[llvm-exegesis] Fix buildbot - power was using native target for X86.

tools/llvm-exegesis/lib/LlvmState.h

 namespace exegesis {
 
 // An object to initialize LLVM and prepare objects needed to run the
 // measurements.
 class LLVMState {
 public:
   LLVMState();
 
+  LLVMState(const std::string &Triple,
+            const std::string &CpuName); // For tests.
+
   llvm::StringRef getTriple() const { return TheTriple; }
   llvm::StringRef getCpuName() const { return CpuName; }
   llvm::StringRef getFeatures() const { return Features; }
 
   const llvm::MCInstrInfo &getInstrInfo() const { return *InstrInfo; }
 
   const llvm::MCRegisterInfo &getRegInfo() const { return *RegInfo; }
 

tools/llvm-exegesis/lib/LlvmState.cpp

 #include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
 
 namespace exegesis {
 
-LLVMState::LLVMState()
-    : TheTriple(llvm::sys::getProcessTriple()),
-      CpuName(llvm::sys::getHostCPUName().str()) {
+LLVMState::LLVMState(const std::string &Triple, const std::string &CpuName)
+    : TheTriple(Triple), CpuName(CpuName) {
   std::string Error;
   TheTarget = llvm::TargetRegistry::lookupTarget(TheTriple, Error);
   assert(TheTarget && "unknown target for host");
   SubtargetInfo.reset(
       TheTarget->createMCSubtargetInfo(TheTriple, CpuName, Features));
   InstrInfo.reset(TheTarget->createMCInstrInfo());
   RegInfo.reset(TheTarget->createMCRegInfo(TheTriple));
   AsmInfo.reset(TheTarget->createMCAsmInfo(*RegInfo, TheTriple));
 }
 
+LLVMState::LLVMState()
+    : LLVMState(llvm::sys::getProcessTriple(),
+                llvm::sys::getHostCPUName().str()) {}
+
 std::unique_ptr<llvm::LLVMTargetMachine>
 LLVMState::createTargetMachine() const {
   const llvm::TargetOptions Options;
   return std::unique_ptr<llvm::LLVMTargetMachine>(
       static_cast<llvm::LLVMTargetMachine *>(TheTarget->createTargetMachine(
           TheTriple, CpuName, Features, Options, llvm::Reloc::Model::Static)));
 }
 

unittests/tools/llvm-exegesis/X86/SnippetGeneratorTest.cpp

 #include <unordered_set>
 
 namespace exegesis {
 namespace {
 
 class X86SnippetGeneratorTest : public ::testing::Test {
 protected:
   X86SnippetGeneratorTest()
-      : MCInstrInfo(State.getInstrInfo()), MCRegisterInfo(State.getRegInfo()) {}
+      : State("x86_64-unknown-linux", "haswell"),
+        MCInstrInfo(State.getInstrInfo()), MCRegisterInfo(State.getRegInfo()) {}
 
   static void SetUpTestCase() {
     LLVMInitializeX86TargetInfo();
     LLVMInitializeX86TargetMC();
     LLVMInitializeX86Target();
     LLVMInitializeX86AsmPrinter();
   }