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/DenseMap.h"
19 #include "llvm/ADT/STLExtras.h"
20 #include "llvm/ADT/Sequence.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/iterator_range.h"
23 #include "llvm/IR/Attributes.h"
24 #include "llvm/IR/Function.h"
25 #include "llvm/IR/GlobalVariable.h"
26 #include "llvm/IR/InstVisitor.h"
27 #include "llvm/IR/InstrTypes.h"
28 #include "llvm/IR/Intrinsics.h"
29 #include "llvm/IR/Module.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include <algorithm>
32 #include <cassert>
33 #include <iterator>
34 #include <utility>
35 #include <vector>
36
37 namespace llvm {
38 class LLVMContext;
39 } // namespace llvm
40
41 using namespace llvm;
42
43 namespace {
44
45 /// Given ChunksToKeep, produce a map of global variables/functions/calls
46 /// and indexes of attributes to be preserved for each of them.
47 class AttributeRemapper : public InstVisitor<AttributeRemapper> {
48 Oracle &O;
49 LLVMContext &Context;
50
51 public:
AttributeRemapper(Oracle & O,LLVMContext & C)52 AttributeRemapper(Oracle &O, LLVMContext &C) : O(O), Context(C) {}
53
visitModule(Module & M)54 void visitModule(Module &M) {
55 for (GlobalVariable &GV : M.globals())
56 visitGlobalVariable(GV);
57 }
58
visitGlobalVariable(GlobalVariable & GV)59 void visitGlobalVariable(GlobalVariable &GV) {
60 // Global variables only have one attribute set.
61 AttributeSet AS = GV.getAttributes();
62 if (AS.hasAttributes()) {
63 AttrBuilder AttrsToPreserve(Context);
64 visitAttributeSet(AS, AttrsToPreserve);
65 GV.setAttributes(AttributeSet::get(Context, AttrsToPreserve));
66 }
67 }
68
visitFunction(Function & F)69 void visitFunction(Function &F) {
70 // We can neither add nor remove attributes from intrinsics.
71 if (F.getIntrinsicID() == Intrinsic::not_intrinsic)
72 F.setAttributes(visitAttributeList(F.getAttributes()));
73 }
74
visitCallBase(CallBase & CB)75 void visitCallBase(CallBase &CB) {
76 CB.setAttributes(visitAttributeList(CB.getAttributes()));
77 }
78
visitAttributeIndex(AttributeList AL,unsigned Index)79 AttributeSet visitAttributeIndex(AttributeList AL, unsigned Index) {
80 AttrBuilder AttributesToPreserve(Context);
81 visitAttributeSet(AL.getAttributes(Index), AttributesToPreserve);
82
83 if (AttributesToPreserve.attrs().empty())
84 return {};
85 return AttributeSet::get(Context, AttributesToPreserve);
86 }
87
visitAttributeList(AttributeList AL)88 AttributeList visitAttributeList(AttributeList AL) {
89 SmallVector<std::pair<unsigned, AttributeSet>> NewAttrList;
90 NewAttrList.reserve(AL.getNumAttrSets());
91
92 for (unsigned SetIdx : AL.indexes()) {
93 if (SetIdx == AttributeList::FunctionIndex)
94 continue;
95
96 AttributeSet AttrSet = visitAttributeIndex(AL, SetIdx);
97 if (AttrSet.hasAttributes())
98 NewAttrList.emplace_back(SetIdx, AttrSet);
99 }
100
101 // FIXME: It's ridiculous that indexes() doesn't give us the correct order
102 // for contructing a new AttributeList. Special case the function index so
103 // we don't have to sort.
104 AttributeSet FnAttrSet =
105 visitAttributeIndex(AL, AttributeList::FunctionIndex);
106 if (FnAttrSet.hasAttributes())
107 NewAttrList.emplace_back(AttributeList::FunctionIndex, FnAttrSet);
108
109 return AttributeList::get(Context, NewAttrList);
110 }
111
visitAttributeSet(const AttributeSet & AS,AttrBuilder & AttrsToPreserve)112 void visitAttributeSet(const AttributeSet &AS, AttrBuilder &AttrsToPreserve) {
113 // Optnone requires noinline, so removing noinline requires removing the
114 // pair.
115 Attribute NoInline = AS.getAttribute(Attribute::NoInline);
116 bool RemoveNoInline = false;
117 if (NoInline.isValid()) {
118 RemoveNoInline = !O.shouldKeep();
119 if (!RemoveNoInline)
120 AttrsToPreserve.addAttribute(NoInline);
121 }
122
123 for (Attribute A : AS) {
124 if (A.isEnumAttribute()) {
125 Attribute::AttrKind Kind = A.getKindAsEnum();
126 if (Kind == Attribute::NoInline)
127 continue;
128
129 if (RemoveNoInline && Kind == Attribute::OptimizeNone)
130 continue;
131
132 // TODO: Could only remove this if there are no constrained calls in the
133 // function.
134 if (Kind == Attribute::StrictFP) {
135 AttrsToPreserve.addAttribute(A);
136 continue;
137 }
138 }
139
140 if (O.shouldKeep())
141 AttrsToPreserve.addAttribute(A);
142 }
143 }
144 };
145
146 } // namespace
147
148 /// Removes out-of-chunk attributes from module.
extractAttributesFromModule(Oracle & O,ReducerWorkItem & WorkItem)149 static void extractAttributesFromModule(Oracle &O, ReducerWorkItem &WorkItem) {
150 AttributeRemapper R(O, WorkItem.getContext());
151 R.visit(WorkItem.getModule());
152 }
153
reduceAttributesDeltaPass(TestRunner & Test)154 void llvm::reduceAttributesDeltaPass(TestRunner &Test) {
155 runDeltaPass(Test, extractAttributesFromModule, "Reducing Attributes");
156 }
157