1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
//===- AMDGPULDSUtils.cpp -------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// AMDGPU LDS related helper utility functions.
//
//===----------------------------------------------------------------------===//
#include "AMDGPULDSUtils.h"
#include "AMDGPU.h"
#include "Utils/AMDGPUBaseInfo.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/ReplaceConstant.h"
using namespace llvm;
namespace llvm {
namespace AMDGPU {
bool isKernelCC(const Function *Func) {
return AMDGPU::isModuleEntryFunctionCC(Func->getCallingConv());
}
Align getAlign(DataLayout const &DL, const GlobalVariable *GV) {
return DL.getValueOrABITypeAlignment(GV->getPointerAlignment(DL),
GV->getValueType());
}
static void collectFunctionUses(User *U, const Function *F,
SetVector<Instruction *> &InstUsers) {
SmallVector<User *> Stack{U};
while (!Stack.empty()) {
U = Stack.pop_back_val();
if (auto *I = dyn_cast<Instruction>(U)) {
if (I->getFunction() == F)
InstUsers.insert(I);
continue;
}
if (!isa<ConstantExpr>(U))
continue;
append_range(Stack, U->users());
}
}
void replaceConstantUsesInFunction(ConstantExpr *C, const Function *F) {
SetVector<Instruction *> InstUsers;
collectFunctionUses(C, F, InstUsers);
for (Instruction *I : InstUsers) {
convertConstantExprsToInstructions(I, C);
}
}
static bool shouldLowerLDSToStruct(const GlobalVariable &GV,
const Function *F) {
// We are not interested in kernel LDS lowering for module LDS itself.
if (F && GV.getName() == "llvm.amdgcn.module.lds")
return false;
bool Ret = false;
SmallPtrSet<const User *, 8> Visited;
SmallVector<const User *, 16> Stack(GV.users());
assert(!F || isKernelCC(F));
while (!Stack.empty()) {
const User *V = Stack.pop_back_val();
Visited.insert(V);
if (isa<GlobalValue>(V)) {
// This use of the LDS variable is the initializer of a global variable.
// This is ill formed. The address of an LDS variable is kernel dependent
// and unknown until runtime. It can't be written to a global variable.
continue;
}
if (auto *I = dyn_cast<Instruction>(V)) {
const Function *UF = I->getFunction();
if (UF == F) {
// Used from this kernel, we want to put it into the structure.
Ret = true;
} else if (!F) {
// For module LDS lowering, lowering is required if the user instruction
// is from non-kernel function.
Ret |= !isKernelCC(UF);
}
continue;
}
// User V should be a constant, recursively visit users of V.
assert(isa<Constant>(V) && "Expected a constant.");
append_range(Stack, V->users());
}
return Ret;
}
std::vector<GlobalVariable *> findVariablesToLower(Module &M,
const Function *F) {
std::vector<llvm::GlobalVariable *> LocalVars;
for (auto &GV : M.globals()) {
if (GV.getType()->getPointerAddressSpace() != AMDGPUAS::LOCAL_ADDRESS) {
continue;
}
if (!GV.hasInitializer()) {
// addrspace(3) without initializer implies cuda/hip extern __shared__
// the semantics for such a variable appears to be that all extern
// __shared__ variables alias one another, in which case this transform
// is not required
continue;
}
if (!isa<UndefValue>(GV.getInitializer())) {
// Initializers are unimplemented for LDS address space.
// Leave such variables in place for consistent error reporting.
continue;
}
if (GV.isConstant()) {
// A constant undef variable can't be written to, and any load is
// undef, so it should be eliminated by the optimizer. It could be
// dropped by the back end if not. This pass skips over it.
continue;
}
if (!shouldLowerLDSToStruct(GV, F)) {
continue;
}
LocalVars.push_back(&GV);
}
return LocalVars;
}
} // end namespace AMDGPU
} // end namespace llvm
|
