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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
|
//===-- NVPTXImageOptimizer.cpp - Image optimization pass -----------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This pass implements IR-level optimizations of image access code,
// including:
//
// 1. Eliminate istypep intrinsics when image access qualifier is known
//
//===----------------------------------------------------------------------===//
#include "NVPTX.h"
#include "NVPTXUtilities.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/IntrinsicsNVPTX.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
using namespace llvm;
namespace {
class NVPTXImageOptimizer : public FunctionPass {
private:
static char ID;
SmallVector<Instruction*, 4> InstrToDelete;
public:
NVPTXImageOptimizer();
bool runOnFunction(Function &F) override;
private:
bool replaceIsTypePSampler(Instruction &I);
bool replaceIsTypePSurface(Instruction &I);
bool replaceIsTypePTexture(Instruction &I);
Value *cleanupValue(Value *V);
void replaceWith(Instruction *From, ConstantInt *To);
};
}
char NVPTXImageOptimizer::ID = 0;
NVPTXImageOptimizer::NVPTXImageOptimizer()
: FunctionPass(ID) {}
bool NVPTXImageOptimizer::runOnFunction(Function &F) {
if (skipFunction(F))
return false;
bool Changed = false;
InstrToDelete.clear();
// Look for call instructions in the function
for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE;
++BI) {
for (BasicBlock::iterator I = (*BI).begin(), E = (*BI).end();
I != E; ++I) {
Instruction &Instr = *I;
if (CallInst *CI = dyn_cast<CallInst>(I)) {
Function *CalledF = CI->getCalledFunction();
if (CalledF && CalledF->isIntrinsic()) {
// This is an intrinsic function call, check if its an istypep
switch (CalledF->getIntrinsicID()) {
default: break;
case Intrinsic::nvvm_istypep_sampler:
Changed |= replaceIsTypePSampler(Instr);
break;
case Intrinsic::nvvm_istypep_surface:
Changed |= replaceIsTypePSurface(Instr);
break;
case Intrinsic::nvvm_istypep_texture:
Changed |= replaceIsTypePTexture(Instr);
break;
}
}
}
}
}
// Delete any istypep instances we replaced in the IR
for (unsigned i = 0, e = InstrToDelete.size(); i != e; ++i)
InstrToDelete[i]->eraseFromParent();
return Changed;
}
bool NVPTXImageOptimizer::replaceIsTypePSampler(Instruction &I) {
Value *TexHandle = cleanupValue(I.getOperand(0));
if (isSampler(*TexHandle)) {
// This is an OpenCL sampler, so it must be a samplerref
replaceWith(&I, ConstantInt::getTrue(I.getContext()));
return true;
} else if (isImage(*TexHandle)) {
// This is an OpenCL image, so it cannot be a samplerref
replaceWith(&I, ConstantInt::getFalse(I.getContext()));
return true;
} else {
// The image type is unknown, so we cannot eliminate the intrinsic
return false;
}
}
bool NVPTXImageOptimizer::replaceIsTypePSurface(Instruction &I) {
Value *TexHandle = cleanupValue(I.getOperand(0));
if (isImageReadWrite(*TexHandle) ||
isImageWriteOnly(*TexHandle)) {
// This is an OpenCL read-only/read-write image, so it must be a surfref
replaceWith(&I, ConstantInt::getTrue(I.getContext()));
return true;
} else if (isImageReadOnly(*TexHandle) ||
isSampler(*TexHandle)) {
// This is an OpenCL read-only/ imageor sampler, so it cannot be
// a surfref
replaceWith(&I, ConstantInt::getFalse(I.getContext()));
return true;
} else {
// The image type is unknown, so we cannot eliminate the intrinsic
return false;
}
}
bool NVPTXImageOptimizer::replaceIsTypePTexture(Instruction &I) {
Value *TexHandle = cleanupValue(I.getOperand(0));
if (isImageReadOnly(*TexHandle)) {
// This is an OpenCL read-only image, so it must be a texref
replaceWith(&I, ConstantInt::getTrue(I.getContext()));
return true;
} else if (isImageWriteOnly(*TexHandle) ||
isImageReadWrite(*TexHandle) ||
isSampler(*TexHandle)) {
// This is an OpenCL read-write/write-only image or a sampler, so it
// cannot be a texref
replaceWith(&I, ConstantInt::getFalse(I.getContext()));
return true;
} else {
// The image type is unknown, so we cannot eliminate the intrinsic
return false;
}
}
void NVPTXImageOptimizer::replaceWith(Instruction *From, ConstantInt *To) {
// We implement "poor man's DCE" here to make sure any code that is no longer
// live is actually unreachable and can be trivially eliminated by the
// unreachable block elimination pass.
for (CallInst::use_iterator UI = From->use_begin(), UE = From->use_end();
UI != UE; ++UI) {
if (BranchInst *BI = dyn_cast<BranchInst>(*UI)) {
if (BI->isUnconditional()) continue;
BasicBlock *Dest;
if (To->isZero())
// Get false block
Dest = BI->getSuccessor(1);
else
// Get true block
Dest = BI->getSuccessor(0);
BranchInst::Create(Dest, BI);
InstrToDelete.push_back(BI);
}
}
From->replaceAllUsesWith(To);
InstrToDelete.push_back(From);
}
Value *NVPTXImageOptimizer::cleanupValue(Value *V) {
if (ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(V)) {
return cleanupValue(EVI->getAggregateOperand());
}
return V;
}
FunctionPass *llvm::createNVPTXImageOptimizerPass() {
return new NVPTXImageOptimizer();
}
|