Rob Suderman 0763f12213 [mlir][tosa] Handle rescale case where shift > 63
It is possible for the shift value to exceed the number of bits. In these
cases we can just multiply by zero. This is relatively rare occurence but
should be handled.

Reviewed By: not-jenni

Differential Revision: https://reviews.llvm.org/D115779
2021-12-16 15:30:48 -08:00

368 lines
12 KiB
C++

//===- QuantUtils.cpp -----------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains TOSA numerical support functions and quantization
// attribute builders.
//
//===----------------------------------------------------------------------===//
#include "mlir/Dialect/Tosa/Utils/QuantUtils.h"
using namespace mlir;
using namespace mlir::tosa;
/// From a scale value, generates multiplier and shift values where
/// mantissa is in [-1.0,-0.5] or [0.5, 1.0] such that
/// multiplier = mantissa*2^shift for 16-bit scaling.
static void computeMultiplierAndShiftTosaScale16(double scale,
int32_t &multiplier,
int32_t &shift) {
const double mantissa = std::frexp(scale, &shift);
auto shiftedM = std::round(mantissa * (int64_t(1) << 15));
// Can't be greater than 1.0.
assert(shiftedM <= (int64_t(1) << 15) &&
"Shifted mantissa exceeds 16 signed bits");
if (shiftedM == (int64_t(1) << 15)) {
shiftedM /= 2;
shift++;
}
// TOSA expects right shift to be positive and embed (1 << 15) into right
// shift bits.
shift = (-shift) + 15;
assert(shiftedM <= std::numeric_limits<int32_t>::max() &&
"Shifted mantissa exceeds 32-bit signed output type");
multiplier = static_cast<int32_t>(shiftedM);
// Shifting tops out at 63 bits. Right shift to make 63 bits the max.
if (shift > 63) {
// Shifting the multiplier by more than 32-bits is unnecessary.
multiplier = multiplier >> std::min<int32_t>(32, shift - 63);
shift = 63;
}
}
/// From a scale value, generates multiplier and shift values where
/// mantissa is in [-1.0,-0.5] or [0.5, 1.0] such that
/// multiplier = mantissa*2^shift for 32-bit scaling.
static void computeMultiplierAndShiftTosaScale32(double scale,
int32_t &multiplier,
int32_t &shift) {
const double mantissa = std::frexp(scale, &shift);
auto shiftedM = std::round(mantissa * (int64_t(1) << 31));
// Can't be greater than 1.0.
assert(shiftedM <= (int64_t(1) << 31) &&
"Shifted mantissa exceeds 32 signed bits");
if (shiftedM == (int64_t(1) << 31)) {
shiftedM /= 2;
shift++;
}
// TOSA expects right shift to be positive, and embed (1 << 31) into right
// shift bits.
shift = (-shift) + 31;
assert(shiftedM <= std::numeric_limits<int32_t>::max() &&
"Shifted mantissa exceeds 32-bit signed output type");
multiplier = static_cast<int32_t>(shiftedM);
// Shifting tops out at 63 bits. Right shift to make 63 bits the max.
if (shift > 63) {
// Shifting the multiplier by more than 32-bits is unnecessary.
multiplier = multiplier >> std::min<int32_t>(32, shift - 63);
shift = 63;
}
}
/// Generates a quantized multiplier/shift from double.
void mlir::tosa::computeMultiplierAndShift(double scale, int32_t &multiplier,
int32_t &shift, int32_t scaleWidth) {
switch (scaleWidth) {
case 16:
computeMultiplierAndShiftTosaScale16(scale, multiplier, shift);
return;
case 32:
computeMultiplierAndShiftTosaScale32(scale, multiplier, shift);
return;
default:
assert(0 && "Unsupported Tosa quantized_scale regime specified!");
}
}
#define GET_UQTYPE(input_type) \
((input_type).getElementType().dyn_cast<quant::UniformQuantizedType>())
#define GET_QTYPE(input_type) \
((input_type).getElementType().dyn_cast<quant::QuantizedType>())
/// Method to build ConvOpQuantizationAttr, called from
/// ConvOpQuantInfoBuilder/TransConvOpQuantInfoBuilder:
/// input_zp: input zeropoint
/// weight_zp: weight zeropoint.
