MLIR  19.0.0git
ConvertLaunchFuncToLLVMCalls.cpp
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1 //===- ConvertLaunchFuncToLLVMCalls.cpp - MLIR GPU launch to LLVM pass ----===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements passes to convert `gpu.launch_func` op into a sequence
10 // of LLVM calls that emulate the host and device sides.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 
27 #include "mlir/IR/BuiltinOps.h"
28 #include "mlir/IR/SymbolTable.h"
29 #include "mlir/Pass/Pass.h"
31 #include "llvm/ADT/DenseMap.h"
32 #include "llvm/ADT/StringExtras.h"
33 #include "llvm/Support/FormatVariadic.h"
34 
35 namespace mlir {
36 #define GEN_PASS_DEF_LOWERHOSTCODETOLLVMPASS
37 #include "mlir/Conversion/Passes.h.inc"
38 } // namespace mlir
39 
40 using namespace mlir;
41 
42 static constexpr const char kSPIRVModule[] = "__spv__";
43 
44 //===----------------------------------------------------------------------===//
45 // Utility functions
46 //===----------------------------------------------------------------------===//
47 
48 /// Returns the string name of the `DescriptorSet` decoration.
49 static std::string descriptorSetName() {
50  return llvm::convertToSnakeFromCamelCase(
51  stringifyDecoration(spirv::Decoration::DescriptorSet));
52 }
53 
54 /// Returns the string name of the `Binding` decoration.
55 static std::string bindingName() {
56  return llvm::convertToSnakeFromCamelCase(
57  stringifyDecoration(spirv::Decoration::Binding));
58 }
59 
60 /// Calculates the index of the kernel's operand that is represented by the
61 /// given global variable with the `bind` attribute. We assume that the index of
62 /// each kernel's operand is mapped to (descriptorSet, binding) by the map:
63 /// i -> (0, i)
64 /// which is implemented under `LowerABIAttributesPass`.
65 static unsigned calculateGlobalIndex(spirv::GlobalVariableOp op) {
66  IntegerAttr binding = op->getAttrOfType<IntegerAttr>(bindingName());
67  return binding.getInt();
68 }
69 
70 /// Copies the given number of bytes from src to dst pointers.
71 static void copy(Location loc, Value dst, Value src, Value size,
72  OpBuilder &builder) {
73  builder.create<LLVM::MemcpyOp>(loc, dst, src, size, /*isVolatile=*/false);
74 }
75 
76 /// Encodes the binding and descriptor set numbers into a new symbolic name.
77 /// The name is specified by
78 /// {kernel_module_name}_{variable_name}_descriptor_set{ds}_binding{b}
79 /// to avoid symbolic conflicts, where 'ds' and 'b' are descriptor set and
80 /// binding numbers.
81 static std::string
82 createGlobalVariableWithBindName(spirv::GlobalVariableOp op,
83  StringRef kernelModuleName) {
84  IntegerAttr descriptorSet =
85  op->getAttrOfType<IntegerAttr>(descriptorSetName());
86  IntegerAttr binding = op->getAttrOfType<IntegerAttr>(bindingName());
87  return llvm::formatv("{0}_{1}_descriptor_set{2}_binding{3}",
88  kernelModuleName.str(), op.getSymName().str(),
89  std::to_string(descriptorSet.getInt()),
90  std::to_string(binding.getInt()));
91 }
92 
93 /// Returns true if the given global variable has both a descriptor set number
94 /// and a binding number.
95 static bool hasDescriptorSetAndBinding(spirv::GlobalVariableOp op) {
96  IntegerAttr descriptorSet =
97  op->getAttrOfType<IntegerAttr>(descriptorSetName());
98  IntegerAttr binding = op->getAttrOfType<IntegerAttr>(bindingName());
99  return descriptorSet && binding;
100 }
101 
102 /// Fills `globalVariableMap` with SPIR-V global variables that represent kernel
103 /// arguments from the given SPIR-V module. We assume that the module contains a
104 /// single entry point function. Hence, all `spirv.GlobalVariable`s with a bind
105 /// attribute are kernel arguments.
