similar to: Question about Constant expressions

The attached patch includes no test-case and isn't consistent with the rest of the file: - constants should be on the right hand side of comparisons - the braces around your single line 'if' aren't needed. On Sun, Sep 15, 2013 at 2:39 PM, James Courtier-Dutton < james.dutton at gmail.com> wrote: > I attach a patch that fixes this bug. Applies to llvm 3.4svn > >

On Mon, Oct 28, 2013 at 10:09 AM, James Courtier-Dutton <james.dutton at gmail.com> wrote: > My guess is that this is a missed optimization, but in real life, all > projects i have worked fix this in the C or C++ code using macros that > change what instructions are used based on target platform and its > endedness. One reason for writing code like this, i.e. explicitly spelling

Hi, I am looking at the "LLVMOpInfoCallback GetOpInfo" callback. Example 1 GOOD: 41 c6 84 24 16 04 00 00 0c : movb $12, 1046(%r12) Makes calls to the callback with: Offset = 0x4, Size = 0x4 <- Octets: 16 04 00 00 Offset = 0x8, Size = 0x1 <- Octets: 0c That was correct. Example 2 BAD: c7 45 98 a1 ff ff ff : movl $4294967201, -104(%rbp) Makes calls to the callback

Test case attached. It is not a test case that works within the llvm test-suite yet, but it does demonstrate the problem. I would like some advice on how to modify this test_case so that it can be added to the automated llvm test cases. On 15 September 2013 23:02, David Majnemer <david.majnemer at gmail.com> wrote: > The attached patch includes no test-case and isn't consistent

On Sun, Apr 16, 2017 at 2:34 AM James Courtier-Dutton via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Hi, > > Did this work ever get done? There was a long thread about it back in 2015. > > I wish to use IRBuilder. > Is there any documentation? > How do I use the singular pointer type in GEP, LOAD, STORE instructions? > Sorry, no, the work is not complete - for

Hi, I think this is a very simple question, and it must just be missing something. I am looking for find out how to assign a constant integer value to the variable in llvm ir. The following returns 12, and %var2 = 12. ; ModuleID = 't.c' target datalayout =

On Mar 15, 2013 10:53 PM, "Óscar Fuentes" <ofv at wanadoo.es> wrote: > > James Courtier-Dutton <james.dutton at gmail.com> writes: > > > I think this is a very simple question, and it must just be missing something. > > > > I am looking for find out how to assign a constant integer value to > > the variable in llvm ir. > > > > The

I attach a patch that fixes this bug. Applies to llvm 3.4svn Please commit it please. Kind Regards James On 13 September 2013 17:46, James Courtier-Dutton <james.dutton at gmail.com>wrote: > Hi, > > I am looking at the "LLVMOpInfoCallback GetOpInfo" callback. > > Example 1 GOOD: > 41 c6 84 24 16 04 00 00 0c : movb $12, 1046(%r12) > > Makes

On 7 May 2012 16:31, John Criswell <criswell at illinois.edu> wrote: > On 5/7/12 5:47 AM, James Courtier-Dutton wrote: >> >> Hi, >> >> I am writing a decompiler. I was wondering if some of LLVM could be >> used for a decompiler. >> There are several stages in the decompiler process. >> 1) Take binary and create a higher level representation of it.

Hi, I know most compilers go from AST to CFG. I am writing a decompiler, so I was wondering if anyone knew of any documents describing how best to get from CFG to AST. The decompiler project is open source. https://github.com/jcdutton/libbeauty The decompiler already contains a disassembler and a virtual machine resulting in an annotated CFG. It uses information gained from using a virtual

Hi, I have the x86 SBB instruction. how should I represent this in LLVM IR. (as part of a decompiler from binary to LLVM IR) Pre-conditions: %eax = 0xffffffff %edx = 0xffffffff %carry = 1 SBB %eax, %edx // %edx is the destination doing %edx = %edx - (%eax + carry) JC jump_destination1 // If the Carry flag is set, jump to jump_destination1 How do I represent this correctly in LLVM

----- Original Message ----- > On Mon, Oct 28, 2013 at 10:09 AM, James Courtier-Dutton > <james.dutton at gmail.com> wrote: > > My guess is that this is a missed optimization, but in real life, > > all > > projects i have worked fix this in the C or C++ code using macros > > that > > change what instructions are used based on target platform and its >

I am getting the following error while compiling my pass file with clang to emit bitcode Hello1.cpp:1:10: fatal error: 'llvm/Pass.h' file not found #include "llvm/Pass.h" ^ 1 error generated. I had included this .cpp file for implementing function pass in lib/Transform/Hello1 directory and also made approriate changes in cmakelists.txt file and again build from the

I wrote up this optimization as an LLVM IR pass last month, actually: https://code.google.com/p/foster/source/browse/compiler/llvm/passes/BitcastLoadRecognizer.cpp It recognizes trees of `or' operations where the leaves are (buf[v+c] << c * sizeof(buf[0])). There are a few improvements needed to make it fit for general consumption; it assumes (without checking) that it's targeting

Hi, I am looking to decompile x86 ASM to LLVM IR. The original C is this: int test61 ( unsigned value ) { int ret; if (value < 1) ret = 0x40; else ret = 0x61; return ret; } It compiles with GCC -O2 to (rather cleverly removing any branches): 0000000000000000 <test61>: 0: 83 ff 01 cmp $0x1,%edi 3:

Hi, James, Thanks for your reply. I do not think it is always true, that "mul then add" is faster than "add then mul". For example, A small immediate can be directly encoded in the instruction, but it becomes a larger one after a multiplication, which has to be loaded from the constant pool (extra memory access). So I wonder, is it possile to prevent it, via changes

The following piece of IR is a fixed point for opt -std-compile-opts/-O3: --- target datalayout = "e-p:64:64:64-S128-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f16:16:16-f32:32:32-f64:64:64-f128:128:128-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64" target triple = "x86_64-unknown-linux-gnu" ; Function Attrs: nounwind readonly define i32 @get32Bits(i8*

On 12 March 2013 16:39, Óscar Fuentes <ofv at wanadoo.es> wrote: > > This is not possible, except for specific cases. > > Consider this code: > > long foo(long *p) { > ++p; > return *p; > } > > The X86 machine code would do something like > > add %eax, 4 > > for `++p', but for x86_64 it would be > > add %rax, 8 > > But you

On Mon, 6 May 2019 at 10:13, James Courtier-Dutton via llvm-dev <llvm-dev at lists.llvm.org> wrote: > Although the above is mentioning bytes, looking at the "/ 8" and "& 0x7" makes it look like the author meant octets and not bytes. > Bytes can be any size of bits. I don't think you'll have much luck trying to make that stick for a general audience,

Hi, I am writing a decompiler. I was wondering if some of LLVM could be used for a decompiler. There are several stages in the decompiler process. 1) Take binary and create a higher level representation of it. Like RTL. 2) The output is then broken into blocks or nodes, each block ends in a CALL, JMP, RET, or 2-way or multiway conditional JMP. 3) The blocks or nodes are then analyzed for