[lld] r361206 - [COFF] Store alignment in log2 form, NFC
Reid Kleckner via llvm-commits
llvm-commits at lists.llvm.org
Mon May 20 15:57:52 PDT 2019
Author: rnk
Date: Mon May 20 15:57:52 2019
New Revision: 361206
URL: http://llvm.org/viewvc/llvm-project?rev=361206&view=rev
Log:
[COFF] Store alignment in log2 form, NFC
Summary:
Valid section or chunk alignments are powers of 2 in the range [1,
8192]. These can be stored more canonically in log2 form to free up some
bits in Chunk. Combined with D61696, SectionChunk gets 8 bytes smaller.
Reviewers: ruiu, aganea
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61698
Modified:
lld/trunk/COFF/Chunks.cpp
lld/trunk/COFF/Chunks.h
lld/trunk/COFF/DLL.cpp
lld/trunk/COFF/Driver.cpp
lld/trunk/COFF/ICF.cpp
lld/trunk/COFF/MapFile.cpp
lld/trunk/COFF/Writer.cpp
Modified: lld/trunk/COFF/Chunks.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Chunks.cpp?rev=361206&r1=361205&r2=361206&view=diff
==============================================================================
--- lld/trunk/COFF/Chunks.cpp (original)
+++ lld/trunk/COFF/Chunks.cpp Mon May 20 15:57:52 2019
@@ -41,7 +41,7 @@ SectionChunk::SectionChunk(ObjFile *F, c
SectionNameData = SectionName.data();
SectionNameSize = SectionName.size();
- Alignment = Header->getAlignment();
+ setAlignment(Header->getAlignment());
// If linker GC is disabled, every chunk starts out alive. If linker GC is
// enabled, treat non-comdat sections as roots. Generally optimized object
@@ -53,7 +53,7 @@ SectionChunk::SectionChunk(ObjFile *F, c
// SectionChunk is one of the most frequently allocated classes, so it is
// important to keep it as compact as possible. As of this writing, the number
// below is the size of this class on x64 platforms.
-static_assert(sizeof(SectionChunk) <= 112, "SectionChunk grew unexpectedly");
+static_assert(sizeof(SectionChunk) <= 104, "SectionChunk grew unexpectedly");
static void add16(uint8_t *P, int16_t V) { write16le(P, read16le(P) + V); }
static void add32(uint8_t *P, int32_t V) { write32le(P, read32le(P) + V); }
@@ -625,7 +625,7 @@ SectionChunk *SectionChunk::findByName(A
}
void SectionChunk::replace(SectionChunk *Other) {
- Alignment = std::max(Alignment, Other->Alignment);
+ P2Align = std::max(P2Align, Other->P2Align);
Other->Repl = Repl;
Other->Live = false;
}
@@ -640,7 +640,7 @@ uint32_t SectionChunk::getSectionNumber(
CommonChunk::CommonChunk(const COFFSymbolRef S) : Sym(S) {
// Common symbols are aligned on natural boundaries up to 32 bytes.
// This is what MSVC link.exe does.
- Alignment = std::min(uint64_t(32), PowerOf2Ceil(Sym.getValue()));
+ setAlignment(std::min(32U, Sym.getValue()));
}
uint32_t CommonChunk::getOutputCharacteristics() const {
@@ -656,7 +656,7 @@ void StringChunk::writeTo(uint8_t *Buf)
ImportThunkChunkX64::ImportThunkChunkX64(Defined *S) : ImpSymbol(S) {
// Intel Optimization Manual says that all branch targets
// should be 16-byte aligned. MSVC linker does this too.
- Alignment = 16;
+ setAlignment(16);
}
void ImportThunkChunkX64::writeTo(uint8_t *Buf) const {
@@ -854,17 +854,20 @@ uint8_t Baserel::getDefaultType() {
}
}
-std::map<uint32_t, MergeChunk *> MergeChunk::Instances;
+MergeChunk *MergeChunk::Instances[Log2MaxSectionAlignment + 1] = {};
MergeChunk::MergeChunk(uint32_t Alignment)
: Builder(StringTableBuilder::RAW, Alignment) {
- this->Alignment = Alignment;
+ setAlignment(Alignment);
}
void MergeChunk::addSection(SectionChunk *C) {
- auto *&MC = Instances[C->Alignment];
+ assert(isPowerOf2_32(C->getAlignment()));
+ uint8_t P2Align = llvm::Log2_32(C->getAlignment());
+ assert(P2Align >= 0 && P2Align < array_lengthof(Instances));
+ auto *&MC = Instances[P2Align];
if (!MC)
- MC = make<MergeChunk>(C->Alignment);
+ MC = make<MergeChunk>(C->getAlignment());
MC->Sections.push_back(C);
}
Modified: lld/trunk/COFF/Chunks.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Chunks.h?rev=361206&r1=361205&r2=361206&view=diff
==============================================================================
--- lld/trunk/COFF/Chunks.h (original)
+++ lld/trunk/COFF/Chunks.h Mon May 20 15:57:52 2019
@@ -44,6 +44,9 @@ const uint32_t PermMask = 0xFE000000;
// Mask for section types (code, data, bss).
const uint32_t TypeMask = 0x000000E0;
+// The log base 2 of the largest section alignment, which is log2(8192), or 13.
