How deeply does Hacking Cryptography cover branch prediction?

Demonstrates prediction patterns, compares timings, and reaches CMOV-based code, but does not detail predictor hardware internals.

Branch prediction

As explained in Hacking Cryptography

Branch prediction is a processor mechanism that forecasts the outcome or target of a control-flow branch to keep instruction execution supplied.

Branch prediction forecasts which control-flow path a conditional branch will take, helping the processor keep execution supplied. Predictable patterns run faster than irregular ones, so secret-dependent branches can make runtime vary with data. section 10.5

Summing values above a threshold

A C loop summing values above 500 runs two to three times faster on a sorted 100-million-element array than on an unsorted array of the same size. Sorting produces long runs of not-taken and taken branches, while unsorted data produces an irregular pattern. section 10.5

Avoid data-dependent control-flow variation when constant-time behavior matters:

Replace the conditional branch with a conditional move where appropriate; CMOV updates a value according to a comparison without diverging into separate code paths. section 10.5

How Hacking Cryptography covers it

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100 Go Mistakes and How to Avoid ThemBranch prediction is a processor technique that forecasts the outcome of a conditional branch so subsequent instructions can be executed speculatively.

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Related concepts

control hazardaddresses · A control hazard is an instruction-execution dependency caused by a conditional branch whose outcome determines subsequent instructions.
CPUuses · A central processing unit (CPU) is a general-purpose processor that executes computer instructions and performs computational operations.
hardwarepart of · Hardware is the physical equipment and components of a computing system that provide resources for computation and software execution.
branchaddresses · Branching is the selection among alternative execution paths according to a condition, outcome, or program state.

This explainer was generated by Manning's knowledge graph from the text of Hacking Cryptography. The section links point to the parts of the book it draws on.