1 //===- ForceFunctionAttrs.cpp - Force function attrs for debugging --------===//
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 #include "llvm/Transforms/IPO/ForceFunctionAttrs.h"
10 #include "llvm/ADT/StringSwitch.h"
11 #include "llvm/IR/Function.h"
12 #include "llvm/IR/LLVMContext.h"
13 #include "llvm/IR/Module.h"
14 #include "llvm/InitializePasses.h"
15 #include "llvm/Support/CommandLine.h"
16 #include "llvm/Support/Debug.h"
17 #include "llvm/Support/raw_ostream.h"
18 using namespace llvm;
19 
20 #define DEBUG_TYPE "forceattrs"
21 
22 static cl::list<std::string>
23     ForceAttributes("force-attribute", cl::Hidden,
24                     cl::desc("Add an attribute to a function. This should be a "
25                              "pair of 'function-name:attribute-name', for "
26                              "example -force-attribute=foo:noinline. This "
27                              "option can be specified multiple times."));
28 
29 static Attribute::AttrKind parseAttrKind(StringRef Kind) {
30   return StringSwitch<Attribute::AttrKind>(Kind)
31       .Case("alwaysinline", Attribute::AlwaysInline)
32       .Case("builtin", Attribute::Builtin)
33       .Case("cold", Attribute::Cold)
34       .Case("convergent", Attribute::Convergent)
35       .Case("inlinehint", Attribute::InlineHint)
36       .Case("jumptable", Attribute::JumpTable)
37       .Case("minsize", Attribute::MinSize)
38       .Case("naked", Attribute::Naked)
39       .Case("nobuiltin", Attribute::NoBuiltin)
40       .Case("noduplicate", Attribute::NoDuplicate)
41       .Case("noimplicitfloat", Attribute::NoImplicitFloat)
42       .Case("noinline", Attribute::NoInline)
43       .Case("nonlazybind", Attribute::NonLazyBind)
44       .Case("noredzone", Attribute::NoRedZone)
45       .Case("noreturn", Attribute::NoReturn)
46       .Case("nocf_check", Attribute::NoCfCheck)
47       .Case("norecurse", Attribute::NoRecurse)
48       .Case("nounwind", Attribute::NoUnwind)
49       .Case("optforfuzzing", Attribute::OptForFuzzing)
50       .Case("optnone", Attribute::OptimizeNone)
51       .Case("optsize", Attribute::OptimizeForSize)
52       .Case("readnone", Attribute::ReadNone)
53       .Case("readonly", Attribute::ReadOnly)
54       .Case("argmemonly", Attribute::ArgMemOnly)
55       .Case("returns_twice", Attribute::ReturnsTwice)
56       .Case("safestack", Attribute::SafeStack)
57       .Case("shadowcallstack", Attribute::ShadowCallStack)
58       .Case("sanitize_address", Attribute::SanitizeAddress)
59       .Case("sanitize_hwaddress", Attribute::SanitizeHWAddress)
60       .Case("sanitize_memory", Attribute::SanitizeMemory)
61       .Case("sanitize_thread", Attribute::SanitizeThread)
62       .Case("sanitize_memtag", Attribute::SanitizeMemTag)
63       .Case("speculative_load_hardening", Attribute::SpeculativeLoadHardening)
64       .Case("ssp", Attribute::StackProtect)
65       .Case("sspreq", Attribute::StackProtectReq)
66       .Case("sspstrong", Attribute::StackProtectStrong)
67       .Case("strictfp", Attribute::StrictFP)
68       .Case("uwtable", Attribute::UWTable)
69       .Default(Attribute::None);
70 }
71 
72 /// If F has any forced attributes given on the command line, add them.
73 static void addForcedAttributes(Function &F) {
74   for (auto &S : ForceAttributes) {
75     auto KV = StringRef(S).split(':');
76     if (KV.first != F.getName())
77       continue;
78 
79     auto Kind = parseAttrKind(KV.second);
80     if (Kind == Attribute::None) {
81       LLVM_DEBUG(dbgs() << "ForcedAttribute: " << KV.second
82                         << " unknown or not handled!\n");
83       continue;
84     }
85     if (F.hasFnAttribute(Kind))
86       continue;
87     F.addFnAttr(Kind);
88   }
89 }
90 
91 static bool hasForceAttributes() { return !ForceAttributes.empty(); }
92 
93 PreservedAnalyses ForceFunctionAttrsPass::run(Module &M,
94                                               ModuleAnalysisManager &) {
95   if (!hasForceAttributes())
96     return PreservedAnalyses::all();
97 
98   for (Function &F : M.functions())
99     addForcedAttributes(F);
100 
101   // Just conservatively invalidate analyses, this isn't likely to be important.
102   return PreservedAnalyses::none();
103 }
104 
105 namespace {
106 struct ForceFunctionAttrsLegacyPass : public ModulePass {
107   static char ID; // Pass identification, replacement for typeid
108   ForceFunctionAttrsLegacyPass() : ModulePass(ID) {
109     initializeForceFunctionAttrsLegacyPassPass(
110         *PassRegistry::getPassRegistry());
111   }
112 
113   bool runOnModule(Module &M) override {
114     if (ForceAttributes.empty())
115       return false;
116 
117     for (Function &F : M.functions())
118       addForcedAttributes(F);
119 
120     // Conservatively assume we changed something.
121     return true;
122   }
123 };
124 }
125 
126 char ForceFunctionAttrsLegacyPass::ID = 0;
127 INITIALIZE_PASS(ForceFunctionAttrsLegacyPass, "forceattrs",
128                 "Force set function attributes", false, false)
129 
130 Pass *llvm::createForceFunctionAttrsLegacyPass() {
131   return new ForceFunctionAttrsLegacyPass();
132 }
133