107  spirv::ModuleOp module,
108  DenseMap<uint32_t, spirv::GlobalVariableOp> &globalVariableMap) {
109  auto entryPoints = module.getOps<spirv::EntryPointOp>();
110  if (!llvm::hasSingleElement(entryPoints)) {
111  return module.emitError(
112  "The module must contain exactly one entry point function");
113  }
114  auto globalVariables = module.getOps<spirv::GlobalVariableOp>();
115  for (auto globalOp : globalVariables) {
116  if (hasDescriptorSetAndBinding(globalOp))
117  globalVariableMap[calculateGlobalIndex(globalOp)] = globalOp;
118  }
119  return success();
120 }
121 
122 /// Encodes the SPIR-V module's symbolic name into the name of the entry point
123 /// function.
124 static LogicalResult encodeKernelName(spirv::ModuleOp module) {
125  StringRef spvModuleName = module.getSymName().value_or(kSPIRVModule);
126  // We already know that the module contains exactly one entry point function
127  // based on `getKernelGlobalVariables()` call. Update this function's name
128  // to:
129  // {spv_module_name}_{function_name}
130  auto entryPoints = module.getOps<spirv::EntryPointOp>();
131  if (!llvm::hasSingleElement(entryPoints)) {
132  return module.emitError(
133  "The module must contain exactly one entry point function");
134  }
135  spirv::EntryPointOp entryPoint = *entryPoints.begin();
136  StringRef funcName = entryPoint.getFn();
137  auto funcOp = module.lookupSymbol<spirv::FuncOp>(entryPoint.getFnAttr());
138  StringAttr newFuncName =
139  StringAttr::get(module->getContext(), spvModuleName + "_" + funcName);
140  if (failed(SymbolTable::replaceAllSymbolUses(funcOp, newFuncName, module)))
141  return failure();
142  SymbolTable::setSymbolName(funcOp, newFuncName);
143  return success();
144 }
145 
146 //===----------------------------------------------------------------------===//
147 // Conversion patterns
148 //===----------------------------------------------------------------------===//
149 
150 namespace {
151 
152 /// Structure to group information about the variables being copied.
153 struct CopyInfo {
154  Value dst;
155  Value src;
156  Value size;
157 };
158 
159 /// This pattern emulates a call to the kernel in LLVM dialect. For that, we
160 /// copy the data to the global variable (emulating device side), call the
161 /// kernel as a normal void LLVM function, and copy the data back (emulating the
162 /// host side).
163 class GPULaunchLowering : public ConvertOpToLLVMPattern<gpu::LaunchFuncOp> {
165 
167  matchAndRewrite(gpu::LaunchFuncOp launchOp, OpAdaptor adaptor,
168  ConversionPatternRewriter &rewriter) const override {
169  auto *op = launchOp.getOperation();
170  MLIRContext *context = rewriter.getContext();
171  auto module = launchOp->getParentOfType<ModuleOp>();
172 
173  // Get the SPIR-V module that represents the gpu kernel module. The module
174  // is named:
175  // __spv__{kernel_module_name}
176  // based on GPU to SPIR-V conversion.
177  StringRef kernelModuleName = launchOp.getKernelModuleName().getValue();
178  std::string spvModuleName = kSPIRVModule + kernelModuleName.str();
179  auto spvModule = module.lookupSymbol<spirv::ModuleOp>(
180  StringAttr::get(context, spvModuleName));
181  if (!spvModule) {
182  return launchOp.emitOpError("SPIR-V kernel module '")
183  << spvModuleName << "' is not found";
184  }
185 
186  // Declare kernel function in the main module so that it later can be linked
187  // with its definition from the kernel module. We know that the kernel
188  // function would have no arguments and the data is passed via global
189  // variables. The name of the kernel will be
190  // {spv_module_name}_{kernel_function_name}
191  // to avoid symbolic name conflicts.
