Implement almost-zero-cost --trace-symbol.
--trace-symbol is a command line option to watch a symbol.
Previosly, we looked up a hash table for a new symbol if the
option is given. Any code that looks up a hash table for each
symbol is expensive because the linker handles a lot of symbols.
In our design, we look up a hash table strictly only once
for a symbol, so --trace-symbol was an exception.
This patch improves efficiency of the option by merging the
hash table into the symbol table.
Instead of looking up a separate hash table with a string,
this patch sets `Traced` flag to symbols specified by --trace-symbol.
So, if you insert a symbol and get a symbol with `Traced` flag on,
you know that you need to print out a log message for the symbol.
This is nearly zero cost.
llvm-svn: 275716
diff --git a/lld/ELF/Symbols.cpp b/lld/ELF/Symbols.cpp
index 724a922..4f95281 100644
--- a/lld/ELF/Symbols.cpp
+++ b/lld/ELF/Symbols.cpp
@@ -79,6 +79,7 @@
case SymbolBody::LazyObjectKind:
assert(Body.symbol()->IsUsedInRegularObj && "lazy symbol reached writer");
return 0;
+ case SymbolBody::PlaceholderKind:
case SymbolBody::DefinedBitcodeKind:
llvm_unreachable("should have been replaced");
}
@@ -270,6 +271,21 @@
return (ExportDynamic && VersionId != VER_NDX_LOCAL) || body()->isShared() ||
(body()->isUndefined() && Config->Shared);
}
+
+// Print out a log message for --trace-symbol.
+void elf::printTraceSymbol(Symbol *Sym) {
+ SymbolBody *B = Sym->body();
+ outs() << getFilename(B->File);
+
+ if (B->isUndefined())
+ outs() << ": reference to ";
+ else if (B->isCommon())
+ outs() << ": common definition of ";
+ else
+ outs() << ": definition of ";
+ outs() << B->getName() << "\n";
+}
+
template bool SymbolBody::hasThunk<ELF32LE>() const;
template bool SymbolBody::hasThunk<ELF32BE>() const;
template bool SymbolBody::hasThunk<ELF64LE>() const;
