Make march/target-cpu print a note with the list of valid values for ARM

When rejecting a march= or target-cpu command line parameter,
the message is quite lacking. This patch adds a note that prints
all possible values for the current target, if the target supports it.

This adds support for the ARM/AArch64 targets (more to come!). 

Differential Revision: https://reviews.llvm.org/D42978 

llvm-svn: 324673

1 files changed, 5 insertions, 0 deletions

diff --git a/clang/lib/Basic/Targets.cpp b/clang/lib/Basic/Targets.cpp
index a845a4c3fbe..e325403a1fa 100644
--- a/clang/lib/Basic/Targets.cpp
+++ b/clang/lib/Basic/Targets.cpp
@@ -38,6 +38,7 @@
 #include "Targets/X86.h"
 #include "Targets/XCore.h"
 #include "clang/Basic/Diagnostic.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/Triple.h"
 
 using namespace clang;
@@ -607,6 +608,10 @@ TargetInfo::CreateTargetInfo(DiagnosticsEngine &Diags,
   // Set the target CPU if specified.
   if (!Opts->CPU.empty() && !Target->setCPU(Opts->CPU)) {
     Diags.Report(diag::err_target_unknown_cpu) << Opts->CPU;
+    SmallVector<StringRef, 32> ValidList;
+    Target->fillValidCPUList(ValidList);
+    if (!ValidList.empty())
+      Diags.Report(diag::note_valid_options) << llvm::join(ValidList, ", ");
     return nullptr;
   }