forked from OSchip/llvm-project
99 lines
3.6 KiB
C++
99 lines
3.6 KiB
C++
//===- AMDGPUOpenCLEnqueuedBlockLowering.cpp - Lower enqueued block -------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// \file
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// \brief This post-linking pass replaces the function pointer of enqueued
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// block kernel with a global variable (runtime handle) and adds
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// "runtime-handle" attribute to the enqueued block kernel.
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//
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// In LLVM CodeGen the runtime-handle metadata will be translated to
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// RuntimeHandle metadata in code object. Runtime allocates a global buffer
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// for each kernel with RuntimeHandel metadata and saves the kernel address
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// required for the AQL packet into the buffer. __enqueue_kernel function
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// in device library knows that the invoke function pointer in the block
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// literal is actually runtime handle and loads the kernel address from it
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// and put it into AQL packet for dispatching.
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//
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// This cannot be done in FE since FE cannot create a unique global variable
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// with external linkage across LLVM modules. The global variable with internal
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// linkage does not work since optimization passes will try to replace loads
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// of the global variable with its initialization value.
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//
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//===----------------------------------------------------------------------===//
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#include "AMDGPU.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#define DEBUG_TYPE "amdgpu-lower-enqueued-block"
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using namespace llvm;
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namespace {
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/// \brief Lower enqueued blocks.
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class AMDGPUOpenCLEnqueuedBlockLowering : public ModulePass {
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public:
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static char ID;
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explicit AMDGPUOpenCLEnqueuedBlockLowering() : ModulePass(ID) {}
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private:
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bool runOnModule(Module &M) override;
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};
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} // end anonymous namespace
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char AMDGPUOpenCLEnqueuedBlockLowering::ID = 0;
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char &llvm::AMDGPUOpenCLEnqueuedBlockLoweringID =
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AMDGPUOpenCLEnqueuedBlockLowering::ID;
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INITIALIZE_PASS(AMDGPUOpenCLEnqueuedBlockLowering, DEBUG_TYPE,
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"Lower OpenCL enqueued blocks", false, false)
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ModulePass* llvm::createAMDGPUOpenCLEnqueuedBlockLoweringPass() {
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return new AMDGPUOpenCLEnqueuedBlockLowering();
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}
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bool AMDGPUOpenCLEnqueuedBlockLowering::runOnModule(Module &M) {
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auto &C = M.getContext();
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auto AS = AMDGPU::getAMDGPUAS(M);
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bool Changed = false;
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for (auto &F : M.functions()) {
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if (F.hasFnAttribute("enqueued-block")) {
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if (!F.hasOneUse() || !F.user_begin()->hasOneUse() ||
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!isa<ConstantExpr>(*F.user_begin()) ||
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!isa<ConstantExpr>(*F.user_begin()->user_begin())) {
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continue;
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}
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auto *BitCast = cast<ConstantExpr>(*F.user_begin());
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auto *AddrCast = cast<ConstantExpr>(*BitCast->user_begin());
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auto RuntimeHandle = (F.getName() + "_runtime_handle").str();
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auto *GV = new GlobalVariable(
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M, Type::getInt8Ty(C)->getPointerTo(AS.GLOBAL_ADDRESS),
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/*IsConstant=*/true, GlobalValue::ExternalLinkage,
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/*Initializer=*/nullptr, RuntimeHandle, /*InsertBefore=*/nullptr,
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GlobalValue::NotThreadLocal, AS.GLOBAL_ADDRESS,
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/*IsExternallyInitialized=*/true);
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DEBUG(dbgs() << "runtime handle created: " << *GV << '\n');
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auto *NewPtr = ConstantExpr::getPointerCast(GV, AddrCast->getType());
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AddrCast->replaceAllUsesWith(NewPtr);
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F.addFnAttr("runtime-handle", RuntimeHandle);
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F.setLinkage(GlobalValue::ExternalLinkage);
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Changed = true;
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}
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}
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return Changed;
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}
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