[COFF] Keep the underscore on exported decorated stdcall functions in MSVC mode

This fixes PR35733.

Differential Revision: https://reviews.llvm.org/D41632

llvm-svn: 323036

4 files changed, 13 insertions, 11 deletions

diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 8f79a7b18ae..58058106797 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -540,7 +540,7 @@ static void createImportLibrary(bool AsLib) {
   }
 
   auto E = writeImportLibrary(getImportName(AsLib), getImplibPath(), Exports,
-                              Config->Machine, false);
+                              Config->Machine, false, Config->MinGW);
   handleAllErrors(std::move(E),
                   [&](ErrorInfoBase &EIB) { error(EIB.message()); });
 }
diff --git a/lld/COFF/DriverUtils.cpp b/lld/COFF/DriverUtils.cpp
index 16768a441e2..f2a9da510a8 100644
--- a/lld/COFF/DriverUtils.cpp
+++ b/lld/COFF/DriverUtils.cpp
@@ -558,6 +558,12 @@ err:
 static StringRef undecorate(StringRef Sym) {
   if (Config->Machine != I386)
     return Sym;
+  // In MSVC mode, a fully decorated stdcall function is exported
+  // as-is with the leading underscore (with type IMPORT_NAME).
+  // In MinGW mode, a decorated stdcall function gets the underscore
+  // removed, just like normal cdecl functions.
+  if (Sym.startswith("_") && Sym.contains('@') && !Config->MinGW)
+    return Sym;
   return Sym.startswith("_") ? Sym.substr(1) : Sym;
 }
 
diff --git a/lld/test/COFF/def-export-stdcall.s b/lld/test/COFF/def-export-stdcall.s
index 851ac6d975b..db251406584 100644
--- a/lld/test/COFF/def-export-stdcall.s
+++ b/lld/test/COFF/def-export-stdcall.s
@@ -32,8 +32,7 @@
 # DECORATED-IMPLIB: Name type: name
 # DECORATED-IMPLIB-NEXT: __imp_@fastcall@8
 # DECORATED-IMPLIB-NEXT: @fastcall@8
-# TODO: To match link.exe, this one should also be Name type: name.
-# DECORATED-IMPLIB: Name type: noprefix
+# DECORATED-IMPLIB: Name type: name
 # DECORATED-IMPLIB-NEXT: __imp__stdcall@8
 # DECORATED-IMPLIB-NEXT: _stdcall@8
 # DECORATED-IMPLIB: Name type: name
@@ -41,8 +40,7 @@
 # DECORATED-IMPLIB-NEXT: vectorcall@@8
 
 # DECORATED-EXPORTS: Name: @fastcall@8
-# TODO: To match link.exe, this one should actually be _stdcall@8
-# DECORATED-EXPORTS: Name: stdcall@8
+# DECORATED-EXPORTS: Name: _stdcall@8
 # DECORATED-EXPORTS: Name: vectorcall@@8
 
 
diff --git a/lld/test/COFF/dllexport.s b/lld/test/COFF/dllexport.s
index 27cbd235a53..78d97c97874 100644
--- a/lld/test/COFF/dllexport.s
+++ b/lld/test/COFF/dllexport.s
@@ -8,21 +8,19 @@
 # DECORATED-IMPLIB: Name type: name
 # DECORATED-IMPLIB-NEXT: __imp_@fastcall@8
 # DECORATED-IMPLIB-NEXT: @fastcall@8
+# DECORATED-IMPLIB: Name type: name
+# DECORATED-IMPLIB-NEXT: __imp__stdcall@8
+# DECORATED-IMPLIB-NEXT: _stdcall@8
 # DECORATED-IMPLIB: Name type: noprefix
 # DECORATED-IMPLIB-NEXT: __imp___underscored
 # DECORATED-IMPLIB-NEXT: __underscored
-# TODO: To match link.exe, this one should also be Name type: name.
-# DECORATED-IMPLIB: Name type: noprefix
-# DECORATED-IMPLIB-NEXT: __imp__stdcall@8
-# DECORATED-IMPLIB-NEXT: _stdcall@8
 # DECORATED-IMPLIB: Name type: name
 # DECORATED-IMPLIB-NEXT: __imp_vectorcall@@8
 # DECORATED-IMPLIB-NEXT: vectorcall@@8
 
 # DECORATED-EXPORTS: Name: @fastcall@8
+# DECORATED-EXPORTS: Name: _stdcall@8
 # DECORATED-EXPORTS: Name: _underscored
-# TODO: To match link.exe, this one should actually be _stdcall@8
-# DECORATED-EXPORTS: Name: stdcall@8
 # DECORATED-EXPORTS: Name: vectorcall@@8
 
         .def     _stdcall@8;