1 files changed, 103 insertions, 0 deletions
diff --git a/llvm/lib/ExecutionEngine/TargetSelect.cpp b/llvm/lib/ExecutionEngine/TargetSelect.cpp
new file mode 100644
index 000000000000..0d9c6cfa0908
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+++ b/llvm/lib/ExecutionEngine/TargetSelect.cpp
@@ -0,0 +1,103 @@
+//===-- TargetSelect.cpp - Target Chooser Code ----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This just asks the TargetRegistry for the appropriate target to use, and
+// allows the user to specify a specific one on the commandline with -march=x,
+// -mcpu=y, and -mattr=a,-b,+c. Clients should initialize targets prior to
+// calling selectTarget().
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/Triple.h"
+#include "llvm/ExecutionEngine/ExecutionEngine.h"
+#include "llvm/IR/Module.h"
+#include "llvm/MC/SubtargetFeature.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Target/TargetMachine.h"
+
+using namespace llvm;
+
+TargetMachine *EngineBuilder::selectTarget() {
+  Triple TT;
+
+  // MCJIT can generate code for remote targets, but the old JIT and Interpreter
+  // must use the host architecture.
+  if (WhichEngine != EngineKind::Interpreter && M)
+    TT.setTriple(M->getTargetTriple());
+
+  return selectTarget(TT, MArch, MCPU, MAttrs);
+}
+
+/// selectTarget - Pick a target either via -march or by guessing the native
+/// arch.  Add any CPU features specified via -mcpu or -mattr.
+TargetMachine *EngineBuilder::selectTarget(const Triple &TargetTriple,
+                              StringRef MArch,
+                              StringRef MCPU,
+                              const SmallVectorImpl<std::string>& MAttrs) {
+  Triple TheTriple(TargetTriple);
+  if (TheTriple.getTriple().empty())
+    TheTriple.setTriple(sys::getProcessTriple());
+
+  // Adjust the triple to match what the user requested.
+  const Target *TheTarget = nullptr;
+  if (!MArch.empty()) {
+    auto I = find_if(TargetRegistry::targets(),
+                     [&](const Target &T) { return MArch == T.getName(); });
+
+    if (I == TargetRegistry::targets().end()) {
+      if (ErrorStr)
+        *ErrorStr = "No available targets are compatible with this -march, "
+                    "see -version for the available targets.\n";
+      return nullptr;
+    }
+
+    TheTarget = &*I;
+
+    // Adjust the triple to match (if known), otherwise stick with the
+    // requested/host triple.
+    Triple::ArchType Type = Triple::getArchTypeForLLVMName(MArch);
+    if (Type != Triple::UnknownArch)
+      TheTriple.setArch(Type);
+  } else {
+    std::string Error;
+    TheTarget = TargetRegistry::lookupTarget(TheTriple.getTriple(), Error);
+    if (!TheTarget) {
+      if (ErrorStr)
+        *ErrorStr = Error;
+      return nullptr;
+    }
+  }
+
+  // Package up features to be passed to target/subtarget
+  std::string FeaturesStr;
+  if (!MAttrs.empty()) {
+    SubtargetFeatures Features;
+    for (unsigned i = 0; i != MAttrs.size(); ++i)
+      Features.AddFeature(MAttrs[i]);
+    FeaturesStr = Features.getString();
+  }
+
+  // FIXME: non-iOS ARM FastISel is broken with MCJIT.
+  if (TheTriple.getArch() == Triple::arm &&
+      !TheTriple.isiOS() &&
+      OptLevel == CodeGenOpt::None) {
+    OptLevel = CodeGenOpt::Less;
+  }
+
+  // Allocate a target...
+  TargetMachine *Target =
+      TheTarget->createTargetMachine(TheTriple.getTriple(), MCPU, FeaturesStr,
+                                     Options, RelocModel, CMModel, OptLevel,
+				     /*JIT*/ true);
+  Target->Options.EmulatedTLS = EmulatedTLS;
+  Target->Options.ExplicitEmulatedTLS = true;
+
+  assert(Target && "Could not allocate target machine!");
+  return Target;
+}