llvm-project/llvm/lib/IR/AbstractCallSite.cpp

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AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
//===-- 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
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
//
//===----------------------------------------------------------------------===//
//
// 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/ADT/Statistic.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/IR/CallSite.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);
}
}
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
/// Create an abstract call site from a use.
AbstractCallSite::AbstractCallSite(const Use *U)
: CB(dyn_cast<CallBase>(U->getUser())) {
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
// First handle unknown users.
if (!CB) {
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
// 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.
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U->getUser()))
if (CE->getNumUses() == 1 && CE->isCast()) {
U = &*CE->use_begin();
CB = dyn_cast<CallBase>(U->getUser());
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
}
if (!CB) {
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
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)) {
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
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NumDirectAbstractCallSites++;
return;
}
// If we cannot identify the broker function we cannot create a callback and
// invalidate the abstract call site.
Function *Callee = CB->getCalledFunction();
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
if (!Callee) {
NumInvalidAbstractCallSitesUnknownCallee++;
CB = nullptr;
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
return;
}
MDNode *CallbackMD = Callee->getMetadata(LLVMContext::MD_callback);
if (!CallbackMD) {
NumInvalidAbstractCallSitesNoCallback++;
CB = nullptr;
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
return;
}
unsigned UseIdx = CB->getArgOperandNo(U);
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
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;
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
return;
}
NumCallbackCallSites++;
assert(CallbackEncMD->getNumOperands() >= 2 && "Incomplete !callback metadata");
unsigned NumCallOperands = CB->getNumArgOperands();
AbstractCallSite -- A unified interface for (in)direct and callback calls An abstract call site is a wrapper that allows to treat direct, indirect, and callback calls the same. If an abstract call site represents a direct or indirect call site it behaves like a stripped down version of a normal call site object. The abstract call site can also represent a callback call, thus the fact that the initially called function (=broker) may invoke a third one (=callback callee). In this case, the abstract call side hides the middle man, hence the broker function. The result is a representation of the callback call, inside the broker, but in the context of the original instruction that invoked the broker. Again, there are up to three functions involved when we talk about callback call sites. The caller (1), which invokes the broker function. The broker function (2), that may or may not invoke the callback callee. And finally the callback callee (3), which is the target of the callback call. The abstract call site will handle the mapping from parameters to arguments depending on the semantic of the broker function. However, it is important to note that the mapping is often partial. Thus, some arguments of the call/invoke instruction are mapped to parameters of the callee while others are not. At the same time, arguments of the callback callee might be unknown, thus "null" if queried. This patch introduces also !callback metadata which describe how a callback broker maps from parameters to arguments. This metadata is directly created by clang for known broker functions, provided through source code attributes by the user, or later deduced by analyses. For motivation and additional information please see the corresponding talk (slides/video) https://llvm.org/devmtg/2018-10/talk-abstracts.html#talk20 as well as the LCPC paper http://compilers.cs.uni-saarland.de/people/doerfert/par_opt_lcpc18.pdf Differential Revision: https://reviews.llvm.org/D54498 llvm-svn: 351627
2019-01-19 13:19:06 +08:00
// 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);
}