Add new TargetRegistry.

Targets implement a single global Target structure which will live in a new
<Target>/TargetInfo library; this will be present in any image which the target
is usable in.
 - Optional target specific classes can then be registered and attached to the
   Target description.

 - Registration for normal Targets will be done via the initialization functions
   instead of using static constructors.

 - This allows clients to use a single interface to obtain target data, without
   requiring the code generator be linked in. It also provides a natural
   extension point for adding new optional target data (assembler parser,
   disassembler, etc.).

 - This also provides a new entry point for obtaining a target for a particular
   triple (without a module).

 - Not yet used, however this should eventually replace the TargetMachineRegistry.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75739 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 136 insertions, 0 deletions

diff --git a/lib/Support/TargetRegistry.cpp b/lib/Support/TargetRegistry.cpp
new file mode 100644
index 0000000000..24f87ce682
--- /dev/null
+++ b/lib/Support/TargetRegistry.cpp
@@ -0,0 +1,136 @@
+//===--- TargetRegistry.cpp - Target registration -------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Target/TargetRegistry.h"
+#include <cassert>
+using namespace llvm;
+
+// FIXME: Worry about locking? In general everything should be registered at
+// startup.
+
+static Target *FirstTarget = 0;
+
+const Target *
+TargetRegistry::getClosestStaticTargetForTriple(const std::string &TT,
+                                                std::string &Error) {
+  Target *Best = 0, *EquallyBest = 0;
+  unsigned BestQuality = 0;
+  // FIXME: Use iterator.
+  for (Target *i = FirstTarget; i; i = i->Next) {
+    if (unsigned Qual = i->TripleMatchQualityFn(TT)) {
+      if (!Best || Qual > BestQuality) {
+        Best = i;
+        EquallyBest = 0;
+        BestQuality = Qual;
+      } else if (Qual == BestQuality)
+        EquallyBest = i;
+    }
+  }
+
+  if (!Best) {
+    Error = "No available targets are compatible with this module";
+    return 0;
+  }
+
+  // Otherwise, take the best target, but make sure we don't have two equally
+  // good best targets.
+  if (EquallyBest) {
+    Error = std::string("Cannot choose between targets \"") +
+      Best->Name  + "\" and \"" + EquallyBest->Name + "\"";
+    return 0;
+  }
+
+  return Best;
+}
+
+const Target *
+TargetRegistry::getClosestStaticTargetForModule(const Module &M,
+                                                std::string &Error) {
+  Target *Best = 0, *EquallyBest = 0;
+  unsigned BestQuality = 0;
+  // FIXME: Use iterator.
+  for (Target *i = FirstTarget; i; i = i->Next) {
+    if (unsigned Qual = i->ModuleMatchQualityFn(M)) {
+      if (!Best || Qual > BestQuality) {
+        Best = i;
+        EquallyBest = 0;
+        BestQuality = Qual;
+      } else if (Qual == BestQuality)
+        EquallyBest = i;
+    }
+  }
+
+  if (!Best) {
+    Error = "No available targets are compatible with this module";
+    return 0;
+  }
+
+  // Otherwise, take the best target, but make sure we don't have two equally
+  // good best targets.
+  if (EquallyBest) {
+    Error = std::string("Cannot choose between targets \"") +
+      Best->Name  + "\" and \"" + EquallyBest->Name + "\"";
+    return 0;
+  }
+
+  return Best;
+}
+
+const Target *
+TargetRegistry::getClosestTargetForJIT(std::string &Error) {
+  Target *Best = 0, *EquallyBest = 0;
+  unsigned BestQuality = 0;
+  // FIXME: Use iterator.
+  for (Target *i = FirstTarget; i; i = i->Next) {
+    if (unsigned Qual = i->JITMatchQualityFn()) {
+      if (!Best || Qual > BestQuality) {
+        Best = i;
+        EquallyBest = 0;
+        BestQuality = Qual;
+      } else if (Qual == BestQuality)
+        EquallyBest = i;
+    }
+  }
+
+  if (!Best) {
+    Error = "No JIT is available for this host";
+    return 0;
+  }
+
+  // Return the best, ignoring ties.
+  return Best;
+}
+
+void TargetRegistry::RegisterTarget(Target &T,
+                                    const char *Name,
+                                    const char *ShortDesc,
+                                    Target::TripleMatchQualityFnTy TQualityFn,
+                                    Target::ModuleMatchQualityFnTy MQualityFn,
+                                    Target::JITMatchQualityFnTy JITQualityFn) {
+  // Note that we don't require the constructor functions already be defined, in
+  // case a module happens to initialize the optional functionality before the
+  // target.
+  assert(!T.Next && !T.Name && !T.ShortDesc && !T.TripleMatchQualityFn &&
+         !T.ModuleMatchQualityFn && !T.JITMatchQualityFn && 
+         "This Target already registered!");
+
+  assert(Name && ShortDesc && TQualityFn && MQualityFn && JITQualityFn &&
+         "Missing required target information!");
+         
+  // Add to the list of targets.
+  T.Next = FirstTarget;
+  FirstTarget = T.Next;
+
+  T.Name = Name;
+  T.ShortDesc = ShortDesc;
+  T.TripleMatchQualityFn = TQualityFn;
+  T.ModuleMatchQualityFn = MQualityFn;
+  T.JITMatchQualityFn = JITQualityFn;
+}
+