X86: repair export compatibility with MinGW/cygwin

Both MinGW and cygwin (i686) construct export directives without the global
leader prefix.  This is mostly due to the fact that they use GNU ld which does
not correctly handle the export directive.  This apparently has been been broken
for a while.  However, this was recently reported as being broken by
mingwandroid and diorcety of the msys2 project.

Remove the global leader prefix if targeting MinGW or cygwin, otherwise, retain
the global leader prefix.  Add an explicit test for cygwin's behaviour of export
directives.

llvm-svn: 207926

2 files changed, 47 insertions, 37 deletions

diff --git a/llvm/lib/Target/X86/X86AsmPrinter.cpp b/llvm/lib/Target/X86/X86AsmPrinter.cpp
index 8a7417fcff6..525fb6c8be9 100644
--- a/llvm/lib/Target/X86/X86AsmPrinter.cpp
+++ b/llvm/lib/Target/X86/X86AsmPrinter.cpp
@@ -553,13 +553,18 @@ emitNonLazySymbolPointer(MCStreamer &OutStreamer, MCSymbol *StubLabel,
 void X86AsmPrinter::GenerateExportDirective(const MCSymbol *Sym, bool IsData) {
   SmallString<128> Directive;
   raw_svector_ostream OS(Directive);
+  StringRef Name = Sym->getName();
 
   if (Subtarget->isTargetKnownWindowsMSVC())
     OS << " /EXPORT:";
   else
     OS << " -export:";
 
-  OS << Sym->getName();
+  if ((Subtarget->isTargetWindowsGNU() || Subtarget->isTargetWindowsCygwin()) &&
+      (Name[0] == getDataLayout().getGlobalPrefix()))
+    Name = Name.drop_front();
+
+  OS << Name;
 
   if (IsData) {
     if (Subtarget->isTargetKnownWindowsMSVC())
diff --git a/llvm/test/CodeGen/X86/dllexport.ll b/llvm/test/CodeGen/X86/dllexport.ll
index eba6d6946e9..6103a412112 100644
--- a/llvm/test/CodeGen/X86/dllexport.ll
+++ b/llvm/test/CodeGen/X86/dllexport.ll
@@ -1,5 +1,9 @@
-; RUN: llc -mtriple i386-pc-win32 < %s | FileCheck -check-prefix=CHECK -check-prefix=WIN32 %s
-; RUN: llc -mtriple i386-pc-mingw32 < %s | FileCheck -check-prefix=CHECK -check-prefix=MINGW %s
+; RUN: llc -mtriple i386-pc-win32 < %s \
+; RUN:    | FileCheck -check-prefix CHECK -check-prefix CHECK-CL %s
+; RUN: llc -mtriple i386-pc-mingw32 < %s \
+; RUN:    | FileCheck -check-prefix CHECK -check-prefix CHECK-GCC %s
+; RUN: llc -mtriple i686-pc-cygwin %s -o - \
+; RUN:    | FileCheck -check-prefix CHECK -check-prefix CHECK-GCC %s
 
 ; CHECK: .text
 
@@ -89,37 +93,38 @@ define weak_odr dllexport void @weak1() {
 
 
 ; CHECK: .section .drectve
-; WIN32: /EXPORT:_Var1,DATA
-; WIN32: /EXPORT:_Var2,DATA
-; WIN32: /EXPORT:_Var3,DATA
-; WIN32: /EXPORT:_WeakVar1,DATA
-; WIN32: /EXPORT:_WeakVar2,DATA
-; WIN32: /EXPORT:_f1
-; WIN32: /EXPORT:_f2
-; WIN32: /EXPORT:_stdfun@0
-; WIN32: /EXPORT:@fastfun@0
-; WIN32: /EXPORT:_thisfun
-; WIN32: /EXPORT:_lnk1
-; WIN32: /EXPORT:_lnk2
-; WIN32: /EXPORT:_weak1
-; WIN32: /EXPORT:_alias
-; WIN32: /EXPORT:_alias2
-; WIN32: /EXPORT:_alias3
-; WIN32: /EXPORT:_weak_alias
-; MINGW: -export:_Var1,data
-; MINGW: -export:_Var2,data
-; MINGW: -export:_Var3,data
-; MINGW: -export:_WeakVar1,data
-; MINGW: -export:_WeakVar2,data
-; MINGW: -export:_f1
-; MINGW: -export:_f2
-; MINGW: -export:_stdfun@0
-; MINGW: -export:@fastfun@0
-; MINGW: -export:_thisfun
-; MINGW: -export:_lnk1
-; MINGW: -export:_lnk2
-; MINGW: -export:_weak1
-; MINGW: -export:_alias
-; MINGW: -export:_alias2
-; MINGW: -export:_alias3
-; MINGW: -export:_weak_alias
+; CHECK-CL: /EXPORT:_Var1,DATA
+; CHECK-CL: /EXPORT:_Var2,DATA
+; CHECK-CL: /EXPORT:_Var3,DATA
+; CHECK-CL: /EXPORT:_WeakVar1,DATA
+; CHECK-CL: /EXPORT:_WeakVar2,DATA
+; CHECK-CL: /EXPORT:_f1
+; CHECK-CL: /EXPORT:_f2
+; CHECK-CL: /EXPORT:_stdfun@0
+; CHECK-CL: /EXPORT:@fastfun@0
+; CHECK-CL: /EXPORT:_thisfun
+; CHECK-CL: /EXPORT:_lnk1
+; CHECK-CL: /EXPORT:_lnk2
+; CHECK-CL: /EXPORT:_weak1
+; CHECK-CL: /EXPORT:_alias
+; CHECK-CL: /EXPORT:_alias2
+; CHECK-CL: /EXPORT:_alias3
+; CHECK-CL: /EXPORT:_weak_alias
+; CHECK-GCC: -export:Var1,data
+; CHECK-GCC: -export:Var2,data
+; CHECK-GCC: -export:Var3,data
+; CHECK-GCC: -export:WeakVar1,data
+; CHECK-GCC: -export:WeakVar2,data
+; CHECK-GCC: -export:f1
+; CHECK-GCC: -export:f2
+; CHECK-GCC: -export:stdfun@0
+; CHECK-GCC: -export:@fastfun@0
+; CHECK-GCC: -export:thisfun
+; CHECK-GCC: -export:lnk1
+; CHECK-GCC: -export:lnk2
+; CHECK-GCC: -export:weak1
+; CHECK-GCC: -export:alias
+; CHECK-GCC: -export:alias2
+; CHECK-GCC: -export:alias3
+; CHECK-GCC: -export:weak_alias
+