1 //===- SerializeToBlob.cpp - MLIR GPU lowering 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 a base class for a pass to serialize a gpu module
10 // into a binary blob that can be executed on a GPU. The binary blob is added
11 // as a string attribute to the gpu module.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "mlir/Dialect/GPU/Passes.h"
16 #include "mlir/Pass/Pass.h"
17 #include "mlir/Target/LLVMIR/Dialect/LLVMIR/LLVMToLLVMIRTranslation.h"
18 #include "mlir/Target/LLVMIR/Export.h"
19 #include "llvm/IR/LegacyPassManager.h"
20 #include "llvm/Support/TargetRegistry.h"
21 #include "llvm/Support/TargetSelect.h"
22 #include "llvm/Target/TargetMachine.h"
23 
24 using namespace mlir;
25 
26 std::string gpu::getDefaultGpuBinaryAnnotation() { return "gpu.binary"; }
27 
28 gpu::SerializeToBlobPass::SerializeToBlobPass(TypeID passID)
29     : OperationPass<gpu::GPUModuleOp>(passID) {}
30 
31 gpu::SerializeToBlobPass::SerializeToBlobPass(const SerializeToBlobPass &other)
32     : OperationPass<gpu::GPUModuleOp>(other) {}
33 
34 static std::string translateToISA(llvm::Module &llvmModule,
35                                   llvm::TargetMachine &targetMachine) {
36   llvmModule.setDataLayout(targetMachine.createDataLayout());
37 
38   std::string targetISA;
39   llvm::raw_string_ostream stream(targetISA);
40   llvm::buffer_ostream pstream(stream);
41   llvm::legacy::PassManager codegenPasses;
42   targetMachine.addPassesToEmitFile(codegenPasses, pstream, nullptr,
43                                     llvm::CGFT_AssemblyFile);
44   codegenPasses.run(llvmModule);
45   return targetISA;
46 }
47 
48 void gpu::SerializeToBlobPass::runOnOperation() {
49   // Lower the module to an LLVM IR module using a separate context to enable
50   // multi-threaded processing.
51   llvm::LLVMContext llvmContext;
52   std::unique_ptr<llvm::Module> llvmModule = translateToLLVMIR(llvmContext);
53   if (!llvmModule)
54     return signalPassFailure();
55 
56   // Lower the LLVM IR module to target ISA.
57   std::unique_ptr<llvm::TargetMachine> targetMachine = createTargetMachine();
58   if (!targetMachine)
59     return signalPassFailure();
60 
61   std::string targetISA = translateToISA(*llvmModule, *targetMachine);
62 
63   // Serialize the target ISA.
64   std::unique_ptr<std::vector<char>> blob = serializeISA(targetISA);
65   if (!blob)
66     return signalPassFailure();
67 
68   // Add the blob as module attribute.
69   auto attr = StringAttr::get(&getContext(), {blob->data(), blob->size()});
70   getOperation()->setAttr(gpuBinaryAnnotation, attr);
71 }
72 
73 void gpu::SerializeToBlobPass::getDependentDialects(
74     DialectRegistry &registry) const {
75   registerLLVMDialectTranslation(registry);
76   OperationPass<gpu::GPUModuleOp>::getDependentDialects(registry);
77 }
78 
79 std::unique_ptr<llvm::TargetMachine>
80 gpu::SerializeToBlobPass::createTargetMachine() {
81   Location loc = getOperation().getLoc();
82   std::string error;
83   const llvm::Target *target =
84       llvm::TargetRegistry::lookupTarget(triple, error);
85   if (!target) {
86     emitError(loc, Twine("failed to lookup target: ") + error);
87     return {};
88   }
89   llvm::TargetMachine *machine =
90       target->createTargetMachine(triple, chip, features, {}, {});
91   if (!machine) {
92     emitError(loc, "failed to create target machine");
93     return {};
94   }
95 
96   return std::unique_ptr<llvm::TargetMachine>{machine};
97 }
98 
99 std::unique_ptr<llvm::Module>
100 gpu::SerializeToBlobPass::translateToLLVMIR(llvm::LLVMContext &llvmContext) {
101   return translateModuleToLLVMIR(getOperation(), llvmContext,
102                                  "LLVMDialectModule");
103 }
104