[lld] r303270 - Revert r303225 "Garbage collect dllimported symbols."
Hans Wennborg via llvm-commits
llvm-commits at lists.llvm.org
Wed May 17 09:22:03 PDT 2017
Author: hans
Date: Wed May 17 11:22:03 2017
New Revision: 303270
URL: http://llvm.org/viewvc/llvm-project?rev=303270&view=rev
Log:
Revert r303225 "Garbage collect dllimported symbols."
and follow-up r303226 "Fix Windows buildbots."
This broke the sanitizer-windows buildbot.
> Previously, the garbage collector (enabled by default or by explicitly
> passing /opt:ref) did not kill dllimported symbols. As a result,
> dllimported symbols could be added to resulting executables' dllimport
> list even if no one was actually using them.
>
> This patch implements dllexported symbol garbage collection. Just like
> COMDAT sections, dllimported symbols now have Live bits to manage their
> liveness, and MarkLive marks reachable dllimported symbols.
>
> Fixes https://bugs.llvm.org/show_bug.cgi?id=32950
>
> Reviewers: pcc
>
> Subscribers: llvm-commits
>
> Differential Revision: https://reviews.llvm.org/D33264
Removed:
lld/trunk/test/COFF/dllimport-gc.test
Modified:
lld/trunk/COFF/InputFiles.cpp
lld/trunk/COFF/MarkLive.cpp
lld/trunk/COFF/Symbols.cpp
lld/trunk/COFF/Symbols.h
lld/trunk/COFF/Writer.cpp
lld/trunk/test/COFF/Inputs/import.yaml
Modified: lld/trunk/COFF/InputFiles.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/InputFiles.cpp?rev=303270&r1=303269&r2=303270&view=diff
==============================================================================
--- lld/trunk/COFF/InputFiles.cpp (original)
+++ lld/trunk/COFF/InputFiles.cpp Wed May 17 11:22:03 2017
@@ -325,21 +325,12 @@ void ImportFile::parse() {
this->Hdr = Hdr;
ExternalName = ExtName;
- // Instantiate symbol objects.
ImpSym = cast<DefinedImportData>(
Symtab->addImportData(ImpName, this)->body());
-
- if (Hdr->getType() == llvm::COFF::IMPORT_CONST) {
+ if (Hdr->getType() == llvm::COFF::IMPORT_CONST)
ConstSym =
cast<DefinedImportData>(Symtab->addImportData(Name, this)->body());
- // A __imp_ and non-__imp_ symbols for the same dllimport'ed symbol
- // should be gc'ed as a group. Add a bidirectional edge.
- // Used by MarkLive.cpp.
- ImpSym->Sibling = ConstSym;
- ConstSym->Sibling = ImpSym;
- }
-
// If type is function, we need to create a thunk which jump to an
// address pointed by the __imp_ symbol. (This allows you to call
// DLL functions just like regular non-DLL functions.)
Modified: lld/trunk/COFF/MarkLive.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/MarkLive.cpp?rev=303270&r1=303269&r2=303270&view=diff
==============================================================================
--- lld/trunk/COFF/MarkLive.cpp (original)
+++ lld/trunk/COFF/MarkLive.cpp Wed May 17 11:22:03 2017
@@ -15,16 +15,16 @@
namespace lld {
namespace coff {
-// Set live bit for each reachable COMDAT chunk and dllimported symbol.
-// Unmarked (or unreachable) chunks or symbols are ignored by Writer,
-// so they are not included in the final output.
+// Set live bit on for each reachable chunk. Unmarked (unreachable)
+// COMDAT chunks will be ignored by Writer, so they will be excluded
+// from the final output.
void markLive(const std::vector<Chunk *> &Chunks) {
// We build up a worklist of sections which have been marked as live. We only
// push into the worklist when we discover an unmarked section, and we mark
// as we push, so sections never appear twice in the list.
SmallVector<SectionChunk *, 256> Worklist;
- // Non-COMDAT chunks are never be gc'ed, so they are gc-root.
+ // COMDAT section chunks are dead by default. Add non-COMDAT chunks.
for (Chunk *C : Chunks)
if (auto *SC = dyn_cast<SectionChunk>(C))
if (SC->isLive())
@@ -37,37 +37,19 @@ void markLive(const std::vector<Chunk *>
Worklist.push_back(C);
};
- // Mark a given symbol as reachable.
