1 //===-- AMDGPUAnnotateUniformValues.cpp - ---------------------------------===//
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 /// \file
10 /// This pass adds amdgpu.uniform metadata to IR values so this information
11 /// can be used during instruction selection.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "AMDGPU.h"
16 #include "Utils/AMDGPUBaseInfo.h"
17 #include "Utils/AMDGPUMemoryUtils.h"
18 #include "llvm/Analysis/AliasAnalysis.h"
19 #include "llvm/Analysis/MemorySSA.h"
20 #include "llvm/Analysis/UniformityAnalysis.h"
21 #include "llvm/IR/InstVisitor.h"
22 #include "llvm/InitializePasses.h"
23
24 #define DEBUG_TYPE "amdgpu-annotate-uniform"
25
26 using namespace llvm;
27
28 namespace {
29
30 class AMDGPUAnnotateUniformValues : public FunctionPass,
31 public InstVisitor<AMDGPUAnnotateUniformValues> {
32 UniformityInfo *UA;
33 MemorySSA *MSSA;
34 AliasAnalysis *AA;
35 bool isEntryFunc;
36 bool Changed;
37
setUniformMetadata(Instruction * I)38 void setUniformMetadata(Instruction *I) {
39 I->setMetadata("amdgpu.uniform", MDNode::get(I->getContext(), {}));
40 Changed = true;
41 }
42
setNoClobberMetadata(Instruction * I)43 void setNoClobberMetadata(Instruction *I) {
44 I->setMetadata("amdgpu.noclobber", MDNode::get(I->getContext(), {}));
45 Changed = true;
46 }
47
48 public:
49 static char ID;
AMDGPUAnnotateUniformValues()50 AMDGPUAnnotateUniformValues() :
51 FunctionPass(ID) { }
52 bool doInitialization(Module &M) override;
53 bool runOnFunction(Function &F) override;
getPassName() const54 StringRef getPassName() const override {
55 return "AMDGPU Annotate Uniform Values";
56 }
getAnalysisUsage(AnalysisUsage & AU) const57 void getAnalysisUsage(AnalysisUsage &AU) const override {
58 AU.addRequired<UniformityInfoWrapperPass>();
59 AU.addRequired<MemorySSAWrapperPass>();
60 AU.addRequired<AAResultsWrapperPass>();
61 AU.setPreservesAll();
62 }
63
64 void visitBranchInst(BranchInst &I);
65 void visitLoadInst(LoadInst &I);
66 };
67
68 } // End anonymous namespace
69
70 INITIALIZE_PASS_BEGIN(AMDGPUAnnotateUniformValues, DEBUG_TYPE,
71 "Add AMDGPU uniform metadata", false, false)
72 INITIALIZE_PASS_DEPENDENCY(UniformityInfoWrapperPass)
73 INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)
74 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
75 INITIALIZE_PASS_END(AMDGPUAnnotateUniformValues, DEBUG_TYPE,
76 "Add AMDGPU uniform metadata", false, false)
77
78 char AMDGPUAnnotateUniformValues::ID = 0;
79
visitBranchInst(BranchInst & I)80 void AMDGPUAnnotateUniformValues::visitBranchInst(BranchInst &I) {
81 if (UA->isUniform(&I))
82 setUniformMetadata(&I);
83 }
84
visitLoadInst(LoadInst & I)85 void AMDGPUAnnotateUniformValues::visitLoadInst(LoadInst &I) {
86 Value *Ptr = I.getPointerOperand();
87 if (!UA->isUniform(Ptr))
88 return;
89 Instruction *PtrI = dyn_cast<Instruction>(Ptr);
90 if (PtrI)
91 setUniformMetadata(PtrI);
92
93 // We're tracking up to the Function boundaries, and cannot go beyond because
94 // of FunctionPass restrictions. We can ensure that is memory not clobbered
95 // for memory operations that are live in to entry points only.
96 if (!isEntryFunc)
97 return;
98 bool GlobalLoad = I.getPointerAddressSpace() == AMDGPUAS::GLOBAL_ADDRESS;
99 if (GlobalLoad && !AMDGPU::isClobberedInFunction(&I, MSSA, AA))
100 setNoClobberMetadata(&I);
101 }
102
doInitialization(Module & M)103 bool AMDGPUAnnotateUniformValues::doInitialization(Module &M) {
104 return false;
105 }
106
runOnFunction(Function & F)107 bool AMDGPUAnnotateUniformValues::runOnFunction(Function &F) {
108 if (skipFunction(F))
109 return false;
110
111 UA = &getAnalysis<UniformityInfoWrapperPass>().getUniformityInfo();
112 MSSA = &getAnalysis<MemorySSAWrapperPass>().getMSSA();
113 AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
114 isEntryFunc = AMDGPU::isEntryFunctionCC(F.getCallingConv());
115
116 Changed = false;
117 visit(F);
118 return Changed;
119 }
120
121 FunctionPass *
createAMDGPUAnnotateUniformValues()122 llvm::createAMDGPUAnnotateUniformValues() {
123 return new AMDGPUAnnotateUniformValues();
124 }
125