llvm-project/mlir/lib/Conversion/GPUCommon/GPUOpsLowering.cpp

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//===- GPUOpsLowering.cpp - GPU FuncOp / ReturnOp lowering ----------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "GPUOpsLowering.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/BuiltinTypes.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/FormatVariadic.h"
using namespace mlir;
LogicalResult
GPUFuncOpLowering::matchAndRewrite(gpu::GPUFuncOp gpuFuncOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const {
Location loc = gpuFuncOp.getLoc();
SmallVector<LLVM::GlobalOp, 3> workgroupBuffers;
workgroupBuffers.reserve(gpuFuncOp.getNumWorkgroupAttributions());
for (const auto &en : llvm::enumerate(gpuFuncOp.getWorkgroupAttributions())) {
Value attribution = en.value();
auto type = attribution.getType().dyn_cast<MemRefType>();
assert(type && type.hasStaticShape() && "unexpected type in attribution");
uint64_t numElements = type.getNumElements();
auto elementType =
typeConverter->convertType(type.getElementType()).template cast<Type>();
auto arrayType = LLVM::LLVMArrayType::get(elementType, numElements);
std::string name = std::string(
llvm::formatv("__wg_{0}_{1}", gpuFuncOp.getName(), en.index()));
auto globalOp = rewriter.create<LLVM::GlobalOp>(
gpuFuncOp.getLoc(), arrayType, /*isConstant=*/false,
LLVM::Linkage::Internal, name, /*value=*/Attribute(),
/*alignment=*/0, gpu::GPUDialect::getWorkgroupAddressSpace());
workgroupBuffers.push_back(globalOp);
}
// Rewrite the original GPU function to an LLVM function.
auto convertedType = typeConverter->convertType(gpuFuncOp.getFunctionType());
if (!convertedType)
return failure();
auto funcType =
convertedType.template cast<LLVM::LLVMPointerType>().getElementType();
// Remap proper input types.
TypeConverter::SignatureConversion signatureConversion(
gpuFuncOp.front().getNumArguments());
getTypeConverter()->convertFunctionSignature(
gpuFuncOp.getFunctionType(), /*isVariadic=*/false, signatureConversion);
// Create the new function operation. Only copy those attributes that are
// not specific to function modeling.
SmallVector<NamedAttribute, 4> attributes;
for (const auto &attr : gpuFuncOp->getAttrs()) {
if (attr.getName() == SymbolTable::getSymbolAttrName() ||
attr.getName() == FunctionOpInterface::getTypeAttrName() ||
attr.getName() == gpu::GPUFuncOp::getNumWorkgroupAttributionsAttrName())
continue;
attributes.push_back(attr);
}
// Add a dialect specific kernel attribute in addition to GPU kernel
// attribute. The former is necessary for further translation while the
// latter is expected by gpu.launch_func.
if (gpuFuncOp.isKernel())
attributes.emplace_back(kernelAttributeName, rewriter.getUnitAttr());
auto llvmFuncOp = rewriter.create<LLVM::LLVMFuncOp>(
gpuFuncOp.getLoc(), gpuFuncOp.getName(), funcType,
LLVM::Linkage::External, /*dsoLocal*/ false, /*cconv*/ LLVM::CConv::C,
attributes);
{
// Insert operations that correspond to converted workgroup and private
// memory attributions to the body of the function. This must operate on
// the original function, before the body region is inlined in the new
// function to maintain the relation between block arguments and the
// parent operation that assigns their semantics.
OpBuilder::InsertionGuard guard(rewriter);
// Rewrite workgroup memory attributions to addresses of global buffers.
rewriter.setInsertionPointToStart(&gpuFuncOp.front());
unsigned numProperArguments = gpuFuncOp.getNumArguments();
for (const auto &en : llvm::enumerate(workgroupBuffers)) {
LLVM::GlobalOp global = en.value();
Value address = rewriter.create<LLVM::AddressOfOp>(loc, global);
auto elementType =
global.getType().cast<LLVM::LLVMArrayType>().getElementType();
Value memory = rewriter.create<LLVM::GEPOp>(
loc, LLVM::LLVMPointerType::get(elementType, global.getAddrSpace()),
address, ArrayRef<LLVM::GEPArg>{0, 0});
// Build a memref descriptor pointing to the buffer to plug with the
// existing memref infrastructure. This may use more registers than
// otherwise necessary given that memref sizes are fixed, but we can try
// and canonicalize that away later.
