[llvm] r360205 - Reapply r360194 "[JITLink] Add support for MachO .alt_entry atoms." with fixes.
Lang Hames via llvm-commits
llvm-commits at lists.llvm.org
Tue May 7 15:56:40 PDT 2019
Author: lhames
Date: Tue May 7 15:56:40 2019
New Revision: 360205
URL: http://llvm.org/viewvc/llvm-project?rev=360205&view=rev
Log:
Reapply r360194 "[JITLink] Add support for MachO .alt_entry atoms." with fixes.
This patch modifies MachOAtomGraphBuilder to use setLayoutNext rather than
addEdge, and fixes a bug in the section layout algorithm that could result in
atoms appearing more than once in the section ordering (which resulted in those
atoms being assigned invalid addresses during layout).
Modified:
llvm/trunk/include/llvm/ExecutionEngine/JITLink/JITLink.h
llvm/trunk/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
llvm/trunk/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.cpp
llvm/trunk/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.h
llvm/trunk/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
llvm/trunk/test/ExecutionEngine/JITLink/X86/MachO_x86-64_relocations.s
Modified: llvm/trunk/include/llvm/ExecutionEngine/JITLink/JITLink.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ExecutionEngine/JITLink/JITLink.h?rev=360205&r1=360204&r2=360205&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ExecutionEngine/JITLink/JITLink.h (original)
+++ llvm/trunk/include/llvm/ExecutionEngine/JITLink/JITLink.h Tue May 7 15:56:40 2019
@@ -470,7 +470,7 @@ public:
void addEdge(Edge::Kind K, Edge::OffsetT Offset, Atom &Target,
Edge::AddendT Addend) {
assert(K != Edge::LayoutNext &&
- "Layout edges should be added via addLayoutNext");
+ "Layout edges should be added via setLayoutNext");
Edges.push_back(Edge(K, Offset, Target, Addend));
}
Modified: llvm/trunk/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp?rev=360205&r1=360204&r2=360205&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp Tue May 7 15:56:40 2019
@@ -170,31 +170,31 @@ void JITLinkerBase::layOutAtoms() {
auto &SL = KV.second;
for (auto *SIList : {&SL.ContentSections, &SL.ZeroFillSections}) {
for (auto &SI : *SIList) {
- std::vector<DefinedAtom *> LayoutHeads;
- LayoutHeads.reserve(SI.S->atoms_size());
+ // First build the set of layout-heads (i.e. "heads" of layout-next
+ // chains) by copying the section atoms, then eliminating any that
+ // appear as layout-next targets.
+ DenseSet<DefinedAtom *> LayoutHeads;
+ for (auto *DA : SI.S->atoms())
+ LayoutHeads.insert(DA);
- // First build the list of layout-heads (i.e. "heads" of layout-next
- // chains).
- DenseSet<DefinedAtom *> AlreadyLayedOut;
- for (auto *DA : SI.S->atoms()) {
- if (AlreadyLayedOut.count(DA))
- continue;
- LayoutHeads.push_back(DA);
- while (DA->hasLayoutNext()) {
- auto &Next = DA->getLayoutNext();
- AlreadyLayedOut.insert(&Next);
- DA = &Next;
- }
- }
+ for (auto *DA : SI.S->atoms())
+ if (DA->hasLayoutNext())
+ LayoutHeads.erase(&DA->getLayoutNext());
+
+ // Next, sort the layout heads by address order.
+ std::vector<DefinedAtom *> OrderedLayoutHeads;
+ OrderedLayoutHeads.reserve(LayoutHeads.size());
+ for (auto *DA : LayoutHeads)
+ OrderedLayoutHeads.push_back(DA);
// Now sort the list of layout heads by address.
- std::sort(LayoutHeads.begin(), LayoutHeads.end(),
+ std::sort(OrderedLayoutHeads.begin(), OrderedLayoutHeads.end(),
[](const DefinedAtom *LHS, const DefinedAtom *RHS) {
return LHS->getAddress() < RHS->getAddress();
});
// Now populate the SI.Atoms field by appending each of the chains.
- for (auto *DA : LayoutHeads) {
+ for (auto *DA : OrderedLayoutHeads) {
SI.Atoms.push_back(DA);
while (DA->hasLayoutNext()) {
auto &Next = DA->getLayoutNext();
Modified: llvm/trunk/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.cpp?rev=360205&r1=360204&r2=360205&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.cpp Tue May 7 15:56:40 2019
@@ -44,6 +44,33 @@ void MachOAtomGraphBuilder::addCustomAto
CustomAtomizeFunctions[SectionName] = std::move(Atomizer);
}
+bool MachOAtomGraphBuilder::areLayoutLocked(const Atom &A, const Atom &B) {
+ // If these atoms are the same then they're trivially "locked".
