1 files changed, 297 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/JumpInstrTables.cpp b/contrib/llvm/lib/CodeGen/JumpInstrTables.cpp
new file mode 100644
index 000000000000..750f71f6022e
--- /dev/null
+++ b/contrib/llvm/lib/CodeGen/JumpInstrTables.cpp
@@ -0,0 +1,297 @@
+//===-- JumpInstrTables.cpp: Jump-Instruction Tables ----------------------===//
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief An implementation of jump-instruction tables.
+///
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "jt"
+
+#include "llvm/CodeGen/JumpInstrTables.h"
+
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/JumpInstrTableInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/IR/Attributes.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Operator.h"
+#include "llvm/IR/Type.h"
+#include "llvm/IR/Verifier.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include <vector>
+
+using namespace llvm;
+
+char JumpInstrTables::ID = 0;
+
+INITIALIZE_PASS_BEGIN(JumpInstrTables, "jump-instr-tables",
+                      "Jump-Instruction Tables", true, true)
+INITIALIZE_PASS_DEPENDENCY(JumpInstrTableInfo);
+INITIALIZE_PASS_END(JumpInstrTables, "jump-instr-tables",
+                    "Jump-Instruction Tables", true, true)
+
+STATISTIC(NumJumpTables, "Number of indirect call tables generated");
+STATISTIC(NumFuncsInJumpTables, "Number of functions in the jump tables");
+
+ModulePass *llvm::createJumpInstrTablesPass() {
+  // The default implementation uses a single table for all functions.
+  return new JumpInstrTables(JumpTable::Single);
+}
+
+ModulePass *llvm::createJumpInstrTablesPass(JumpTable::JumpTableType JTT) {
+  return new JumpInstrTables(JTT);
+}
+
+namespace {
+static const char jump_func_prefix[] = "__llvm_jump_instr_table_";
+static const char jump_section_prefix[] = ".jump.instr.table.text.";
+
+// Checks to see if a given CallSite is making an indirect call, including
+// cases where the indirect call is made through a bitcast.
+bool isIndirectCall(CallSite &CS) {
+  if (CS.getCalledFunction())
+    return false;
+
+  // Check the value to see if it is merely a bitcast of a function. In
+  // this case, it will translate to a direct function call in the resulting
+  // assembly, so we won't treat it as an indirect call here.
+  const Value *V = CS.getCalledValue();
+  if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
+    return !(CE->isCast() && isa<Function>(CE->getOperand(0)));
+  }
+
+  // Otherwise, since we know it's a call, it must be an indirect call
+  return true;
+}
+
+// Replaces Functions and GlobalAliases with a different Value.
+bool replaceGlobalValueIndirectUse(GlobalValue *GV, Value *V, Use *U) {
+  User *Us = U->getUser();
+  if (!Us)
+    return false;
+  if (Instruction *I = dyn_cast<Instruction>(Us)) {
+    CallSite CS(I);
+
+    // Don't do the replacement if this use is a direct call to this function.
+    // If the use is not the called value, then replace it.
+    if (CS && (isIndirectCall(CS) || CS.isCallee(U))) {
+      return false;
+    }
+
+    U->set(V);
+  } else if (Constant *C = dyn_cast<Constant>(Us)) {
+    // Don't replace calls to bitcasts of function symbols, since they get
+    // translated to direct calls.
+    if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Us)) {
+      if (CE->getOpcode() == Instruction::BitCast) {
+        // This bitcast must have exactly one user.
+        if (CE->user_begin() != CE->user_end()) {
+          User *ParentUs = *CE->user_begin();
+          if (CallInst *CI = dyn_cast<CallInst>(ParentUs)) {
+            CallSite CS(CI);
+            Use &CEU = *CE->use_begin();
+            if (CS.isCallee(&CEU)) {
+              return false;
+            }
+          }
+        }
+      }
+    }
+
+    // GlobalAlias doesn't support replaceUsesOfWithOnConstant. And the verifier
+    // requires alias to point to a defined function. So, GlobalAlias is handled
+    // as a separate case in runOnModule.
+    if (!isa<GlobalAlias>(C))
+      C->replaceUsesOfWithOnConstant(GV, V, U);
+  } else {
+    assert(false && "The Use of a Function symbol is neither an instruction nor"
+                    " a constant");
+  }
+
+  return true;
+}
+
+// Replaces all replaceable address-taken uses of GV with a pointer to a
+// jump-instruction table entry.
+void replaceValueWithFunction(GlobalValue *GV, Function *F) {
+  // Go through all uses of this function and replace the uses of GV with the
+  // jump-table version of the function. Get the uses as a vector before
+  // replacing them, since replacing them changes the use list and invalidates
+  // the iterator otherwise.
+  for (Value::use_iterator I = GV->use_begin(), E = GV->use_end(); I != E;) {
+    Use &U = *I++;
+
+    // Replacement of constants replaces all instances in the constant. So, some
+    // uses might have already been handled by the time we reach them here.
