1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
| //===- InlineAlways.cpp - Code to inline always_inline functions ----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements a custom inliner that handles only functions that
// are marked as "always inline".
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO/AlwaysInliner.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/InlineCost.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/Inliner.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
using namespace llvm;
#define DEBUG_TYPE "inline"
PreservedAnalyses AlwaysInlinerPass::run(Module &M,
ModuleAnalysisManager &MAM) {
// Add inline assumptions during code generation.
FunctionAnalysisManager &FAM =
MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
std::function<AssumptionCache &(Function &)> GetAssumptionCache =
[&](Function &F) -> AssumptionCache & {
return FAM.getResult<AssumptionAnalysis>(F);
};
InlineFunctionInfo IFI(/*cg=*/nullptr, &GetAssumptionCache);
SmallSetVector<CallSite, 16> Calls;
bool Changed = false;
SmallVector<Function *, 16> InlinedFunctions;
for (Function &F : M)
if (!F.isDeclaration() && F.hasFnAttribute(Attribute::AlwaysInline) &&
isInlineViable(F)) {
Calls.clear();
for (User *U : F.users())
if (auto CS = CallSite(U))
if (CS.getCalledFunction() == &F)
Calls.insert(CS);
for (CallSite CS : Calls)
// FIXME: We really shouldn't be able to fail to inline at this point!
// We should do something to log or check the inline failures here.
Changed |=
InlineFunction(CS, IFI, /*CalleeAAR=*/nullptr, InsertLifetime);
// Remember to try and delete this function afterward. This both avoids
// re-walking the rest of the module and avoids dealing with any iterator
// invalidation issues while deleting functions.
InlinedFunctions.push_back(&F);
}
// Remove any live functions.
erase_if(InlinedFunctions, [&](Function *F) {
F->removeDeadConstantUsers();
return !F->isDefTriviallyDead();
});
// Delete the non-comdat ones from the module and also from our vector.
auto NonComdatBegin = partition(
InlinedFunctions, [&](Function *F) { return F->hasComdat(); });
for (Function *F : make_range(NonComdatBegin, InlinedFunctions.end()))
M.getFunctionList().erase(F);
InlinedFunctions.erase(NonComdatBegin, InlinedFunctions.end());
if (!InlinedFunctions.empty()) {
// Now we just have the comdat functions. Filter out the ones whose comdats
// are not actually dead.
filterDeadComdatFunctions(M, InlinedFunctions);
// The remaining functions are actually dead.
for (Function *F : InlinedFunctions)
M.getFunctionList().erase(F);
}
return Changed ? PreservedAnalyses::none() : PreservedAnalyses::all();
}
namespace {
/// Inliner pass which only handles "always inline" functions.
///
/// Unlike the \c AlwaysInlinerPass, this uses the more heavyweight \c Inliner
/// base class to provide several facilities such as array alloca merging.
class AlwaysInlinerLegacyPass : public LegacyInlinerBase {
public:
AlwaysInlinerLegacyPass() : LegacyInlinerBase(ID, /*InsertLifetime*/ true) {
initializeAlwaysInlinerLegacyPassPass(*PassRegistry::getPassRegistry());
}
AlwaysInlinerLegacyPass(bool InsertLifetime)
: LegacyInlinerBase(ID, InsertLifetime) {
initializeAlwaysInlinerLegacyPassPass(*PassRegistry::getPassRegistry());
}
/// Main run interface method. We override here to avoid calling skipSCC().
bool runOnSCC(CallGraphSCC &SCC) override { return inlineCalls(SCC); }
static char ID; // Pass identification, replacement for typeid
InlineCost getInlineCost(CallSite CS) override;
using llvm::Pass::doFinalization;
bool doFinalization(CallGraph &CG) override {
return removeDeadFunctions(CG, /*AlwaysInlineOnly=*/true);
}
};
}
char AlwaysInlinerLegacyPass::ID = 0;
INITIALIZE_PASS_BEGIN(AlwaysInlinerLegacyPass, "always-inline",
"Inliner for always_inline functions", false, false)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(AlwaysInlinerLegacyPass, "always-inline",
"Inliner for always_inline functions", false, false)
Pass *llvm::createAlwaysInlinerLegacyPass(bool InsertLifetime) {
return new AlwaysInlinerLegacyPass(InsertLifetime);
}
/// Get the inline cost for the always-inliner.
///
/// The always inliner *only* handles functions which are marked with the
/// attribute to force inlining. As such, it is dramatically simpler and avoids
/// using the powerful (but expensive) inline cost analysis. Instead it uses
/// a very simple and boring direct walk of the instructions looking for
/// impossible-to-inline constructs.
///
/// Note, it would be possible to go to some lengths to cache the information
/// computed here, but as we only expect to do this for relatively few and
/// small functions which have the explicit attribute to force inlining, it is
/// likely not worth it in practice.
InlineCost AlwaysInlinerLegacyPass::getInlineCost(CallSite CS) {
Function *Callee = CS.getCalledFunction();
// Only inline direct calls to functions with always-inline attributes
// that are viable for inlining.
if (!Callee)
return InlineCost::getNever("indirect call");
// FIXME: We shouldn't even get here for declarations.
if (Callee->isDeclaration())
return InlineCost::getNever("no definition");
if (!CS.hasFnAttr(Attribute::AlwaysInline))
return InlineCost::getNever("no alwaysinline attribute");
auto IsViable = isInlineViable(*Callee);
if (!IsViable)
return InlineCost::getNever(IsViable.message);
return InlineCost::getAlways("always inliner");
}
|