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Loop splitting is a compiler optimization technique. It attempts to simplify a loop or eliminate dependencies by breaking it into multiple loops which have the same bodies but iterate over different contiguous portions of the index range.
Loop-invariant code motion – this can vastly improve efficiency by moving a computation from inside the loop to outside of it, computing a value just once before the loop begins, if the resultant quantity of the calculation will be the same for every loop iteration (i.e., a loop-invariant quantity). This is particularly important with address ...
^c The ALGOL 68, C and C++ languages do not specify the exact width of the integer types short, int, long, and (C99, C++11) long long, so they are implementation-dependent. In C and C++ short , long , and long long types are required to be at least 16, 32, and 64 bits wide, respectively, but can be more.
Push the length (of type native unsigned int) of array on the stack. Object model instruction 0xFE 0x0C ldloc <uint16 (indx)> Load local variable of index indx onto stack. Base instruction 0x06 ldloc.0: Load local variable 0 onto stack. Base instruction 0x07 ldloc.1: Load local variable 1 onto stack. Base instruction 0x08 ldloc.2
Example of branch table in Wikibooks for IBM S/360; Examples of, and arguments for, Jump Tables via Function Pointer Arrays in C/C++; Example code generated by 'Switch/Case' branch table in C, versus IF/ELSE. Example code generated for array indexing if structure size is divisible by powers of 2 or otherwise.
Once this is done, everything is straightforward: the code continues by doing iterations of groups of eight instructions; this has become possible since the remaining number of iterations is a multiple of eight. [1] Duff's device provides a compact loop unrolling by using the case keyword both inside and outside the loop. This is unusual ...
Loop unrolling, also known as loop unwinding, is a loop transformation technique that attempts to optimize a program's execution speed at the expense of its binary size, which is an approach known as space–time tradeoff. The transformation can be undertaken manually by the programmer or by an optimizing compiler.
If n is greater than the length of the string then most implementations return the whole string (exceptions exist – see code examples). Note that for variable-length encodings such as UTF-8 , UTF-16 or Shift-JIS , it can be necessary to remove string positions at the end, in order to avoid invalid strings.