Value attribution = gpuFuncOp.getWorkgroupAttributions()[en.index()];
auto type = attribution.getType().cast<MemRefType>();
auto descr = MemRefDescriptor::fromStaticShape(
rewriter, loc, *getTypeConverter(), type, memory);
signatureConversion.remapInput(numProperArguments + en.index(), descr);
}
// Rewrite private memory attributions to alloca'ed buffers.
unsigned numWorkgroupAttributions = gpuFuncOp.getNumWorkgroupAttributions();
auto int64Ty = IntegerType::get(rewriter.getContext(), 64);
for (const auto &en : llvm::enumerate(gpuFuncOp.getPrivateAttributions())) {
Value attribution = en.value();
auto type = attribution.getType().cast<MemRefType>();
assert(type && type.hasStaticShape() && "unexpected type in attribution");
// Explicitly drop memory space when lowering private memory
// attributions since NVVM models it as `alloca`s in the default
// memory space and does not support `alloca`s with addrspace(5).
auto ptrType = LLVM::LLVMPointerType::get(
typeConverter->convertType(type.getElementType())
.template cast<Type>(),
allocaAddrSpace);
Value numElements = rewriter.create<LLVM::ConstantOp>(
gpuFuncOp.getLoc(), int64Ty, type.getNumElements());
Value allocated = rewriter.create<LLVM::AllocaOp>(
gpuFuncOp.getLoc(), ptrType, numElements, /*alignment=*/0);
auto descr = MemRefDescriptor::fromStaticShape(
rewriter, loc, *getTypeConverter(), type, allocated);
signatureConversion.remapInput(
numProperArguments + numWorkgroupAttributions + en.index(), descr);
}
}
// Move the region to the new function, update the entry block signature.
rewriter.inlineRegionBefore(gpuFuncOp.getBody(), llvmFuncOp.getBody(),
llvmFuncOp.end());
if (failed(rewriter.convertRegionTypes(&llvmFuncOp.getBody(), *typeConverter,
&signatureConversion)))
return failure();
// If bare memref pointers are being used, remap them back to memref
// descriptors This must be done after signature conversion to get rid of the
// unrealized casts.
if (getTypeConverter()->getOptions().useBarePtrCallConv) {
OpBuilder::InsertionGuard guard(rewriter);
rewriter.setInsertionPointToStart(&llvmFuncOp.getBody().front());
for (const auto &en : llvm::enumerate(gpuFuncOp.getArgumentTypes())) {
auto memrefTy = en.value().dyn_cast<MemRefType>();
if (!memrefTy)
continue;
assert(memrefTy.hasStaticShape() &&
"Bare pointer convertion used with dynamically-shaped memrefs");
// Use a placeholder when replacing uses of the memref argument to prevent
// circular replacements.
auto remapping = signatureConversion.getInputMapping(en.index());
assert(remapping && remapping->size == 1 &&
"Type converter should produce 1-to-1 mapping for bare memrefs");
BlockArgument newArg =
llvmFuncOp.getBody().getArgument(remapping->inputNo);
auto placeholder = rewriter.create<LLVM::UndefOp>(
loc, getTypeConverter()->convertType(memrefTy));
rewriter.replaceUsesOfBlockArgument(newArg, placeholder);
Value desc = MemRefDescriptor::fromStaticShape(
rewriter, loc, *getTypeConverter(), memrefTy, newArg);
rewriter.replaceOp(placeholder, {desc});
}
}
rewriter.eraseOp(gpuFuncOp);
return success();
}
static const char formatStringPrefix[] = "printfFormat_";
template <typename T>
static LLVM::LLVMFuncOp getOrDefineFunction(T &moduleOp, const Location loc,
ConversionPatternRewriter &rewriter,
StringRef name,
LLVM::LLVMFunctionType type) {
LLVM::LLVMFuncOp ret;
if (!(ret = moduleOp.template lookupSymbol<LLVM::LLVMFuncOp>(name))) {
ConversionPatternRewriter::InsertionGuard guard(rewriter);
rewriter.setInsertionPointToStart(moduleOp.getBody());
ret = rewriter.create<LLVM::LLVMFuncOp>(loc, name, type,
LLVM::Linkage::External);
}
return ret;
}
LogicalResult GPUPrintfOpToHIPLowering::matchAndRewrite(
gpu::PrintfOp gpuPrintfOp, gpu::PrintfOpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const {
Location loc = gpuPrintfOp->getLoc();
mlir::Type llvmI8 = typeConverter->convertType(rewriter.getI8Type());
mlir::Type i8Ptr = LLVM::LLVMPointerType::get(llvmI8);