+ if (&A == &B)
+ return true;
+
+ // If A and B are different, check whether either is undefined. (in which
+ // case they are not locked).
+ if (!A.isDefined() || !B.isDefined())
+ return false;
+
+ // A and B are different, but they're both defined atoms. We need to check
+ // whether they're part of the same alt_entry chain.
+ auto &DA = static_cast<const DefinedAtom &>(A);
+ auto &DB = static_cast<const DefinedAtom &>(B);
+
+ auto AStartItr = AltEntryStarts.find(&DA);
+ if (AStartItr == AltEntryStarts.end()) // If A is not in a chain bail out.
+ return false;
+
+ auto BStartItr = AltEntryStarts.find(&DB);
+ if (BStartItr == AltEntryStarts.end()) // If B is not in a chain bail out.
+ return false;
+
+ // A and B are layout locked if they're in the same chain.
+ return AStartItr->second == BStartItr->second;
+}
+
unsigned
MachOAtomGraphBuilder::getPointerSize(const object::MachOObjectFile &Obj) {
return Obj.is64Bit() ? 8 : 4;
@@ -126,6 +153,9 @@ Error MachOAtomGraphBuilder::addNonCusto
DenseMap<MachOSection *, AddrToAtomMap> SecToAtoms;
DenseMap<MachOSection *, unsigned> FirstOrdinal;
+ std::vector<DefinedAtom *> AltEntryAtoms;
+
+ DenseSet<StringRef> ProcessedSymbols; // Used to check for duplicate defs.
for (auto SymI = Obj.symbol_begin(), SymE = Obj.symbol_end(); SymI != SymE;
++SymI) {
@@ -135,6 +165,14 @@ Error MachOAtomGraphBuilder::addNonCusto
if (!Name)
return Name.takeError();
+ // Bail out on duplicate definitions: There should never be more than one
+ // definition for a symbol in a given object file.
+ if (ProcessedSymbols.count(*Name))
+ return make_error<JITLinkError>("Duplicate definition within object: " +
+ *Name);
+ else
+ ProcessedSymbols.insert(*Name);
+
auto Addr = Sym.getAddress();
if (!Addr)
return Addr.takeError();
@@ -189,24 +227,35 @@ Error MachOAtomGraphBuilder::addNonCusto
auto &Sec = SecByIndexItr->second;
- auto &A = G->addDefinedAtom(Sec.getGenericSection(), *Name, *Addr,
- std::max(Sym.getAlignment(), 1U));
-
- A.setGlobal(Flags & object::SymbolRef::SF_Global);
- A.setExported(Flags & object::SymbolRef::SF_Exported);
- A.setWeak(Flags & object::SymbolRef::SF_Weak);
+ auto &DA = G->addDefinedAtom(Sec.getGenericSection(), *Name, *Addr,
+ std::max(Sym.getAlignment(), 1U));
- A.setCallable(*SymType & object::SymbolRef::ST_Function);
+ DA.setGlobal(Flags & object::SymbolRef::SF_Global);
+ DA.setExported(Flags & object::SymbolRef::SF_Exported);
+ DA.setWeak(Flags & object::SymbolRef::SF_Weak);
+
+ DA.setCallable(*SymType & object::SymbolRef::ST_Function);
+
+ // Check alt-entry.
+ {
+ uint16_t NDesc = 0;
+ if (Obj.is64Bit())
+ NDesc = Obj.getSymbolTableEntry(SymI->getRawDataRefImpl()).n_desc;
+ else
+ NDesc = Obj.getSymbolTableEntry(SymI->getRawDataRefImpl()).n_desc;
+ if (NDesc & MachO::N_ALT_ENTRY)
+ AltEntryAtoms.push_back(&DA);
+ }
LLVM_DEBUG({
dbgs() << " Added " << *Name
<< " addr: " << format("0x%016" PRIx64, *Addr)
- << ", align: " << A.getAlignment()
+ << ", align: " << DA.getAlignment()
<< ", section: " << Sec.getGenericSection().getName() << "\n";
});
auto &SecAtoms = SecToAtoms[&Sec];
- SecAtoms[A.getAddress() - Sec.getAddress()] = &A;
+ SecAtoms[DA.getAddress() - Sec.getAddress()] = &DA;
}
// Add anonymous atoms.
@@ -263,6 +312,50 @@ Error MachOAtomGraphBuilder::addNonCusto
}
}
+ LLVM_DEBUG(dbgs() << "Adding alt-entry starts\n");
+
+ // Sort alt-entry atoms by address in ascending order.
