Revert part of r148839 and keep DefaultTargetTriple in the form adjusted
by -target and similar options. As discussed in PR 12026, the change
broke support for target-prefixed tools, i.e. calling x86_64--linux-ld
when compiling for x86_64--linux. Improve the test cases added
originally in r149083 to not require execution, just executable files.
Document the hack with appropiate FIXME comments.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151185 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Driver.cpp b/lib/Driver/Driver.cpp
index 0695317..e71f5a6 100644
--- a/lib/Driver/Driver.cpp
+++ b/lib/Driver/Driver.cpp
@@ -310,6 +310,10 @@
       Cur = Split.second;
     }
   }
+  // FIXME: DefaultTargetTriple is used by the target-prefixed calls to as/ld
+  // and getToolChain is const.
+  if (const Arg *A = Args->getLastArg(options::OPT_target))
+    DefaultTargetTriple = A->getValue(*Args);
   if (const Arg *A = Args->getLastArg(options::OPT_ccc_install_dir))
     Dir = InstalledDir = A->getValue(*Args);
   for (arg_iterator it = Args->filtered_begin(options::OPT_B),
@@ -1513,6 +1517,7 @@
 
 std::string Driver::GetProgramPath(const char *Name, const ToolChain &TC,
                                    bool WantFile) const {
+  // FIXME: Needs a better variable than DefaultTargetTriple
   std::string TargetSpecificExecutable(DefaultTargetTriple + "-" + Name);
   // Respect a limited subset of the '-Bprefix' functionality in GCC by
   // attempting to use this prefix when lokup up program paths.
@@ -1583,6 +1588,7 @@
 static llvm::Triple computeTargetTriple(StringRef DefaultTargetTriple,
                                         const ArgList &Args,
                                         StringRef DarwinArchName) {
+  // FIXME: Already done in Compilation *Driver::BuildCompilation
   if (const Arg *A = Args.getLastArg(options::OPT_target))
     DefaultTargetTriple = A->getValue(Args);