[PATCH] D113365: [LLD][COFF] Support GNU style == aliases

[Ayke via Phabricator via llvm-commits]

aykevl created this revision.
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D46245 <https://reviews.llvm.org/D46245> added support for this in `llvm-libtool`, but while `lld-link` can also create .lib files from .def files it didn't support aliases.

I compared the Inputs/library.def test against the output from `llvm-libtool` and it matches, except for the fact that `lld-link` reorders functions for some reason.

I have also verified that this fixes a bug I was running into while trying to compile .def files to .lib files in MinGW-w64 (using `lld-link` instead of `llvm-libtool`).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D113365

Files:
  lld/COFF/Config.h
  lld/COFF/Driver.cpp
  lld/test/COFF/Inputs/library.def
  lld/test/COFF/lib.test


Index: lld/test/COFF/lib.test
===================================================================
--- lld/test/COFF/lib.test
+++ lld/test/COFF/lib.test
@@ -1,6 +1,16 @@
 # RUN: lld-link /machine:x64 /def:%S/Inputs/library.def /out:%t.lib
 # RUN: llvm-nm %t.lib | FileCheck %s
 
+CHECK: 00000000 a @comp.id
+CHECK: 00000000 a @feat.00
+CHECK: 00000000 W alias
+CHECK:          U function
+
+CHECK: 00000000 a @comp.id
+CHECK: 00000000 a @feat.00
+CHECK: 00000000 W __imp_alias
+CHECK:          U __imp_function
+
 CHECK: 00000000 R __imp_constant
 CHECK: 00000000 R constant
 
Index: lld/test/COFF/Inputs/library.def
===================================================================
--- lld/test/COFF/Inputs/library.def
+++ lld/test/COFF/Inputs/library.def
@@ -1,5 +1,6 @@
 LIBRARY library
 EXPORTS
   function
+  alias == function
   data DATA
   constant CONSTANT
Index: lld/COFF/Driver.cpp
===================================================================
--- lld/COFF/Driver.cpp
+++ lld/COFF/Driver.cpp
@@ -815,6 +815,7 @@
     e2.Name = std::string(e1.name);
     e2.SymbolName = std::string(e1.symbolName);
     e2.ExtName = std::string(e1.extName);
+    e2.AliasTarget = std::string(e1.aliasTarget);
     e2.Ordinal = e1.ordinal;
     e2.Noname = e1.noname;
     e2.Data = e1.data;
@@ -913,6 +914,7 @@
     }
     e2.name = saver.save(e1.Name);
     e2.extName = saver.save(e1.ExtName);
+    e2.aliasTarget = saver.save(e1.AliasTarget);
     e2.ordinal = e1.Ordinal;
     e2.noname = e1.Noname;
     e2.data = e1.Data;
Index: lld/COFF/Config.h
===================================================================
--- lld/COFF/Config.h
+++ lld/COFF/Config.h
@@ -43,6 +43,7 @@
 struct Export {
   StringRef name;       // N in /export:N or /export:E=N
   StringRef extName;    // E in /export:E=N
+  StringRef aliasTarget; // GNU specific: N in "alias == N"
   Symbol *sym = nullptr;
   uint16_t ordinal = 0;
   bool noname = false;
@@ -63,6 +64,7 @@
 
   bool operator==(const Export &e) {
     return (name == e.name && extName == e.extName &&
+            aliasTarget == e.aliasTarget &&
             ordinal == e.ordinal && noname == e.noname &&
             data == e.data && isPrivate == e.isPrivate);
   }


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