Enhancement: avoid applying canonicalizing rules on canonical form

[shashi]

fixes #347

Before

julia> @btime simplify(z*x)
  41.083 μs (511 allocations: 27.11 KiB)
x*z

julia> @btime simplify(z*x+z*y)
  252.292 μs (3063 allocations: 159.59 KiB)
z*(x + y)

After

julia> @btime simplify(z*x)
  27.458 μs (294 allocations: 16.25 KiB)
x*z

julia> @btime simplify(z*x+z*y)
  151.834 μs (1724 allocations: 92.55 KiB)
z*(x + y)

[github-actions[bot]]

Benchmark Results

	master	7169244e587d15...	t[master]/t[7169244e587d15...]
overhead/acrule/a+2	1.31 ± 0.3 μs	1.24 ± 0.27 μs	1.06
overhead/acrule/a+2+b	1.27 ± 0.31 μs	1.22 ± 0.29 μs	1.04
overhead/acrule/a+b	0.505 ± 0.057 μs	0.486 ± 0.055 μs	1.04
overhead/acrule/noop:Int	29.8 ± 1 ns	30.1 ± 2.1 ns	0.99
overhead/acrule/noop:Sym	0.0533 ± 0.0061 μs	0.0542 ± 0.0093 μs	0.983
overhead/rule/noop:Int	0.0454 ± 0.0063 μs	0.0463 ± 0.0048 μs	0.979
overhead/rule/noop:Sym	0.0756 ± 0.011 μs	0.0782 ± 0.011 μs	0.966
overhead/rule/noop:Term	0.0732 ± 0.0099 μs	0.0792 ± 0.011 μs	0.924
overhead/ruleset/noop:Int	0.188 ± 0.017 μs	0.18 ± 0.019 μs	1.04
overhead/ruleset/noop:Sym	0.248 ± 0.031 μs	0.23 ± 0.022 μs	1.08
overhead/ruleset/noop:Term	6.52 ± 0.83 μs	6.4 ± 0.63 μs	1.02
overhead/simplify/noop:Int	0.247 ± 0.031 μs	0.243 ± 0.025 μs	1.01
overhead/simplify/noop:Sym	0.278 ± 0.03 μs	0.281 ± 0.033 μs	0.989
overhead/simplify/noop:Term	0.15 ± 0.015 ms	0.0929 ± 0.011 ms	1.61
overhead/simplify/randterm (+, *):serial	0.346 ± 0.013 s	0.204 ± 0.0061 s	1.7
overhead/simplify/randterm (+, *):thread	0.216 ± 0.015 s	0.136 ± 0.016 s	1.59
overhead/simplify/randterm (/, *):serial	0.798 ± 0.062 ms	0.497 ± 0.043 ms	1.61
overhead/simplify/randterm (/, *):thread	0.881 ± 0.069 ms	0.617 ± 0.055 ms	1.43
overhead/substitute/a	0.148 ± 0.015 ms	0.147 ± 0.017 ms	1.01
overhead/substitute/a,b	0.143 ± 0.013 ms	0.136 ± 0.015 ms	1.05
overhead/substitute/a,b,c	0.0566 ± 0.0052 ms	0.0539 ± 0.0063 ms	1.05
polyform/easy_iszero	0.0822 ± 0.013 ms	0.0802 ± 0.01 ms	1.02
polyform/isone	3.6 ± 0.1 ns	3.3 ± 0.2 ns	1.09
polyform/iszero	2.8 ± 0.27 ms	2.67 ± 0.25 ms	1.05
polyform/simplify_fractions	4.1 ± 0.37 ms	3.86 ± 0.32 ms	1.06
time_to_load	5.98 ± 0.11 s	6.07 ± 0.021 s	0.984

Benchmark Plots

A plot of the benchmark results have been uploaded as an artifact to the workflow run for this PR. Go to "Actions"->"Benchmark a pull request"->[the most recent run]->"Artifacts" (at the bottom).