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c++ Programming Glossary: instructionWhy is processing a sorted array faster than an unsorted array? http://stackoverflow.com/questions/11227809/why-is-processing-a-sorted-array-faster-than-an-unsorted-array an if statement At the processor level it is a branch instruction You are a processor and you see a branch. You have no idea which.. do you do You halt execution and wait until the previous instructions are complete. Then you continue down the correct path. Modern..
What is “cache-friendly” code? http://stackoverflow.com/questions/16699247/what-is-cache-friendly-code several levels of cache within the CPU chip L1 L2 L3 instruction caches ... RAM HDDs armed with their own caches and so forth...
Constants and compiler optimization in C++ http://stackoverflow.com/questions/212237/constants-and-compiler-optimization-in-c the object's value directly into the machines instruction opcodes complete elimination of code that can never be reached..
How does C compute sin() and other math functions? http://stackoverflow.com/questions/2284860/how-does-c-compute-sin-and-other-math-functions in assembly. It simply uses the FPU's built in fsin instruction. Source sysdeps i386 fpu s_sin.S fdlibm's implementation of..
Why is volatile not considered useful in multithreaded C or C++ programming? http://stackoverflow.com/questions/2484980/why-is-volatile-not-considered-useful-in-multithreaded-c-or-c-programming by another thread probably using an appropriate machine instruction the reading thread sees this situation in the same way it sees.. preparing the data so all looks fine. But what if the instructions are reordered so the flag is set first volatile does guarantee..
How to use Boost in Visual Studio 2010 http://stackoverflow.com/questions/2629421/how-to-use-boost-in-visual-studio-2010 boost download and set up the environment variables. The instruction below set the environment variables for Visual Studio only and.. a movie or 2 .... Go through steps 2 6 from the set of instruction above to set the environment variables. Edit the Library Directories.. boost libraries output. The default for the example and instructions above would be C boost_1_47_0 stage lib . Rename and move the..
Optimizing away a “while(1);” in C++0x http://stackoverflow.com/questions/3592557/optimizing-away-a-while1-in-c0x any form of parallel processing including separate VLIW instruction streams. EDIT Dumb example while complicated_condition x complicated_but_externally_invisible_operation..
What can I use to profile C++ code in Linux? http://stackoverflow.com/questions/375913/what-can-i-use-to-profile-c-code-in-linux the same information because 1 they don't summarize at the instruction level and 2 they give confusing summaries in the presence of.. is that the time that would be saved by removal of an instruction is approximated by the fraction of samples containing it regardless.. explanation of how it works. Suppose there is some instruction I call or otherwise which is on the call stack some fraction..
When to use volatile with multi threading? http://stackoverflow.com/questions/4557979/when-to-use-volatile-with-multi-threading hardware signal handlers and the setjmp machine code instruction. This makes volatile directly applicable to systems level programming.. that occurs before a write to a volatile object in the instruction sequence will occur before that volatile write in the compiled.. object that occurs after a read of volatile memory in the instruction sequence will occur after that volatile read in the compiled..
Operator Precedence vs Order of Evaluation http://stackoverflow.com/questions/5473107/operator-precedence-vs-order-of-evaluation as some DSPs allow a compiler to designate a number of instructions to be executed in parallel. Most VLIW machines have a specific.. executed in parallel. Most VLIW machines have a specific instruction packet size that limits the number of instructions executed.. specific instruction packet size that limits the number of instructions executed in parallel. The Itanium also uses packets of instructions..
Accessing class members on a NULL pointer http://stackoverflow.com/questions/669742/accessing-class-members-on-a-null-pointer will get called so it can generate a CALL machine code instruction to go directly to the desired function. It simply passes a pointer..
I've heard i++ isn't thread safe, is ++i thread-safe? http://stackoverflow.com/questions/680097/ive-heard-i-isnt-thread-safe-is-i-thread-safe far as I can tell this would reduce to a single assembly instruction such as 'add r1 r1 1' and since it's only one instruction it'd.. instruction such as 'add r1 r1 1' and since it's only one instruction it'd be uninterruptable by a context switch. Can anyone clarify.. safe on my imaginary CPU that has no memory increment instructions. Or it may be smart and compile it into lock disable task switching..
Building GMP library with Visual Studio? http://stackoverflow.com/questions/1017058/building-gmp-library-with-visual-studio
http://stackoverflow.com/questions/12135518/is-faster-than tricky to answer but here's what I can give In the Intel Instruction Set Reference they are all grouped together under one common..
Heisenbug: WinApi program crashes on some computers http://stackoverflow.com/questions/132116/heisenbug-winapi-program-crashes-on-some-computers at 0x0044a26a in CintaNotes.exe 0xC000001D Illegal Instruction. and code breaks on 0044A26A cvtsi2sd xmm1 dword ptr esp 14h.. the problem was in the Code Generation Enable Enhanced Instruction Set compiler option. It was set to arch SSE2 and was crashing..
Vectors and polymorphism in C++ http://stackoverflow.com/questions/16126578/vectors-and-polymorphism-in-c Its simplified form is something like this class Instruction public virtual void execute class Add public Instruction private.. Instruction public virtual void execute class Add public Instruction private int a int b int c public Add int x int y int z a x b.. one class I do something like... void some_method vector Instruction v Instruction i new Add 1 2 3 v.push_back i And in yet another..
http://stackoverflow.com/questions/3576292/create-linux-make-build-file no prerequisite or if older that any of the prerequisites. Instruction An Instruction is shell commands starting with one tab. Each.. or if older that any of the prerequisites. Instruction An Instruction is shell commands starting with one tab. Each instruction line..
How to check if a CPU supports the SSE3 instruction set? http://stackoverflow.com/questions/6121792/how-to-check-if-a-cpu-supports-the-sse3-instruction-set info for id 1 if nIds 1 __cpuid CPUInfo 1 bool bSSE3NewInstructions CPUInfo 2 0x1 false return bSSE3NewInstructions return false.. bSSE3NewInstructions CPUInfo 2 0x1 false return bSSE3NewInstructions return false c sse instruction set avx cpuid share improve.. nIds info 0 cpuid info 0x80000000 int nExIds info 0 Detect Instruction Set if nIds 1 cpuid info 0x00000001 MMX info 3 int 1 23 0 SSE..
Optimizations for pow() with const non-integer exponent? http://stackoverflow.com/questions/6475373/optimizations-for-pow-with-const-non-integer-exponent the underestimate. Average the above one addps one mulps . Instruction tally fourteen including two conversions with latency 5 and..
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