llvm-project/llvm/test/Transforms/HardwareLoops
Florian Hahn ee1c12708a [SCEV] If Start>=RHS, simplify (Start smin RHS) = RHS for trip counts.
In some cases, it seems like we can get rid of unnecessary s/umins by
using information from the loop guards (unless I am missing something).

One place where this seems to be helpful in practice is when computing
loop trip counts. This patch just changes howManyGreaterThans for now.
Note that this requires a loop for which we can check 'is guarded'.

On SPEC2000/SPEC2006/MultiSource, there are some notable changes for
some programs in the number of loops unrolled and trip counts computed.

```
Same hash: 179 (filtered out)
Remaining: 58
Metric: scalar-evolution.NumTripCountsComputed

Program                                        base    patch   diff
 test-suite...langs-C/compiler/compiler.test    25.00   31.00  24.0%
 test-suite.../Applications/SPASS/SPASS.test   2020.00 2323.00 15.0%
 test-suite...langs-C/allroots/allroots.test    29.00   32.00  10.3%
 test-suite.../Prolangs-C/loader/loader.test    17.00   18.00   5.9%
 test-suite...fice-ispell/office-ispell.test   253.00  265.00   4.7%
 test-suite...006/450.soplex/450.soplex.test   3552.00 3692.00  3.9%
 test-suite...chmarks/MallocBench/gs/gs.test   453.00  470.00   3.8%
 test-suite...ngs-C/assembler/assembler.test    29.00   30.00   3.4%
 test-suite.../Benchmarks/Ptrdist/bc/bc.test   263.00  270.00   2.7%
 test-suite...rks/FreeBench/pifft/pifft.test   722.00  741.00   2.6%
 test-suite...count/automotive-bitcount.test    41.00   42.00   2.4%
 test-suite...0/253.perlbmk/253.perlbmk.test   1417.00 1451.00  2.4%
 test-suite...000/197.parser/197.parser.test   387.00  396.00   2.3%
 test-suite...lications/sqlite3/sqlite3.test   1168.00 1189.00  1.8%
 test-suite...000/255.vortex/255.vortex.test   173.00  176.00   1.7%

Metric: loop-unroll.NumUnrolled

Program                                        base   patch  diff
 test-suite...langs-C/compiler/compiler.test     1.00   3.00 200.0%
 test-suite.../Applications/SPASS/SPASS.test   134.00 234.00 74.6%
 test-suite...count/automotive-bitcount.test     3.00   4.00 33.3%
 test-suite.../Prolangs-C/loader/loader.test     3.00   4.00 33.3%
 test-suite...langs-C/allroots/allroots.test     3.00   4.00 33.3%
 test-suite...Source/Benchmarks/sim/sim.test    10.00  12.00 20.0%
 test-suite...fice-ispell/office-ispell.test    21.00  25.00 19.0%
 test-suite.../Benchmarks/Ptrdist/bc/bc.test    32.00  38.00 18.8%
 test-suite...006/450.soplex/450.soplex.test   300.00 352.00 17.3%
 test-suite...rks/FreeBench/pifft/pifft.test    60.00  69.00 15.0%
 test-suite...chmarks/MallocBench/gs/gs.test    57.00  63.00 10.5%
 test-suite...ngs-C/assembler/assembler.test    10.00  11.00 10.0%
 test-suite...0/253.perlbmk/253.perlbmk.test   145.00 157.00  8.3%
 test-suite...000/197.parser/197.parser.test    43.00  46.00  7.0%
 test-suite...TimberWolfMC/timberwolfmc.test   205.00 214.00  4.4%
 Geomean difference                                           7.6%
```

Fixes https://bugs.llvm.org/show_bug.cgi?id=46939
Fixes https://bugs.llvm.org/show_bug.cgi?id=46924 on X86.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D85046
2020-08-03 17:22:42 +01:00
..
ARM [HardwareLoops] llvm.loop.decrement.reg definition 2020-05-21 10:48:16 +01:00
loop-guards.ll
scalar-while.ll [SCEV] If Start>=RHS, simplify (Start smin RHS) = RHS for trip counts. 2020-08-03 17:22:42 +01:00
sibling-loops.ll [HardwareLoops] Add sibling loop test. 2020-07-15 16:36:17 +01:00
unconditional-latch.ll
unscevable.ll