mlir::Type llvmI32 = typeConverter->convertType(rewriter.getI32Type());
mlir::Type llvmI64 = typeConverter->convertType(rewriter.getI64Type());
// Note: this is the GPUModule op, not the ModuleOp that surrounds it
// This ensures that global constants and declarations are placed within
// the device code, not the host code
auto moduleOp = gpuPrintfOp->getParentOfType<gpu::GPUModuleOp>();
auto ocklBegin =
getOrDefineFunction(moduleOp, loc, rewriter, "__ockl_printf_begin",
LLVM::LLVMFunctionType::get(llvmI64, {llvmI64}));
LLVM::LLVMFuncOp ocklAppendArgs;
if (!adaptor.getArgs().empty()) {
ocklAppendArgs = getOrDefineFunction(
moduleOp, loc, rewriter, "__ockl_printf_append_args",
LLVM::LLVMFunctionType::get(
llvmI64, {llvmI64, /*numArgs*/ llvmI32, llvmI64, llvmI64, llvmI64,
llvmI64, llvmI64, llvmI64, llvmI64, /*isLast*/ llvmI32}));
}
auto ocklAppendStringN = getOrDefineFunction(
moduleOp, loc, rewriter, "__ockl_printf_append_string_n",
LLVM::LLVMFunctionType::get(
llvmI64,
{llvmI64, i8Ptr, /*length (bytes)*/ llvmI64, /*isLast*/ llvmI32}));
/// Start the printf hostcall
Value zeroI64 = rewriter.create<LLVM::ConstantOp>(loc, llvmI64, 0);
auto printfBeginCall = rewriter.create<LLVM::CallOp>(loc, ocklBegin, zeroI64);
Value printfDesc = printfBeginCall.getResult();
// Create a global constant for the format string
unsigned stringNumber = 0;
SmallString<16> stringConstName;
do {
stringConstName.clear();
(formatStringPrefix + Twine(stringNumber++)).toStringRef(stringConstName);
} while (moduleOp.lookupSymbol(stringConstName));
llvm::SmallString<20> formatString(adaptor.getFormat());
formatString.push_back('\0'); // Null terminate for C
size_t formatStringSize = formatString.size_in_bytes();
auto globalType = LLVM::LLVMArrayType::get(llvmI8, formatStringSize);
LLVM::GlobalOp global;
{
ConversionPatternRewriter::InsertionGuard guard(rewriter);
rewriter.setInsertionPointToStart(moduleOp.getBody());
global = rewriter.create<LLVM::GlobalOp>(
loc, globalType,
/*isConstant=*/true, LLVM::Linkage::Internal, stringConstName,
rewriter.getStringAttr(formatString));
}
// Get a pointer to the format string's first element and pass it to printf()
Value globalPtr = rewriter.create<LLVM::AddressOfOp>(loc, global);
Value stringStart = rewriter.create<LLVM::GEPOp>(
loc, i8Ptr, globalPtr, ArrayRef<LLVM::GEPArg>{0, 0});
Value stringLen =
rewriter.create<LLVM::ConstantOp>(loc, llvmI64, formatStringSize);
Value oneI32 = rewriter.create<LLVM::ConstantOp>(loc, llvmI32, 1);
Value zeroI32 = rewriter.create<LLVM::ConstantOp>(loc, llvmI32, 0);
auto appendFormatCall = rewriter.create<LLVM::CallOp>(
loc, ocklAppendStringN,
ValueRange{printfDesc, stringStart, stringLen,
adaptor.getArgs().empty() ? oneI32 : zeroI32});
printfDesc = appendFormatCall.getResult();
// __ockl_printf_append_args takes 7 values per append call
constexpr size_t argsPerAppend = 7;
size_t nArgs = adaptor.getArgs().size();
for (size_t group = 0; group < nArgs; group += argsPerAppend) {
size_t bound = std::min(group + argsPerAppend, nArgs);
size_t numArgsThisCall = bound - group;
SmallVector<mlir::Value, 2 + argsPerAppend + 1> arguments;
arguments.push_back(printfDesc);
arguments.push_back(
rewriter.create<LLVM::ConstantOp>(loc, llvmI32, numArgsThisCall));
for (size_t i = group; i < bound; ++i) {
Value arg = adaptor.getArgs()[i];
if (auto floatType = arg.getType().dyn_cast<FloatType>()) {
if (!floatType.isF64())
arg = rewriter.create<LLVM::FPExtOp>(
loc, typeConverter->convertType(rewriter.getF64Type()), arg);
arg = rewriter.create<LLVM::BitcastOp>(loc, llvmI64, arg);
}
if (arg.getType().getIntOrFloatBitWidth() != 64)
arg = rewriter.create<LLVM::ZExtOp>(loc, llvmI64, arg);
arguments.push_back(arg);
}
// Pad out to 7 arguments since the hostcall always needs 7
for (size_t extra = numArgsThisCall; extra < argsPerAppend; ++extra) {
arguments.push_back(zeroI64);
}
auto isLast = (bound == nArgs) ? oneI32 : zeroI32;
arguments.push_back(isLast);
