Lei Zhang 2320a4ae90 [mlir][spirv] Workaround driver bug in math.ctlz conversion again
The previous approach does not work as the Adreno driver is
clever at optimizing away the selection. So now check two
inputs together.

Reviewed By: ThomasRaoux

Differential Revision: https://reviews.llvm.org/D127930
2022-06-16 10:53:49 -04:00

284 lines
12 KiB
C++

//===- MathToSPIRV.cpp - Math to SPIR-V Patterns --------------------------===//
//
// 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 implements patterns to convert Math dialect to SPIR-V dialect.
//
//===----------------------------------------------------------------------===//
#include "../SPIRVCommon/Pattern.h"
#include "mlir/Dialect/Math/IR/Math.h"
#include "mlir/Dialect/SPIRV/IR/SPIRVDialect.h"
#include "mlir/Dialect/SPIRV/IR/SPIRVOps.h"
#include "mlir/Dialect/SPIRV/Transforms/SPIRVConversion.h"
#include "mlir/IR/BuiltinTypes.h"
#include "mlir/Transforms/DialectConversion.h"
#include "llvm/Support/Debug.h"
#define DEBUG_TYPE "math-to-spirv-pattern"
using namespace mlir;
//===----------------------------------------------------------------------===//
// Utility functions
//===----------------------------------------------------------------------===//
/// Creates a 32-bit scalar/vector integer constant. Returns nullptr if the
/// given type is not a 32-bit scalar/vector type.
static Value getScalarOrVectorI32Constant(Type type, int value,
OpBuilder &builder, Location loc) {
if (auto vectorType = type.dyn_cast<VectorType>()) {
if (!vectorType.getElementType().isInteger(32))
return nullptr;
SmallVector<int> values(vectorType.getNumElements(), value);
return builder.create<spirv::ConstantOp>(loc, type,
builder.getI32VectorAttr(values));
}
if (type.isInteger(32))
return builder.create<spirv::ConstantOp>(loc, type,
builder.getI32IntegerAttr(value));
return nullptr;
}
//===----------------------------------------------------------------------===//
// Operation conversion
//===----------------------------------------------------------------------===//
// Note that DRR cannot be used for the patterns in this file: we may need to
// convert type along the way, which requires ConversionPattern. DRR generates
// normal RewritePattern.
namespace {
/// Converts math.copysign to SPIR-V ops.
class CopySignPattern final : public OpConversionPattern<math::CopySignOp> {
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(math::CopySignOp copySignOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto type = getTypeConverter()->convertType(copySignOp.getType());
if (!type)
return failure();
FloatType floatType;
if (auto scalarType = copySignOp.getType().dyn_cast<FloatType>()) {
floatType = scalarType;
} else if (auto vectorType = copySignOp.getType().dyn_cast<VectorType>()) {
floatType = vectorType.getElementType().cast<FloatType>();
} else {
return failure();
}
Location loc = copySignOp.getLoc();
int bitwidth = floatType.getWidth();
Type intType = rewriter.getIntegerType(bitwidth);
uint64_t intValue = uint64_t(1) << (bitwidth - 1);
Value signMask = rewriter.create<spirv::ConstantOp>(
loc, intType, rewriter.getIntegerAttr(intType, intValue));
Value valueMask = rewriter.create<spirv::ConstantOp>(
loc, intType, rewriter.getIntegerAttr(intType, intValue - 1u));
if (auto vectorType = copySignOp.getType().dyn_cast<VectorType>()) {
assert(vectorType.getRank() == 1);
int count = vectorType.getNumElements();
intType = VectorType::get(count, intType);
SmallVector<Value> signSplat(count, signMask);
signMask =
rewriter.create<spirv::CompositeConstructOp>(loc, intType, signSplat);
SmallVector<Value> valueSplat(count, valueMask);
valueMask = rewriter.create<spirv::CompositeConstructOp>(loc, intType,
valueSplat);
}
Value lhsCast =
rewriter.create<spirv::BitcastOp>(loc, intType, adaptor.getLhs());
Value rhsCast =
rewriter.create<spirv::BitcastOp>(loc, intType, adaptor.getRhs());
Value value = rewriter.create<spirv::BitwiseAndOp>(
loc, intType, ValueRange{lhsCast, valueMask});
Value sign = rewriter.create<spirv::BitwiseAndOp>(
loc, intType, ValueRange{rhsCast, signMask});
Value result = rewriter.create<spirv::BitwiseOrOp>(loc, intType,
ValueRange{value, sign});
rewriter.replaceOpWithNewOp<spirv::BitcastOp>(copySignOp, type, result);
return success();
}
};
/// Converts math.ctlz to SPIR-V ops.