+ llvm::sort(AltEntryAtoms.begin(), AltEntryAtoms.end(),
+ [](const DefinedAtom *LHS, const DefinedAtom *RHS) {
+ return LHS->getAddress() < RHS->getAddress();
+ });
+
+ // Process alt-entry atoms in address order to build the table of alt-entry
+ // atoms to alt-entry chain starts.
+ for (auto *DA : AltEntryAtoms) {
+ assert(!AltEntryStarts.count(DA) && "Duplicate entry in AltEntryStarts");
+
+ // DA is an alt-entry atom. Look for the predecessor atom that it is locked
+ // to, bailing out if we do not find one.
+ auto AltEntryPred = G->findAtomByAddress(DA->getAddress() - 1);
+ if (!AltEntryPred)
+ return AltEntryPred.takeError();
+
+ // Add a LayoutNext edge from the predecessor to this atom.
+ AltEntryPred->setLayoutNext(*DA);
+
+ // Check to see whether the predecessor itself is an alt-entry atom.
+ auto AltEntryStartItr = AltEntryStarts.find(&*AltEntryPred);
+ if (AltEntryStartItr != AltEntryStarts.end()) {
+ // If the predecessor was an alt-entry atom then re-use its value.
+ AltEntryStarts[DA] = AltEntryStartItr->second;
+ LLVM_DEBUG({
+ dbgs() << " " << *DA << " -> " << *AltEntryStartItr->second
+ << " (based on existing entry for " << *AltEntryPred << ")\n";
+ });
+ } else {
+ // If the predecessor does not have an entry then add an entry for this
+ // atom (i.e. the alt_entry atom) and a self-reference entry for the
+ /// predecessory atom that is the start of this chain.
+ AltEntryStarts[&*AltEntryPred] = &*AltEntryPred;
+ AltEntryStarts[DA] = &*AltEntryPred;
+ LLVM_DEBUG({
+ dbgs() << " " << *AltEntryPred << " -> " << *AltEntryPred << "\n"
+ << " " << *DA << " -> " << *AltEntryPred << "\n";
+ });
+ }
+ }
+
return Error::success();
}
Modified: llvm/trunk/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.h?rev=360205&r1=360204&r2=360205&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.h (original)
+++ llvm/trunk/lib/ExecutionEngine/JITLink/MachOAtomGraphBuilder.h Tue May 7 15:56:40 2019
@@ -96,6 +96,10 @@ protected:
virtual Error addRelocations() = 0;
+ /// Returns true if Atom A and Atom B are at a fixed offset from one another
+ /// (i.e. if they're part of the same alt-entry chain).
+ bool areLayoutLocked(const Atom &A, const Atom &B);
+
private:
static unsigned getPointerSize(const object::MachOObjectFile &Obj);
static support::endianness getEndianness(const object::MachOObjectFile &Obj);
@@ -108,6 +112,7 @@ private:
const object::MachOObjectFile &Obj;
std::unique_ptr<AtomGraph> G;
+ DenseMap<const DefinedAtom *, const DefinedAtom *> AltEntryStarts;
DenseMap<unsigned, MachOSection> Sections;
StringMap<CustomAtomizeFunction> CustomAtomizeFunctions;
Optional<MachOSection> CommonSymbolsSection;
Modified: llvm/trunk/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp?rev=360205&r1=360204&r2=360205&view=diff
==============================================================================
--- llvm/trunk/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp Tue May 7 15:56:40 2019
@@ -181,19 +181,20 @@ private:
MachOX86RelocationKind DeltaKind;
Atom *TargetAtom;
uint64_t Addend;
- if (&AtomToFix == &*FromAtom) {
+ if (areLayoutLocked(AtomToFix, *FromAtom)) {
TargetAtom = ToAtom;
DeltaKind = (SubRI.r_length == 3) ? Delta64 : Delta32;
Addend = FixupValue + (FixupAddress - FromAtom->getAddress());
// FIXME: handle extern 'from'.
