[PATCH] D49138: [LTO] Handle __imp_ (dllimport) symbols consistently with lld

[Teresa Johnson via Phabricator via llvm-commits]

tejohnson created this revision.
tejohnson added a reviewer: pcc.
Herald added subscribers: dexonsmith, steven_wu, inglorion, mehdi_amini.

Similar to what lld already does for dllimport symbols which are
prefaced with __imp_ (see lld patch r240620), strip off the __imp_
prefix in LTO. Otherwise we can get 2 separate GlobalResolution for
a single symbol, the dllimport declaration, and the definition, which
leads to incorrect LTO handling.

Tests coming in separate tools/lld patch.

Fixes PR38105.


Repository:
  rL LLVM

https://reviews.llvm.org/D49138

Files:
  lib/LTO/LTO.cpp


Index: lib/LTO/LTO.cpp
===================================================================
--- lib/LTO/LTO.cpp
+++ lib/LTO/LTO.cpp
@@ -428,7 +428,10 @@
     assert(ResI != ResE);
     SymbolResolution Res = *ResI++;
 
-    auto &GlobalRes = GlobalResolutions[Sym.getName()];
+    StringRef Name = Sym.getName();
+    if (Name.startswith("__imp_"))
+      Name = Name.substr(strlen("__imp_"));
+    auto &GlobalRes = GlobalResolutions[Name];
     GlobalRes.UnnamedAddr &= Sym.isUnnamedAddr();
     if (Res.Prevailing) {
       assert(!GlobalRes.Prevailing &&


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