192  StringRef kernelFuncName = launchOp.getKernelName().getValue();
193  std::string newKernelFuncName = spvModuleName + "_" + kernelFuncName.str();
194  auto kernelFunc = module.lookupSymbol<LLVM::LLVMFuncOp>(
195  StringAttr::get(context, newKernelFuncName));
196  if (!kernelFunc) {
197  OpBuilder::InsertionGuard guard(rewriter);
198  rewriter.setInsertionPointToStart(module.getBody());
199  kernelFunc = rewriter.create<LLVM::LLVMFuncOp>(
200  rewriter.getUnknownLoc(), newKernelFuncName,
202  ArrayRef<Type>()));
203  rewriter.setInsertionPoint(launchOp);
204  }
205 
206  // Get all global variables associated with the kernel operands.
208  if (failed(getKernelGlobalVariables(spvModule, globalVariableMap)))
209  return failure();
210 
211  // Traverse kernel operands that were converted to MemRefDescriptors. For
212  // each operand, create a global variable and copy data from operand to it.
213  Location loc = launchOp.getLoc();
214  SmallVector<CopyInfo, 4> copyInfo;
215  auto numKernelOperands = launchOp.getNumKernelOperands();
216  auto kernelOperands = adaptor.getOperands().take_back(numKernelOperands);
217  for (const auto &operand : llvm::enumerate(kernelOperands)) {
218  // Check if the kernel's operand is a ranked memref.
219  auto memRefType = dyn_cast<MemRefType>(
220  launchOp.getKernelOperand(operand.index()).getType());
221  if (!memRefType)
222  return failure();
223 
224  // Calculate the size of the memref and get the pointer to the allocated
225  // buffer.
226  SmallVector<Value, 4> sizes;
227  SmallVector<Value, 4> strides;
228  Value sizeBytes;
229  getMemRefDescriptorSizes(loc, memRefType, {}, rewriter, sizes, strides,
230  sizeBytes);
231  MemRefDescriptor descriptor(operand.value());
232  Value src = descriptor.allocatedPtr(rewriter, loc);
233 
234  // Get the global variable in the SPIR-V module that is associated with
235  // the kernel operand. Construct its new name and create a corresponding
236  // LLVM dialect global variable.
237  spirv::GlobalVariableOp spirvGlobal = globalVariableMap[operand.index()];
238  auto pointeeType =
239  cast<spirv::PointerType>(spirvGlobal.getType()).getPointeeType();
240  auto dstGlobalType = typeConverter->convertType(pointeeType);
241  if (!dstGlobalType)
242  return failure();
243  std::string name =
244  createGlobalVariableWithBindName(spirvGlobal, spvModuleName);
245  // Check if this variable has already been created.
246  auto dstGlobal = module.lookupSymbol<LLVM::GlobalOp>(name);
247  if (!dstGlobal) {
248  OpBuilder::InsertionGuard guard(rewriter);
249  rewriter.setInsertionPointToStart(module.getBody());
250  dstGlobal = rewriter.create<LLVM::GlobalOp>(
251  loc, dstGlobalType,
252  /*isConstant=*/false, LLVM::Linkage::Linkonce, name, Attribute(),
253  /*alignment=*/0);
254  rewriter.setInsertionPoint(launchOp);
255  }
256 
257  // Copy the data from src operand pointer to dst global variable. Save
258  // src, dst and size so that we can copy data back after emulating the
259  // kernel call.
260  Value dst = rewriter.create<LLVM::AddressOfOp>(
261  loc, typeConverter->convertType(spirvGlobal.getType()),
262  dstGlobal.getSymName());
263  copy(loc, dst, src, sizeBytes, rewriter);
264 
265  CopyInfo info;
266  info.dst = dst;
267  info.src = src;
268  info.size = sizeBytes;
269  copyInfo.push_back(info);
270  }
271  // Create a call to the kernel and copy the data back.
