Some basic questions about JIT-Compiler and installation
There are 3 JIT compilers and even the new RyuJIT. Pre-JIT :compiles complete source code into native code in a single compilation cycle. This is done at the time of deployment of the application. Econo-JIT :compiles only those methods that are called at runtime. However, these compiled methods are removed...
Differences of x86 and x86-64 machine code
assembly,x86,x86-64,jit,machine-code
There's actually no difference between the old 32bit push and the new 64bit push, that's one of the few instructions that are implicitly 64bit. Relative branches and calls still use 32bit offsets. Some actual differences are: the REX prefix, obviously, for extra registers (also remember sil and dil - a...
How does JIT compilation actually execute the machine code at runtime?
compiler-construction,compilation,llvm,jit,machine-code
You mentioned that you played around with assembly so you have some idea how that works, good. Imagine that you write code that allocates a buffer (ex: at address 0x75612d39). Then your code saves the assembly ops to that buffer to pop a number from the stack, the assembly to...
How do I know what registers function parameters will be mapped on?
When you call a function, the compiler doesn't normally* have a choice about where to put the arguments for the call. This is dictated by the ABI. If your host program is written in C++ and runs on a Linux/x86-64 machine, it will generally emit code that conforms to the...
JMockit: Mocked apis are getting reverted after somtime
java,bytecode,jit,jmockit,java-bytecode-asm
This happens because the JIT optimizer in the JVM does not check for redefined methods (redefinition is done through a different subsystem in the JVM). So, eventually the JVM decides to optimize the code containing the call to System.currentTimeMillis(), inlining the call to the native Java method so that it...
Cross fading two jit.windows with opengl content
I assume that you want the OpenGL content to end up in the same output window as the web cam capture. I would advise sending the matrix from the webcam input to a jit.gl.texture object, then rendering it with a jit.gl.videoplane, like so: ----------begin_max5_patcher---------- 348.3ocwSsraCCBD7L9q.wYWKamG8wo7eTEEgsWkPDFr.bhihx+dMKFklFop V0V0Kf2gcmc7vx4DBqRO.VF8E5qTB4bBgfPd.xTLg0xGpkbKlFSAG0U6Yogi bvfCg2KbYakYGDMftSxU.ck+rdCPOBU071XEp9VgRBNjshqf5dWDsbBsi6p2 ITa2XfZWPiKVjkmRKJCaOOyuUVlkSWOUi0cRBnhhMTzfgih9gYQrPybm5f.s...
Why use JMH if you can switch off JIT?
TL;DR; Assess the Formula 1 performance by riding a bycicle at the same track. The question is very odd, especially if you ask yourself a simple follow-up question. What would be the point of running the benchmark in the conditions that are drastically different from your production environment? In other...
How do you go about knowing what is happening in a JIT'ed code?
debugging,firefox,reverse-engineering,jit,disassembling
or something else is wrong with my understanding Yes: something else is wrong with your understanding. Sections (such as .text and .data) only make sense at static link time (the static linker groups .text from multiple .o files together into a single .text in the final executable). They are...
Dynamically loading Jar file in java
In past experience, the JVM will not attempt to compile a class until needed. If a class refers to another class then that other class will also be compiled. Where it is located in the classpath, Jar A or Jar B is not relevant to compilation. Despite the long history...
Can Java compiler optimize adding to a set in recursive methods
java,optimization,recursion,compiler-construction,jit
The question is, do I need to do option two if I'm worried about optimizing this sort of method? Definitely yes. If performance is a concern (and most of the time it is not!), then you need it. The compiler optimizes a lot but on a very different scale....
Is there a way to set break point to make program stop at call instruction to a particular function?
I want that the debugger should break before taking that branch But why? Stopping before the branch is taken (as opposed to stopping immediately after) provides you absolutely no additional info. As Iwillnotexist Idonotexist correctly pointed out, there are many ways to CALL a given function, e.g. CALL 0x8(%rax)...
What is a de-reflection optimization in HotSpot JIT and how does it implemented?
java,optimization,jvm,jit,jvm-hotspot
Yes, there is an optimization to reduce Reflection costs, though it is implemented mostly in Class Library rather than in JVM. Before Java 1.4 Method.invoke worked through a JNI call to VM runtime. Each invocation required at least two transitions from Java to Native and back to Java. The VM...
