Prevent errors of omission when adding backend names.

[dougk]

Summary

Add test that getArchTypeForLLVMName() returns something other than Unknown for all but 1 special case.

[dougk]

For context, this test would have prevented the bug that I fixed in http://reviews.llvm.org/D9436 ("Add 'sparcel' in one more place")

[chandlerc]

Please use the LLVM naming conventions for variables. Please use a range based for loop. I would prefer EXPECT_NE here rather than ASSERT_NE.

[dougk]

To use a range-based for loop requires an artificial object as the head of the registry because begin() and end() are static methods.
Something like this:

llvm::TargetRegistry RegistryRoot;
for (const auto& Target : RegistryRoot ) {

Do you prefer that and/or should I change the other (6 ish) places where the explicit loop appears?

[dougk]

changes per review, and moved new file to Support instead of MC

[chandlerc]

LGTM

unittests/Support/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
+  ${LLVM_TARGETS_TO_BUILD}
   Support
   )
 
 add_llvm_unittest(SupportTests
   AlignOfTest.cpp
   AllocatorTest.cpp
   ArrayRecyclerTest.cpp
   BlockFrequencyTest.cpp
add_llvm_unittest(SupportTests
   ProgramTest.cpp
   RegexTest.cpp
   ScaledNumberTest.cpp
   SourceMgrTest.cpp
   SpecialCaseListTest.cpp
   StreamingMemoryObject.cpp
   StringPool.cpp
   SwapByteOrderTest.cpp
+  TargetRegistry.cpp
   ThreadLocalTest.cpp
   TimeValueTest.cpp
   UnicodeTest.cpp
   YAMLIOTest.cpp
   YAMLParserTest.cpp
   formatted_raw_ostream_test.cpp
   raw_ostream_test.cpp
   raw_pwrite_stream_test.cpp
   )
 
 # ManagedStatic.cpp uses <pthread>.
 if(LLVM_ENABLE_THREADS AND HAVE_LIBPTHREAD)
   target_link_libraries(SupportTests pthread)
 endif()

unittests/Support/TargetRegistry.cpp

+//===- unittests/Support/TargetRegistry.cpp - -----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/TargetSelect.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+TEST(TargetRegistry, TargetHasArchType) {
+  // Presence of at least one target will be asserted when done with the loop,
+  // else this would pass by accident if InitializeAllTargetInfos were omitted.
+  int Count = 0;
+
+  llvm::InitializeAllTargetInfos();
+
+  llvm::TargetRegistry RegistryRoot;
+  for (const auto &Target : RegistryRoot) {
+    StringRef Name = Target.getName();
+    // There is really no way (at present) to ask a Target whether it targets
+    // a specific architecture, because the logic for that is buried in a
+    // predicate.
+    // We can't ask the predicate "Are you a function that always returns
+    // false?"
+    // So given that the cpp backend truly has no target arch, it is skipped.
+    if (Name != "cpp") {
+      Triple::ArchType Arch = Triple::getArchTypeForLLVMName(Name);
+      EXPECT_NE(Arch, Triple::UnknownArch);
+      ++Count;
+    }
+  }
+  ASSERT_NE(Count, 0);
+}
+
+} // end namespace