- std::function<void(SymbolBody * B)> AddSym = [&](SymbolBody *B) {
- if (auto *Sym = dyn_cast<DefinedRegular>(B)) {
- Enqueue(Sym->getChunk());
- } else if (auto *Sym = dyn_cast<DefinedImportData>(B)) {
- if (Sym->Live)
- return;
- Sym->Live = true;
- if (Sym->Sibling)
- Sym->Sibling->Live = true;
- } else if (auto *Sym = dyn_cast<DefinedImportThunk>(B)) {
- if (Sym->Live)
- return;
- Sym->Live = true;
- AddSym(Sym->WrappedSym);
- } else if (auto *Sym = dyn_cast<DefinedLocalImport>(B)) {
- AddSym(Sym->WrappedSym);
- }
- };
-
- // Add gc-root symbols.
+ // Add GC root chunks.
for (SymbolBody *B : Config->GCRoot)
- AddSym(B);
+ if (auto *D = dyn_cast<DefinedRegular>(B))
+ Enqueue(D->getChunk());
while (!Worklist.empty()) {
SectionChunk *SC = Worklist.pop_back_val();
assert(SC->isLive() && "We mark as live when pushing onto the worklist!");
// Mark all symbols listed in the relocation table for this section.
- for (SymbolBody *B : SC->symbols())
- AddSym(B);
+ for (SymbolBody *S : SC->symbols())
+ if (auto *D = dyn_cast<DefinedRegular>(S))
+ Enqueue(D->getChunk());
// Mark associative sections if any.
for (SectionChunk *C : SC->children())
Modified: lld/trunk/COFF/Symbols.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Symbols.cpp?rev=303270&r1=303269&r2=303270&view=diff
==============================================================================
--- lld/trunk/COFF/Symbols.cpp (original)
+++ lld/trunk/COFF/Symbols.cpp Wed May 17 11:22:03 2017
@@ -63,8 +63,7 @@ COFFSymbolRef DefinedCOFF::getCOFFSymbol
DefinedImportThunk::DefinedImportThunk(StringRef Name, DefinedImportData *S,
uint16_t Machine)
- : Defined(DefinedImportThunkKind, Name), Live(!Config->DoGC),
- WrappedSym(S) {
+ : Defined(DefinedImportThunkKind, Name) {
switch (Machine) {
case AMD64: Data = make<ImportThunkChunkX64>(S); return;
case I386: Data = make<ImportThunkChunkX86>(S); return;
Modified: lld/trunk/COFF/Symbols.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Symbols.h?rev=303270&r1=303269&r2=303270&view=diff
==============================================================================
--- lld/trunk/COFF/Symbols.h (original)
+++ lld/trunk/COFF/Symbols.h Wed May 17 11:22:03 2017
@@ -287,29 +287,19 @@ public:
class DefinedImportData : public Defined {
public:
DefinedImportData(StringRef N, ImportFile *F)
- : Defined(DefinedImportDataKind, N), Live(!Config->DoGC), File(F) {}
+ : Defined(DefinedImportDataKind, N), File(F) {
+ }
static bool classof(const SymbolBody *S) {
return S->kind() == DefinedImportDataKind;
}
uint64_t getRVA() { return File->Location->getRVA(); }
-
StringRef getDLLName() { return File->DLLName; }
StringRef getExternalName() { return File->ExternalName; }
void setLocation(Chunk *AddressTable) { File->Location = AddressTable; }
uint16_t getOrdinal() { return File->Hdr->OrdinalHint; }
- // If all sections referring a dllimported symbol become dead by gc,
- // we want to kill the symbol as well, so that a resulting binary has
- // fewer number of dependencies to DLLs. "Live" bit manages reachability.
- bool Live;
-
- // For a dllimported data symbol, we create two symbols.
- // They should be considered as a unit by gc. This pointer points
- // to the other symbol.
- DefinedImportData *Sibling = nullptr;
-
private:
ImportFile *File;
};
@@ -330,10 +320,6 @@ public:
uint64_t getRVA() { return Data->getRVA(); }
Chunk *getChunk() { return Data; }
- // For GC.
- bool Live;
- DefinedImportData *WrappedSym;
-
private:
Chunk *Data;
};
@@ -346,8 +332,7 @@ private:
class DefinedLocalImport : public Defined {
public:
DefinedLocalImport(StringRef N, Defined *S)
- : Defined(DefinedLocalImportKind, N), WrappedSym(S),
- Data(make<LocalImportChunk>(S)) {}
+ : Defined(DefinedLocalImportKind, N), Data(make<LocalImportChunk>(S)) {}
static bool classof(const SymbolBody *S) {
return S->kind() == DefinedLocalImportKind;
@@ -356,9 +341,6 @@ public:
uint64_t getRVA() { return Data->getRVA(); }
Chunk *getChunk() { return Data; }
- // For GC.
