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path: root/llvm/lib/Transforms/Scalar/LoopUnrollAndJamPass.cpp
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* [UnJ] Improve explicit loop count checksDavid Green2018-08-111-52/+67
| | | | | | | | | | | | | Try to improve the computed counts when it has been explicitly set by a pragma or command line option. This moves the code around, so that first call to computeUnrollCount to get a sensible count and override that if explicit unroll and jam counts are specified. Also added some extra debug messages for when unroll and jamming is disabled. Differential Revision: https://reviews.llvm.org/D50075 llvm-svn: 339501
* [UnrollAndJam] New Unroll and Jam passDavid Green2018-07-011-0/+447
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a simple implementation of the unroll-and-jam classical loop optimisation. The basic idea is that we take an outer loop of the form: for i.. ForeBlocks(i) for j.. SubLoopBlocks(i, j) AftBlocks(i) Instead of doing normal inner or outer unrolling, we unroll as follows: for i... i+=2 ForeBlocks(i) ForeBlocks(i+1) for j.. SubLoopBlocks(i, j) SubLoopBlocks(i+1, j) AftBlocks(i) AftBlocks(i+1) Remainder Loop So we have unrolled the outer loop, then jammed the two inner loops into one. This can lead to a simpler inner loop if memory accesses can be shared between the now jammed loops. To do this we have to prove that this is all safe, both for the memory accesses (using dependence analysis) and that ForeBlocks(i+1) can move before AftBlocks(i) and SubLoopBlocks(i, j). Differential Revision: https://reviews.llvm.org/D41953 llvm-svn: 336062
* Revert 333358 as it's failing on some builders.David Green2018-05-271-441/+0
| | | | | | I'm guessing the tests reply on the ARM backend being built. llvm-svn: 333359
* [UnrollAndJam] Add a new Unroll and Jam passDavid Green2018-05-271-0/+441
This is a simple implementation of the unroll-and-jam classical loop optimisation. The basic idea is that we take an outer loop of the form: for i.. ForeBlocks(i) for j.. SubLoopBlocks(i, j) AftBlocks(i) Instead of doing normal inner or outer unrolling, we unroll as follows: for i... i+=2 ForeBlocks(i) ForeBlocks(i+1) for j.. SubLoopBlocks(i, j) SubLoopBlocks(i+1, j) AftBlocks(i) AftBlocks(i+1) Remainder So we have unrolled the outer loop, then jammed the two inner loops into one. This can lead to a simpler inner loop if memory accesses can be shared between the now-jammed loops. To do this we have to prove that this is all safe, both for the memory accesses (using dependence analysis) and that ForeBlocks(i+1) can move before AftBlocks(i) and SubLoopBlocks(i, j). Differential Revision: https://reviews.llvm.org/D41953 llvm-svn: 333358
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