Comparing two byte arrays guarding against timing attacks
c#,.net,arrays,jit,timing-attack
You can use the MethodImplAttribute-Class of the System.Runtime.CompilerServices namespace with the MethodImplOptions.NoOptimization option like this: [MethodImpl(MethodImplOptions.NoOptimization)] static bool AreEqual(byte[] a1, byte[] a2) { // ... } ...
clang+llvm provides a bad function pointers for JIT compiled functions
This assignment is incredibly messed up: *(int **) (&funcPtr) = *(int **) fPtr; Not only does it violate strict-aliasing to write an int* and then use it as a function pointer on the next line, but a data pointer is often not large enough to hold an entire code pointer....
Trouble with speeding up functions with numba JIT
Simply, numba doesn't know how to convert np.arange into a low level native loop, so it defaults to the object layer which is much slower and usually the same speed as pure python. A nice trick is to pass the nopython=True keyword argument to jit to see if it can...
Inter segment distance using numba jit, Python
Here's my version of your code which is significantly faster: @jit(nopython=True) def dot(a,b): res = a[0]*b[0]+a[1]*b[1]+a[2]*b[2] return res @jit def compute_stuff2(array_to_compute): N = array_to_compute.shape[0] con_mat = np.zeros((N,N)) p0 = np.zeros(3) p1 = np.zeros(3) q0 = np.zeros(3) q1 = np.zeros(3) p0m1 = np.zeros(3) p1m0 = np.zeros(3) q0m1 = np.zeros(3) q1m0 =...
Compiler time in ipython3
IPython does not implement any kind of JIT compiler. 'Compiler time' represents the time for Python to compile your textual code to Python bytecode. I was surprised by your timing - it's a very simple expression, and should take almost no time to compile. IPython doesn't report the compiler time...
Are deterministically unchangable Actions, and Funcs Inlined by the JIT?
c#,optimization,inline,compiler-optimization,jit
Non optimization itself is related to fact that it's not a function itself that matters, but the code they execute. You assign a const reference to action, but there is no any guarantee that the code executed by them is not mutable and/or is able produce constant behavior. If you...
Clarification regarding traditional interpreter,Compiler and JIT compiler/Interpreter (JAVA)
java,compilation,interpreter,jit
Disclaimer: Take all of this with a grain of salt; it's pretty oversimplified. 1: You are correct in that the computer itself doesn't understand the code, which is why the JVM itself is needed. Let's pretend XY means "add the top two elements on the stack and push the result"....
Why the disassembler plugin doesn't work in this case?
java,assembly,jvm,jit,disassembling
Only the "just-in-time-compiled" code is displayed, as that is the only thing that is assembler, the rest is interpreted byte code. For the initial program, there was so little work to do that nothing was compiled, i.e. everything merely interpreted. The more loops and stuff you do in the program,...
Clarifications on JIT Compiler and Interpreter
1) It's always said JIT=runtime, why doesn't an Interpreter work at runtime? Doesn't an Interpreter translate and execute each line at runtime, while the program is running? You are correct; interpretation necessarily occurs at run time. 2) It's always said JIT translates a non-native code to native-code, so what?...
Some questions about the usage of MethodImpl Attribute
MSDN: Unmanaged The method is implemented in unmanaged code. This means the method body is in unmanaged code, not that it will get compiled to it. This flag is used in C++/CLI assemblies. I'd say don't use this attribute, the JIT should handle inlining by itself, when needed (as it...
Will JVM optimization break down my code?
As pointed out by @yshavit Because the File methods are going to eventually end up as OS calls, and the JVM can't assume those don't have side effects (and aren't affected by state other than their arguments) so, the JVM will not optimize the code involving if(!file.exists() || !file.isDirectory()) by...
When does a numba function compile?
python,multithreading,jit,numba
Unless I'm missing something, your two examples are exactly equivalent, not because of anything numba does (or doesn't do), but because that's how decorators work. I'll explain the general principle and you can double-check whether that's the transformation you are asking about. This code: @d(arg) def f(x): ... is by...
C: Dynamic Code Generation/Compilation Options [closed]
c++,c,licensing,jit,software-distribution
Given your requirements you should take a serious look at LCC (code). It's a compact, well written, and easy to work with ANSI-C compiler with a retargetable back end. It includes code generators for DEC ALPHA, SPARC, MIPS R3000, and X86 (Windows 95/98/NT and Linux) which are a breeze to...
