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.

llvm-svn: 125965

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

lib/Target/CMakeLists.txt

@@ -9,6 +9,7 @@ add_llvm_library(LLVMTarget
   TargetFrameLowering.cpp
   TargetInstrInfo.cpp
   TargetIntrinsicInfo.cpp
+  TargetLibraryInfo.cpp
   TargetLoweringObjectFile.cpp
   TargetMachine.cpp
   TargetRegisterInfo.cpp

lib/Target/Target.cpp

@@ -24,6 +24,7 @@ using namespace llvm;
 
 void llvm::initializeTarget(PassRegistry &Registry) {
   initializeTargetDataPass(Registry);
+  initializeTargetLibraryInfoPass(Registry);
 }
 
 void LLVMInitializeTarget(LLVMPassRegistryRef R) {

lib/Target/TargetLibraryInfo.cpp

@@ -0,0 +1,49 @@
+//===-- TargetLibraryInfo.cpp - Runtime library information ----------------==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the TargetLibraryInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Target/TargetLibraryInfo.h"
+#include "llvm/ADT/Triple.h"
+using namespace llvm;
+
+// Register the default implementation.
+INITIALIZE_PASS(TargetLibraryInfo, "targetlibinfo",
+                "Target Library Information", false, true)
+char TargetLibraryInfo::ID = 0;
+
+/// initialize - Initialize the set of available library functions based on the
+/// specified target triple.  This should be carefully written so that a missing
+/// target triple gets a sane set of defaults.
+static void initialize(TargetLibraryInfo &TLI, const Triple &T) {
+  initializeTargetLibraryInfoPass(*PassRegistry::getPassRegistry());
+
+  
+  // memset_pattern16 is only available on iOS 3.0 and Mac OS/X 10.5 and later.
+  if (T.getOS() != Triple::Darwin || T.getDarwinMajorNumber() < 9)
+    TLI.setUnavailable(LibFunc::memset_pattern16);
+  
+}
+
+
+TargetLibraryInfo::TargetLibraryInfo() : ImmutablePass(ID) {
+  // Default to everything being available.
+  memset(AvailableArray, -1, sizeof(AvailableArray));
+
+  initialize(*this, Triple());
+}
+
+TargetLibraryInfo::TargetLibraryInfo(const Triple &T) : ImmutablePass(ID) {
+  // Default to everything being available.
+  memset(AvailableArray, -1, sizeof(AvailableArray));
+  
+  initialize(*this, T);
+}