- Defined *WrappedSym;
-
private:
LocalImportChunk *Data;
};
Modified: lld/trunk/COFF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Writer.cpp?rev=303270&r1=303269&r2=303270&view=diff
==============================================================================
--- lld/trunk/COFF/Writer.cpp (original)
+++ lld/trunk/COFF/Writer.cpp Wed May 17 11:22:03 2017
@@ -376,24 +376,18 @@ void Writer::createImportTables() {
OutputSection *Text = createSection(".text");
for (ImportFile *File : Symtab->ImportFiles) {
if (DefinedImportThunk *Thunk = File->ThunkSym)
- if (Thunk->Live)
- Text->addChunk(Thunk->getChunk());
-
+ Text->addChunk(Thunk->getChunk());
if (Config->DelayLoads.count(StringRef(File->DLLName).lower())) {
- if (File->ImpSym->Live)
- DelayIdata.add(File->ImpSym);
+ DelayIdata.add(File->ImpSym);
} else {
- if (File->ImpSym->Live)
- Idata.add(File->ImpSym);
+ Idata.add(File->ImpSym);
}
}
-
if (!Idata.empty()) {
OutputSection *Sec = createSection(".idata");
for (Chunk *C : Idata.getChunks())
Sec->addChunk(C);
}
-
if (!DelayIdata.empty()) {
Defined *Helper = cast<Defined>(Config->DelayLoadHelper);
DelayIdata.create(Helper);
Modified: lld/trunk/test/COFF/Inputs/import.yaml
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/COFF/Inputs/import.yaml?rev=303270&r1=303269&r2=303270&view=diff
==============================================================================
--- lld/trunk/test/COFF/Inputs/import.yaml (original)
+++ lld/trunk/test/COFF/Inputs/import.yaml Wed May 17 11:22:03 2017
@@ -7,13 +7,6 @@ sections:
Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
Alignment: 4
SectionData: 0000000000000000
- Relocations:
- - VirtualAddress: 0
- SymbolName: exportfn1
- Type: IMAGE_REL_AMD64_ADDR32NB
- - VirtualAddress: 4
- SymbolName: exportfn2
- Type: IMAGE_REL_AMD64_ADDR32NB
symbols:
- Name: .text
Value: 0
@@ -23,7 +16,7 @@ symbols:
StorageClass: IMAGE_SYM_CLASS_STATIC
SectionDefinition:
Length: 8
- NumberOfRelocations: 2
+ NumberOfRelocations: 0
NumberOfLinenumbers: 0
CheckSum: 0
Number: 0
Removed: lld/trunk/test/COFF/dllimport-gc.test
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/COFF/dllimport-gc.test?rev=303269&view=auto
==============================================================================
--- lld/trunk/test/COFF/dllimport-gc.test (original)
+++ lld/trunk/test/COFF/dllimport-gc.test (removed)
@@ -1,51 +0,0 @@
-# REQUIRES: winres
-
-# RUN: yaml2obj < %p/Inputs/export.yaml > %t-lib.obj
-# RUN: lld-link /out:%t.dll /dll %t-lib.obj /implib:%t.lib /export:exportfn1
-
-# RUN: yaml2obj < %s > %t.obj
-
-# RUN: lld-link /out:%t1.exe /entry:main %t.obj %t.lib
-# RUN: llvm-readobj -coff-imports %t1.exe | FileCheck -check-prefix=REF %s
-# REF-NOT: Symbol: exportfn1
-
-# RUN: lld-link /out:%t2.exe /entry:main %t.obj %t.lib /opt:noref
-# RUN: llvm-readobj -coff-imports %t2.exe | FileCheck -check-prefix=NOREF %s
-# NOREF: Symbol: exportfn1
-
---- !COFF
-header:
- Machine: IMAGE_FILE_MACHINE_AMD64
- Characteristics: []
-sections:
- - Name: .text
- Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
- Alignment: 4
- SectionData: 0000000000000000
- Relocations:
-symbols:
- - Name: .text
- Value: 0
- SectionNumber: 1
- SimpleType: IMAGE_SYM_TYPE_NULL
- ComplexType: IMAGE_SYM_DTYPE_NULL
- StorageClass: IMAGE_SYM_CLASS_STATIC
- SectionDefinition:
- Length: 8
- NumberOfRelocations: 2
- NumberOfLinenumbers: 0
- CheckSum: 0
- Number: 0
- - Name: main
- Value: 0
- SectionNumber: 1
- SimpleType: IMAGE_SYM_TYPE_NULL
- ComplexType: IMAGE_SYM_DTYPE_FUNCTION
- StorageClass: IMAGE_SYM_CLASS_EXTERNAL
- - Name: exportfn1
- Value: 0
- SectionNumber: 0
- SimpleType: IMAGE_SYM_TYPE_NULL
- ComplexType: IMAGE_SYM_DTYPE_NULL
- StorageClass: IMAGE_SYM_CLASS_EXTERNAL
-...
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