Add a new attribute called 'jumptable' that creates jump-instruction tables for functions marked with this attribute.

It includes a pass that rewrites all indirect calls to jumptable functions to pass through these tables.

This also adds backend support for generating the jump-instruction tables on ARM and X86.
Note that since the jumptable attribute creates a second function pointer for a
function, any function marked with jumptable must also be marked with unnamed_addr.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210280 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/JumpInstrTableInfo.cpp

@@ -0,0 +1,40 @@
+//===-- JumpInstrTableInfo.cpp: Info for Jump-Instruction Tables ----------===//
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief Information about jump-instruction tables that have been created by
+/// JumpInstrTables pass.
+///
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "jiti"
+
+#include "llvm/Analysis/JumpInstrTableInfo.h"
+#include "llvm/Analysis/Passes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Type.h"
+
+using namespace llvm;
+
+INITIALIZE_PASS(JumpInstrTableInfo, "jump-instr-table-info",
+                "Jump-Instruction Table Info", true, true)
+char JumpInstrTableInfo::ID = 0;
+
+ImmutablePass *llvm::createJumpInstrTableInfoPass() {
+  return new JumpInstrTableInfo();
+}
+
+JumpInstrTableInfo::JumpInstrTableInfo() : ImmutablePass(ID), Tables() {
+  initializeJumpInstrTableInfoPass(*PassRegistry::getPassRegistry());
+}
+
+JumpInstrTableInfo::~JumpInstrTableInfo() {}
+
+void JumpInstrTableInfo::insertEntry(FunctionType *TableFunTy, Function *Target,
+                                     Function *Jump) {
+  Tables[TableFunTy].push_back(JumpPair(Target, Jump));
+}