272  rewriter.replaceOpWithNewOp<LLVM::CallOp>(op, kernelFunc,
273  ArrayRef<Value>());
274  for (CopyInfo info : copyInfo)
275  copy(loc, info.src, info.dst, info.size, rewriter);
276  return success();
277  }
278 };
279 
280 class LowerHostCodeToLLVM
281  : public impl::LowerHostCodeToLLVMPassBase<LowerHostCodeToLLVM> {
282 public:
283  using Base::Base;
284 
285  void runOnOperation() override {
286  ModuleOp module = getOperation();
287 
288  // Erase the GPU module.
289  for (auto gpuModule :
290  llvm::make_early_inc_range(module.getOps<gpu::GPUModuleOp>()))
291  gpuModule.erase();
292 
293  // Request C wrapper emission.
294  for (auto func : module.getOps<func::FuncOp>()) {
295  func->setAttr(LLVM::LLVMDialect::getEmitCWrapperAttrName(),
297  }
298 
299  // Specify options to lower to LLVM and pull in the conversion patterns.
300  LowerToLLVMOptions options(module.getContext());
301 
302  auto *context = module.getContext();
303  RewritePatternSet patterns(context);
304  LLVMTypeConverter typeConverter(context, options);
306  populateFinalizeMemRefToLLVMConversionPatterns(typeConverter, patterns);
307  populateFuncToLLVMConversionPatterns(typeConverter, patterns);
308  patterns.add<GPULaunchLowering>(typeConverter);
309 
310  // Pull in SPIR-V type conversion patterns to convert SPIR-V global
311  // variable's type to LLVM dialect type.
312  populateSPIRVToLLVMTypeConversion(typeConverter);
313 
314  ConversionTarget target(*context);
315  target.addLegalDialect<LLVM::LLVMDialect>();
316  if (failed(applyPartialConversion(module, target, std::move(patterns))))
317  signalPassFailure();
318 
319  // Finally, modify the kernel function in SPIR-V modules to avoid symbolic
320  // conflicts.
321  for (auto spvModule : module.getOps<spirv::ModuleOp>()) {
322  if (failed(encodeKernelName(spvModule))) {
323  signalPassFailure();
324  return;
325  }
326  }
327  }
328 };
329 } // namespace
static std::string bindingName()
Returns the string name of the Binding decoration.
static std::string descriptorSetName()
Returns the string name of the DescriptorSet decoration.
static void copy(Location loc, Value dst, Value src, Value size, OpBuilder &builder)
Copies the given number of bytes from src to dst pointers.
static constexpr const char kSPIRVModule[]
static std::string createGlobalVariableWithBindName(spirv::GlobalVariableOp op, StringRef kernelModuleName)
Encodes the binding and descriptor set numbers into a new symbolic name.
static unsigned calculateGlobalIndex(spirv::GlobalVariableOp op)
Calculates the index of the kernel's operand that is represented by the given global variable with th...
static LogicalResult encodeKernelName(spirv::ModuleOp module)
Encodes the SPIR-V module's symbolic name into the name of the entry point function.
static LogicalResult getKernelGlobalVariables(spirv::ModuleOp module, DenseMap< uint32_t, spirv::GlobalVariableOp > &globalVariableMap)
Fills globalVariableMap with SPIR-V global variables that represent kernel arguments from the given S...
static bool hasDescriptorSetAndBinding(spirv::GlobalVariableOp op)
Returns true if the given global variable has both a descriptor set number and a binding number.
static MLIRContext * getContext(OpFoldResult val)
static llvm::ManagedStatic< PassManagerOptions > options
Attributes are known-constant values of operations.
