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
|
//===-- AbstractCallSite.cpp - Implementation of abstract call sites ------===//
//
// 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 abstract call sites which unify the interface for
// direct, indirect, and callback call sites.
//
// For more information see:
// https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20
//
//===----------------------------------------------------------------------===//
#include "llvm/IR/AbstractCallSite.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
#define DEBUG_TYPE "abstract-call-sites"
STATISTIC(NumCallbackCallSites, "Number of callback call sites created");
STATISTIC(NumDirectAbstractCallSites,
"Number of direct abstract call sites created");
STATISTIC(NumInvalidAbstractCallSitesUnknownUse,
"Number of invalid abstract call sites created (unknown use)");
STATISTIC(NumInvalidAbstractCallSitesUnknownCallee,
"Number of invalid abstract call sites created (unknown callee)");
STATISTIC(NumInvalidAbstractCallSitesNoCallback,
"Number of invalid abstract call sites created (no callback)");
void AbstractCallSite::getCallbackUses(
const CallBase &CB, SmallVectorImpl<const Use *> &CallbackUses) {
const Function *Callee = CB.getCalledFunction();
if (!Callee)
return;
MDNode *CallbackMD = Callee->getMetadata(LLVMContext::MD_callback);
if (!CallbackMD)
return;
for (const MDOperand &Op : CallbackMD->operands()) {
MDNode *OpMD = cast<MDNode>(Op.get());
auto *CBCalleeIdxAsCM = cast<ConstantAsMetadata>(OpMD->getOperand(0));
uint64_t CBCalleeIdx =
cast<ConstantInt>(CBCalleeIdxAsCM->getValue())->getZExtValue();
if (CBCalleeIdx < CB.arg_size())
CallbackUses.push_back(CB.arg_begin() + CBCalleeIdx);
}
}
/// Create an abstract call site from a use.
AbstractCallSite::AbstractCallSite(const Use *U)
: CB(dyn_cast<CallBase>(U->getUser())) {
// First handle unknown users.
if (!CB) {
// If the use is actually in a constant cast expression which itself
// has only one use, we look through the constant cast expression.
// This happens by updating the use @p U to the use of the constant
// cast expression and afterwards re-initializing CB accordingly.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U->getUser()))
if (CE->hasOneUse() && CE->isCast()) {
U = &*CE->use_begin();
CB = dyn_cast<CallBase>(U->getUser());
}
if (!CB) {
NumInvalidAbstractCallSitesUnknownUse++;
return;
}
}
// Then handle direct or indirect calls. Thus, if U is the callee of the
// call site CB it is not a callback and we are done.
if (CB->isCallee(U)) {
NumDirectAbstractCallSites++;
return;
}
// If we cannot identify the broker function we cannot create a callback and
// invalidate the abstract call site.
Function *Callee = CB->getCalledFunction();
if (!Callee) {
NumInvalidAbstractCallSitesUnknownCallee++;
CB = nullptr;
return;
}
MDNode *CallbackMD = Callee->getMetadata(LLVMContext::MD_callback);
if (!CallbackMD) {
NumInvalidAbstractCallSitesNoCallback++;
CB = nullptr;
return;
}
unsigned UseIdx = CB->getArgOperandNo(U);
MDNode *CallbackEncMD = nullptr;
for (const MDOperand &Op : CallbackMD->operands()) {
MDNode *OpMD = cast<MDNode>(Op.get());
auto *CBCalleeIdxAsCM = cast<ConstantAsMetadata>(OpMD->getOperand(0));
uint64_t CBCalleeIdx =
cast<ConstantInt>(CBCalleeIdxAsCM->getValue())->getZExtValue();
if (CBCalleeIdx != UseIdx)
continue;
CallbackEncMD = OpMD;
break;
}
if (!CallbackEncMD) {
NumInvalidAbstractCallSitesNoCallback++;
CB = nullptr;
return;
}
NumCallbackCallSites++;
assert(CallbackEncMD->getNumOperands() >= 2 && "Incomplete !callback metadata");
unsigned NumCallOperands = CB->arg_size();
// Skip the var-arg flag at the end when reading the metadata.
for (unsigned u = 0, e = CallbackEncMD->getNumOperands() - 1; u < e; u++) {
Metadata *OpAsM = CallbackEncMD->getOperand(u).get();
auto *OpAsCM = cast<ConstantAsMetadata>(OpAsM);
assert(OpAsCM->getType()->isIntegerTy(64) &&
"Malformed !callback metadata");
int64_t Idx = cast<ConstantInt>(OpAsCM->getValue())->getSExtValue();
assert(-1 <= Idx && Idx <= NumCallOperands &&
"Out-of-bounds !callback metadata index");
CI.ParameterEncoding.push_back(Idx);
}
if (!Callee->isVarArg())
return;
Metadata *VarArgFlagAsM =
CallbackEncMD->getOperand(CallbackEncMD->getNumOperands() - 1).get();
auto *VarArgFlagAsCM = cast<ConstantAsMetadata>(VarArgFlagAsM);
assert(VarArgFlagAsCM->getType()->isIntegerTy(1) &&
"Malformed !callback metadata var-arg flag");
if (VarArgFlagAsCM->getValue()->isNullValue())
return;
// Add all variadic arguments at the end.
for (unsigned u = Callee->arg_size(); u < NumCallOperands; u++)
CI.ParameterEncoding.push_back(u);
}
|
