1 | //===-- NVPTXImageOptimizer.cpp - Image optimization pass -----------------===// |
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 | // This pass implements IR-level optimizations of image access code, |
10 | // including: |
11 | // |
12 | // 1. Eliminate istypep intrinsics when image access qualifier is known |
13 | // |
14 | //===----------------------------------------------------------------------===// |
15 | |
16 | #include "NVPTX.h" |
17 | #include "NVPTXUtilities.h" |
18 | #include "llvm/Analysis/ConstantFolding.h" |
19 | #include "llvm/IR/Instructions.h" |
20 | #include "llvm/IR/Intrinsics.h" |
21 | #include "llvm/IR/IntrinsicsNVPTX.h" |
22 | #include "llvm/Pass.h" |
23 | |
24 | using namespace llvm; |
25 | |
26 | namespace { |
27 | class NVPTXImageOptimizer : public FunctionPass { |
28 | private: |
29 | static char ID; |
30 | SmallVector<Instruction*, 4> InstrToDelete; |
31 | |
32 | public: |
33 | NVPTXImageOptimizer(); |
34 | |
35 | bool runOnFunction(Function &F) override; |
36 | |
37 | StringRef getPassName() const override { return "NVPTX Image Optimizer" ; } |
38 | |
39 | private: |
40 | bool replaceIsTypePSampler(Instruction &I); |
41 | bool replaceIsTypePSurface(Instruction &I); |
42 | bool replaceIsTypePTexture(Instruction &I); |
43 | Value *cleanupValue(Value *V); |
44 | void replaceWith(Instruction *From, ConstantInt *To); |
45 | }; |
46 | } |
47 | |
48 | char NVPTXImageOptimizer::ID = 0; |
49 | |
50 | NVPTXImageOptimizer::NVPTXImageOptimizer() |
51 | : FunctionPass(ID) {} |
52 | |
53 | bool NVPTXImageOptimizer::runOnFunction(Function &F) { |
54 | if (skipFunction(F)) |
55 | return false; |
56 | |
57 | bool Changed = false; |
58 | InstrToDelete.clear(); |
59 | |
60 | // Look for call instructions in the function |
61 | for (BasicBlock &BB : F) { |
62 | for (Instruction &Instr : BB) { |
63 | if (CallInst *CI = dyn_cast<CallInst>(Val: &Instr)) { |
64 | Function *CalledF = CI->getCalledFunction(); |
65 | if (CalledF && CalledF->isIntrinsic()) { |
66 | // This is an intrinsic function call, check if its an istypep |
67 | switch (CalledF->getIntrinsicID()) { |
68 | default: break; |
69 | case Intrinsic::nvvm_istypep_sampler: |
70 | Changed |= replaceIsTypePSampler(I&: Instr); |
71 | break; |
72 | case Intrinsic::nvvm_istypep_surface: |
73 | Changed |= replaceIsTypePSurface(I&: Instr); |
74 | break; |
75 | case Intrinsic::nvvm_istypep_texture: |
76 | Changed |= replaceIsTypePTexture(I&: Instr); |
77 | break; |
78 | } |
79 | } |
80 | } |
81 | } |
82 | } |
83 | |
84 | // Delete any istypep instances we replaced in the IR |
85 | for (Instruction *I : InstrToDelete) |
86 | I->eraseFromParent(); |
87 | |
88 | return Changed; |
89 | } |
90 | |
91 | bool NVPTXImageOptimizer::replaceIsTypePSampler(Instruction &I) { |
92 | Value *TexHandle = cleanupValue(V: I.getOperand(i: 0)); |
93 | if (isSampler(*TexHandle)) { |
94 | // This is an OpenCL sampler, so it must be a samplerref |
95 | replaceWith(From: &I, To: ConstantInt::getTrue(Context&: I.getContext())); |
96 | return true; |
97 | } else if (isImage(*TexHandle)) { |
98 | // This is an OpenCL image, so it cannot be a samplerref |