Definition: Attributes.h:25
MLIRContext * getContext() const
Definition: Builders.h:55
Location getUnknownLoc()
Definition: Builders.cpp:27
This class implements a pattern rewriter for use with ConversionPatterns.
This class describes a specific conversion target.
Utility class for operation conversions targeting the LLVM dialect that match exactly one source oper...
Definition: Pattern.h:139
Conversion from types to the LLVM IR dialect.
Definition: TypeConverter.h:34
This class defines the main interface for locations in MLIR and acts as a non-nullable wrapper around...
Definition: Location.h:63
Options to control the LLVM lowering.
MLIRContext is the top-level object for a collection of MLIR operations.
Definition: MLIRContext.h:60
Helper class to produce LLVM dialect operations extracting or inserting elements of a MemRef descript...
Definition: MemRefBuilder.h:33
RAII guard to reset the insertion point of the builder when destroyed.
Definition: Builders.h:350
This class helps build Operations.
Definition: Builders.h:209
void setInsertionPointToStart(Block *block)
Sets the insertion point to the start of the specified block.
Definition: Builders.h:433
void setInsertionPoint(Block *block, Block::iterator insertPoint)
Set the insertion point to the specified location.
Definition: Builders.h:400
Operation * create(const OperationState &state)
Creates an operation given the fields represented as an OperationState.
Definition: Builders.cpp:464
AttrClass getAttrOfType(StringAttr name)
Definition: Operation.h:545
OpTy replaceOpWithNewOp(Operation *op, Args &&...args)
Replace the results of the given (original) op with a new op that is created without verification (re...
Definition: PatternMatch.h:536
static LogicalResult replaceAllSymbolUses(StringAttr oldSymbol, StringAttr newSymbol, Operation *from)
Attempt to replace all uses of the given symbol 'oldSymbol' with the provided symbol 'newSymbol' that...
static void setSymbolName(Operation *symbol, StringAttr name)
Sets the name of the given symbol operation.
This class represents an instance of an SSA value in the MLIR system, representing a computable value...
Definition: Value.h:96
void populateArithToLLVMConversionPatterns(LLVMTypeConverter &converter, RewritePatternSet &patterns)
constexpr void enumerate(std::tuple< Tys... > &tuple, CallbackT &&callback)
Definition: Matchers.h:285
Include the generated interface declarations.
LogicalResult failure(bool isFailure=true)
Utility function to generate a LogicalResult.
Definition: LogicalResult.h:62
void populateFuncToLLVMConversionPatterns(LLVMTypeConverter &converter, RewritePatternSet &patterns, const SymbolTable *symbolTable=nullptr)
Collect the patterns to convert from the Func dialect to LLVM.
Definition: FuncToLLVM.cpp:752
void populateSPIRVToLLVMTypeConversion(LLVMTypeConverter &typeConverter, spirv::ClientAPI clientAPIForAddressSpaceMapping=spirv::ClientAPI::Unknown)
Populates type conversions with additional SPIR-V types.
void populateFinalizeMemRefToLLVMConversionPatterns(LLVMTypeConverter &converter, RewritePatternSet &patterns)
Collect a set of patterns to convert memory-related operations from the MemRef dialect to the LLVM di...
LogicalResult success(bool isSuccess=true)
Utility function to generate a LogicalResult.
Definition: LogicalResult.h:56
auto get(MLIRContext *context, Ts &&...params)
Helper method that injects context only if needed, this helps unify some of the attribute constructio...
LogicalResult applyPartialConversion(ArrayRef< Operation * > ops, const ConversionTarget &target, const FrozenRewritePatternSet &patterns, ConversionConfig config=ConversionConfig())
Below we define several entry points for operation conversion.
bool failed(LogicalResult result)
Utility function that returns true if the provided LogicalResult corresponds to a failure value.
Definition: LogicalResult.h:72
This class represents an efficient way to signal success or failure.
Definition: LogicalResult.h:26