Примери коришћења Branch prediction на Енглеском и њихови преводи на Српски
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Scott McFarling proposed combined branch prediction in his 1993 paper.
Branch prediction attempts to guess whether a conditional jump will be taken or not.
The architecture implements predication,speculation, and branch prediction.
In particular, Spectre centers on branch prediction, which is a special case of speculative execution.
Branch prediction and branch target prediction are often combined into the same circuitry.
Other than this, RISC-V does not require branch prediction, but core implementations are allowed to add it.
The VAX 9000, announced in 1989, is both microprogrammed and pipelined,and performs branch prediction.
The Intel Pentium 4 accepts branch prediction hints, but this feature was abandoned in later Intel processors.
The Burroughs B4900, a microprogrammed COBOL machine released around 1982,was pipelined and used branch prediction.
The B4900 branch prediction history state is stored back into the in-memory instructions during program execution.
However, in addition to the IBM 3090,there are several other examples of microprogrammed designs that incorporated branch prediction.
Multiple Branch Prediction examines the program flow along several branches and predicts where the next instruction will be found in memory.
The first commercial RISC processors, the MIPS R2000 and R3000 andthe earlier SPARC processors, do only trivial"not-taken" branch prediction.
The B4900 implements 4-state branch prediction by using 4 semantically equivalent branch opcodes to represent each branch operator type.
Microprogrammed processors, popular from the 1960s to the 1980s and beyond,took multiple cycles per instruction, and generally did not require branch prediction.
Some processors allow branch prediction hints to be inserted into the code to tell whether the static prediction should be taken or not taken.
The Alpha 21264 and Alpha EV8 microprocessors used a fast single-cycle next-line predictor to handle the branch target recurrence andprovide a simple and fast branch prediction.
The trade-off between fast branch prediction and good branch prediction is sometimes dealt with by having two branch predictors.
Sometimes a designer focuses on improving performance by making significant improvements in CPI(with techniques such as out-of-order execution, superscalar CPUs, larger caches, caches with improved hit rates,improved branch prediction, speculative execution, etc.), while(hopefully) not sacrificing too much clock frequency-leading to a brainiac CPU design.
First, it shows that branch prediction logic in modern processors can be trained to reliably hit or miss based on the internal workings of a malicious program.
The early implementations of SPARC and MIPS(two of the first commercial RISC architectures)used single-direction static branch prediction: they always predict that a conditional jump will not be taken, so they always fetch the next sequential instruction.
Branch prediction became more important with the introduction of pipelined superscalar processors like the Intel Pentium, DEC Alpha 21064, the MIPS R8000, and the IBM POWER series.
As is usual for this class of CPU,the K8 has fairly complex branch prediction, with tables that help predict whether branches are taken and other tables which predict the targets of branches and jumps.
Sometimes a designer focuses on improving performance by making significant improvements in CPI(with techniques such as out-of-order execution, superscalar CPUs, larger caches, caches with improved hit rates,improved branch prediction, speculative execution, etc.), while(hopefully) not sacrificing too much clock frequency- leading to a brainiac CPU design.
The later, R4000 uses the same trivial"not-taken" branch prediction, and loses two cycles to each taken branch because the branch resolution recurrence is four cycles long.
Without branch prediction, the processor would have to wait until the conditional jump instruction has passed the execute stage before the next instruction can enter the fetch stage in the pipeline.
Spectre is a vulnerability that affects modern microprocessors that perform branch prediction.[1][2][3] On most processors, the speculative execution resulting from a branch misprediction may leave observable side effects that may reveal private data to attackers.
Static branch prediction added to pipeline Optional level-2 cache 64-bit or 128-bit path to AMBA AHB interface Higher performance possible(claimed by manufacturer: 1.7 DMIPS/MHz as opposed to 1.4 DMIPS/MHz of LEON3) Rad hardened.[1].
If the hardware determines that the branch prediction state of a particular branch needs to be updated, it rewrites the opcode with the semantically equivalent opcode that hinted the proper history.