Unify linker argument order across platforms

Previously extra linker arguments had different behavior on darwin vs
other unix platforms. On darwin the arguments passed with -Xlinker would
be passed to the linker before the default arguments, where as with the
default unix toolchain they would be passed afterwards.

There isn't really a great option for which order these should be in.
If you want to have a custom rpath that takes precedence over the
default rpaths, you want them to be passed before, but if you want to
negate a default argument you want them to come after.

This change unifies the behavior so at least you always get the same
behavior across platforms.

Author: keith

lib/Driver/UnixToolChains.cpp

@@ -210,6 +210,9 @@ toolchains::GenericUnix::constructInvocation(const LinkJobAction &job,
   SmallString<128> StaticRuntimeLibPath;
   getRuntimeLibraryPath(StaticRuntimeLibPath, context.Args, /*Shared=*/false);
 
+  context.Args.AddAllArgs(Arguments, options::OPT_Xlinker);
+  context.Args.AddAllArgs(Arguments, options::OPT_linker_option_Group);
+
   // Add the runtime library link path, which is platform-specific and found
   // relative to the compiler.
   if (!(staticExecutable || staticStdlib) && shouldProvideRPathToLinker()) {
@@ -317,9 +320,6 @@ toolchains::GenericUnix::constructInvocation(const LinkJobAction &job,
         Twine("-u", llvm::getInstrProfRuntimeHookVarName())));
   }
 
-  context.Args.AddAllArgs(Arguments, options::OPT_Xlinker);
-  context.Args.AddAllArgs(Arguments, options::OPT_linker_option_Group);
-
   // Run clang++ in verbose mode if "-v" is set
   if (context.Args.hasArg(options::OPT_v)) {
     Arguments.push_back("-v");

test/Driver/linker.swift

@@ -43,6 +43,12 @@
 // RUN: %FileCheck %s < %t.complex.txt
 // RUN: %FileCheck -check-prefix COMPLEX %s < %t.complex.txt
 
+// RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-ios7.1 -Xlinker -rpath -Xlinker customrpath %s 2>&1 > %t.simple.txt
+// RUN: %FileCheck -check-prefix IOS-custom-rpath %s < %t.simple.txt
+
+// RUN: %swiftc_driver -driver-print-jobs -target armv7-unknown-linux-gnueabihf -Xlinker -rpath -Xlinker customrpath %s 2>&1 > %t.linux.txt
+// RUN: %FileCheck -check-prefix LINUX-custom-rpath %s < %t.linux.txt
+
 // RUN: %swiftc_driver -driver-print-jobs -target x86_64-apple-macosx10.9 -g %s | %FileCheck -check-prefix DEBUG %s
 
 // RUN: %empty-directory(%t)
@@ -276,16 +282,30 @@
 // LINUX_DYNLIB-x86_64: clang++{{"? }}
 // LINUX_DYNLIB-x86_64-DAG: -shared
 // LINUX_DYNLIB-x86_64-DAG: -fuse-ld=gold
+// LINUX_DYNLIB-x86_64-DAG: -L bar
 // LINUX_DYNLIB-x86_64-NOT: -pie
 // LINUX_DYNLIB-x86_64-DAG: -Xlinker -rpath -Xlinker [[STDLIB_PATH:[^ ]+/lib/swift/linux]]
 // LINUX_DYNLIB-x86_64: [[STDLIB_PATH]]/x86_64/swiftrt.o
 // LINUX_DYNLIB-x86_64-DAG: [[OBJECTFILE]]
 // LINUX_DYNLIB-x86_64-DAG: @[[AUTOLINKFILE]]
 // LINUX_DYNLIB-x86_64-DAG: [[STDLIB_PATH]]
 // LINUX_DYNLIB-x86_64-DAG: -lswiftCore
-// LINUX_DYNLIB-x86_64-DAG: -L bar
 // LINUX_DYNLIB-x86_64: -o dynlib.out
 
+// IOS-custom-rpath: swift
+// IOS-custom-rpath: -o [[OBJECTFILE:.*]]
+
+// IOS-custom-rpath: bin/ld{{"? }}
+// IOS-custom-rpath: -rpath customrpath
+// IOS-custom-rpath: -rpath [[STDLIB_PATH:[^ ]+/lib/swift/iphonesimulator]]
+
+// LINUX-custom-rpath: swift
+// LINUX-custom-rpath: -o [[OBJECTFILE:.*]]
+
+// LINUX-custom-rpath: clang++{{"? }}
+// LINUX-custom-rpath: -Xlinker -rpath -Xlinker customrpath
+// LINUX-custom-rpath: -Xlinker -rpath -Xlinker [[STDLIB_PATH:[^ ]+/lib/swift/linux]]
+
 // DEBUG: bin/swift
 // DEBUG-NEXT: bin/swift
 // DEBUG-NEXT: bin/ld{{"? }}