void doJumpTableViaSwitch(
NativeModulePtr natM,
BasicBlock *& block,
InstPtr ip,
MCInst &inst)
{
llvm::dbgs() << __FUNCTION__ << ": Doing jumpt table via switch\n";
Function *F = block->getParent();
Module *M = F->getParent();
// we know this conforms to
// jmp [reg*4+displacement]
// sanity check
const MCOperand& scale = OP(1);
const MCOperand& index = OP(2);
TASSERT(index.isReg(), "Conformant jump tables need index to be a register");
TASSERT(scale.isImm() && scale.getImm() == 4, "Conformant jump tables have scale == 4");
MCSJumpTablePtr jmpptr = ip->get_jump_table();
// to ensure no negative entries
Value *adjustment = CONST_V<32>(block, jmpptr->getInitialEntry());
Value *reg_val = R_READ<32>(block, index.getReg());
Value *real_index =
BinaryOperator::Create(Instruction::Add, adjustment, reg_val, "", block);
// create a default block that just traps
BasicBlock *defaultBlock =
BasicBlock::Create(block->getContext(), "", block->getParent(), 0);
Function *trapFn = Intrinsic::getDeclaration(M, Intrinsic::trap);
CallInst::Create(trapFn, "", defaultBlock);
ReturnInst::Create(defaultBlock->getContext(), defaultBlock);
// end default block
const std::vector<VA> &jmpblocks = jmpptr->getJumpTable();
// create a switch inst
SwitchInst *theSwitch = SwitchInst::Create(
real_index,
defaultBlock,
jmpblocks.size(),
block);
// populate switch
int myindex = 0;
for(std::vector<VA>::const_iterator itr = jmpblocks.begin();
itr != jmpblocks.end();
itr++)
{
std::string bbname = "block_0x"+to_string<VA>(*itr, std::hex);
BasicBlock *toBlock = bbFromStrName(bbname, F);
TASSERT(toBlock != NULL, "Could not find block: "+bbname);
theSwitch->addCase(CONST_V<32>(block, myindex), toBlock);
++myindex;
}
}
void doJumpTableViaSwitchReg(
BasicBlock *& block,
InstPtr ip,
Value *regVal,
BasicBlock *&default_block)
{
llvm::dbgs() << __FUNCTION__ << ": Doing jumpt table via switch(reg)\n";
Function *F = block->getParent();
Module *M = F->getParent();
MCSJumpTablePtr jmpptr = ip->get_jump_table();
// create a default block that just traps
default_block =
BasicBlock::Create(block->getContext(), "", block->getParent(), 0);
// end default block
const std::vector<VA> &jmpblocks = jmpptr->getJumpTable();
std::unordered_set<VA> uniq_blocks(jmpblocks.begin(), jmpblocks.end());
// create a switch inst
SwitchInst *theSwitch = SwitchInst::Create(
regVal,
default_block,
uniq_blocks.size(),
block);
// populate switch
for(auto blockVA : uniq_blocks)
{
std::string bbname = "block_0x"+to_string<VA>(blockVA, std::hex);
BasicBlock *toBlock = bbFromStrName(bbname, F);
llvm::dbgs() << __FUNCTION__ << ": Mapping from " << to_string<VA>(blockVA, std::hex) << " => " << bbname << "\n";
TASSERT(toBlock != NULL, "Could not find block: "+bbname);
theSwitch->addCase(CONST_V<32>(block, blockVA), toBlock);
}
}