[lld] r305555 - [ELF] Enable createThunks to be called more than once.
Peter Smith via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 16 06:10:09 PDT 2017
Author: psmith
Date: Fri Jun 16 08:10:08 2017
New Revision: 305555
URL: http://llvm.org/viewvc/llvm-project?rev=305555&view=rev
Log:
[ELF] Enable createThunks to be called more than once.
In preparation for supporting range extension thunks we now continually
call createThunks() until no more thunks are added. This requires us to
record the thunks we add on each pass and only merge the new ones into the
OutputSection. We also need to check if a Relocation is targeting a thunk
to prevent us from infinitely creating more thunks.
Differential Revision: https://reviews.llvm.org/D34034
Modified:
lld/trunk/ELF/Relocations.cpp
lld/trunk/ELF/Relocations.h
lld/trunk/ELF/Writer.cpp
Modified: lld/trunk/ELF/Relocations.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Relocations.cpp?rev=305555&r1=305554&r2=305555&view=diff
==============================================================================
--- lld/trunk/ELF/Relocations.cpp (original)
+++ lld/trunk/ELF/Relocations.cpp Fri Jun 16 08:10:08 2017
@@ -1009,8 +1009,7 @@ ThunkSection *ThunkCreator::getOSThunkSe
if ((IS->Flags & SHF_EXECINSTR) == 0)
break;
}
- CurTS = make<ThunkSection>(OS, Off);
- ThunkSections[ISR].push_back(CurTS);
+ CurTS = addThunkSection(OS, ISR, Off);
}
return CurTS;
}
@@ -1020,7 +1019,6 @@ ThunkSection *ThunkCreator::getISThunkSe
if (TS)
return TS;
auto *TOS = IS->getParent();
- TS = make<ThunkSection>(TOS, IS->OutSecOff);
// Find InputSectionRange within TOS that IS is in
OutputSectionCommand *C = Script->getCmd(TOS);
@@ -1035,11 +1033,20 @@ ThunkSection *ThunkCreator::getISThunkSe
break;
}
}
- ThunkSections[Range].push_back(TS);
+ TS = addThunkSection(TOS, Range, IS->OutSecOff);
ThunkedSections[IS] = TS;
return TS;
}
+ThunkSection *ThunkCreator::addThunkSection(OutputSection *OS,
+ std::vector<InputSection *> *ISR,
+ uint64_t Off) {
+ auto *TS = make<ThunkSection>(OS, Off);
+ ThunkSections[ISR].push_back(TS);
+ return TS;
+}
+
+
std::pair<Thunk *, bool> ThunkCreator::getThunk(SymbolBody &Body,
uint32_t Type) {
auto res = ThunkedSymbols.insert({&Body, nullptr});
@@ -1081,6 +1088,9 @@ void ThunkCreator::forEachExecInputSecti
// extension Thunks are not yet supported.
bool ThunkCreator::createThunks(
ArrayRef<OutputSectionCommand *> OutputSections) {
+ if (Pass > 0)
+ ThunkSections.clear();
+
// Create all the Thunks and insert them into synthetic ThunkSections. The
// ThunkSections are later inserted back into the OutputSection.
@@ -1088,11 +1098,12 @@ bool ThunkCreator::createThunks(
// ThunkSections back into the OutputSection as ThunkSections are not always
// inserted into the same OutputSection as the caller.
forEachExecInputSection(
- OutputSections, [=](OutputSection *OS, std::vector<InputSection*> *ISR,
+ OutputSections, [&](OutputSection *OS, std::vector<InputSection*> *ISR,
InputSection *IS) {
for (Relocation &Rel : IS->Relocations) {
SymbolBody &Body = *Rel.Sym;
- if (!Target->needsThunk(Rel.Expr, Rel.Type, IS->File, Body))
+ if (Thunks.find(&Body) != Thunks.end() ||
+ !Target->needsThunk(Rel.Expr, Rel.Type, IS->File, Body))
continue;
Thunk *T;
bool IsNew;
@@ -1105,15 +1116,16 @@ bool ThunkCreator::createThunks(
else
TS = getOSThunkSec(OS, ISR);
TS->addThunk(T);
+ Thunks[T->ThunkSym] = T;
}
// Redirect relocation to Thunk, we never go via the PLT to a Thunk
Rel.Sym = T->ThunkSym;
Rel.Expr = fromPlt(Rel.Expr);
}
});
-
// Merge all created synthetic ThunkSections back into OutputSection
mergeThunks();
+ ++Pass;
return !ThunkSections.empty();
}
Modified: lld/trunk/ELF/Relocations.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Relocations.h?rev=305555&r1=305554&r2=305555&view=diff
==============================================================================
--- lld/trunk/ELF/Relocations.h (original)
+++ lld/trunk/ELF/Relocations.h Fri Jun 16 08:10:08 2017
@@ -126,6 +126,11 @@ public:
// Return true if Thunks have been added to OutputSections
bool createThunks(ArrayRef<OutputSectionCommand *> OutputSections);
+ // The number of completed passes of createThunks this permits us
+ // to do one time initialization on Pass 0 and put a limit on the
+ // number of times it can be called to prevent infinite loops.
+ uint32_t Pass = 0;
+
private:
void mergeThunks();
ThunkSection *getOSThunkSec(OutputSection *OS,
@@ -137,14 +142,22 @@ private:
InputSection *)>
Fn);
std::pair<Thunk *, bool> getThunk(SymbolBody &Body, uint32_t Type);
-
+ ThunkSection *addThunkSection(OutputSection *OS,
+ std::vector<InputSection *> *, uint64_t Off);
// Track Symbols that already have a Thunk
llvm::DenseMap<SymbolBody *, Thunk *> ThunkedSymbols;
+ // Find a Thunk from the Thunks symbol definition, we can use this to find
+ // the Thunk from a relocation to the Thunks symbol definition.
+ llvm::DenseMap<SymbolBody *, Thunk *> Thunks;
+
// Track InputSections that have a ThunkSection placed in front
llvm::DenseMap<InputSection *, ThunkSection *> ThunkedSections;
- // Track the ThunksSections that need to be inserted into an OutputSection
+ // All the ThunkSections that we have created, organised by OutputSection
+ // will contain a mix of ThunkSections that have been created this pass, and
+ // ThunkSections that have been merged into the OutputSection on previous
+ // passes
std::map<std::vector<InputSection *> *, std::vector<ThunkSection *>>
ThunkSections;
Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=305555&r1=305554&r2=305555&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Fri Jun 16 08:10:08 2017
@@ -1281,9 +1281,12 @@ template <class ELFT> void Writer<ELFT>:
// are out of range. This will need to turn into a loop that converges
// when no more Thunks are added
ThunkCreator TC;
- if (TC.createThunks(OutputSectionCommands))
+ if (TC.createThunks(OutputSectionCommands)) {
applySynthetic({InX::MipsGot},
[](SyntheticSection *SS) { SS->updateAllocSize(); });
+ if (TC.createThunks(OutputSectionCommands))
+ fatal("All non-range thunks should be created in first call");
+ }
}
// Fill other section headers. The dynamic table is finalized
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