ConvOpQuantizationAttr
mlir::tosa::buildConvOpQuantizationAttr(OpBuilder &builder, Value input,
Value weight) {
auto inputType = input.getType().dyn_cast<ShapedType>();
auto weightType = weight.getType().dyn_cast<ShapedType>();
if (!inputType || !weightType)
return nullptr;
auto inputQType = GET_UQTYPE(inputType);
auto weightPerTensorQType = GET_UQTYPE(weightType);
auto weightPerAxisQType = weightType.getElementType()
.dyn_cast<quant::UniformQuantizedPerAxisType>();
// Weights must be either per-tensor quantized or per-axis quantized.
assert(!((bool)weightPerTensorQType && (bool)weightPerAxisQType) &&
"Weights must be either per-tensor or per-axis quantized");
// Either all quantized or all not quantized.
assert(!((bool)inputQType ^
((bool)weightPerTensorQType || (bool)weightPerAxisQType)) &&
"Inputs and weights must be all quantized or all not quantized");
if (inputQType) {
int64_t inputZp = inputQType.getZeroPoint();
int64_t weightZp = 0;
if (weightPerTensorQType) {
weightZp = weightPerTensorQType.getZeroPoint();
} else if (weightPerAxisQType) {
weightZp = weightPerAxisQType.getZeroPoints().front();
}
auto quantAttr = tosa::ConvOpQuantizationAttr::get(
builder.getI32IntegerAttr(inputZp), builder.getI32IntegerAttr(weightZp),
builder.getContext());
return quantAttr;
}
return nullptr;
}
/// Builds MatMulOpQuantizationAttr, called from
/// MatMulOpQuantInfoBuilder:
/// aZp: input a zeropoint
/// bZp: input b zeropoint.
MatMulOpQuantizationAttr
mlir::tosa::buildMatMulOpQuantizationAttr(OpBuilder &builder, Value a,
Value b) {
auto aType = a.getType().dyn_cast<ShapedType>();
auto bType = b.getType().dyn_cast<ShapedType>();
if (!aType || !bType)
return nullptr;
auto aQType = GET_UQTYPE(aType);
auto bQType = GET_UQTYPE(bType);
// A and B are either all quantized or all not quantized.
assert(!((bool)aQType ^ (bool)bQType) &&
"Matmul operands must be all quantized or all not quantized");
if (aQType) {
int64_t aZp = aQType.getZeroPoint();
int64_t bZp = bQType.getZeroPoint();
auto quantAttr = tosa::MatMulOpQuantizationAttr::get(
builder.getI32IntegerAttr(aZp), builder.getI32IntegerAttr(bZp),
builder.getContext());
return quantAttr;
}
return nullptr;
}
/// Builds UnaryOpQuantizationAttr
/// UnaryOpQuantInfoBuilder:
/// inputZp: input zeropoint
/// outputZp: output zeropoint.
UnaryOpQuantizationAttr
mlir::tosa::buildUnaryOpQuantizationAttr(OpBuilder &builder, Value input,
Type outputRawType) {
auto inputType = input.getType().dyn_cast<ShapedType>();
auto outputType = outputRawType.dyn_cast<ShapedType>();
if (!inputType || !outputType)
return nullptr;
auto inputQType = GET_UQTYPE(inputType);
auto outputQType = GET_UQTYPE(outputType);
// Either all quantized or all not quantized.
assert(!((bool)inputQType ^ (bool)outputQType) &&
"Unary inputs/outputs must be all quantized or all not quantized");
if (inputQType) {
int64_t inputZp = inputQType.getZeroPoint();
int64_t outputZp = outputQType.getZeroPoint();
auto quantAttr = tosa::UnaryOpQuantizationAttr::get(
builder.getI32IntegerAttr(inputZp), builder.getI32IntegerAttr(outputZp),
builder.getContext());
return quantAttr;
}
return nullptr;
}
/// Builds PadOpQuantizationAttr, called from PadOpQuantInfoBuilder:
/// inputZp: input zeropoint.
PadOpQuantizationAttr mlir::tosa::buildPadOpQuantizationAttr(OpBuilder &builder,
Value input) {
auto inputType = input.getType().dyn_cast<ShapedType>();
if (!inputType)
return nullptr;
auto inputQType = GET_UQTYPE(inputType);
if (inputQType) {
int64_t inputZp = inputQType.getZeroPoint();
auto quantAttr = tosa::PadOpQuantizationAttr::get(
builder.getI32IntegerAttr(inputZp), builder.getContext());
return quantAttr;
}
return nullptr;
}
/// Builds output type for a quantized ConvOp with the right bitwidth.