- } else if (&AtomToFix == ToAtom) {
+ } else if (areLayoutLocked(AtomToFix, *ToAtom)) {
TargetAtom = &*FromAtom;
DeltaKind = (SubRI.r_length == 3) ? NegDelta64 : NegDelta32;
Addend = FixupValue - (FixupAddress - ToAtom->getAddress());
} else {
// AtomToFix was neither FromAtom nor ToAtom.
return make_error<JITLinkError>("SUBTRACTOR relocation must fix up "
- "either 'A' or 'B'");
+ "either 'A' or 'B' (or an atom in one "
+ "of their alt-entry groups)");
}
return PairRelocInfo(DeltaKind, TargetAtom, Addend);
Modified: llvm/trunk/test/ExecutionEngine/JITLink/X86/MachO_x86-64_relocations.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/ExecutionEngine/JITLink/X86/MachO_x86-64_relocations.s?rev=360205&r1=360204&r2=360205&view=diff
==============================================================================
--- llvm/trunk/test/ExecutionEngine/JITLink/X86/MachO_x86-64_relocations.s (original)
+++ llvm/trunk/test/ExecutionEngine/JITLink/X86/MachO_x86-64_relocations.s Tue May 7 15:56:40 2019
@@ -129,13 +129,19 @@ Lanon_minuend_quad:
Lanon_minuend_long:
.long Lanon_minuend_long - named_data + 2
-
# Named quad storage target (first named atom in __data).
.globl named_data
.p2align 3
named_data:
.quad 0x2222222222222222
+# An alt-entry point for named_data
+ .globl named_data_alt_entry
+ .p2align 3
+ .alt_entry named_data_alt_entry
+named_data_alt_entry:
+ .quad 0
+
# Check X86_64_RELOC_UNSIGNED / extern handling by putting the address of a
# local named function in a pointer variable.
#
@@ -201,4 +207,60 @@ minuend_quad3:
minuend_long3:
.long minuend_long3 - named_data + 2
+# Check X86_64_RELOC_SUBTRACTOR handling for exprs of the form
+# "A: .quad/long B - C + D", where 'B' or 'C' is at a fixed offset from 'A'
+# (i.e. is part of an alt_entry chain that includes 'A').
+#
+# Check "A: .long B - C + D" where 'B' is an alt_entry for 'A'.
+# jitlink-check: *{4}subtractor_with_alt_entry_minuend_long = (subtractor_with_alt_entry_minuend_long_B - named_data + 2)[31:0]
+ .globl subtractor_with_alt_entry_minuend_long
+ .p2align 2
+subtractor_with_alt_entry_minuend_long:
+ .long subtractor_with_alt_entry_minuend_long_B - named_data + 2
+
+ .globl subtractor_with_alt_entry_minuend_long_B
+ .p2align 2
+ .alt_entry subtractor_with_alt_entry_minuend_long_B
+subtractor_with_alt_entry_minuend_long_B:
+ .long 0
+
+# Check "A: .quad B - C + D" where 'B' is an alt_entry for 'A'.
+# jitlink-check: *{8}subtractor_with_alt_entry_minuend_quad = (subtractor_with_alt_entry_minuend_quad_B - named_data + 2)
+ .globl subtractor_with_alt_entry_minuend_quad
+ .p2align 3
+subtractor_with_alt_entry_minuend_quad:
+ .quad subtractor_with_alt_entry_minuend_quad_B - named_data + 2
+
+ .globl subtractor_with_alt_entry_minuend_quad_B
+ .p2align 3
+ .alt_entry subtractor_with_alt_entry_minuend_quad_B
+subtractor_with_alt_entry_minuend_quad_B:
+ .quad 0
+
+# Check "A: .long B - C + D" where 'C' is an alt_entry for 'A'.
+# jitlink-check: *{4}subtractor_with_alt_entry_subtrahend_long = (named_data - subtractor_with_alt_entry_subtrahend_long_B + 2)[31:0]
+ .globl subtractor_with_alt_entry_subtrahend_long
+ .p2align 2
+subtractor_with_alt_entry_subtrahend_long:
+ .long named_data - subtractor_with_alt_entry_subtrahend_long_B + 2
+
+ .globl subtractor_with_alt_entry_subtrahend_long_B
+ .p2align 2
+ .alt_entry subtractor_with_alt_entry_subtrahend_long_B
+subtractor_with_alt_entry_subtrahend_long_B:
+ .long 0
+
+# Check "A: .quad B - C + D" where 'B' is an alt_entry for 'A'.
+# jitlink-check: *{8}subtractor_with_alt_entry_subtrahend_quad = (named_data - subtractor_with_alt_entry_subtrahend_quad_B + 2)
+ .globl subtractor_with_alt_entry_subtrahend_quad
+ .p2align 3
+subtractor_with_alt_entry_subtrahend_quad:
+ .quad named_data - subtractor_with_alt_entry_subtrahend_quad_B + 2
+
+ .globl subtractor_with_alt_entry_subtrahend_quad_B
+ .p2align 3
+ .alt_entry subtractor_with_alt_entry_subtrahend_quad_B
+subtractor_with_alt_entry_subtrahend_quad_B:
+ .quad 0
+
.subsections_via_symbols
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