[lld] 3e95180 - [lld-macho][nfc] Comments and style fixes
Jez Ng via llvm-commits
llvm-commits at lists.llvm.org
Tue Feb 1 10:46:05 PST 2022
Author: Jez Ng
Date: 2022-02-01T13:45:59-05:00
New Revision: 3e951808d53895a376a71e5cb0d36bc836bbfc8d
URL: https://github.com/llvm/llvm-project/commit/3e951808d53895a376a71e5cb0d36bc836bbfc8d
DIFF: https://github.com/llvm/llvm-project/commit/3e951808d53895a376a71e5cb0d36bc836bbfc8d.diff
LOG: [lld-macho][nfc] Comments and style fixes
Added some comments (particularly around finalize() and
finalizeContents()) as well as doing some rephrasing / grammar fixes for
existing comments.
Also did some minor style fixups, such as by putting methods together in
a class definition and having fields of similar types next to each
other.
Reviewed By: #lld-macho, oontvoo
Differential Revision: https://reviews.llvm.org/D118714
Added:
Modified:
lld/MachO/Driver.h
lld/MachO/InputFiles.h
lld/MachO/OutputSection.h
lld/MachO/SyntheticSections.h
lld/MachO/UnwindInfoSection.cpp
lld/MachO/Writer.cpp
Removed:
################################################################################
diff --git a/lld/MachO/Driver.h b/lld/MachO/Driver.h
index c2933344e6118..dbfc05a0497cf 100644
--- a/lld/MachO/Driver.h
+++ b/lld/MachO/Driver.h
@@ -81,9 +81,8 @@ class DependencyTracker {
notFounds.insert(path.str());
}
- // Writes the dependencies to specified path.
- // The content is sorted by its Op Code, then within each section,
- // alphabetical order.
+ // Writes the dependencies to specified path. The content is first sorted by
+ // OpCode and then by the filename (in alphabetical order).
void write(llvm::StringRef version,
const llvm::SetVector<InputFile *> &inputs,
llvm::StringRef output);
diff --git a/lld/MachO/InputFiles.h b/lld/MachO/InputFiles.h
index 6a4a4fdb43b6d..0b661c828c7c9 100644
--- a/lld/MachO/InputFiles.h
+++ b/lld/MachO/InputFiles.h
@@ -177,6 +177,7 @@ class DylibFile final : public InputFile {
void parseLoadCommands(MemoryBufferRef mb);
void parseReexports(const llvm::MachO::InterfaceFile &interface);
+ bool isReferenced() const { return numReferencedSymbols > 0; }
static bool classof(const InputFile *f) { return f->kind() == DylibKind; }
@@ -187,21 +188,17 @@ class DylibFile final : public InputFile {
uint32_t compatibilityVersion = 0;
uint32_t currentVersion = 0;
int64_t ordinal = 0; // Ordinal numbering starts from 1, so 0 is a sentinel
+ unsigned numReferencedSymbols = 0;
RefState refState;
bool reexport = false;
bool forceNeeded = false;
bool forceWeakImport = false;
bool deadStrippable = false;
bool explicitlyLinked = false;
-
- unsigned numReferencedSymbols = 0;
-
- bool isReferenced() const { return numReferencedSymbols > 0; }
-
// An executable can be used as a bundle loader that will load the output
// file being linked, and that contains symbols referenced, but not
// implemented in the bundle. When used like this, it is very similar
- // to a Dylib, so we re-used the same class to represent it.
+ // to a dylib, so we've used the same class to represent it.
bool isBundleLoader;
private:
diff --git a/lld/MachO/OutputSection.h b/lld/MachO/OutputSection.h
index eb554854cc893..51f39dd3498de 100644
--- a/lld/MachO/OutputSection.h
+++ b/lld/MachO/OutputSection.h
@@ -58,13 +58,23 @@ class OutputSection {
// Unneeded sections are omitted entirely (header and body).
virtual bool isNeeded() const { return true; }
- virtual void finalize() {
- // TODO investigate refactoring synthetic section finalization logic into
- // overrides of this function.
