LLVM 17.0.0git
NVPTXLowerAlloca.cpp
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1//===-- NVPTXLowerAlloca.cpp - Make alloca to use local memory =====--===//
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// For all alloca instructions, and add a pair of cast to local address for
10// each of them. For example,
11//
12// %A = alloca i32
13// store i32 0, i32* %A ; emits st.u32
14//
15// will be transformed to
16//
17// %A = alloca i32
18// %Local = addrspacecast i32* %A to i32 addrspace(5)*
19// %Generic = addrspacecast i32 addrspace(5)* %A to i32*
20// store i32 0, i32 addrspace(5)* %Generic ; emits st.local.u32
21//
22// And we will rely on NVPTXInferAddressSpaces to combine the last two
23// instructions.
24//
25//===----------------------------------------------------------------------===//
26
27#include "NVPTX.h"
28#include "NVPTXUtilities.h"
30#include "llvm/IR/Function.h"
33#include "llvm/IR/Module.h"
34#include "llvm/IR/Type.h"
35#include "llvm/Pass.h"
36
37using namespace llvm;
38
39namespace llvm {
41}
42
43namespace {
44class NVPTXLowerAlloca : public FunctionPass {
45 bool runOnFunction(Function &F) override;
46
47public:
48 static char ID; // Pass identification, replacement for typeid
49 NVPTXLowerAlloca() : FunctionPass(ID) {}
50 StringRef getPassName() const override {
51 return "convert address space of alloca'ed memory to local";
52 }
53};
54} // namespace
55
56char NVPTXLowerAlloca::ID = 1;
57
58INITIALIZE_PASS(NVPTXLowerAlloca, "nvptx-lower-alloca",
59 "Lower Alloca", false, false)
60
61// =============================================================================
62// Main function for this pass.
63// =============================================================================
64bool NVPTXLowerAlloca::runOnFunction(Function &F) {
65 if (skipFunction(F))
66 return false;
67
68 bool Changed = false;
69 for (auto &BB : F)
70 for (auto &I : BB) {
71 if (auto allocaInst = dyn_cast<AllocaInst>(&I)) {
72 Changed = true;
73 auto ETy = allocaInst->getAllocatedType();
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 =
78 new AddrSpaceCastInst(NewASCToLocal, GenericAddrTy, "");
79 NewASCToLocal->insertAfter(allocaInst);
80 NewASCToGeneric->insertAfter(NewASCToLocal);
81 for (Use &AllocaUse : llvm::make_early_inc_range(allocaInst->uses())) {
82 // Check Load, Store, GEP, and BitCast Uses on alloca and make them
83 // use the converted generic address, in order to expose non-generic
84 // addrspacecast to NVPTXInferAddressSpaces. For other types
85 // of instructions this is unnecessary and may introduce redundant
86 // address cast.
87 auto LI = dyn_cast<LoadInst>(AllocaUse.getUser());
88 if (LI && LI->getPointerOperand() == allocaInst &&
89 !LI->isVolatile()) {
90 LI->setOperand(LI->getPointerOperandIndex(), NewASCToGeneric);
91 continue;
92 }
93 auto SI = dyn_cast<StoreInst>(AllocaUse.getUser());
94 if (SI && SI->getPointerOperand() == allocaInst &&
95 !SI->isVolatile()) {
96 SI->setOperand(SI->getPointerOperandIndex(), NewASCToGeneric);
97 continue;
98 }
99 auto GI = dyn_cast<GetElementPtrInst>(AllocaUse.getUser());
100 if (GI && GI->getPointerOperand() == allocaInst) {
101 GI->setOperand(GI->getPointerOperandIndex(), NewASCToGeneric);
102 continue;
103 }
104 auto BI = dyn_cast<BitCastInst>(AllocaUse.getUser());
105 if (BI && BI->getOperand(0) == allocaInst) {
106 BI->setOperand(0, NewASCToGeneric);
107 continue;
108 }
109 }
110 }
111 }
112 return Changed;
113}
114
116 return new NVPTXLowerAlloca();
117}
static bool runOnFunction(Function &F, bool PostInlining)
#define F(x, y, z)
Definition: MD5.cpp:55
#define I(x, y, z)
Definition: MD5.cpp:58
Module.h This file contains the declarations for the Module class.
#define INITIALIZE_PASS(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:38
@ SI
This class represents a conversion between pointers from one address space to another.
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:308
virtual bool runOnFunction(Function &F)=0
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass.
PassRegistry - This class manages the registration and intitialization of the pass subsystem as appli...
Definition: PassRegistry.h:38
virtual StringRef getPassName() const
getPassName - Return a nice clean name for a pass.
Definition: Pass.cpp:81
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:50
A Use represents the edge between a Value definition and its users.
Definition: Use.h:43
unsigned ID
LLVM IR allows to use arbitrary numbers as calling convention identifiers.
Definition: CallingConv.h:24
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
void initializeNVPTXLowerAllocaPass(PassRegistry &)
@ ADDRESS_SPACE_GENERIC
Definition: NVPTXBaseInfo.h:22
@ ADDRESS_SPACE_LOCAL
Definition: NVPTXBaseInfo.h:26
iterator_range< early_inc_iterator_impl< detail::IterOfRange< RangeT > > > make_early_inc_range(RangeT &&Range)
Make a range that does early increment to allow mutation of the underlying range without disrupting i...
Definition: STLExtras.h:721
FunctionPass * createNVPTXLowerAllocaPass()