInsert, IR::Type::U32>(
state, EmitF32ToF16RtzBits(state, arg0), EmitF32ToF16RtzBits(state, arg1),
state, EmitF32BitsToF16RtzBits(state, EmitBitcastF32ToU32(state, arg0)),
EmitF32BitsToF16RtzBits(state, EmitBitcastF32ToU32(state, arg1)),
ConstantU32(state, 16), ConstantU32(state, 16));
}
@@ -531,6 +531,7 @@ inline constexpr auto EmitFNegateValue = EmitNative<spv::OpFNegate, IR::Type::F3
inline constexpr auto EmitFAbsValue = EmitGlsl<GLSLstd450FAbs, IR::Type::F32, uint32_t>;
uint32_t EmitF16BitsToF32(EmitterState& state, uint32_t bits);
uint32_t EmitF32BitsToF16RtzBits(EmitterState& state, uint32_t bits);
void EmitProgram(EmitterState& state);
@@ -472,6 +472,17 @@ uint32_t EncodeFormattedStoreComponent(EmitterState& state, const Format::Buffer
UnormRounding rounding) {
EXIT_IF(rounding != UnormRounding::RoundEven && info.type != Format::ComponentType::Unorm);
const auto bits = info.component_bits[component];
if (info.type == Format::ComponentType::Float && bits < 16u) {
// Truncate to f16, whose bias the unsigned 11/10-bit floats share, and drop mantissa
// bits; negatives and NaN, whose f16 bits lie above +inf, store zero.
const auto half = data_bits == 16u ? EmitAndConstant(state, data, 0xffffu)
: EmitF32BitsToF16RtzBits(state, data);
return Select(state, TypeU32(state),
EmitCompareU32Constant(state, spv::OpUGreaterThan, half, 0x7c00u),
ConstantU32(state, 0),
EmitBinaryU32(state, spv::OpShiftRightLogical, half,
ConstantU32(state, 15u - bits)));
}
if (data_bits == 16u) {
if (info.type == Format::ComponentType::Uint) {
data = EmitBitFieldUExtract(state, data, ConstantU32(state, 0), ConstantU32(state, 16));
+12
View File
@@ -34198,6 +34198,8 @@ std::vector<TestCase> BufferStoreFormatD16Cases() {
{0xc0003c00u, 0xdead3800u}, {0xc0003c00u, 0x00003800u}, 2, 0x86u},
{"BufferStoreFormatD16XyzUint8", F::k8_8_8_8UInt,
{0x00020001u, 0xdead0003u}, {0x00030201u}, 1, 0x86u},
{"BufferStoreFormatD16XyzFloat11_11_10", F::k11_11_10Float,
{0xc0003c7fu, 0xdead7bffu}, {0xf7c003c7u}, 1, 0x86u},
};
constexpr O formats[] = {O::BUFFER_STORE_FORMAT_D16_X, O::BUFFER_STORE_FORMAT_D16_XY,
O::BUFFER_STORE_FORMAT_D16_XYZ, O::BUFFER_STORE_FORMAT_D16_XYZW};
@@ -34326,6 +34328,16 @@ std::vector<TestCase> FormattedStoreConversionCases() {
F::k8_8_8_8UScaled, 4, {nan, inf, -inf, -0.0f}, 0x0000ff00u},
{{"BufferStoreSscaled8SpecialValues", "TBufferStoreSscaled8SpecialValues"},
F::k8_8_8_8SScaled, 4, {nan, inf, -inf, -0.0f}, 0x00807f00u},
// Unsigned 11/10-bit floats truncate, clamp finite values and store negatives and NaN as 0.
{{"BufferStoreFloat11_11_10Truncates", "TBufferStoreFloat11_11_10Truncates"},
F::k11_11_10Float, 3, {1.0f, std::bit_cast<float>(0x3f87ffffu), 65520.0f}, 0xf7de1bc0u},
{{"BufferStoreFloat11_11_10Clamps", "TBufferStoreFloat11_11_10Clamps"},
F::k11_11_10Float, 3, {1e10f, -1.0f, inf}, 0xf80007bfu},
{{"BufferStoreFloat11_11_10Denormals", "TBufferStoreFloat11_11_10Denormals"},
F::k11_11_10Float, 3,
{nan, std::bit_cast<float>(0x35800000u), std::bit_cast<float>(0x38400000u)}, 0x06000800u},
{{"BufferStoreFloat10_11_11Truncates", "TBufferStoreFloat10_11_11Truncates"},
F::k10_11_11Float, 3, {std::bit_cast<float>(0x3f87ffffu), 1.0f, 65520.0f}, 0xf7ef01e1u},
};
constexpr O store_opcodes[2][4] = {
{O::BUFFER_STORE_FORMAT_X, O::BUFFER_STORE_FORMAT_XY,