1 //===-- AMDGPULowerIntrinsics.cpp -----------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "AMDGPU.h"
11 #include "AMDGPUSubtarget.h"
12 #include "llvm/IR/Constants.h"
13 #include "llvm/IR/Instructions.h"
14 #include "llvm/IR/IntrinsicInst.h"
15 #include "llvm/IR/Module.h"
16 #include "llvm/Transforms/Utils/LowerMemIntrinsics.h"
17 
18 #define DEBUG_TYPE "amdgpu-lower-intrinsics"
19 
20 using namespace llvm;
21 
22 namespace {
23 
24 const unsigned MaxStaticSize = 1024;
25 
26 class AMDGPULowerIntrinsics : public ModulePass {
27 private:
28   const TargetMachine *TM;
29 
30   bool makeLIDRangeMetadata(Function &F) const;
31 
32 public:
33   static char ID;
34 
35   AMDGPULowerIntrinsics(const TargetMachine *TM = nullptr)
36     : ModulePass(ID), TM(TM) { }
37   bool runOnModule(Module &M) override;
38   StringRef getPassName() const override {
39     return "AMDGPU Lower Intrinsics";
40   }
41 };
42 
43 }
44 
45 char AMDGPULowerIntrinsics::ID = 0;
46 
47 char &llvm::AMDGPULowerIntrinsicsID = AMDGPULowerIntrinsics::ID;
48 
49 INITIALIZE_TM_PASS(AMDGPULowerIntrinsics, DEBUG_TYPE,
50                   "Lower intrinsics", false, false)
51 
52 // TODO: Should refine based on estimated number of accesses (e.g. does it
53 // require splitting based on alignment)
54 static bool shouldExpandOperationWithSize(Value *Size) {
55   ConstantInt *CI = dyn_cast<ConstantInt>(Size);
56   return !CI || (CI->getZExtValue() > MaxStaticSize);
57 }
58 
59 static bool expandMemIntrinsicUses(Function &F) {
60   Intrinsic::ID ID = F.getIntrinsicID();
61   bool Changed = false;
62 
63   for (auto I = F.user_begin(), E = F.user_end(); I != E;) {
64     Instruction *Inst = cast<Instruction>(*I);
65     ++I;
66 
67     switch (ID) {
68     case Intrinsic::memcpy: {
69       auto *Memcpy = cast<MemCpyInst>(Inst);
70       if (shouldExpandOperationWithSize(Memcpy->getLength())) {
71         expandMemCpyAsLoop(Memcpy);
72         Changed = true;
73         Memcpy->eraseFromParent();
74       }
75 
76       break;
77     }
78     case Intrinsic::memmove: {
79       auto *Memmove = cast<MemMoveInst>(Inst);
80       if (shouldExpandOperationWithSize(Memmove->getLength())) {
81         expandMemMoveAsLoop(Memmove);
82         Changed = true;
83         Memmove->eraseFromParent();
84       }
85 
86       break;
87     }
88     case Intrinsic::memset: {
89       auto *Memset = cast<MemSetInst>(Inst);
90       if (shouldExpandOperationWithSize(Memset->getLength())) {
91         expandMemSetAsLoop(Memset);
92         Changed = true;
93         Memset->eraseFromParent();
94       }
95 
96       break;
97     }
98     default:
99       break;
100     }
101   }
102 
103   return Changed;
104 }
105 
106 bool AMDGPULowerIntrinsics::makeLIDRangeMetadata(Function &F) const {
107   if (!TM)
108     return false;
109 
110   bool Changed = false;
111   const AMDGPUSubtarget &ST = TM->getSubtarget<AMDGPUSubtarget>(F);
112 
113   for (auto *U : F.users()) {
114     auto *CI = dyn_cast<CallInst>(U);
115     if (!CI)
116       continue;
117 
118     Changed |= ST.makeLIDRangeMetadata(CI);
119   }
120   return Changed;
121 }
122 
123 bool AMDGPULowerIntrinsics::runOnModule(Module &M) {
124   bool Changed = false;
125 
126   for (Function &F : M) {
127     if (!F.isDeclaration())
128       continue;
129 
130     switch (F.getIntrinsicID()) {
131     case Intrinsic::memcpy:
132     case Intrinsic::memmove:
133     case Intrinsic::memset:
134       if (expandMemIntrinsicUses(F))
135         Changed = true;
136       break;
137 
138     case Intrinsic::amdgcn_workitem_id_x:
139     case Intrinsic::r600_read_tidig_x:
140     case Intrinsic::amdgcn_workitem_id_y:
141     case Intrinsic::r600_read_tidig_y:
142     case Intrinsic::amdgcn_workitem_id_z:
143     case Intrinsic::r600_read_tidig_z:
144     case Intrinsic::r600_read_local_size_x:
145     case Intrinsic::r600_read_local_size_y:
146     case Intrinsic::r600_read_local_size_z:
147       Changed |= makeLIDRangeMetadata(F);
148       break;
149 
150     default:
151       break;
152     }
153   }
154 
155   return Changed;
156 }
157 
158 ModulePass *llvm::createAMDGPULowerIntrinsicsPass(const TargetMachine *TM) {
159   return new AMDGPULowerIntrinsics(TM);
160 }
161