Unrool基本的步骤是:确定induction variable以及每次迭代增加的值,展开loop body,确定要展开的次数,然后进行复制。 Unrooll and jam 就是Unroll 外部的循环,jam内部的循环,比如: for(inti=0;i<2*n;i++)for(intj=0;j<m;j++)a[i]=a[i]+b[j];// 先runrollfor(inti=0;i<2*n;i+=2){for(intj=...
最后,当分布后,每个小循环可以由编译器进一步单独优化。 3.4 循环展开和融合(Loop Unroll and Jam) 要执行这种转换,首先需要展开外循环,然后将多个内循环融合在一起,如下面清单所示。这种转换增加了内循环的ILP(指令级并行性),因为内循环中执行了更多的独立指令。在代码示例中,内循环是一个归约操作,它累积数组a和...
coder.loop.unrollAndJam("loopID",unrollFactor)prompts the code generator to unroll and jam the loop with index nameloopIDby a factor specified byunrollFactorin the generated code. Unroll and jam transforms are usually applied to perfectly nested loops, which are loops where all data elements ar...
包括Loop Unswitching:减少分支跳转的执行次数;Loop unroll-and-jam:改善内存和 cache 局部性及利用率;Loop Fusion:直接复用其他循环中的值,暴露更多的指令调度机会;Loop Distribution:减少循环中的寄存器压力,暴露更多的矢量化机会;Loop Unrolling:可以减少动态的指令数量,发现更多的优化机会点,比如数据复用,范围更广的...
LastValueMap[VI->first] = VI->second; } 开发者ID:jaredmcneill,项目名称:netbsd-src,代码行数:67,代码来源:LoopUnrollAndJam.cpp 示例12: while ▲点赞 1▼ /// CloneLoop - Clone Loop. Clone dominator info. Populate ValueMap/// using old blocks to new blocks mapping....
開發者ID:jaredmcneill,項目名稱:netbsd-src,代碼行數:101,代碼來源:LoopUnrollAndJam.cpp 注:中的ScalarEvolution::getLoopDisposition方法示例由純淨天空整理自Github/MSDocs等開源代碼及文檔管理平台,相關代碼片段篩選自各路編程大神貢獻的開源項目,源碼版權歸原作者所有,傳播和使用請參考對應項目的License...
Besides straightforward loop unrolling, another unrolling variant known as “loop unroll and jam” can be quite effective if you have multiple nested loops and enough registers still available. This is a key technique that I used to achieve massive performance gains in our Coulomb potential kernels...
Unroll and jam is a loop transformation that unrolls an outer loop by a factor and then fuse/merge (jam) the inner loops resultant from the outer loop unrolling. The following example shows an unrolling of 2 × and a jam which results in two stores of the y array per iteration of the...
5.6.13 Unroll and Jam Unroll and jam is a loop transformation that unrolls an outer loop by a factor and then fuse/merge (jam) the inner loops resultant from the outer loop unrolling. The following example shows an unrolling of 2 × and a jam which results in two stores of the y arr...
unroll-and-jam at last generate SIMD code using SLP(superword level parallelism) algorithm.The test results on Intel platform show that the average speedup factor of some numerical/video/communication kernels achieved by this approach is 2.13/1.41,better than the innermost loop vectorization and ...