LLVM  10.0.0svn
AMDGPUAlwaysInlinePass.cpp
Go to the documentation of this file.
1 //===-- AMDGPUAlwaysInlinePass.cpp - Promote Allocas ----------------------===//
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 marks all internal functions as always_inline and creates
11 /// duplicates of all other functions and marks the duplicates as always_inline.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "AMDGPU.h"
16 #include "AMDGPUTargetMachine.h"
17 #include "Utils/AMDGPUBaseInfo.h"
18 #include "llvm/ADT/SmallPtrSet.h"
19 #include "llvm/IR/Module.h"
21 
22 using namespace llvm;
23 
24 namespace {
25 
26 static cl::opt<bool> StressCalls(
27  "amdgpu-stress-function-calls",
28  cl::Hidden,
29  cl::desc("Force all functions to be noinline"),
30  cl::init(false));
31 
32 class AMDGPUAlwaysInline : public ModulePass {
33  bool GlobalOpt;
34 
35  void recursivelyVisitUsers(GlobalValue &GV,
36  SmallPtrSetImpl<Function *> &FuncsToAlwaysInline);
37 public:
38  static char ID;
39 
40  AMDGPUAlwaysInline(bool GlobalOpt = false) :
41  ModulePass(ID), GlobalOpt(GlobalOpt) { }
42  bool runOnModule(Module &M) override;
43 
44  void getAnalysisUsage(AnalysisUsage &AU) const override {
45  AU.setPreservesAll();
46  }
47 };
48 
49 } // End anonymous namespace
50 
51 INITIALIZE_PASS(AMDGPUAlwaysInline, "amdgpu-always-inline",
52  "AMDGPU Inline All Functions", false, false)
53 
54 char AMDGPUAlwaysInline::ID = 0;
55 
56 void AMDGPUAlwaysInline::recursivelyVisitUsers(
57  GlobalValue &GV,
58  SmallPtrSetImpl<Function *> &FuncsToAlwaysInline) {
60 
62 
63  for (User *U : GV.users())
64  Stack.push_back(U);
65 
66  while (!Stack.empty()) {
67  User *U = Stack.pop_back_val();
68  if (!Visited.insert(U).second)
69  continue;
70 
71  if (Instruction *I = dyn_cast<Instruction>(U)) {
72  Function *F = I->getParent()->getParent();
74  FuncsToAlwaysInline.insert(F);
75  Stack.push_back(F);
76  }
77 
78  // No need to look at further users, but we do need to inline any callers.
79  continue;
80  }
81 
82  for (User *UU : U->users())
83  Stack.push_back(UU);
84  }
85 }
86 
87 bool AMDGPUAlwaysInline::runOnModule(Module &M) {
88  std::vector<GlobalAlias*> AliasesToRemove;
89 
90  SmallPtrSet<Function *, 8> FuncsToAlwaysInline;
91  SmallPtrSet<Function *, 8> FuncsToNoInline;
92 
93  for (GlobalAlias &A : M.aliases()) {
94  if (Function* F = dyn_cast<Function>(A.getAliasee())) {
95  A.replaceAllUsesWith(F);
96  AliasesToRemove.push_back(&A);
97  }
98 
99  // FIXME: If the aliasee isn't a function, it's some kind of constant expr
100  // cast that won't be inlined through.
101  }
102 
103  if (GlobalOpt) {
104  for (GlobalAlias* A : AliasesToRemove) {
105  A->eraseFromParent();
106  }
107  }
108 
109  // Always force inlining of any function that uses an LDS global address. This
110  // is something of a workaround because we don't have a way of supporting LDS
111  // objects defined in functions. LDS is always allocated by a kernel, and it
112  // is difficult to manage LDS usage if a function may be used by multiple
113  // kernels.
114  //
115  // OpenCL doesn't allow declaring LDS in non-kernels, so in practice this
116  // should only appear when IPO passes manages to move LDs defined in a kernel
117  // into a single user function.
118 
119  for (GlobalVariable &GV : M.globals()) {
120  // TODO: Region address
121  unsigned AS = GV.getType()->getAddressSpace();
123  continue;
124 
125  recursivelyVisitUsers(GV, FuncsToAlwaysInline);
126  }
127 
128  if (!AMDGPUTargetMachine::EnableFunctionCalls || StressCalls) {
129  auto IncompatAttr
130  = StressCalls ? Attribute::AlwaysInline : Attribute::NoInline;
131 
132  for (Function &F : M) {
133  if (!F.isDeclaration() && !F.use_empty() &&
134  !F.hasFnAttribute(IncompatAttr)) {
135  if (StressCalls) {
136  if (!FuncsToAlwaysInline.count(&F))
137  FuncsToNoInline.insert(&F);
138  } else
139  FuncsToAlwaysInline.insert(&F);
140  }
141  }
142  }
143 
144  for (Function *F : FuncsToAlwaysInline)
145  F->addFnAttr(Attribute::AlwaysInline);
146 
147  for (Function *F : FuncsToNoInline)
148  F->addFnAttr(Attribute::NoInline);
149 
150  return !FuncsToAlwaysInline.empty() || !FuncsToNoInline.empty();
151 }
152 
154  return new AMDGPUAlwaysInline(GlobalOpt);
155 }
156 
ModulePass * createAMDGPUAlwaysInlinePass(bool GlobalOpt=true)
This class represents lattice values for constants.
Definition: AllocatorList.h:23
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:66
bool hasFnAttribute(Attribute::AttrKind Kind) const
Return true if the function has the attribute.
Definition: Function.h:323
F(f)
Address space for region memory. (GDS)
Definition: AMDGPU.h:271
A templated base class for SmallPtrSet which provides the typesafe interface that is common across al...
Definition: SmallPtrSet.h:343
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:432
Address space for local memory.
Definition: AMDGPU.h:274
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:370
bool isEntryFunctionCC(CallingConv::ID CC)
Represent the analysis usage information of a pass.
size_type count(ConstPtrType Ptr) const
count - Return 1 if the specified pointer is in the set, 0 otherwise.
Definition: SmallPtrSet.h:381
The AMDGPU TargetMachine interface definition for hw codgen targets.
#define INITIALIZE_PASS(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:33
CallingConv::ID getCallingConv() const
getCallingConv()/setCallingConv(CC) - These method get and set the calling convention of this functio...
Definition: Function.h:212
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
Module.h This file contains the declarations for the Module class.
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:374
void setPreservesAll()
Set by analyses that do not transform their input at all.
iterator_range< user_iterator > users()
Definition: Value.h:420
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:55
#define I(x, y, z)
Definition: MD5.cpp:58
ModulePass class - This class is used to implement unstructured interprocedural optimizations and ana...
Definition: Pass.h:224
bool isDeclaration() const
Return true if the primary definition of this global value is outside of the current translation unit...
Definition: Globals.cpp:231
void addFnAttr(Attribute::AttrKind Kind)
Add function attributes to this function.
Definition: Function.h:229
iterator_range< global_iterator > globals()
Definition: Module.h:588
bool use_empty() const
Definition: Value.h:343
iterator_range< alias_iterator > aliases()
Definition: Module.h:628