[Codegen] Alter the default promotion for saturating adds and subs
[llvm-complete.git] / lib / Target / AMDGPU / AMDGPUOpenCLEnqueuedBlockLowering.cpp
blobf7231471c1077eb04f7faccc97112e834474a76c
1 //===- AMDGPUOpenCLEnqueuedBlockLowering.cpp - Lower enqueued block -------===//
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 post-linking pass replaces the function pointer of enqueued
11 // block kernel with a global variable (runtime handle) and adds
12 // "runtime-handle" attribute to the enqueued block kernel.
14 // In LLVM CodeGen the runtime-handle metadata will be translated to
15 // RuntimeHandle metadata in code object. Runtime allocates a global buffer
16 // for each kernel with RuntimeHandel metadata and saves the kernel address
17 // required for the AQL packet into the buffer. __enqueue_kernel function
18 // in device library knows that the invoke function pointer in the block
19 // literal is actually runtime handle and loads the kernel address from it
20 // and put it into AQL packet for dispatching.
22 // This cannot be done in FE since FE cannot create a unique global variable
23 // with external linkage across LLVM modules. The global variable with internal
24 // linkage does not work since optimization passes will try to replace loads
25 // of the global variable with its initialization value.
27 // It also identifies the kernels directly or indirectly enqueues kernels
28 // and adds "calls-enqueue-kernel" function attribute to them, which will
29 // be used to determine whether to emit runtime metadata for the kernel
30 // enqueue related hidden kernel arguments.
32 //===----------------------------------------------------------------------===//
34 #include "AMDGPU.h"
35 #include "llvm/ADT/DenseSet.h"
36 #include "llvm/ADT/StringRef.h"
37 #include "llvm/IR/Constants.h"
38 #include "llvm/IR/DerivedTypes.h"
39 #include "llvm/IR/Instructions.h"
40 #include "llvm/IR/Mangler.h"
41 #include "llvm/IR/Module.h"
42 #include "llvm/IR/User.h"
43 #include "llvm/Pass.h"
44 #include "llvm/Support/Debug.h"
45 #include "llvm/Support/raw_ostream.h"
47 #define DEBUG_TYPE "amdgpu-lower-enqueued-block"
49 using namespace llvm;
51 namespace {
53 /// Lower enqueued blocks.
54 class AMDGPUOpenCLEnqueuedBlockLowering : public ModulePass {
55 public:
56 static char ID;
58 explicit AMDGPUOpenCLEnqueuedBlockLowering() : ModulePass(ID) {}
60 private:
61 bool runOnModule(Module &M) override;
64 } // end anonymous namespace
66 char AMDGPUOpenCLEnqueuedBlockLowering::ID = 0;
68 char &llvm::AMDGPUOpenCLEnqueuedBlockLoweringID =
69 AMDGPUOpenCLEnqueuedBlockLowering::ID;
71 INITIALIZE_PASS(AMDGPUOpenCLEnqueuedBlockLowering, DEBUG_TYPE,
72 "Lower OpenCL enqueued blocks", false, false)
74 ModulePass* llvm::createAMDGPUOpenCLEnqueuedBlockLoweringPass() {
75 return new AMDGPUOpenCLEnqueuedBlockLowering();
78 /// Collect direct or indrect callers of \p F and save them
79 /// to \p Callers.
80 static void collectCallers(Function *F, DenseSet<Function *> &Callers) {
81 for (auto U : F->users()) {
82 if (auto *CI = dyn_cast<CallInst>(&*U)) {
83 auto *Caller = CI->getParent()->getParent();
84 if (Callers.insert(Caller).second)
85 collectCallers(Caller, Callers);
90 /// If \p U is instruction or constant, collect functions which directly or
91 /// indirectly use it.
92 static void collectFunctionUsers(User *U, DenseSet<Function *> &Funcs) {
93 if (auto *I = dyn_cast<Instruction>(U)) {
94 auto *F = I->getParent()->getParent();
95 if (Funcs.insert(F).second)
96 collectCallers(F, Funcs);
97 return;
99 if (!isa<Constant>(U))
100 return;
101 for (auto UU : U->users())
102 collectFunctionUsers(&*UU, Funcs);
105 bool AMDGPUOpenCLEnqueuedBlockLowering::runOnModule(Module &M) {
106 DenseSet<Function *> Callers;
107 auto &C = M.getContext();
108 bool Changed = false;
109 for (auto &F : M.functions()) {
110 if (F.hasFnAttribute("enqueued-block")) {
111 if (!F.hasName()) {
112 SmallString<64> Name;
113 Mangler::getNameWithPrefix(Name, "__amdgpu_enqueued_kernel",
114 M.getDataLayout());
115 F.setName(Name);
117 LLVM_DEBUG(dbgs() << "found enqueued kernel: " << F.getName() << '\n');
118 auto RuntimeHandle = (F.getName() + ".runtime_handle").str();
119 auto T = ArrayType::get(Type::getInt64Ty(C), 2);
120 auto *GV = new GlobalVariable(
121 M, T,
122 /*isConstant=*/false, GlobalValue::ExternalLinkage,
123 /*Initializer=*/Constant::getNullValue(T), RuntimeHandle,
124 /*InsertBefore=*/nullptr, GlobalValue::NotThreadLocal,
125 AMDGPUAS::GLOBAL_ADDRESS,
126 /*isExternallyInitialized=*/false);
127 LLVM_DEBUG(dbgs() << "runtime handle created: " << *GV << '\n');
129 for (auto U : F.users()) {
130 auto *UU = &*U;
131 if (!isa<ConstantExpr>(UU))
132 continue;
133 collectFunctionUsers(UU, Callers);
134 auto *BitCast = cast<ConstantExpr>(UU);
135 auto *NewPtr = ConstantExpr::getPointerCast(GV, BitCast->getType());
136 BitCast->replaceAllUsesWith(NewPtr);
137 F.addFnAttr("runtime-handle", RuntimeHandle);
138 F.setLinkage(GlobalValue::ExternalLinkage);
139 Changed = true;
144 for (auto F : Callers) {
145 if (F->getCallingConv() != CallingConv::AMDGPU_KERNEL)
146 continue;
147 F->addFnAttr("calls-enqueue-kernel");
148 LLVM_DEBUG(dbgs() << "mark enqueue_kernel caller:" << F->getName() << '\n');
150 return Changed;