99 | replaceWith(From: &I, To: ConstantInt::getFalse(Context&: I.getContext())); |
100 | return true; |
101 | } else { |
102 | // The image type is unknown, so we cannot eliminate the intrinsic |
103 | return false; |
104 | } |
105 | } |
106 | |
107 | bool NVPTXImageOptimizer::replaceIsTypePSurface(Instruction &I) { |
108 | Value *TexHandle = cleanupValue(V: I.getOperand(i: 0)); |
109 | if (isImageReadWrite(*TexHandle) || |
110 | isImageWriteOnly(*TexHandle)) { |
111 | // This is an OpenCL read-only/read-write image, so it must be a surfref |
112 | replaceWith(From: &I, To: ConstantInt::getTrue(Context&: I.getContext())); |
113 | return true; |
114 | } else if (isImageReadOnly(*TexHandle) || |
115 | isSampler(*TexHandle)) { |
116 | // This is an OpenCL read-only/ imageor sampler, so it cannot be |
117 | // a surfref |
118 | replaceWith(From: &I, To: ConstantInt::getFalse(Context&: I.getContext())); |
119 | return true; |
120 | } else { |
121 | // The image type is unknown, so we cannot eliminate the intrinsic |
122 | return false; |
123 | } |
124 | } |
125 | |
126 | bool NVPTXImageOptimizer::replaceIsTypePTexture(Instruction &I) { |
127 | Value *TexHandle = cleanupValue(V: I.getOperand(i: 0)); |
128 | if (isImageReadOnly(*TexHandle)) { |
129 | // This is an OpenCL read-only image, so it must be a texref |
130 | replaceWith(From: &I, To: ConstantInt::getTrue(Context&: I.getContext())); |
131 | return true; |
132 | } else if (isImageWriteOnly(*TexHandle) || |
133 | isImageReadWrite(*TexHandle) || |
134 | isSampler(*TexHandle)) { |
135 | // This is an OpenCL read-write/write-only image or a sampler, so it |
136 | // cannot be a texref |
137 | replaceWith(From: &I, To: ConstantInt::getFalse(Context&: I.getContext())); |
138 | return true; |
139 | } else { |
140 | // The image type is unknown, so we cannot eliminate the intrinsic |
141 | return false; |
142 | } |
143 | } |
144 | |
145 | void NVPTXImageOptimizer::replaceWith(Instruction *From, ConstantInt *To) { |
146 | // We implement "poor man's DCE" here to make sure any code that is no longer |
147 | // live is actually unreachable and can be trivially eliminated by the |
148 | // unreachable block elimination pass. |
149 | for (Use &U : From->uses()) { |
150 | if (BranchInst *BI = dyn_cast<BranchInst>(Val&: U)) { |
151 | if (BI->isUnconditional()) continue; |
152 | BasicBlock *Dest; |
153 | if (To->isZero()) |
154 | // Get false block |
155 | Dest = BI->getSuccessor(i: 1); |
156 | else |
157 | // Get true block |
158 | Dest = BI->getSuccessor(i: 0); |
159 | BranchInst::Create(IfTrue: Dest, InsertBefore: BI->getIterator()); |
160 | InstrToDelete.push_back(Elt: BI); |
161 | } |
162 | } |
163 | From->replaceAllUsesWith(V: To); |
164 | InstrToDelete.push_back(Elt: From); |
165 | } |
166 | |
167 | Value *NVPTXImageOptimizer::cleanupValue(Value *V) { |
168 | if (ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(Val: V)) { |
169 | return cleanupValue(V: EVI->getAggregateOperand()); |
170 | } |
171 | return V; |
172 | } |
173 | |
174 | FunctionPass *llvm::createNVPTXImageOptimizerPass() { |
175 | return new NVPTXImageOptimizer(); |
176 | } |
177 | |