///
/// SPIR-V does not have a direct operations for counting leading zeros. If
/// Shader capability is supported, we can leverage GLSL FindUMsb to calculate
/// it.
class CountLeadingZerosPattern final
: public OpConversionPattern<math::CountLeadingZerosOp> {
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(math::CountLeadingZerosOp countOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto type = getTypeConverter()->convertType(countOp.getType());
if (!type)
return failure();
// We can only support 32-bit integer types for now.
unsigned bitwidth = 0;
if (type.isa<IntegerType>())
bitwidth = type.getIntOrFloatBitWidth();
if (auto vectorType = type.dyn_cast<VectorType>())
bitwidth = vectorType.getElementTypeBitWidth();
if (bitwidth != 32)
return failure();
Location loc = countOp.getLoc();
Value input = adaptor.getOperand();
Value val1 = getScalarOrVectorI32Constant(type, 1, rewriter, loc);
Value val31 = getScalarOrVectorI32Constant(type, 31, rewriter, loc);
Value val32 = getScalarOrVectorI32Constant(type, 32, rewriter, loc);
Value msb = rewriter.create<spirv::GLSLFindUMsbOp>(loc, input);
// We need to subtract from 31 given that the index returned by GLSL
// FindUMsb is counted from the least significant bit. Theoretically this
// also gives the correct result even if the integer has all zero bits, in
// which case GLSL FindUMsb would return -1.
Value subMsb = rewriter.create<spirv::ISubOp>(loc, val31, msb);
// However, certain Vulkan implementations have driver bugs for the corner
// case where the input is zero. And.. it can be smart to optimize a select
// only involving the corner case. So separately compute the result when the
// input is either zero or one.
Value subInput = rewriter.create<spirv::ISubOp>(loc, val32, input);
Value cmp = rewriter.create<spirv::ULessThanEqualOp>(loc, input, val1);
rewriter.replaceOpWithNewOp<spirv::SelectOp>(countOp, cmp, subInput,
subMsb);
return success();
}
};
/// Converts math.expm1 to SPIR-V ops.
///
/// SPIR-V does not have a direct operations for exp(x)-1. Explicitly lower to
/// these operations.
template <typename ExpOp>
struct ExpM1OpPattern final : public OpConversionPattern<math::ExpM1Op> {
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(math::ExpM1Op operation, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
assert(adaptor.getOperands().size() == 1);
Location loc = operation.getLoc();
auto type = this->getTypeConverter()->convertType(operation.getType());
auto exp = rewriter.create<ExpOp>(loc, type, adaptor.getOperand());
auto one = spirv::ConstantOp::getOne(type, loc, rewriter);
rewriter.replaceOpWithNewOp<spirv::FSubOp>(operation, exp, one);
return success();
}
};
/// Converts math.log1p to SPIR-V ops.
///
/// SPIR-V does not have a direct operations for log(1+x). Explicitly lower to
/// these operations.
template <typename LogOp>
struct Log1pOpPattern final : public OpConversionPattern<math::Log1pOp> {
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(math::Log1pOp operation, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
assert(adaptor.getOperands().size() == 1);
Location loc = operation.getLoc();
auto type = this->getTypeConverter()->convertType(operation.getType());
auto one = spirv::ConstantOp::getOne(type, operation.getLoc(), rewriter);
auto onePlus =
rewriter.create<spirv::FAddOp>(loc, one, adaptor.getOperand());
rewriter.replaceOpWithNewOp<LogOp>(operation, type, onePlus);
return success();
}
};
/// Converts math.powf to SPIRV-Ops.
struct PowFOpPattern final : public OpConversionPattern<math::PowFOp> {
using OpConversionPattern::OpConversionPattern;
LogicalResult
matchAndRewrite(math::PowFOp powfOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
auto dstType = getTypeConverter()->convertType(powfOp.getType());
if (!dstType)
return failure();
// Per GLSL Pow extended instruction spec:
// "Result is undefined if x < 0. Result is undefined if x = 0 and y <= 0."
