lld: make pe targets use the coff linker

[compnerd]

lib/Driver/UniversalDriver.cpp

97

I think we should flip this around, and make this more getTargetFromEmulation. It should return a tuple (pair) for architecture, format for the emulation mode. So, i386pe -> (COFF,I386), thumb2pe -> (COFF,ARMNT). This could then be used in the future to extend it for the other GNU emulations.

212

Space after if. Although, this would change with the above to switch off of the format that we converted the emulation to.

[martell]

Address compnerd's review

[ruiu]

This simply dispatch to the link.exe-compatible driver, so all options except -m have to be in link.exe style. What's the point of this change?

[martell]

This simply dispatch to the link.exe-compatible driver, so all options except -m have to be in link.exe style. What's the point of this change?

Yes it currently forces gnu COFF targets to use the link driver
http://reviews.llvm.org/D13933
then adds the some needed alias's to support GNU style where needed.
Or at least at the minute enough to compile a simple hello world

[martell]

we have come a long way since then @ruiu :) , abandoning a really old revision

lib/Driver/UniversalDriver.cpp

 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/Triple.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/Option.h"
 #include "llvm/Support/CommandLine.h"

   return ret;
 }
 
+static std::pair<llvm::Triple::ObjectFormatType, uint16_t> getTargetFromEmulation(StringRef S) {
+  if (S == "i386pe")
+    return {llvm::Triple::COFF, llvm::Triple::ArchType::x86};
+  if (S == "i386pep")
+    return {llvm::Triple::COFF, llvm::Triple::ArchType::x86_64};
+  if (S == "thumb2pe")
+    return {llvm::Triple::COFF, llvm::Triple::ArchType::arm};
+
+  return {llvm::Triple::UnknownObjectFormat, llvm::Triple::ArchType::UnknownArch};
+}
+
 // Removes the argument from argv along with its value, if exists, and updates
 // argc.
 static void removeArg(llvm::opt::Arg *arg,

 
   Flavor flavor = getFlavor(args, parsedArgs);
 
+  // Override -m for coff targets
+  if (llvm::opt::Arg *argMachine = parsedArgs.getLastArg(OPT_m)) {
+    std::pair<llvm::Triple::ObjectFormatType, uint16_t> targetEmulation =
+        getTargetFromEmulation(argMachine->getValue());
+
+    if(targetEmulation.first == llvm::Triple::COFF) {
+      coff::link(args);
+      return true;
+    }
+  }
+
   // Switch to appropriate driver.
   switch (flavor) {
   case Flavor::gnu_ld:

lib/Driver/UniversalDriverOptions.td

 def target: Separate<["-"], "target">,
      HelpText<"Select the target">;
 
+// Used to override gnu pe targets
+def m : Separate<["-"], "m">, MetaVarName<"<emulation>">,
+     HelpText<"Select target emulation">;
+
 def version: Flag<["-"], "version">,
      HelpText<"Display the version">;