+enum : unsigned { Log2MaxSectionAlignment = 13 };
+
// A Chunk represents a chunk of data that will occupy space in the
// output (if the resolver chose that). It may or may not be backed by
// a section of an input file. It could be linker-created data, or
@@ -57,6 +60,18 @@ public:
// Returns the size of this chunk (even if this is a common or BSS.)
virtual size_t getSize() const = 0;
+ // Returns chunk alignment in power of two form. Value values are powers of
+ // two from 1 to 8192.
+ uint32_t getAlignment() const { return 1U << P2Align; }
+ void setAlignment(uint32_t Align) {
+ // Treat zero byte alignment as 1 byte alignment.
+ Align = Align ? Align : 1;
+ assert(llvm::isPowerOf2_32(Align) && "alignment is not a power of 2");
+ P2Align = llvm::Log2_32(Align);
+ assert(P2Align <= Log2MaxSectionAlignment &&
+ "impossible requested alignment");
+ }
+
// Write this chunk to a mmap'ed file, assuming Buf is pointing to
// beginning of the file. Because this function may use RVA values
// of other chunks for relocations, you need to set them properly
@@ -103,9 +118,6 @@ public:
// bytes, so this is used only for logging or debugging.
virtual StringRef getDebugName() { return ""; }
- // The alignment of this chunk. The writer uses the value.
- uint32_t Alignment = 1;
-
virtual bool isHotPatchable() const { return false; }
protected:
@@ -118,6 +130,10 @@ public:
bool KeepUnique = false;
protected:
+ // The alignment of this chunk, stored in log2 form. The writer uses the
+ // value.
+ uint8_t P2Align = 0;
+
// The RVA of this chunk in the output. The writer sets a value.
uint32_t RVA = 0;
@@ -313,7 +329,7 @@ public:
size_t getSize() const override;
void writeTo(uint8_t *Buf) const override;
- static std::map<uint32_t, MergeChunk *> Instances;
+ static MergeChunk *Instances[Log2MaxSectionAlignment + 1];
std::vector<SectionChunk *> Sections;
private:
@@ -437,7 +453,7 @@ public:
class LocalImportChunk : public Chunk {
public:
explicit LocalImportChunk(Defined *S) : Sym(S) {
- Alignment = Config->Wordsize;
+ setAlignment(Config->Wordsize);
}
size_t getSize() const override;
void getBaserels(std::vector<Baserel> *Res) override;
@@ -528,7 +544,7 @@ class PseudoRelocTableChunk : public Chu
public:
PseudoRelocTableChunk(std::vector<RuntimePseudoReloc> &Relocs)
: Relocs(std::move(Relocs)) {
- Alignment = 4;
+ setAlignment(4);
}
size_t getSize() const override;
void writeTo(uint8_t *Buf) const override;
@@ -558,7 +574,7 @@ public:
class AbsolutePointerChunk : public Chunk {
public:
AbsolutePointerChunk(uint64_t Value) : Value(Value) {
- Alignment = getSize();
+ setAlignment(getSize());
}
size_t getSize() const override;
void writeTo(uint8_t *Buf) const override;
Modified: lld/trunk/COFF/DLL.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/DLL.cpp?rev=361206&r1=361205&r2=361206&view=diff
==============================================================================
--- lld/trunk/COFF/DLL.cpp (original)
+++ lld/trunk/COFF/DLL.cpp Mon May 20 15:57:52 2019
@@ -59,7 +59,9 @@ private:
// A chunk for the import descriptor table.
class LookupChunk : public Chunk {
public:
- explicit LookupChunk(Chunk *C) : HintName(C) { Alignment = Config->Wordsize; }
+ explicit LookupChunk(Chunk *C) : HintName(C) {
+ setAlignment(Config->Wordsize);
+ }
size_t getSize() const override { return Config->Wordsize; }
void writeTo(uint8_t *Buf) const override {
@@ -78,7 +80,7 @@ public:
class OrdinalOnlyChunk : public Chunk {
public:
explicit OrdinalOnlyChunk(uint16_t V) : Ordinal(V) {
- Alignment = Config->Wordsize;
+ setAlignment(Config->Wordsize);
}
size_t getSize() const override { return Config->Wordsize; }
@@ -364,7 +366,7 @@ public:
class DelayAddressChunk : public Chunk {
public:
explicit DelayAddressChunk(Chunk *C) : Thunk(C) {
- Alignment = Config->Wordsize;
+ setAlignment(Config->Wordsize);
}
size_t getSize() const override { return Config->Wordsize; }
@@ -576,7 +578,7 @@ void DelayLoadContents::create(Defined *
for (int I = 0, E = Syms.size(); I < E; ++I)
Syms[I]->setLocation(Addresses[Base + I]);
auto *MH = make<NullChunk>(8);
- MH->Alignment = 8;
+ MH->setAlignment(8);
ModuleHandles.push_back(MH);
// Fill the delay import table header fields.
