[lld] e1adf90 - [LLD] [COFF] Avoid doing repeated fuzzy symbol lookup for each iteration. NFC.

[Martin Storsjö via llvm-commits]

Author: Martin Storsjö
Date: 2021-06-19T22:32:37+03:00
New Revision: e1adf90826a57b674eee79b071fb46c1f5683cd0

URL: https://github.com/llvm/llvm-project/commit/e1adf90826a57b674eee79b071fb46c1f5683cd0
DIFF: https://github.com/llvm/llvm-project/commit/e1adf90826a57b674eee79b071fb46c1f5683cd0.diff

LOG: [LLD] [COFF] Avoid doing repeated fuzzy symbol lookup for each iteration. NFC.

This is run every time around in the main linker loop. Once a match
has been found, stop trying to rematch such a symbol.

Not sure if this has any actual measurable performance impact though
(SymbolTable::findMangle() iterates over the whole symbol table for
each call and does fuzzy matching on top of that) but this makes the
code more reassuring to read at least. (This is in practice run for def
files listing undecorated stdcall functions to be exported.)

Differential Revision: https://reviews.llvm.org/D104529

Added: 
    

Modified: 
    lld/COFF/Driver.cpp

Removed: 
    


################################################################################
diff  --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 97b3c9029e34f..5eab3fbbde069 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -549,7 +549,7 @@ Symbol *LinkerDriver::addUndefined(StringRef name) {
 StringRef LinkerDriver::mangleMaybe(Symbol *s) {
   // If the plain symbol name has already been resolved, do nothing.
   Undefined *unmangled = dyn_cast<Undefined>(s);
-  if (!unmangled)
+  if (!unmangled || unmangled->getWeakAlias())
     return "";
 
   // Otherwise, see if a similar, mangled symbol exists in the symbol table.