auto call = rewriter.create<LLVM::CallOp>(loc, ocklAppendArgs, arguments);
printfDesc = call.getResult();
}
rewriter.eraseOp(gpuPrintfOp);
return success();
}
LogicalResult GPUPrintfOpToLLVMCallLowering::matchAndRewrite(
gpu::PrintfOp gpuPrintfOp, gpu::PrintfOpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const {
Location loc = gpuPrintfOp->getLoc();
mlir::Type llvmI8 = typeConverter->convertType(rewriter.getIntegerType(8));
mlir::Type i8Ptr = LLVM::LLVMPointerType::get(llvmI8, addressSpace);
// Note: this is the GPUModule op, not the ModuleOp that surrounds it
// This ensures that global constants and declarations are placed within
// the device code, not the host code
auto moduleOp = gpuPrintfOp->getParentOfType<gpu::GPUModuleOp>();
auto printfType = LLVM::LLVMFunctionType::get(rewriter.getI32Type(), {i8Ptr},
/*isVarArg=*/true);
LLVM::LLVMFuncOp printfDecl =
getOrDefineFunction(moduleOp, loc, rewriter, "printf", printfType);
// Create a global constant for the format string
unsigned stringNumber = 0;
SmallString<16> stringConstName;
do {
stringConstName.clear();
(formatStringPrefix + Twine(stringNumber++)).toStringRef(stringConstName);
} while (moduleOp.lookupSymbol(stringConstName));
llvm::SmallString<20> formatString(adaptor.getFormat());
formatString.push_back('\0'); // Null terminate for C
auto globalType =
LLVM::LLVMArrayType::get(llvmI8, formatString.size_in_bytes());
LLVM::GlobalOp global;
{
ConversionPatternRewriter::InsertionGuard guard(rewriter);
rewriter.setInsertionPointToStart(moduleOp.getBody());
global = rewriter.create<LLVM::GlobalOp>(
loc, globalType,
/*isConstant=*/true, LLVM::Linkage::Internal, stringConstName,
rewriter.getStringAttr(formatString), /*allignment=*/0, addressSpace);
}
// Get a pointer to the format string's first element
Value globalPtr = rewriter.create<LLVM::AddressOfOp>(loc, global);
Value stringStart = rewriter.create<LLVM::GEPOp>(
loc, i8Ptr, globalPtr, ArrayRef<LLVM::GEPArg>{0, 0});
// Construct arguments and function call
auto argsRange = adaptor.getArgs();
SmallVector<Value, 4> printfArgs;
printfArgs.reserve(argsRange.size() + 1);
printfArgs.push_back(stringStart);
printfArgs.append(argsRange.begin(), argsRange.end());
rewriter.create<LLVM::CallOp>(loc, printfDecl, printfArgs);
rewriter.eraseOp(gpuPrintfOp);
return success();
}
/// Unrolls op if it's operating on vectors.
LogicalResult impl::scalarizeVectorOp(Operation *op, ValueRange operands,
ConversionPatternRewriter &rewriter,
LLVMTypeConverter &converter) {
TypeRange operandTypes(operands);
if (llvm::none_of(operandTypes,
[](Type type) { return type.isa<VectorType>(); })) {
return rewriter.notifyMatchFailure(op, "expected vector operand");
}
if (op->getNumRegions() != 0 || op->getNumSuccessors() != 0)
return rewriter.notifyMatchFailure(op, "expected no region/successor");
if (op->getNumResults() != 1)
return rewriter.notifyMatchFailure(op, "expected single result");
VectorType vectorType = op->getResult(0).getType().dyn_cast<VectorType>();
if (!vectorType)
return rewriter.notifyMatchFailure(op, "expected vector result");
Location loc = op->getLoc();
Value result = rewriter.create<LLVM::UndefOp>(loc, vectorType);
Type indexType = converter.convertType(rewriter.getIndexType());
StringAttr name = op->getName().getIdentifier();
Type elementType = vectorType.getElementType();
for (int64_t i = 0; i < vectorType.getNumElements(); ++i) {
Value index = rewriter.create<LLVM::ConstantOp>(loc, indexType, i);
auto extractElement = [&](Value operand) -> Value {
if (!operand.getType().isa<VectorType>())
return operand;
return rewriter.create<LLVM::ExtractElementOp>(loc, operand, index);
};
auto scalarOperands =
llvm::to_vector(llvm::map_range(operands, extractElement));
Operation *scalarOp =
rewriter.create(loc, name, scalarOperands, elementType, op->getAttrs());
rewriter.create<LLVM::InsertElementOp>(loc, result, scalarOp->getResult(0),
index);
}
rewriter.replaceOp(op, result);
return success();
}