[lld] [ELF] Merge verdefIndex into versionId. NFC (PR #72208)
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Mon Nov 13 21:16:31 PST 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lld
Author: Fangrui Song (MaskRay)
<details>
<summary>Changes</summary>
The two fields are similar.
`versionId` is the Verdef index in the output file. It is set for
version script patterns and `sym@<!-- -->ver` symbols.
`verdefIndex` is the Verdef index of a SharedSymbol. The default value
-1 is also used to indicate that the symbol has not been matched by a
version script pattern (https://reviews.llvm.org/D65716).
It seems confusing to have two fields. Merge them so that we can
allocate one bit for #<!-- -->70130 (suppress --no-allow-shlib-undefined
error in the presence of a DSO definition).
---
Full diff: https://github.com/llvm/llvm-project/pull/72208.diff
5 Files Affected:
- (modified) lld/ELF/InputFiles.cpp (+2-2)
- (modified) lld/ELF/Relocations.cpp (-1)
- (modified) lld/ELF/SymbolTable.cpp (+5-7)
- (modified) lld/ELF/Symbols.h (+5-5)
- (modified) lld/ELF/SyntheticSections.cpp (+4-6)
``````````diff
diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index 8c7f2c8773f2cbc..4b4d7d6db93cd57 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -1546,7 +1546,7 @@ template <class ELFT> void SharedFile::parse() {
SharedSymbol{*this, name, sym.getBinding(), sym.st_other,
sym.getType(), sym.st_value, sym.st_size, alignment});
if (s->file == this)
- s->verdefIndex = ver;
+ s->versionId = ver;
}
// Also add the symbol with the versioned name to handle undefined symbols
@@ -1563,7 +1563,7 @@ template <class ELFT> void SharedFile::parse() {
SharedSymbol{*this, saver().save(name), sym.getBinding(), sym.st_other,
sym.getType(), sym.st_value, sym.st_size, alignment});
if (s->file == this)
- s->verdefIndex = idx;
+ s->versionId = idx;
}
}
diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index 6765461805dadb0..d4685ce70ece8cb 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -309,7 +309,6 @@ static void replaceWithDefined(Symbol &sym, SectionBase &sec, uint64_t value,
size, &sec)
.overwrite(sym);
- sym.verdefIndex = old.verdefIndex;
sym.exportDynamic = true;
sym.isUsedInRegularObj = true;
// A copy relocated alias may need a GOT entry.
diff --git a/lld/ELF/SymbolTable.cpp b/lld/ELF/SymbolTable.cpp
index fe7edd5b0eb49aa..b3d97e4de779068 100644
--- a/lld/ELF/SymbolTable.cpp
+++ b/lld/ELF/SymbolTable.cpp
@@ -92,7 +92,6 @@ Symbol *SymbolTable::insert(StringRef name) {
memset(sym, 0, sizeof(Symbol));
sym->setName(name);
sym->partition = 1;
- sym->verdefIndex = -1;
sym->versionId = VER_NDX_GLOBAL;
if (pos != StringRef::npos)
sym->hasVersionSuffix = true;
@@ -235,10 +234,9 @@ bool SymbolTable::assignExactVersion(SymbolVersion ver, uint16_t versionId,
sym->getName().contains('@'))
continue;
- // If the version has not been assigned, verdefIndex is -1. Use an arbitrary
- // number (0) to indicate the version has been assigned.
- if (sym->verdefIndex == uint16_t(-1)) {
- sym->verdefIndex = 0;
+ // If the version has not been assigned, assign versionId to the symbol.
+ if (!sym->versionScriptAssigned) {
+ sym->versionScriptAssigned = true;
sym->versionId = versionId;
}
if (sym->versionId == versionId)
@@ -256,8 +254,8 @@ void SymbolTable::assignWildcardVersion(SymbolVersion ver, uint16_t versionId,
// so we set a version to a symbol only if no version has been assigned
// to the symbol. This behavior is compatible with GNU.
for (Symbol *sym : findAllByVersion(ver, includeNonDefault))
- if (sym->verdefIndex == uint16_t(-1)) {
- sym->verdefIndex = 0;
+ if (!sym->versionScriptAssigned) {
+ sym->versionScriptAssigned = true;
sym->versionId = versionId;
}
}
diff --git a/lld/ELF/Symbols.h b/lld/ELF/Symbols.h
index 4addb79d1257914..0c79efccb548680 100644
--- a/lld/ELF/Symbols.h
+++ b/lld/ELF/Symbols.h
@@ -313,11 +313,12 @@ class Symbol {
uint32_t auxIdx;
uint32_t dynsymIndex;
- // This field is a index to the symbol's version definition.
- uint16_t verdefIndex;
-
- // Version definition index.
+ // For a Defined symbol, this represents the Verdef index (VER_NDX_LOCAL,
+ // VER_NDX_GLOBAL, or a named version). For a SharedSymbol, this represents
+ // the Verdef index within the input DSO, which will be converted to a Verneed
+ // index in the output.
uint16_t versionId;
+ uint8_t versionScriptAssigned : 1;
void setFlags(uint16_t bits) {
flags.fetch_or(bits, std::memory_order_relaxed);
@@ -357,7 +358,6 @@ class Defined : public Symbol {
}
void overwrite(Symbol &sym) const {
Symbol::overwrite(sym, DefinedKind);
- sym.verdefIndex = -1;
auto &s = static_cast<Defined &>(sym);
s.value = value;
s.size = size;
diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index 0f7ebf9d7ba840b..2b32eb3a0fe3558 100644
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -3140,10 +3140,8 @@ bool VersionTableSection::isNeeded() const {
void elf::addVerneed(Symbol *ss) {
auto &file = cast<SharedFile>(*ss->file);
- if (ss->verdefIndex == VER_NDX_GLOBAL) {
- ss->versionId = VER_NDX_GLOBAL;
+ if (ss->versionId == VER_NDX_GLOBAL)
return;
- }
if (file.vernauxs.empty())
file.vernauxs.resize(file.verdefs.size());
@@ -3152,10 +3150,10 @@ void elf::addVerneed(Symbol *ss) {
// already allocated one. The verdef identifiers cover the range
// [1..getVerDefNum()]; this causes the vernaux identifiers to start from
// getVerDefNum()+1.
- if (file.vernauxs[ss->verdefIndex] == 0)
- file.vernauxs[ss->verdefIndex] = ++SharedFile::vernauxNum + getVerDefNum();
+ if (file.vernauxs[ss->versionId] == 0)
+ file.vernauxs[ss->versionId] = ++SharedFile::vernauxNum + getVerDefNum();
- ss->versionId = file.vernauxs[ss->verdefIndex];
+ ss->versionId = file.vernauxs[ss->versionId];
}
template <class ELFT>
``````````
</details>
https://github.com/llvm/llvm-project/pull/72208
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