[PATCH] D19338: New code hoisting pass based on GVN (optimistic approach)

[Sebastian Pop via llvm-commits]

sebpop added a comment.

The following experiments were performed with the last posted patch on an intel i7-4790K 4.4GHz x86_64-linux.

- SPEC 2006 run 3 times in validation mode: the improvements are all in the INT part of the benchmark (we discarded everything less than +/-0.5% as noise.)

433.milc: 0
444.namd: 0
447.dealII: 0
450.soplex: 0
453.povray: 0
470.lbm: 0
482.sphinx3: 0
400.perlbench: 1.5
401.bzip2: 1.3
403.gcc: 0
429.mcf: 0
445.gobmk: 0
456.hmmer: 0
458.sjeng: 0
462.libquantum: 1.1
464.h264ref: 0
471.omnetpp: 1
473.astar: 1.5

- On the SPEC 2006 we have the following compile time statistics:

Number of call sites deleted, not inlined: 406 (+0)
Number of functions deleted because all callers found: 70492 (+0)
Number of functions inlined: 202127 (-5)
Number of allocas merged together: 225 (+0)
Number of caller-callers analyzed: 225239 (-13)
Number of call sites analyzed: 488920 (-1748)
gvn-hoist.*Number of instructions hoisted: 24017
gvn-hoist.*Number of instructions removed: 26349
gvn-hoist.*Number of loads hoisted: 8482
gvn-hoist.*Number of loads removed: 9719
gvn-hoist.*Number of stores hoisted: 9
gvn-hoist.*Number of stores removed: 9
gvn-hoist.*Number of calls hoisted: 34
gvn-hoist.*Number of calls removed: 34

- On the LLVM test-suite we have seen numbers that vary too much: about 30% noise.

We ran the test-suite 3 times and selected the best run, discarded all benchmarks running for less than 2 seconds, and discarded all results less than +/-2%:
On 2mm.c -stats reports that gvn-hoist does not hoist any instruction: that is just noise.
Most likely all llvm test-suite execution times that we report are noisy.

- Execution time slow down (first two numbers are base and peak execution time in seconds, the third number is percent speedup, positive is better)

SingleSource/Benchmarks/Polybench/linear-algebra/kernels/2mm/2mm.test: 6.728 6.104 -9.2700
MultiSource/Applications/JM/lencod/lencod.test: 2.928 2.836 -3.1400

- Execution time speed up:

SingleSource/Benchmarks/Shootout/hash.test: 2.22 2.292 3.2400
SingleSource/Benchmarks/CoyoteBench/huffbench.test: 7.212 7.496 3.9300

- Code size decrease: (first two numbers are code size of base and peak, the third number is percent improvement in code size, negative is better)

SingleSource/Benchmarks/Shootout/ary3.test: 12832 8736 -31.9200
MultiSource/Benchmarks/MiBench/consumer-typeset/consumer-typeset.test: 656680 652584 -.6200
MultiSource/Applications/sqlite3/sqlite3.test: 791408 787312 -.5100
MultiSource/Benchmarks/FreeBench/distray/distray.test: 18528 18488 -.2100
SingleSource/Benchmarks/Adobe-C++/stepanov_vector.test: 45464 45400 -.1400
SingleSource/Benchmarks/Adobe-C++/stepanov_abstraction.test: 46752 46696 -.1100
MultiSource/Benchmarks/Ptrdist/yacr2/yacr2.test: 45904 45856 -.1000
MultiSource/Applications/SIBsim4/SIBsim4.test: 69768 69728 -.0500

- Code size increase (these regressions may be due to more inlining):

SingleSource/Benchmarks/Linpack/linpack-pc.test: 30128 30176 .1500
MultiSource/Benchmarks/Trimaran/enc-pc1/enc-pc1.test: 13600 13656 .4100
MultiSource/Benchmarks/Prolangs-C/TimberWolfMC/timberwolfmc.test: 325224 329320 1.2500
MultiSource/Benchmarks/Prolangs-C/agrep/agrep.test: 81272 85368 5.0300
MultiSource/Benchmarks/TSVC/InductionVariable-flt/InductionVariable-flt.test: 79840 83936 5.1300
MultiSource/Benchmarks/MiBench/security-rijndael/security-rijndael.test: 42656 46752 9.6000


http://reviews.llvm.org/D19338