introduce a new TargetLibraryInfo pass, which transformations can use to

query about available library functions.  For now this just has 
memset_pattern16, which exists on darwin, but it can be extended for a 
bunch of other things in the future.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125965 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/InitializePasses.h

@@ -220,6 +220,7 @@ void initializeStrongPHIEliminationPass(PassRegistry&);
 void initializeTailCallElimPass(PassRegistry&);
 void initializeTailDupPass(PassRegistry&);
 void initializeTargetDataPass(PassRegistry&);
+void initializeTargetLibraryInfoPass(PassRegistry&);
 void initializeTwoAddressInstructionPassPass(PassRegistry&);
 void initializeTypeBasedAliasAnalysisPass(PassRegistry&);
 void initializeUnifyFunctionExitNodesPass(PassRegistry&);

include/llvm/Target/TargetLibraryInfo.h

@@ -0,0 +1,56 @@
+//===-- llvm/Target/TargetLibraryInfo.h - Library information ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TARGET_TARGETLIBRARYINFO_H
+#define LLVM_TARGET_TARGETLIBRARYINFO_H
+
+#include "llvm/Pass.h"
+
+namespace llvm {
+  class Triple;
+
+  namespace LibFunc {
+    enum Func {
+      /// void memset_pattern16(void *b, const void *pattern16, size_t len);
+      memset_pattern16,
+      
+      NumLibFuncs
+    };
+  }
+
+/// TargetLibraryInfo - This immutable pass captures information about what
+/// library functions are available for the current target, and allows a
+/// frontend to disable optimizations through -fno-builtin etc.
+class TargetLibraryInfo : public ImmutablePass {
+  unsigned char AvailableArray[(LibFunc::NumLibFuncs+7)/8];
+public:
+  static char ID;
+  TargetLibraryInfo();
+  TargetLibraryInfo(const Triple &T);
+  
+  /// has - This function is used by optimizations that want to match on or form
+  /// a given library function.
+  bool has(LibFunc::Func F) const {
+    return (AvailableArray[F/8] & (1 << (F&7))) != 0;
+  }
+
+  /// setUnavailable - this can be used by whatever sets up TargetLibraryInfo to
+  /// ban use of specific library functions.
+  void setUnavailable(LibFunc::Func F) {
+    AvailableArray[F/8] &= ~(1 << (F&7));
+  }
+
+  void setAvailable(LibFunc::Func F) {
+    AvailableArray[F/8] |= 1 << (F&7);
+  }
+};
+
+} // end namespace llvm
+
+#endif