Modified: lld/trunk/COFF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Driver.cpp?rev=361206&r1=361205&r2=361206&view=diff
==============================================================================
--- lld/trunk/COFF/Driver.cpp (original)
+++ lld/trunk/COFF/Driver.cpp Mon May 20 15:57:52 2019
@@ -1743,7 +1743,7 @@ void LinkerDriver::link(ArrayRef<const c
continue;
CommonChunk *C = DC->getChunk();
- C->Alignment = std::max(C->Alignment, Alignment);
+ C->setAlignment(std::max(C->getAlignment(), Alignment));
}
// Windows specific -- Create a side-by-side manifest file.
Modified: lld/trunk/COFF/ICF.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/ICF.cpp?rev=361206&r1=361205&r2=361206&view=diff
==============================================================================
--- lld/trunk/COFF/ICF.cpp (original)
+++ lld/trunk/COFF/ICF.cpp Mon May 20 15:57:52 2019
@@ -256,9 +256,10 @@ void ICF::run(ArrayRef<Chunk *> Vec) {
// Make sure that ICF doesn't merge sections that are being handled by string
// tail merging.
- for (auto &P : MergeChunk::Instances)
- for (SectionChunk *SC : P.second->Sections)
- SC->Class[0] = NextId++;
+ for (MergeChunk *MC : MergeChunk::Instances)
+ if (MC)
+ for (SectionChunk *SC : MC->Sections)
+ SC->Class[0] = NextId++;
// Initially, we use hash values to partition sections.
parallelForEach(Chunks, [&](SectionChunk *SC) {
Modified: lld/trunk/COFF/MapFile.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/MapFile.cpp?rev=361206&r1=361205&r2=361206&view=diff
==============================================================================
--- lld/trunk/COFF/MapFile.cpp (original)
+++ lld/trunk/COFF/MapFile.cpp Mon May 20 15:57:52 2019
@@ -114,7 +114,7 @@ void coff::writeMapFile(ArrayRef<OutputS
if (!SC)
continue;
- writeHeader(OS, SC->getRVA(), SC->getSize(), SC->Alignment);
+ writeHeader(OS, SC->getRVA(), SC->getSize(), SC->getAlignment());
OS << Indent8 << SC->File->getName() << ":(" << SC->getSectionName()
<< ")\n";
for (DefinedRegular *Sym : SectionSyms[SC])
Modified: lld/trunk/COFF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Writer.cpp?rev=361206&r1=361205&r2=361206&view=diff
==============================================================================
--- lld/trunk/COFF/Writer.cpp (original)
+++ lld/trunk/COFF/Writer.cpp Mon May 20 15:57:52 2019
@@ -865,8 +865,9 @@ void Writer::createSections() {
}
void Writer::createMiscChunks() {
- for (auto &P : MergeChunk::Instances)
- RdataSec->addChunk(P.second);
+ for (MergeChunk *P : MergeChunk::Instances)
+ if (P)
+ RdataSec->addChunk(P);
// Create thunks for locally-dllimported symbols.
if (!Symtab->LocalImportChunks.empty()) {
@@ -1159,7 +1160,7 @@ void Writer::assignAddresses() {
for (Chunk *C : Sec->Chunks) {
if (Padding && C->isHotPatchable())
VirtualSize += Padding;
- VirtualSize = alignTo(VirtualSize, C->Alignment);
+ VirtualSize = alignTo(VirtualSize, C->getAlignment());
C->setRVA(RVA + VirtualSize);
C->finalizeContents();
VirtualSize += C->getSize();
@@ -1519,8 +1520,8 @@ void Writer::createGuardCFTables() {
// Ensure sections referenced in the gfid table are 16-byte aligned.
for (const ChunkAndOffset &C : AddressTakenSyms)
- if (C.InputChunk->Alignment < 16)
- C.InputChunk->Alignment = 16;
+ if (C.InputChunk->getAlignment() < 16)
+ C.InputChunk->setAlignment(16);
maybeAddRVATable(std::move(AddressTakenSyms), "__guard_fids_table",
"__guard_fids_count");
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