1 //===- ReduceAttributes.cpp - Specialized Delta 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 file implements a function which calls the Generic Delta pass in order
10 // to reduce uninteresting attributes.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "ReduceAttributes.h"
15 #include "Delta.h"
16 #include "TestRunner.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/Sequence.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/IR/Attributes.h"
22 #include "llvm/IR/Function.h"
23 #include "llvm/IR/GlobalVariable.h"
24 #include "llvm/IR/InstVisitor.h"
25 #include "llvm/IR/InstrTypes.h"
26 #include "llvm/IR/Intrinsics.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include <algorithm>
30 #include <cassert>
31 #include <iterator>
32 #include <utility>
33
34 namespace llvm {
35 class LLVMContext;
36 } // namespace llvm
37
38 using namespace llvm;
39
40 namespace {
41
42 /// Given ChunksToKeep, produce a map of global variables/functions/calls
43 /// and indexes of attributes to be preserved for each of them.
44 class AttributeRemapper : public InstVisitor<AttributeRemapper> {
45 Oracle &O;
46 LLVMContext &Context;
47
48 public:
AttributeRemapper(Oracle & O,LLVMContext & C)49 AttributeRemapper(Oracle &O, LLVMContext &C) : O(O), Context(C) {}
50
visitModule(Module & M)51 void visitModule(Module &M) {
52 for (GlobalVariable &GV : M.globals())
53 visitGlobalVariable(GV);
54 }
55
visitGlobalVariable(GlobalVariable & GV)56 void visitGlobalVariable(GlobalVariable &GV) {
57 // Global variables only have one attribute set.
58 AttributeSet AS = GV.getAttributes();
59 if (AS.hasAttributes()) {
60 AttrBuilder AttrsToPreserve(Context);
61 visitAttributeSet(AS, AttrsToPreserve);
62 GV.setAttributes(AttributeSet::get(Context, AttrsToPreserve));
63 }
64 }
65
visitFunction(Function & F)66 void visitFunction(Function &F) {
67 // We can neither add nor remove attributes from intrinsics.
68 if (F.getIntrinsicID() == Intrinsic::not_intrinsic)
69 F.setAttributes(visitAttributeList(F.getAttributes()));
70 }
71
visitCallBase(CallBase & CB)72 void visitCallBase(CallBase &CB) {
73 CB.setAttributes(visitAttributeList(CB.getAttributes()));
74 }
75
visitAttributeIndex(AttributeList AL,unsigned Index)76 AttributeSet visitAttributeIndex(AttributeList AL, unsigned Index) {
77 AttrBuilder AttributesToPreserve(Context);
78 visitAttributeSet(AL.getAttributes(Index), AttributesToPreserve);
79
80 if (AttributesToPreserve.attrs().empty())
81 return {};
82 return AttributeSet::get(Context, AttributesToPreserve);
83 }
84
visitAttributeList(AttributeList AL)85 AttributeList visitAttributeList(AttributeList AL) {
86 SmallVector<std::pair<unsigned, AttributeSet>> NewAttrList;
87 NewAttrList.reserve(AL.getNumAttrSets());
88
89 for (unsigned SetIdx : AL.indexes()) {
90 if (SetIdx == AttributeList::FunctionIndex)
91 continue;
92
93 AttributeSet AttrSet = visitAttributeIndex(AL, SetIdx);
94 if (AttrSet.hasAttributes())
95 NewAttrList.emplace_back(SetIdx, AttrSet);
96 }
97
98 // FIXME: It's ridiculous that indexes() doesn't give us the correct order
99 // for contructing a new AttributeList. Special case the function index so
100 // we don't have to sort.
101 AttributeSet FnAttrSet =
102 visitAttributeIndex(AL, AttributeList::FunctionIndex);
103 if (FnAttrSet.hasAttributes())
104 NewAttrList.emplace_back(AttributeList::FunctionIndex, FnAttrSet);
105
106 return AttributeList::get(Context, NewAttrList);
107 }
108
visitAttributeSet(const AttributeSet & AS,AttrBuilder & AttrsToPreserve)109 void visitAttributeSet(const AttributeSet &AS, AttrBuilder &AttrsToPreserve) {
110 // Optnone requires noinline, so removing noinline requires removing the
111 // pair.
112 Attribute NoInline = AS.getAttribute(Attribute::NoInline);
113 bool RemoveNoInline = false;
114 if (NoInline.isValid()) {
115 RemoveNoInline = !O.shouldKeep();
116 if (!RemoveNoInline)
117 AttrsToPreserve.addAttribute(NoInline);
118 }
119
120 for (Attribute A : AS) {
121 if (A.isEnumAttribute()) {
122 Attribute::AttrKind Kind = A.getKindAsEnum();
123 if (Kind == Attribute::NoInline)
124 continue;
125
126 if (RemoveNoInline && Kind == Attribute::OptimizeNone)
127 continue;
128
129 // TODO: Could only remove this if there are no constrained calls in the
130 // function.
131 if (Kind == Attribute::StrictFP) {
132 AttrsToPreserve.addAttribute(A);
133 continue;
134 }
135 }
136
137 if (O.shouldKeep())
138 AttrsToPreserve.addAttribute(A);
139 }
140 }
141 };
142
143 } // namespace
144
145 /// Removes out-of-chunk attributes from module.
extractAttributesFromModule(Oracle & O,ReducerWorkItem & WorkItem)146 static void extractAttributesFromModule(Oracle &O, ReducerWorkItem &WorkItem) {
147 AttributeRemapper R(O, WorkItem.getContext());
148 R.visit(WorkItem.getModule());
149 }
150
reduceAttributesDeltaPass(TestRunner & Test)151 void llvm::reduceAttributesDeltaPass(TestRunner &Test) {
152 runDeltaPass(Test, extractAttributesFromModule, "Reducing Attributes");
153 }
154