Add backend name to Target to enable runtime info to be fed back into TableGen

Summary:
Make it possible to feed runtime information back to tablegen to enable
profile-guided tablegen-eration, detection of untested tablegen definitions, etc.

Being a cross-compiler by nature, LLVM will potentially collect data for multiple
architectures (e.g. when running 'ninja check'). We therefore need a way for
TableGen to figure out what data applies to the backend it is generating at the
time. This patch achieves that by including the name of the 'def X : Target ...'
for the backend in the TargetRegistry.

Reviewers: qcolombet

Reviewed By: qcolombet

Subscribers: jholewinski, arsenm, jyknight, aditya_nandakumar, sdardis, nemanjai, ab, nhaehnle, t.p.northover, javed.absar, qcolombet, llvm-commits, fedor.sergeev

Differential Revision: https://reviews.llvm.org/D39742

llvm-svn: 318352
diff --git a/llvm/lib/Target/BPF/TargetInfo/BPFTargetInfo.cpp b/llvm/lib/Target/BPF/TargetInfo/BPFTargetInfo.cpp
index 265180b..1f7b8a0 100644
--- a/llvm/lib/Target/BPF/TargetInfo/BPFTargetInfo.cpp
+++ b/llvm/lib/Target/BPF/TargetInfo/BPFTargetInfo.cpp
@@ -28,9 +28,10 @@
 
 extern "C" void LLVMInitializeBPFTargetInfo() {
   TargetRegistry::RegisterTarget(getTheBPFTarget(), "bpf", "BPF (host endian)",
-                                 [](Triple::ArchType) { return false; }, true);
-  RegisterTarget<Triple::bpfel, /*HasJIT=*/true> X(getTheBPFleTarget(), "bpfel",
-                                                   "BPF (little endian)");
+                                 "BPF", [](Triple::ArchType) { return false; },
+                                 true);
+  RegisterTarget<Triple::bpfel, /*HasJIT=*/true> X(
+      getTheBPFleTarget(), "bpfel", "BPF (little endian)", "BPF");
   RegisterTarget<Triple::bpfeb, /*HasJIT=*/true> Y(getTheBPFbeTarget(), "bpfeb",
-                                                   "BPF (big endian)");
+                                                   "BPF (big endian)", "BPF");
 }