+    if (U.get() == GV)
+      replaceGlobalValueIndirectUse(GV, F, &U);
+  }
+
+  return;
+}
+} // end anonymous namespace
+
+JumpInstrTables::JumpInstrTables()
+    : ModulePass(ID), Metadata(), JITI(nullptr), TableCount(0),
+      JTType(JumpTable::Single) {
+  initializeJumpInstrTablesPass(*PassRegistry::getPassRegistry());
+}
+
+JumpInstrTables::JumpInstrTables(JumpTable::JumpTableType JTT)
+    : ModulePass(ID), Metadata(), JITI(nullptr), TableCount(0), JTType(JTT) {
+  initializeJumpInstrTablesPass(*PassRegistry::getPassRegistry());
+}
+
+JumpInstrTables::~JumpInstrTables() {}
+
+void JumpInstrTables::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.addRequired<JumpInstrTableInfo>();
+}
+
+Function *JumpInstrTables::insertEntry(Module &M, Function *Target) {
+  FunctionType *OrigFunTy = Target->getFunctionType();
+  FunctionType *FunTy = transformType(OrigFunTy);
+
+  JumpMap::iterator it = Metadata.find(FunTy);
+  if (Metadata.end() == it) {
+    struct TableMeta Meta;
+    Meta.TableNum = TableCount;
+    Meta.Count = 0;
+    Metadata[FunTy] = Meta;
+    it = Metadata.find(FunTy);
+    ++NumJumpTables;
+    ++TableCount;
+  }
+
+  it->second.Count++;
+
+  std::string NewName(jump_func_prefix);
+  NewName += (Twine(it->second.TableNum) + "_" + Twine(it->second.Count)).str();
+  Function *JumpFun =
+      Function::Create(OrigFunTy, GlobalValue::ExternalLinkage, NewName, &M);
+  // The section for this table
+  JumpFun->setSection((jump_section_prefix + Twine(it->second.TableNum)).str());
+  JITI->insertEntry(FunTy, Target, JumpFun);
+
+  ++NumFuncsInJumpTables;
+  return JumpFun;
+}
+
+bool JumpInstrTables::hasTable(FunctionType *FunTy) {
+  FunctionType *TransTy = transformType(FunTy);
+  return Metadata.end() != Metadata.find(TransTy);
+}
+
+FunctionType *JumpInstrTables::transformType(FunctionType *FunTy) {
+  // Returning nullptr forces all types into the same table, since all types map
+  // to the same type
+  Type *VoidPtrTy = Type::getInt8PtrTy(FunTy->getContext());
+
+  // Ignore the return type.
+  Type *RetTy = VoidPtrTy;
+  bool IsVarArg = FunTy->isVarArg();
+  std::vector<Type *> ParamTys(FunTy->getNumParams());
+  FunctionType::param_iterator PI, PE;
+  int i = 0;
+
+  std::vector<Type *> EmptyParams;
+  Type *Int32Ty = Type::getInt32Ty(FunTy->getContext());
+  FunctionType *VoidFnTy = FunctionType::get(
+      Type::getVoidTy(FunTy->getContext()), EmptyParams, false);
+  switch (JTType) {
+  case JumpTable::Single:
+
+    return FunctionType::get(RetTy, EmptyParams, false);
+  case JumpTable::Arity:
+    // Transform all types to void* so that all functions with the same arity
+    // end up in the same table.
+    for (PI = FunTy->param_begin(), PE = FunTy->param_end(); PI != PE;
+         PI++, i++) {
+      ParamTys[i] = VoidPtrTy;
+    }
+
+    return FunctionType::get(RetTy, ParamTys, IsVarArg);
+  case JumpTable::Simplified:
+    // Project all parameters types to one of 3 types: composite, integer, and
+    // function, matching the three subclasses of Type.
+    for (PI = FunTy->param_begin(), PE = FunTy->param_end(); PI != PE;
+         ++PI, ++i) {
+      assert((isa<IntegerType>(*PI) || isa<FunctionType>(*PI) ||
+              isa<CompositeType>(*PI)) &&
+             "This type is not an Integer or a Composite or a Function");
+      if (isa<CompositeType>(*PI)) {
+        ParamTys[i] = VoidPtrTy;
+      } else if (isa<FunctionType>(*PI)) {
+        ParamTys[i] = VoidFnTy;
+      } else if (isa<IntegerType>(*PI)) {
+        ParamTys[i] = Int32Ty;
+      }
+    }
+
+    return FunctionType::get(RetTy, ParamTys, IsVarArg);
+  case JumpTable::Full:
+    // Don't transform this type at all.
+    return FunTy;
+  }
+
+  return nullptr;
+}
+
+bool JumpInstrTables::runOnModule(Module &M) {
+  JITI = &getAnalysis<JumpInstrTableInfo>();
+
+  // Get the set of jumptable-annotated functions.
+  DenseMap<Function *, Function *> Functions;
+  for (Function &F : M) {
+    if (F.hasFnAttribute(Attribute::JumpTable)) {
+      assert(F.hasUnnamedAddr() &&
+             "Attribute 'jumptable' requires 'unnamed_addr'");
+      Functions[&F] = nullptr;
+    }
+  }
+
+  // Create the jump-table functions.
+  for (auto &KV : Functions) {
+    Function *F = KV.first;
+    KV.second = insertEntry(M, F);
+  }
+
+  // GlobalAlias is a special case, because the target of an alias statement
+  // must be a defined function. So, instead of replacing a given function in
+  // the alias, we replace all uses of aliases that target jumptable functions.
+  // Note that there's no need to create these functions, since only aliases
+  // that target known jumptable functions are replaced, and there's no way to
+  // put the jumptable annotation on a global alias.
+  DenseMap<GlobalAlias *, Function *> Aliases;
+  for (GlobalAlias &GA : M.aliases()) {
+    Constant *Aliasee = GA.getAliasee();
+    if (Function *F = dyn_cast<Function>(Aliasee)) {
+      auto it = Functions.find(F);
+      if (it != Functions.end()) {
+        Aliases[&GA] = it->second;
+      }
+    }
+  }
+
+  // Replace each address taken function with its jump-instruction table entry.
+  for (auto &KV : Functions)
+    replaceValueWithFunction(KV.first, KV.second);
+
+  for (auto &KV : Aliases)
+    replaceValueWithFunction(KV.first, KV.second);
+
+  return !Functions.empty();
+}