Generating Control Flow Graphs in .NET

Make qr-codes in .NET Generating Control Flow Graphs
13
.net Framework qr code iso/iec18004 decoderwith .net
Using Barcode Control SDK for .net framework Control to generate, create, read, scan barcode image in .net framework applications.
couldn t directly update the EFLAGS register (nowadays this is easy, because the two units are implemented on a single chip). This meant that the result of a floating-point comparison was written into a separate floating-point status register, which then had to be loaded into one of the general-purpose registers, and from there it was possible to test its value and perform a conditional branch. Let s look at an example.
QR-Code barcode library in .net
using visual studio .net tobuild qr code jis x 0510 for asp.net web,windows application
00401000 00401004 00401008 0040100A 0040100D FLD DWORD PTR [ESP+4] FCOMP DWORD PTR [ESP+8] FSTSW AX TEST AH,41 JNZ SHORT 0040101D
decoding quick response code with .net
Using Barcode decoder for visual .net Control to read, scan read, scan image in visual .net applications.
This snippet loads one floating-point value into the floating-point stack (essentially like a floating-point register), and compares another value against the first value. Because the older FCOMP instruction is used, the result is stored in the floating-point status word. If the code were to use the newer FCOMIP instruction, the outcome would be written directly into EFLAGS, but this is a newer instruction that didn t exist in older versions of the processor. Because the result is stored in the floating-point status word, you need to somehow get it out of there in order to test the result of the comparison and perform a conditional branch. This is done using the FSTSW instruction, which copies the floating-point status word into the AX register. Once that value is in AX, you can test the specific flags and perform the conditional branch. The bottom line of all of this is that to translate this sequence into the decompiler s intermediate representation (which is not supposed to contain any architecture-specific details), the front end must understand this sequence for what it is, and eliminate the code that tests for specific flags (the constant 0x41) and so on. This is usually implemented by adding specific code in the front end that knows how to decipher these types of sequences.
Bar Code generation for .net
using barcode creation for vs .net control to generate, create barcode image in vs .net applications.
Generating Control Flow Graphs
Visual .net barcode scannerfor .net
Using Barcode recognizer for .net vs 2010 Control to read, scan read, scan image in .net vs 2010 applications.
The code generated by a decompiler s front end is represented in a graph structure, where each code block is called a basic block (BB). This graph structure simply represents the control flow instructions present in the low-level machine code. Each BB ends with a control flow instruction such as a branch instruction, a call, or a ret, or with a label that is referenced by some branch instruction elsewhere in the code (because labels represent a control flow join). Blocks are defined for each code segment that is referenced elsewhere in the code, typically by a branch instruction. Additionally, a BB is created after every conditional branch instruction, so that a conditional branch instruction
Control qr code iso/iec18004 size with c#
to get qr codes and qr data, size, image with c#.net barcode sdk
Decompilation
Paint qr bidimensional barcode in .net
generate, create qr-code none for .net projects
can either flow into the BB representing the branch target address or into the BB that contains the code immediately following the condition. This concept is illustrated in Figure 13.3. Note that to improve readability the actual code in Figure 13.3 is shown as IA-32 assembly language code, whereas in most decompilers BBs are represented using the decompiler s internal instruction set.
Control denso qr bar code image in vb.net
using barcode implementation for .net framework control to generate, create qr code image in .net framework applications.
00401064 00401065 0040106A 0040106F 00401070
PDF417 barcode library for .net
using barcode integrated for visual studio .net control to generate, create pdf417 2d barcode image in visual studio .net applications.
PUSH PUSH PUSH PUSH CALL
GTIN - 12 integration for .net
use .net framework crystal upc-a supplement 2 creator toembed upc symbol in .net
EAX 1008 cryptex.00405050 ESI [<&KERNEL32.ReadFile>]
Visual Studio .NET Crystal ansi/aim code 128 integrationwith .net
using barcode generator for .net crystal control to generate, create code-128c image in .net crystal applications.
00401076 00401078
MSI Plessey barcode library for .net
generate, create msi plessey none with .net projects
TEST EAX,EAX JE SHORT cryptex.004010CB
Control code-128 data with visual c#.net
code 128b data for visual c#.net
004010CB 004010CC 004010CE 004010CF 004010D0
Control barcode 3 of 9 data on vb
code-39 data for vb.net
POP EDI XOR EAX,EAX POP ESI POP ECX RETN
scanning bar code on java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
0040107A 0040107E 00401080 00401088
Control ean13+5 data for .net c#
ean-13 supplement 5 data on visual c#
MOV EAX,[ESP+18] TEST EAX,EAX MOV DWORD PTR [ESP+14],1008 JE SHORT cryptex.004010C2
.net Vs 2010 code 39 extended recognizerfor .net
Using Barcode reader for visual .net Control to read, scan read, scan image in visual .net applications.
0040108A 0040108E 0040108F 00401094 00401096 00401098 0040109A 0040109B
Control 39 barcode image in c#.net
generate, create 39 barcode none for visual c# projects
LEA ECX,[ESP+14] PUSH ECX PUSH cryptex.00405050 PUSH 0 PUSH 1 PUSH 0 PUSH EAX CALL [<&ADVAPI32.CryptDecrypt>]
Control gs1 barcode image for vb
use .net vs 2010 gs1 128 printing toconnect for visual basic.net
004010A1 004010A3
.net Winforms Crystal ean-13 supplement 2 integratingfor c#.net
using barcode integrating for .net winforms crystal control to generate, create ean13+5 image in .net winforms crystal applications.
TEST EAX,EAX JNZ SHORT cryptex.004010C2
004010A5 004010C2 004010C3 004010C8 004010C9 004010CA POP EDI MOV EAX,cryptex.00405050 POP ESI POP ECX RETN
CALL [<&KERNEL32.GetLastError>]
004010AB 004010AC 004010B1
PUSH EDI PUSH cryptex.004030E8 CALL [<&MSVCR71.printf>]
004010B7 004010BA 004010BC
ADD ESP,8 PUSH 1 CALL [<&MSVCR71.exit>]
Figure 13.3 An unstructured control flow graph representing branches in the original program. The dotted arrows represent conditional branch instructions while the plain ones represent fall-through cases this is where execution proceeds when a branch isn t taken.
13
The control flow graph in Figure 13.3 is quite primitive. It is essentially a graphical representation of the low-level control flow statement in the program. It is important to perform this simple analysis at this early stage in decompilation to correctly break the program into basic blocks. The process of actually structuring these graphs into a representation closer to the one used by high-level languages is performed later, during the control flow analysis stage.