/// This is called by the builder when dealing with quantized content.
Type mlir::tosa::buildConvOpResultTypeInfo(OpBuilder &builder, Type outputType,
Value input, Value weight) {
auto inputType = input.getType().dyn_cast<ShapedType>();
auto weightType = weight.getType().dyn_cast<ShapedType>();
assert(inputType && weightType &&
"Could not extract input or weight tensors from Conv op");
auto inputQType = GET_QTYPE(inputType);
auto weightQType = GET_QTYPE(weightType);
assert(inputQType && weightQType &&
"Could not extract input or weight tensor types from Conv op");
unsigned inputBits = inputQType.getStorageTypeIntegralWidth();
unsigned weightBits = weightQType.getStorageTypeIntegralWidth();
auto outputShapedType = outputType.dyn_cast<ShapedType>();
assert(outputShapedType &&
"Could not extract output shape type from Conv op");
IntegerType accElementType;
if (inputBits == 16 && weightBits == 8)
accElementType = builder.getIntegerType(48);
else
accElementType = builder.getI32Type();
auto accType = outputShapedType.clone(accElementType);
return accType;
}
/// Builds Tosa quantization attributes from min/max values.
Type mlir::tosa::buildQTypeFromMinMax(OpBuilder builder, Type inputDType,
Attribute minAttr, Attribute maxAttr,
IntegerAttr quantBits, int filterQuantDim,
bool isSigned, BoolAttr narrowRange) {
quant::QuantizedType retType;
auto convfunc =
quant::ExpressedToQuantizedConverter::forInputType(inputDType);
auto minElems = minAttr.dyn_cast<DenseFPElementsAttr>();
auto maxElems = maxAttr.dyn_cast<DenseFPElementsAttr>();
SmallVector<double, 2> min, max;
// At least one is per-axis quantized elementsattr.
if (minElems || maxElems) {
// Must have the same number of elements.
if (minElems.getNumElements() != maxElems.getNumElements())
return {};
min.reserve(minElems.getNumElements());
max.reserve(maxElems.getNumElements());
for (auto i : minElems)
min.push_back(FloatAttr::getValueAsDouble(i));
for (auto i : maxElems)
max.push_back(FloatAttr::getValueAsDouble(i));
} else { // Just a single FP value.
auto minVal = minAttr.dyn_cast<FloatAttr>();
if (minVal)
min.push_back(minVal.getValueAsDouble());
else
return {};
auto maxVal = maxAttr.dyn_cast<FloatAttr>();
if (maxVal)
max.push_back(maxVal.getValueAsDouble());
else
return {};
}
if (min.size() == max.size()) {
if (min.size() == 1) { // Per-tensor quantization with one min/max pair.
retType = quant::fakeQuantAttrsToType(
builder.getUnknownLoc(), quantBits.getInt(), min[0], max[0],
narrowRange.getValue(), convfunc.expressedType, isSigned);
} else if (min.size() > 1) { // Per-axis quant on filterQuantDim.
auto shape = inputDType.dyn_cast<ShapedType>();
if (!shape)
return {};
if ((filterQuantDim) >= 0 && (shape.getRank() > filterQuantDim)) {
retType = quant::fakeQuantAttrsToType(
builder.getUnknownLoc(), quantBits.getInt(), filterQuantDim, min[0],
max[0], narrowRange.getValue(), convfunc.expressedType, isSigned);
}
} else {
return {};
}
} else {
return {};
}
if (!retType)
return {};
return convfunc.convert(retType);
}
/// Builds Tosa quantization attributes from min/max values.
TypeAttr
mlir::tosa::buildQTypeAttrFromMinMax(OpBuilder builder, Type inputDtype,
Attribute minAttr, Attribute maxAttr,
IntegerAttr quantBits, int filterQuantDim,
bool isSigned, BoolAttr narrowRange) {
return TypeAttr::get(buildQTypeFromMinMax(builder, inputDtype, minAttr,
maxAttr, quantBits, filterQuantDim,
isSigned, narrowRange));
}