Location loc = powfOp.getLoc();
Value zero =
spirv::ConstantOp::getZero(adaptor.getLhs().getType(), loc, rewriter);
Value lessThan =
rewriter.create<spirv::FOrdLessThanOp>(loc, adaptor.getLhs(), zero);
Value abs = rewriter.create<spirv::GLSLFAbsOp>(loc, adaptor.getLhs());
Value pow = rewriter.create<spirv::GLSLPowOp>(loc, abs, adaptor.getRhs());
Value negate = rewriter.create<spirv::FNegateOp>(loc, pow);
rewriter.replaceOpWithNewOp<spirv::SelectOp>(powfOp, lessThan, negate, pow);
return success();
}
};
} // namespace
//===----------------------------------------------------------------------===//
// Pattern population
//===----------------------------------------------------------------------===//
namespace mlir {
void populateMathToSPIRVPatterns(SPIRVTypeConverter &typeConverter,
RewritePatternSet &patterns) {
// Core patterns
patterns.add<CopySignPattern>(typeConverter, patterns.getContext());
// GLSL patterns
patterns
.add<CountLeadingZerosPattern, Log1pOpPattern<spirv::GLSLLogOp>,
ExpM1OpPattern<spirv::GLSLExpOp>, PowFOpPattern,
spirv::ElementwiseOpPattern<math::AbsOp, spirv::GLSLFAbsOp>,
spirv::ElementwiseOpPattern<math::CeilOp, spirv::GLSLCeilOp>,
spirv::ElementwiseOpPattern<math::CosOp, spirv::GLSLCosOp>,
spirv::ElementwiseOpPattern<math::ExpOp, spirv::GLSLExpOp>,
spirv::ElementwiseOpPattern<math::FloorOp, spirv::GLSLFloorOp>,
spirv::ElementwiseOpPattern<math::FmaOp, spirv::GLSLFmaOp>,
spirv::ElementwiseOpPattern<math::LogOp, spirv::GLSLLogOp>,
spirv::ElementwiseOpPattern<math::RsqrtOp, spirv::GLSLInverseSqrtOp>,
spirv::ElementwiseOpPattern<math::SinOp, spirv::GLSLSinOp>,
spirv::ElementwiseOpPattern<math::SqrtOp, spirv::GLSLSqrtOp>,
spirv::ElementwiseOpPattern<math::TanhOp, spirv::GLSLTanhOp>>(
typeConverter, patterns.getContext());
// OpenCL patterns
patterns.add<Log1pOpPattern<spirv::OCLLogOp>, ExpM1OpPattern<spirv::OCLExpOp>,
spirv::ElementwiseOpPattern<math::AbsOp, spirv::OCLFAbsOp>,
spirv::ElementwiseOpPattern<math::CeilOp, spirv::OCLCeilOp>,
spirv::ElementwiseOpPattern<math::CosOp, spirv::OCLCosOp>,
spirv::ElementwiseOpPattern<math::ErfOp, spirv::OCLErfOp>,
spirv::ElementwiseOpPattern<math::ExpOp, spirv::OCLExpOp>,
spirv::ElementwiseOpPattern<math::FloorOp, spirv::OCLFloorOp>,
spirv::ElementwiseOpPattern<math::FmaOp, spirv::OCLFmaOp>,
spirv::ElementwiseOpPattern<math::LogOp, spirv::OCLLogOp>,
spirv::ElementwiseOpPattern<math::PowFOp, spirv::OCLPowOp>,
spirv::ElementwiseOpPattern<math::RsqrtOp, spirv::OCLRsqrtOp>,
spirv::ElementwiseOpPattern<math::SinOp, spirv::OCLSinOp>,
spirv::ElementwiseOpPattern<math::SqrtOp, spirv::OCLSqrtOp>,
spirv::ElementwiseOpPattern<math::TanhOp, spirv::OCLTanhOp>>(
typeConverter, patterns.getContext());
}
} // namespace mlir