[LLD][COFF] Move resolving alternate names to SymbolTable (NFC)#149495

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[LLD][COFF] Move resolving alternate names to SymbolTable (NFC)#149495

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cjacek commentedJul 18, 2025

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[LLD][COFF] Move resolving alternate names to SymbolTable (NFC)

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cjacek requested a review frommstorsjo

July 18, 2025 11:09

llvmbot added lld lld:COFF platform:windows labels

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llvmbot commentedJul 18, 2025•
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@llvm/pr-subscribers-platform-windows

@llvm/pr-subscribers-lld

Author: Jacek Caban (cjacek)

Changes

Full diff:https://github.com/llvm/llvm-project/pull/149495.diff

3 Files Affected:

(modified) lld/COFF/Driver.cpp (+1-22)
(modified) lld/COFF/SymbolTable.cpp (+25)
(modified) lld/COFF/SymbolTable.h (+3)

diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cppindex 283aeed1a19cd..f31cf0a42abbb 100644--- a/lld/COFF/Driver.cpp+++ b/lld/COFF/Driver.cpp@@ -2527,28 +2527,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {             e.symbolName = symtab.mangleMaybe(e.sym);         }-        // Add weak aliases. Weak aliases is a mechanism to give remaining-        // undefined symbols final chance to be resolved successfully.-        for (auto pair : symtab.alternateNames) {-          StringRef from = pair.first;-          StringRef to = pair.second;-          Symbol *sym = symtab.find(from);-          if (!sym)-            continue;-          if (auto *u = dyn_cast<Undefined>(sym)) {-            if (u->weakAlias) {-              // On ARM64EC, anti-dependency aliases are treated as undefined-              // symbols unless a demangled symbol aliases a defined one, which-              // is part of the implementation.-              if (!symtab.isEC() || !u->isAntiDep)-                continue;-              if (!isa<Undefined>(u->weakAlias) &&-                  !isArm64ECMangledFunctionName(u->getName()))-                continue;-            }-            u->setWeakAlias(symtab.addUndefined(to));-          }-        }+        symtab.resolveAlternateNames();       });        ctx.forEachActiveSymtab([&](SymbolTable &symtab) {diff --git a/lld/COFF/SymbolTable.cpp b/lld/COFF/SymbolTable.cppindex 0062df5820e63..1cf750393e6b3 100644--- a/lld/COFF/SymbolTable.cpp+++ b/lld/COFF/SymbolTable.cpp@@ -1344,6 +1344,31 @@ void SymbolTable::parseAlternateName(StringRef s) {   alternateNames.insert(it, std::make_pair(from, to)); }+void SymbolTable::resolveAlternateNames() {+  // Add weak aliases. Weak aliases is a mechanism to give remaining+  // undefined symbols final chance to be resolved successfully.+  for (auto pair : alternateNames) {+    StringRef from = pair.first;+    StringRef to = pair.second;+    Symbol *sym = find(from);+    if (!sym)+      continue;+    if (auto *u = dyn_cast<Undefined>(sym)) {+      if (u->weakAlias) {+        // On ARM64EC, anti-dependency aliases are treated as undefined+        // symbols unless a demangled symbol aliases a defined one, which+        // is part of the implementation.+        if (!isEC() || !u->isAntiDep)+          continue;+        if (!isa<Undefined>(u->weakAlias) &&+            !isArm64ECMangledFunctionName(u->getName()))+          continue;+      }+      u->setWeakAlias(addUndefined(to));+    }+  }+}+ // Parses /aligncomm option argument. void SymbolTable::parseAligncomm(StringRef s) {   auto [name, align] = s.split(',');diff --git a/lld/COFF/SymbolTable.h b/lld/COFF/SymbolTable.hindex 15e2644a6f519..7eb067640dc85 100644--- a/lld/COFF/SymbolTable.h+++ b/lld/COFF/SymbolTable.h@@ -69,6 +69,9 @@ class SymbolTable {   // symbols and warn about imported local symbols.   void resolveRemainingUndefines();+  // Try to resolve undefined symbols with alternate names.+  void resolveAlternateNames();+   // Load lazy objects that are needed for MinGW automatic import and for   // doing stdcall fixups.   void loadMinGWSymbols();