similar to: Finding Size of X86 instruction in MachineFunctionPass

The actual size of even a MC instruction will change during relaxation--we don't choose between 8-bit jumps and wider jumps until relaxation. You can get the actual encoding of an MCInst via MCCodeEmitter, but if you expect relaxation to occur, or particularly if you're testing before register allocation, the size could only be an estimate and shouldn't be trusted for exact size.

Dear All, I'm enhancing a MachineFunctionPass that enforces control-flow integrity. One of the things I want to do is to set the alignment of an instruction (by adding NOPs before it in the MachineBasicBlock or by emitting an alignment directive to the assembler) if it causes a specific sequence of bytes to be generated at a specific alignment. The goal is to ensure that sequences of

Hello, I am writing a MachineFunctionPass that inspects the generated machine code, and examines each opcode and its corresponding operands. If the 'instruction + operands' match a particular sequence, then the pass should replace them with a fixed instruction + operands sequence. I tried using MachineInstr's getOpcode and getOperand functions but the pass didn't work as expected.

On 10/23/12 7:19 PM, Craig Topper wrote: > What function provides the encoding length? X86 in particular is so > difficult to encode that only the old style JIT and the MC Code > Emitter could possibly know how many bytes something takes. The getSize() method of MCInstrDesc which can be fetched from a MachineInstr using the getDesc() method:

> On Jul 2, 2015, at 2:05 PM, Jim Grosbach <grosbach at apple.com> wrote: > >> >> On Jul 2, 2015, at 1:17 PM, Ethan J. Johnson <ejohns48 at cs.rochester.edu <mailto:ejohns48 at cs.rochester.edu>> wrote: >> >> Hi all, >> >> I am working on creating a MachineFunctionPass to perform an analysis on X86 code. After a bit of trouble, I was

What function provides the encoding length? X86 in particular is so difficult to encode that only the old style JIT and the MC Code Emitter could possibly know how many bytes something takes. On Tue, Oct 23, 2012 at 11:58 AM, John Criswell <criswell at illinois.edu>wrote: > Dear All, > > I'm enhancing a MachineFunctionPass that enforces control-flow integrity. > One of the

Hi all, I am working on creating a MachineFunctionPass to perform an analysis on X86 code. After a bit of trouble, I was able to get my pass compiling and running correctly in llc. However, since a machine pass is compiled directly into the code generator, rerunning "make" across the LLVM build tree involves re-linking most of the major libraries and executables. This is a rather

Hi, So, I run my pass in X86 target with llc command and it printed out "hello****". Now I am trying to do the same pass for ARM target. So I did exactly what I did for X86 as mentioned in my previous posts. When I run the following command: llc -march=arm test.ll -o test nothing prints out. I did the same for MIPS target too and I got no result. Can anyone tell me what I'm doing

Hello all, I need to modify llvm bytecode / native code just before it is emitted i.e. after all the regular operations and optimizations are done. I was told that this can be achieved by implementing a MachineFunctionPass. I searched the internet for some tutorials or some example MachineFunctionPass but found nothing. Kindly point some links, or anything that may help. Thank you. Regards,

Yes, I have done exactly the same. The wawanalyzer is the same. I changed ARM.h and ARMTargetMachine.cpp in the tager/arm folder. then I make tool/llc and lib folder. On Tue, Nov 17, 2015 at 10:55 AM, John Criswell <jtcriswel at gmail.com> wrote: > On 11/17/15 12:16 AM, fateme Hoseini via llvm-dev wrote: > > Hi, > So, I run my pass in X86 target with llc command and it printed

On 10/23/2012 1:58 PM, John Criswell wrote: > Dear All, > > I'm enhancing a MachineFunctionPass that enforces control-flow > integrity. One of the things I want to do is to set the alignment of > an instruction (by adding NOPs before it in the MachineBasicBlock or > by emitting an alignment directive to the assembler) if it causes a > specific sequence of bytes to be

On 3/18/16 12:33 PM, Quentin Colombet via llvm-dev wrote: > Hi Vivek, > >> On Mar 16, 2016, at 1:00 PM, vivek pandya via llvm-dev >> <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: >> >> Hello, >> >> Probably this may be too late to start thinking about this project >> but I think this is particularly useful

Thank you so much. That helped alot. Fami On Wed, Nov 4, 2015 at 9:40 AM, John Criswell <jtcriswel at gmail.com> wrote: > On 11/3/15 7:54 PM, fateme Hoseini wrote: > > Dear John, > Thank you so much for your help. I looked at those documents. Could you > kindly answer the following questions: > > Does it mean that I have to make my own backend target in order to write

Hi all, I am attempting to implement the "reaching definitions" data-flow algorithm on (X86) MachineBasicBlocks for an analysis pass. To do this, I need to compute gen/kill sets for machine basic blocks. To start with, I am only considering the general-purpose registers, RAX-R15 and their sub-registers. Thus, I need to examine each MachineInstr to determine which register(s) it

On Oct 23, 2012, at 6:22 PM, Joshua Cranmer <pidgeot18 at gmail.com> wrote: > On 10/23/2012 1:58 PM, John Criswell wrote: >> Dear All, >> >> I'm enhancing a MachineFunctionPass that enforces control-flow integrity. One of the things I want to do is to set the alignment of an instruction (by adding NOPs before it in the MachineBasicBlock or by emitting an alignment

Dear John, Thank you so much for your help. I looked at those documents. Could you kindly answer the following questions: Does it mean that I have to make my own backend target in order to write a machine pass even if I want to run a simple machinefunction pass? for example,if I want my pass to get MIPS instructions as an input, I have to copy all the files from mips target and add a file to it

Hi John Thanks for your suggestions, they all sound reasonable to me. The way I'm thinking right now is to write a MachineFuncionPass that iterate through each MachinBasicBlock, for each MBB, adds up the instructions counts of previous MBBs, that number multiply by 4 should be the offset of that MBB from its MachineFunction. In order to correctly count the instructions, this pass should be

On 2/27/15 6:30 PM, Ziqiang Patrick Huang wrote: > Hi, all > > Is there a way of getting the basic block offset from its parent > function ? At the LLVM IR level, no. At the code generator layer (MachineFunctionPass layer or the MC layer), probably yes. > > What I'm trying to do is to get an execution count of each basic > blocks, so I need to know the starting

Hello, Probably this may be too late to start thinking about this project but I think this is particularly useful feature for LLVM. A quick use I can think of this is Implementing Inter-procedural Register Allocation ( for Research purpose ). I have start looking at the code for MachineFunctionPass, I think currently MachineModule class is not available ( the project work will include that ) but

Hi, all Is there a way of getting the basic block offset from its parent function ? What I'm trying to do is to get an execution count of each basic blocks, so I need to know the starting address of each basic blocks. Obviously we can't get the absolute address before linking the program, but the offset relative to parent function should be available so I can take it and get the function