From: Christoph Egger <siccegge@cs.fau.de>
Date: Tue, 3 Jun 2014 13:24:57 +0000 (+0200)
Subject: Split BasicBlocks if there are backward jumps
X-Git-Tag: v0.1~183
X-Git-Url: https://git.siccegge.de//index.cgi?a=commitdiff_plain;h=370dc79ad6da88b8548d9ebd52601271bf279213;p=frida%2Ffrida.git

Split BasicBlocks if there are backward jumps
---

diff --git a/src/disassembler/llvm/LLVMDisassembler.cxx b/src/disassembler/llvm/LLVMDisassembler.cxx
index a194d21..25a4ecc 100644
--- a/src/disassembler/llvm/LLVMDisassembler.cxx
+++ b/src/disassembler/llvm/LLVMDisassembler.cxx
@@ -121,9 +121,6 @@ LLVMDisassembler::~LLVMDisassembler() {
                   });
 }
 
-/*
- * TODO: If we jump into some Basic Block we need to split it there into two
- */
 void LLVMDisassembler::disassemble() {
     std::stack<LLVMFunction*> remaining_functions;
     std::stack<LLVMBasicBlock*> remaining_blocks;
@@ -245,6 +242,39 @@ void LLVMDisassembler::disassemble() {
         }
         LOG4CXX_DEBUG(logger, "Finished function " << current_function->getName());
     }
+
+	// Split blocks where jumps are going inside the block
+	for (auto it = blocks.begin(); it != blocks.end(); ++it) {
+		LLVMBasicBlock * current_block = it->second;
+		uint64_t inst_size;
+		uint64_t base_address;
+		text_section.getAddress(base_address);
+		uint64_t current_address = current_block->getStartAddress() - base_address;
+		while(current_block->getEndAddress() - base_address != current_address) {
+			MCInst inst;
+			std::string buf;
+			llvm::raw_string_ostream s(buf);
+
+			if(llvm::MCDisassembler::Success ==
+			   DisAsm->getInstruction(inst, inst_size, ref, current_address, nulls(), nulls())) {
+				auto other = blocks.find(current_address + inst_size + base_address);
+
+				if (other != blocks.end()) {
+					LOG4CXX_DEBUG(logger, "Shortening block starting at "
+								  << std::hex
+								  << current_block->getStartAddress()
+								  << " now ending at "
+								  << other->first);
+					current_block->setEndAddress(current_address + inst_size + base_address);
+					current_block->setNextBlock(0, other->first);
+					current_block->setNextBlock(1, 0);
+				}
+			} else {
+				inst_size = 1;
+			}
+			current_address += inst_size;
+		}
+	}
 }
 
 void LLVMDisassembler::readSymbols() {