llvm/lib/Target/AMDGPU/AMDGPUCtorDtorLowering.cpp

   1 //===-- AMDGPUCtorDtorLowering.cpp - Handle global ctors and dtors --------===//
   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 /// \file
  10 /// This pass creates a unified init and fini kernel with the required metadata
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "AMDGPU.h"
  14 #include "llvm/IR/Constants.h"
  15 #include "llvm/IR/Function.h"
  16 #include "llvm/IR/GlobalVariable.h"
  17 #include "llvm/IR/IRBuilder.h"
  18 #include "llvm/IR/Module.h"
  19 #include "llvm/IR/Value.h"
  20 #include "llvm/Pass.h"
  21 #include "llvm/Transforms/Utils/ModuleUtils.h"
  22
  23 using namespace llvm;
  24
  25 #define DEBUG_TYPE "amdgpu-lower-ctor-dtor"
  26
  27 namespace {
  28 class AMDGPUCtorDtorLowering final : public ModulePass {
  29   bool runOnModule(Module &M) override;
  30
  31 public:
  32   Function *createInitOrFiniKernelFunction(Module &M, bool IsCtor) {
  33     StringRef InitOrFiniKernelName = "amdgcn.device.init";
  34     if (!IsCtor)
  35       InitOrFiniKernelName = "amdgcn.device.fini";
  36
  37     Function *InitOrFiniKernel = Function::createWithDefaultAttr(
  38         FunctionType::get(Type::getVoidTy(M.getContext()), false),
  39         GlobalValue::InternalLinkage, 0, InitOrFiniKernelName, &M);
  40     BasicBlock *InitOrFiniKernelBB =
  41         BasicBlock::Create(M.getContext(), "", InitOrFiniKernel);
  42     ReturnInst::Create(M.getContext(), InitOrFiniKernelBB);
  43
  44     InitOrFiniKernel->setCallingConv(CallingConv::AMDGPU_KERNEL);
  45     if (IsCtor)
  46       InitOrFiniKernel->addFnAttr("device-init");
  47     else
  48       InitOrFiniKernel->addFnAttr("device-fini");
  49     return InitOrFiniKernel;
  50   }
  51
  52   bool createInitOrFiniKernel(Module &M, GlobalVariable *GV, bool IsCtor) {
  53     if (!GV)
  54       return false;
  55     ConstantArray *GA = cast<ConstantArray>(GV->getInitializer());
  56     if (GA->getNumOperands() == 0)
  57       return false;
  58     Function *InitOrFiniKernel = createInitOrFiniKernelFunction(M, IsCtor);
  59     IRBuilder<> IRB(InitOrFiniKernel->getEntryBlock().getTerminator());
  60     for (Value *V : GA->operands()) {
  61       auto *CS = cast<ConstantStruct>(V);
  62       if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
  63         FunctionCallee Ctor =
  64             M.getOrInsertFunction(F->getName(), IRB.getVoidTy());
  65         IRB.CreateCall(Ctor);
  66       }
  67     }
  68     appendToUsed(M, {InitOrFiniKernel});
  69     return true;
  70   }
  71
  72   static char ID;
  73   AMDGPUCtorDtorLowering() : ModulePass(ID) {}
  74 };
  75 } // End anonymous namespace
  76
  77 char AMDGPUCtorDtorLowering::ID = 0;
  78 char &llvm::AMDGPUCtorDtorLoweringID = AMDGPUCtorDtorLowering::ID;
  79 INITIALIZE_PASS(AMDGPUCtorDtorLowering, DEBUG_TYPE,
  80                 "Lower ctors and dtors for AMDGPU", false, false)
  81
  82 ModulePass *llvm::createAMDGPUCtorDtorLoweringPass() {
  83   return new AMDGPUCtorDtorLowering();
  84 }
  85
  86 bool AMDGPUCtorDtorLowering::runOnModule(Module &M) {
  87   bool Modified = false;
  88   Modified |=
  89       createInitOrFiniKernel(M, M.getGlobalVariable("llvm.global_ctors"),
  90                              /*IsCtor =*/true);
  91   Modified |=
  92       createInitOrFiniKernel(M, M.getGlobalVariable("llvm.global_dtors"),
  93                              /*IsCtor =*/false);
  94   return Modified;
  95 }