caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[IR] Refactor GlobalIFunc to inherit from GlobalObject, Remove GlobalIndirectSymbol

Browse Source 
As discussed in:
* https://reviews.llvm.org/D94166
* https://lists.llvm.org/pipermail/llvm-dev/2020-September/145031.html

The GlobalIndirectSymbol class lost most of its meaning in
https://reviews.llvm.org/D109792, which disambiguated getBaseObject
(now getAliaseeObject) between GlobalIFunc and everything else.
In addition, as long as GlobalIFunc is not a GlobalObject and
getAliaseeObject returns GlobalObjects, a GlobalAlias whose aliasee
is a GlobalIFunc cannot currently be modeled properly. Creating
aliases for GlobalIFuncs does happen in the wild (e.g. glibc). In addition,
calling getAliaseeObject on a GlobalIFunc will currently return nullptr,
which is undesirable because it should return the object itself for
non-aliases.

This patch refactors the GlobalIFunc class to inherit directly from
GlobalObject, and removes GlobalIndirectSymbol (while inlining the
relevant parts into GlobalAlias and GlobalIFunc). This allows for
calling getAliaseeObject() on a GlobalIFunc to return the GlobalIFunc
itself, making getAliaseeObject() more consistent and enabling
alias-to-ifunc to be properly modeled in the IR.

I exercised some judgement in the API clients of GlobalIndirectSymbol:
some were 'monomorphized' for GlobalAlias and GlobalIFunc, and
some remained shared (with the type adapted to become GlobalValue).

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D108872
This commit is contained in:
Itay Bookstein
2021-10-20 10:29:47 -07:00
committed by Fangrui Song
parent 7562f3df89
commit 08ed216000
22 changed files with 420 additions and 385 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
llvm/lib/Bitcode/Reader/BitcodeReader.cpp
View File

@@ -41,7 +41,6 @@
#include "llvm/IR/GVMaterializer.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalIFunc.h"
#include "llvm/IR/GlobalIndirectSymbol.h"
#include "llvm/IR/GlobalObject.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
@@ -500,7 +499,7 @@ class BitcodeReader : public BitcodeReaderBase, public GVMaterializer {
SmallVector<Instruction *, 64> InstructionList;
std::vector<std::pair<GlobalVariable *, unsigned>> GlobalInits;
std::vector<std::pair<GlobalIndirectSymbol *, unsigned>> IndirectSymbolInits;
std::vector<std::pair<GlobalValue *, unsigned>> IndirectSymbolInits;
struct FunctionOperandInfo {
Function *F;
@@ -2253,8 +2252,7 @@ uint64_t BitcodeReader::decodeSignRotatedValue(uint64_t V) {
/// Resolve all of the initializers for global values and aliases that we can.
Error BitcodeReader::resolveGlobalAndIndirectSymbolInits() {
std::vector<std::pair<GlobalVariable *, unsigned>> GlobalInitWorklist;
std::vector<std::pair<GlobalIndirectSymbol *, unsigned>>
IndirectSymbolInitWorklist;
std::vector<std::pair<GlobalValue *, unsigned>> IndirectSymbolInitWorklist;
std::vector<FunctionOperandInfo> FunctionOperandWorklist;
GlobalInitWorklist.swap(GlobalInits);
@@ -2283,10 +2281,16 @@ Error BitcodeReader::resolveGlobalAndIndirectSymbolInits() {
Constant *C = dyn_cast_or_null<Constant>(ValueList[ValID]);
if (!C)
return error("Expected a constant");
GlobalIndirectSymbol *GIS = IndirectSymbolInitWorklist.back().first;
if (isa<GlobalAlias>(GIS) && C->getType() != GIS->getType())
return error("Alias and aliasee types don't match");
GIS->setIndirectSymbol(C);
GlobalValue *GV = IndirectSymbolInitWorklist.back().first;
if (auto *GA = dyn_cast<GlobalAlias>(GV)) {
if (C->getType() != GV->getType())
return error("Alias and aliasee types don't match");
GA->setAliasee(C);
} else if (auto *GI = dyn_cast<GlobalIFunc>(GV)) {
GI->setResolver(C);
} else {
return error("Expected an alias or an ifunc");
}
}
IndirectSymbolInitWorklist.pop_back();
}
@@ -3118,8 +3122,7 @@ Error BitcodeReader::globalCleanup() {
// Force deallocation of memory for these vectors to favor the client that
// want lazy deserialization.
std::vector<std::pair<GlobalVariable *, unsigned>>().swap(GlobalInits);
std::vector<std::pair<GlobalIndirectSymbol *, unsigned>>().swap(
IndirectSymbolInits);
std::vector<std::pair<GlobalValue *, unsigned>>().swap(IndirectSymbolInits);
return Error::success();
}
@@ -3499,7 +3502,7 @@ Error BitcodeReader::parseGlobalIndirectSymbolRecord(
auto Val = Record[OpNum++];
auto Linkage = Record[OpNum++];
GlobalIndirectSymbol *NewGA;
GlobalValue *NewGA;
if (BitCode == bitc::MODULE_CODE_ALIAS ||
BitCode == bitc::MODULE_CODE_ALIAS_OLD)
NewGA = GlobalAlias::create(Ty, AddrSpace, getDecodedLinkage(Linkage), Name,