[dev.ssa] cmd/compile/internal/ssa: simplify boolean phis
* Decreases the generated code slightly.
* Similar to phiopt pass from gcc, except it only handles
booleans. Handling Eq/Neq had no impact on the generated code.
name old time/op new time/op delta
Template 453ms ± 4% 451ms ± 4% ~ (p=0.468 n=24+24)
GoTypes 1.55s ± 1% 1.55s ± 2% ~ (p=0.287 n=24+25)
Compiler 6.53s ± 2% 6.56s ± 1% +0.46% (p=0.050 n=23+23)
MakeBash 45.8s ± 2% 45.7s ± 2% ~ (p=0.866 n=24+25)
name old text-bytes new text-bytes delta
HelloSize 676k ± 0% 676k ± 0% ~ (all samples are equal)
CmdGoSize 8.07M ± 0% 8.07M ± 0% -0.03% (p=0.000 n=25+25)
Change-Id: Ia62477b7554127958a14cb27f85849b095d63663
Reviewed-on: https://go-review.googlesource.com/20090
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>