User:Awesomeclaw/Code-Block Reordering

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Code Block Reordering

Code-Block Reordering is a compiler optimisation which involves re-ordering the basic blocks of a region of machine code in order to improve performance. A Code-Block Reordering pass is present in most modern optimising compilers and compiler frameworks including GCC and LLVM.

Benefits

Most modern computer processors include Instruction Cache. Instruction Caches increase the rate at which instructions can be executed by reducing the cost of fetching instructions, while Branch Predictors attempt to speculate on the direction taken by branches and other control flow instructions.

Many systems also include Branch Prediction units, which seek to predict which path will be taken by control flow instructions such as branches. By default, many branch predictors will predict that a branch is 'not taken', i.e. the instructions directly after the control flow instruction will be executed.

References

Category:Compiler optimizations Category:Data-flow analysis

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v t e Compiler optimizations
Basic block	Peephole optimization Local value numbering
Loop	Automatic parallelization Automatic vectorization Induction variable Loop fusion Loop-invariant code motion Loop inversion Loop interchange Loop nest optimization Loop splitting Loop unrolling Loop unswitching Software pipelining Strength reduction
Data-flow analysis	Available expression Common subexpression elimination Constant folding Dead store elimination Induction variable recognition and elimination Live-variable analysis Upwards exposed uses Use-define chain Reaching definitions
SSA-based	Global value numbering Sparse conditional constant propagation
Code generation	Instruction scheduling Instruction selection Register allocation Rematerialization
Functional	Deforestation Tail-call elimination
Global	Interprocedural optimization
Other	Bounds-checking elimination Compile-time function execution Dead-code elimination Expression templates Inline expansion Jump threading Partial evaluation Profile-guided optimization
Static analysis	Alias analysis Array-access analysis Control-flow analysis Data-flow analysis Dependence analysis Escape analysis Pointer analysis Shape analysis Value range analysis