LLVM  6.0.0svn
NVPTXLowerAlloca.cpp
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1 //===-- NVPTXLowerAlloca.cpp - Make alloca to use local memory =====--===//
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 // For all alloca instructions, and add a pair of cast to local address for
11 // each of them. For example,
12 //
13 // %A = alloca i32
14 // store i32 0, i32* %A ; emits st.u32
15 //
16 // will be transformed to
17 //
18 // %A = alloca i32
19 // %Local = addrspacecast i32* %A to i32 addrspace(5)*
20 // %Generic = addrspacecast i32 addrspace(5)* %A to i32*
21 // store i32 0, i32 addrspace(5)* %Generic ; emits st.local.u32
22 //
23 // And we will rely on NVPTXInferAddressSpaces to combine the last two
24 // instructions.
25 //
26 //===----------------------------------------------------------------------===//
27 
28 #include "NVPTX.h"
29 #include "NVPTXUtilities.h"
30 #include "llvm/IR/Function.h"
31 #include "llvm/IR/Instructions.h"
32 #include "llvm/IR/IntrinsicInst.h"
33 #include "llvm/IR/Module.h"
34 #include "llvm/IR/Type.h"
35 #include "llvm/Pass.h"
36 
37 using namespace llvm;
38 
39 namespace llvm {
41 }
42 
43 namespace {
44 class NVPTXLowerAlloca : public BasicBlockPass {
45  bool runOnBasicBlock(BasicBlock &BB) override;
46 
47 public:
48  static char ID; // Pass identification, replacement for typeid
49  NVPTXLowerAlloca() : BasicBlockPass(ID) {}
50  StringRef getPassName() const override {
51  return "convert address space of alloca'ed memory to local";
52  }
53 };
54 } // namespace
55 
56 char NVPTXLowerAlloca::ID = 1;
57 
58 INITIALIZE_PASS(NVPTXLowerAlloca, "nvptx-lower-alloca",
59  "Lower Alloca", false, false)
60 
61 // =============================================================================
62 // Main function for this pass.
63 // =============================================================================
64 bool NVPTXLowerAlloca::runOnBasicBlock(BasicBlock &BB) {
65  if (skipBasicBlock(BB))
66  return false;
67 
68  bool Changed = false;
69  for (auto &I : BB) {
70  if (auto allocaInst = dyn_cast<AllocaInst>(&I)) {
71  Changed = true;
72  auto PTy = dyn_cast<PointerType>(allocaInst->getType());
73  auto ETy = PTy->getElementType();
74  auto LocalAddrTy = PointerType::get(ETy, ADDRESS_SPACE_LOCAL);
75  auto NewASCToLocal = new AddrSpaceCastInst(allocaInst, LocalAddrTy, "");
76  auto GenericAddrTy = PointerType::get(ETy, ADDRESS_SPACE_GENERIC);
77  auto NewASCToGeneric = new AddrSpaceCastInst(NewASCToLocal,
78  GenericAddrTy, "");
79  NewASCToLocal->insertAfter(allocaInst);
80  NewASCToGeneric->insertAfter(NewASCToLocal);
81  for (Value::use_iterator UI = allocaInst->use_begin(),
82  UE = allocaInst->use_end();
83  UI != UE; ) {
84  // Check Load, Store, GEP, and BitCast Uses on alloca and make them
85  // use the converted generic address, in order to expose non-generic
86  // addrspacecast to NVPTXInferAddressSpaces. For other types
87  // of instructions this is unnecessary and may introduce redundant
88  // address cast.
89  const auto &AllocaUse = *UI++;
90  auto LI = dyn_cast<LoadInst>(AllocaUse.getUser());
91  if (LI && LI->getPointerOperand() == allocaInst && !LI->isVolatile()) {
92  LI->setOperand(LI->getPointerOperandIndex(), NewASCToGeneric);
93  continue;
94  }
95  auto SI = dyn_cast<StoreInst>(AllocaUse.getUser());
96  if (SI && SI->getPointerOperand() == allocaInst && !SI->isVolatile()) {
97  SI->setOperand(SI->getPointerOperandIndex(), NewASCToGeneric);
98  continue;
99  }
100  auto GI = dyn_cast<GetElementPtrInst>(AllocaUse.getUser());
101  if (GI && GI->getPointerOperand() == allocaInst) {
102  GI->setOperand(GI->getPointerOperandIndex(), NewASCToGeneric);
103  continue;
104  }
105  auto BI = dyn_cast<BitCastInst>(AllocaUse.getUser());
106  if (BI && BI->getOperand(0) == allocaInst) {
107  BI->setOperand(0, NewASCToGeneric);
108  continue;
109  }
110  }
111  }
112  }
113  return Changed;
114 }
115 
117  return new NVPTXLowerAlloca();
118 }
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
static PointerType * get(Type *ElementType, unsigned AddressSpace)
This constructs a pointer to an object of the specified type in a numbered address space...
Definition: Type.cpp:617
An instruction for reading from memory.
Definition: Instructions.h:164
This class represents a conversion between pointers from one address space to another.
INITIALIZE_PASS(NVPTXLowerAlloca, "nvptx-lower-alloca", "Lower Alloca", false, false) bool NVPTXLowerAlloca
This class represents a no-op cast from one type to another.
An instruction for storing to memory.
Definition: Instructions.h:306
Class to represent pointers.
Definition: DerivedTypes.h:467
use_iterator_impl< Use > use_iterator
Definition: Value.h:333
an instruction for type-safe pointer arithmetic to access elements of arrays and structs ...
Definition: Instructions.h:837
static bool runOnBasicBlock(MachineBasicBlock *MBB, std::vector< StringRef > &bbNames, std::vector< unsigned > &renamedInOtherBB, unsigned &basicBlockNum, unsigned &VRegGapIndex)
LLVM Basic Block Representation.
Definition: BasicBlock.h:59
BasicBlockPass class - This class is used to implement most local optimizations.
Definition: Pass.h:319
void initializeNVPTXLowerAllocaPass(PassRegistry &)
BasicBlockPass * createNVPTXLowerAllocaPass()
Module.h This file contains the declarations for the Module class.
void setOperand(unsigned i, Value *Val)
Definition: User.h:159
#define I(x, y, z)
Definition: MD5.cpp:58
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:323
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
PassRegistry - This class manages the registration and intitialization of the pass subsystem as appli...
Definition: PassRegistry.h:39
Type * getElementType() const
Definition: DerivedTypes.h:486