IL optimization for JIT compilers
The two patterns yo described are the easy stuff that the JIT actually gets right (except for non-primitive structs). In SSA form constant propagation and elimination of dead values is very easy. No, you have to test what the JIT can do. Look into compiler literature to see what...
Java 8 JIT thread seems like falling into infinite loop
It indeed looks like a JIT compiler bug, presumably in allocation elimination optimization. Try running with -XX:-EliminateAllocations JVM option. You may also add -XX:+UnlockDiagnosticVMOptions -XX:+LogCompilation to produce detailed compilation log with a separate output file per compiler thread....
Does jitting happen every time a .NET application runs?
The assemblies are jitted piecemeal, as needed. Your question seems to imply that the whole application is jit compiled at once. That's not what happens. The parts that have been jitted at any particular moment in time are in memory. JIT compilation takes into account the fact that some code...
Where does the JIT compiled code reside?
HotSpot JVM has a Method structure in Metaspace (or PermGen in earlier versions). It contains method bytecode which is never overwritten and a pointer to compiled code, initially NULL until the method is compiled. A method may have multiple entry points: _i2i_entry - a pointer to the bytecode interpreter. _code->entry_point()...
Is there a C C++ C# compiler that compiles to machine code [closed]
All C/C++ compilers compile to native machine code, that's why you can directly address memory, have inline assembler, and care about sizeof(int) on the system you are compiling for.
How local variable usage infomation is maintained in .net clr source code
.net,garbage-collection,clr,jit
Disclaimer: I'm no expert on the CLR or RyuJIT. I may be completely wrong about all of this. I came across the following section in the RyuJIT chapter of the Book of the Runtime: For lvlVars with tracked lifetimes, or for expression involving GC references, we report the range over...
TargetedPatchingOptOut and other attributes on abstract methods
c#,.net,implementation,abstract,jit
Whether an attribute is visible on a derived class by default is determined by the AttributeUsageAttribute.Inherited property. Which is false for this attribute: [AttributeUsage(AttributeTargets.Method | AttributeTargets.Constructor, AllowMultiple = false, Inherited = false)] public sealed class TargetedPatchingOptOutAttribute : Attribute { // etc... } It is not exclusive, a method like Type.GetCustomAttribute()...
Does .Net Framework Class libraries in GAC compile each time to Native Code ? Or will it load directly from Native Image Directory ?
Yes, framework libraries are not jitted. They will be loaded from the native images cache. You can verify this yourself by inspecting the loaded assemblies path. Tools like process explorer can be used to view the loaded assemblies for the process. For example : In my machine mscorlib happens to...
C++ and a safe way to jump out of dynamically generated code
Is it theoretically and practically safe to use longjmp/setjmp instead, provided setjmp is set right before calling a dynamically generated function, and provided that longjmp never propagates through C++ functions that rely on RAII (I must make sure that none of runtime helpers implemented in C++ make use of...
Do more methods mean the code is less performant?
You're right in one sense. There's some nuance, though. Do more methods, even if they are not called, have an affect on the performance of a particular class... "Performance" usually refers to speed of execution of the program. Code that is never executed will never (directly) consume any CPU time....
MSIL to Native code stored
The JIT compiler compiles your code when you start the application and stores it in memory. This code can be cached by ngen.exe (Native Image Generator) and stored in the native image cache. This will be automatically loaded the next time you start the application, and you won't have to...
How to disable intrinsics usage for the JIT compiler?
Use java -XX:+UnlockDiagnosticVMOptions -XX:DisableIntrinsic=_<method_name>[,...] For example java -XX:+UnlockDiagnosticVMOptions -XX:DisableIntrinsic=_equals,_hashCode As @apangin noticed, you may use -XX:+PrintIntrinsics first to see which methods are actually intrinsified in your test and disable them....
Numba's jit fails to compile function that has another function as input
You're right in thinking that numba doesn't recognise fdot as a numba compiled function. I don't think you can make it recognise it as a function argument, but you can use this approach (using variable capture so fdot is known when the function is built) to build an ODE solver:...
Does the Hotspot JVM Compile the code to machine code or simply runs it
Meaning we won't have machine code precompiled. The above sentence of yours indicates your misunderstanding of what the JIT compiler is. It doesn't compile code ahead of time, but just in time, hence its name. This makes the rest of your question harder to understand because the "HotSpot compiler"...