Start hoisting the logic for computing the target triple into its own

function. The logic for this, and I want to emphasize that this is the
logic for computing the *target* triple, is currently scattered
throughout various different HostInfo classes ToolChain factoring
functions. Best part, it is largely *duplicated* there. The goal is to
hoist all of that up to here where we can deal with it once, and in
a consistent manner.

Unfortunately, this uncovers more fun problems: the ToolChains assume
that the *actual* target triple is the one passed into them by these
factory functions, while the *host* triple is the one in the driver.
This already was a lie, and a damn lie, when the '-target' flag was
specified. It only really worked when the difference stemmed from '-m32'
and '-m64' flags. I'll have to fix that (and remove all the FIXMEs I've
introduced here to document the problem) before I can finish hoisting
the target-calculation logic.

It's bugs all the way down today it seems...

llvm-svn: 148839

clang/lib/Driver/Driver.cpp

@@ -237,6 +237,18 @@ DerivedArgList *Driver::TranslateInputArgs(const InputArgList &Args) const {
   return DAL;
 }
 
+/// \brief Compute target triple from args.
+///
+/// This routine provides the logic to compute a target triple from various
+/// args passed to the driver and the default triple string.
+static llvm::Triple computeTargetTriple(StringRef DefaultTargetTriple,
+                                        const ArgList &Args) {
+  if (const Arg *A = Args.getLastArg(options::OPT_target))
+    DefaultTargetTriple = A->getValue(Args);
+
+  return llvm::Triple(llvm::Triple::normalize(DefaultTargetTriple));
+}
+
 Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
   llvm::PrettyStackTraceString CrashInfo("Compilation construction");
 
@@ -305,10 +317,6 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
       Cur = Split.second;
     }
   }
-  // FIXME: We shouldn't overwrite the default host triple here, but we have
-  // nowhere else to put this currently.
-  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),
@@ -322,10 +330,8 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
   if (Args->hasArg(options::OPT_nostdlib))
     UseStdLib = false;
 
-  // Reset the target triple here as we may have adjusted the
-  // DefaultTargetTriple string for flags above.
-  // FIXME: Same fix is needed here when the above flag management is fixed.
-  TargetTriple = llvm::Triple(llvm::Triple::normalize(DefaultTargetTriple));
+  // Recompute the target triple based on the args.
+  TargetTriple = computeTargetTriple(DefaultTargetTriple, *Args);
   Host = GetHostInfo(TargetTriple);
 
   // Perform the default argument translations.

clang/lib/Driver/ToolChains.cpp

@@ -1099,7 +1099,10 @@ bool Generic_GCC::GCCVersion::operator<(const GCCVersion &RHS) const {
 /// Once constructed, a GCCInstallation is esentially immutable.
 Generic_GCC::GCCInstallationDetector::GCCInstallationDetector(const Driver &D)
   : IsValid(false),
-    GccTriple(D.DefaultTargetTriple) {
+    // FIXME: GccTriple is using the target triple as both the target and host
+    // triple here. It also shouldn't be using the string representation, and
+    // should instead be using the Triple object.
+    GccTriple(D.TargetTriple.str()) {
   // FIXME: Using CXX_INCLUDE_ROOT is here is a bit of a hack, but
   // avoids adding yet another option to configure/cmake.
   // It would probably be cleaner to break it in two variables
@@ -1137,7 +1140,8 @@ Generic_GCC::GCCInstallationDetector::GCCInstallationDetector(const Driver &D)
 
   // Always include the default host triple as the final fallback if no
   // specific triple is detected.
-  CandidateTriples.push_back(D.DefaultTargetTriple);
+  // FIXME: This is using the Driver's target triple as the host triple!
+  CandidateTriples.push_back(D.TargetTriple.str());
 
   // Compute the set of prefixes for our search.
   SmallVector<std::string, 8> Prefixes(D.PrefixDirs.begin(),
@@ -1543,14 +1547,14 @@ FreeBSD::FreeBSD(const HostInfo &Host, const llvm::Triple& Triple)
 
   // Determine if we are compiling 32-bit code on an x86_64 platform.
   bool Lib32 = false;
+  // FIXME: This is using the Driver's target triple as the host triple!
   if (Triple.getArch() == llvm::Triple::x86 &&
-      llvm::Triple(getDriver().DefaultTargetTriple).getArch() ==
-        llvm::Triple::x86_64)
+      getDriver().TargetTriple.getArch() == llvm::Triple::x86_64)
     Lib32 = true;
 
+  // FIXME: This is using the Driver's target triple as the host triple!
   if (Triple.getArch() == llvm::Triple::ppc &&
-      llvm::Triple(getDriver().DefaultTargetTriple).getArch() ==
-        llvm::Triple::ppc64)
+      getDriver().TargetTriple.getArch() == llvm::Triple::ppc64)
     Lib32 = true;
 
   if (Lib32) {
@@ -1894,8 +1898,8 @@ static std::string getMultiarchTriple(const llvm::Triple TargetTriple,
 
 Linux::Linux(const HostInfo &Host, const llvm::Triple &Triple)
   : Generic_ELF(Host, Triple) {
-  llvm::Triple::ArchType Arch =
-    llvm::Triple(getDriver().DefaultTargetTriple).getArch();
+  // FIXME: This is using the Driver's target triple to emulate the host triple!
+  llvm::Triple::ArchType Arch = getDriver().TargetTriple.getArch();
   const std::string &SysRoot = getDriver().SysRoot;
 
   // OpenSuse stores the linker with the compiler, add that to the search
@@ -2186,8 +2190,8 @@ void Linux::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
   // Check if the target architecture specific dirs need a suffix. Note that we
   // only support the suffix-based bi-arch-like header scheme for host/target
   // mismatches of just bit width.
-  llvm::Triple::ArchType HostArch =
-    llvm::Triple(getDriver().DefaultTargetTriple).getArch();
+  // FIXME: This is using the Driver's target triple to emulate the host triple!
+  llvm::Triple::ArchType HostArch = getDriver().TargetTriple.getArch();
   llvm::Triple::ArchType TargetArch = TargetTriple.getArch();
   StringRef Suffix;
   if ((HostArch == llvm::Triple::x86 && TargetArch == llvm::Triple::x86_64) ||