- }
+ // The implementations of this method can assume that it is only called right
+ // before addresses get assigned to this particular OutputSection. In
+ // particular, this means that it gets called only after addresses have been
+ // assigned to output sections that occur earlier in the output binary.
+ // Naturally, this means
diff erent sections' finalize() methods cannot execute
+ // concurrently with each other. As such, avoid using this method for
+ // operations that do not require this strict sequential guarantee.
+ //
+ // Operations that need to occur late in the linking process, but which do not
+ // need the sequential guarantee, should be named `finalizeContents()`. See
+ // e.g. LinkEditSection::finalizeContents() and
+ // CStringSection::finalizeContents().
+ virtual void finalize() {}
virtual void writeTo(uint8_t *buf) const = 0;
+ // Handle section$start$ and section$end$ symbols.
void assignAddressesToStartEndSymbols();
StringRef name;
diff --git a/lld/MachO/SyntheticSections.h b/lld/MachO/SyntheticSections.h
index 49b68c77672e8..12e422b5c5d86 100644
--- a/lld/MachO/SyntheticSections.h
+++ b/lld/MachO/SyntheticSections.h
@@ -62,6 +62,8 @@ class LinkEditSection : public SyntheticSection {
align = target->wordSize;
}
+ // Implementations of this method can assume that the regular (non-__LINKEDIT)
+ // sections already have their addresses assigned.
virtual void finalizeContents() {}
// Sections in __LINKEDIT are special: their offsets are recorded in the
diff --git a/lld/MachO/UnwindInfoSection.cpp b/lld/MachO/UnwindInfoSection.cpp
index 49af2f6ad9a81..8b1e357499aad 100644
--- a/lld/MachO/UnwindInfoSection.cpp
+++ b/lld/MachO/UnwindInfoSection.cpp
@@ -392,7 +392,7 @@ UnwindInfoSectionImpl<Ptr>::findLsdaReloc(ConcatInputSection *isec) const {
}
// Scan the __LD,__compact_unwind entries and compute the space needs of
-// __TEXT,__unwind_info and __TEXT,__eh_frame
+// __TEXT,__unwind_info and __TEXT,__eh_frame.
template <class Ptr> void UnwindInfoSectionImpl<Ptr>::finalize() {
if (symbols.empty())
return;
diff --git a/lld/MachO/Writer.cpp b/lld/MachO/Writer.cpp
index 2c0794e08ae3e..851cb3db3859a 100644
--- a/lld/MachO/Writer.cpp
+++ b/lld/MachO/Writer.cpp
@@ -1108,8 +1108,10 @@ template <class LP> void Writer::run() {
treatSpecialUndefineds();
if (config->entry && !isa<Undefined>(config->entry))
prepareBranchTarget(config->entry);
+
// Canonicalization of all pointers to InputSections should be handled by
- // these two methods.
+ // these two scan* methods. I.e. from this point onward, for all live
+ // InputSections, we should have `isec->canonical() == isec`.
scanSymbols();
scanRelocations();
@@ -1119,6 +1121,8 @@ template <class LP> void Writer::run() {
if (in.stubHelper->isNeeded())
in.stubHelper->setup();
+ // At this point, we should know exactly which output sections are needed,
+ // courtesy of scanSymbols() and scanRelocations().
createOutputSections<LP>();
// After this point, we create no new segments; HOWEVER, we might
@@ -1146,11 +1150,10 @@ void macho::resetWriter() { LCDylib::resetInstanceCount(); }
void macho::createSyntheticSections() {
in.header = make<MachHeaderSection>();
- if (config->dedupLiterals) {
+ if (config->dedupLiterals)
in.cStringSection = make<DeduplicatedCStringSection>();
- } else {
+ else
in.cStringSection = make<CStringSection>();
- }
in.wordLiteralSection =
config->dedupLiterals ? make<WordLiteralSection>() : nullptr;
in.rebase = make<RebaseSection>();
More information about the llvm-commits
mailing list