Josh Bleecher Snyder
6286188986
cmd/compile: optimize integer "in range" expressions
...
Use unsigned comparisons to reduce from
two comparisons to one for integer "in range"
checks, such as a <= b && b < c.
We already do this for bounds checks.
Extend it to user code.
This is much easier to do in the front end than SSA.
A back end optimization would be more powerful,
but this is a good start.
This reduces the power of some of SSA prove
inferences (#16653 ), but those regressions appear
to be rare and not worth holding this CL for.
Fixes #15844 .
Fixes #16697 .
strconv benchmarks:
name old time/op new time/op delta
Atof64Decimal-8 41.4ns ± 3% 38.9ns ± 2% -5.89% (p=0.000 n=24+25)
Atof64Float-8 48.5ns ± 0% 46.8ns ± 3% -3.64% (p=0.000 n=20+23)
Atof64FloatExp-8 97.7ns ± 4% 93.5ns ± 1% -4.25% (p=0.000 n=25+20)
Atof64Big-8 187ns ± 8% 162ns ± 2% -13.54% (p=0.000 n=24+22)
Atof64RandomBits-8 250ns ± 6% 233ns ± 5% -6.76% (p=0.000 n=25+25)
Atof64RandomFloats-8 160ns ± 0% 152ns ± 0% -5.00% (p=0.000 n=21+22)
Atof32Decimal-8 41.1ns ± 1% 38.7ns ± 2% -5.86% (p=0.000 n=24+24)
Atof32Float-8 46.1ns ± 1% 43.5ns ± 3% -5.63% (p=0.000 n=21+24)
Atof32FloatExp-8 101ns ± 4% 100ns ± 2% -1.59% (p=0.000 n=24+23)
Atof32Random-8 136ns ± 3% 133ns ± 3% -2.83% (p=0.000 n=22+22)
Atoi-8 33.8ns ± 3% 30.6ns ± 3% -9.51% (p=0.000 n=24+25)
AtoiNeg-8 31.6ns ± 3% 29.1ns ± 2% -8.05% (p=0.000 n=23+24)
Atoi64-8 48.6ns ± 1% 43.8ns ± 1% -9.81% (p=0.000 n=20+23)
Atoi64Neg-8 47.1ns ± 4% 42.0ns ± 2% -10.83% (p=0.000 n=25+25)
FormatFloatDecimal-8 177ns ± 9% 178ns ± 6% ~ (p=0.460 n=25+25)
FormatFloat-8 282ns ± 6% 282ns ± 3% ~ (p=0.954 n=25+22)
FormatFloatExp-8 259ns ± 7% 255ns ± 6% ~ (p=0.089 n=25+24)
FormatFloatNegExp-8 253ns ± 6% 254ns ± 6% ~ (p=0.941 n=25+24)
FormatFloatBig-8 340ns ± 6% 341ns ± 8% ~ (p=0.600 n=22+25)
AppendFloatDecimal-8 79.4ns ± 0% 80.6ns ± 6% ~ (p=0.861 n=20+25)
AppendFloat-8 175ns ± 3% 174ns ± 0% ~ (p=0.722 n=25+20)
AppendFloatExp-8 142ns ± 4% 142ns ± 2% ~ (p=0.948 n=25+24)
AppendFloatNegExp-8 137ns ± 2% 138ns ± 2% +0.70% (p=0.001 n=24+25)
AppendFloatBig-8 218ns ± 3% 218ns ± 4% ~ (p=0.596 n=25+25)
AppendFloatBinaryExp-8 80.0ns ± 4% 78.0ns ± 1% -2.43% (p=0.000 n=24+21)
AppendFloat32Integer-8 82.3ns ± 3% 79.3ns ± 4% -3.69% (p=0.000 n=24+25)
AppendFloat32ExactFraction-8 143ns ± 2% 143ns ± 0% ~ (p=0.177 n=23+19)
AppendFloat32Point-8 175ns ± 3% 175ns ± 3% ~ (p=0.062 n=24+25)
AppendFloat32Exp-8 139ns ± 2% 137ns ± 4% -1.05% (p=0.001 n=24+24)
AppendFloat32NegExp-8 134ns ± 0% 137ns ± 4% +2.06% (p=0.000 n=22+25)
AppendFloat64Fixed1-8 97.8ns ± 0% 98.6ns ± 3% ~ (p=0.711 n=20+25)
AppendFloat64Fixed2-8 110ns ± 3% 110ns ± 5% -0.45% (p=0.037 n=24+24)
AppendFloat64Fixed3-8 102ns ± 3% 102ns ± 3% ~ (p=0.684 n=24+24)
AppendFloat64Fixed4-8 112ns ± 3% 110ns ± 0% -1.43% (p=0.000 n=25+18)
FormatInt-8 3.18µs ± 4% 3.10µs ± 6% -2.54% (p=0.001 n=24+25)
AppendInt-8 1.81µs ± 5% 1.80µs ± 5% ~ (p=0.648 n=25+25)
FormatUint-8 812ns ± 6% 816ns ± 6% ~ (p=0.777 n=25+25)
AppendUint-8 536ns ± 4% 538ns ± 3% ~ (p=0.798 n=20+22)
Quote-8 605ns ± 6% 602ns ± 9% ~ (p=0.573 n=25+25)
QuoteRune-8 99.5ns ± 8% 100.2ns ± 7% ~ (p=0.432 n=25+25)
AppendQuote-8 361ns ± 3% 363ns ± 4% ~ (p=0.085 n=25+25)
AppendQuoteRune-8 23.3ns ± 3% 22.4ns ± 2% -3.79% (p=0.000 n=25+24)
UnquoteEasy-8 146ns ± 4% 145ns ± 5% ~ (p=0.112 n=24+24)
UnquoteHard-8 804ns ± 6% 771ns ± 6% -4.10% (p=0.000 n=25+24)
Change-Id: Ibd384e46e90f1cfa40503c8c6352a54c65b72980
Reviewed-on: https://go-review.googlesource.com/27652
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-08-25 03:49:16 +00:00
Alexandru Moșoi
6c6089b3fd
cmd/compile: bce when max and limit are consts
...
Removes 49 more bound checks in make.bash. For example:
var a[100]int
for i := 0; i < 50; i++ {
use a[i+25]
}
Change-Id: I85e0130ee5d07f0ece9b17044bba1a2047414ce7
Reviewed-on: https://go-review.googlesource.com/21379
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-04-11 16:01:22 +00:00
Alexandru Moșoi
8448d3aace
cmd/compile: fold CMPconst and SHR
...
Fold the comparison when the SHR result is small.
Useful for:
- murmur mix like hashing where higher bits are desirable, i.e. hash = uint32(i * C) >> 18
- integer log2 via DeBruijn sequence: http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogDeBruijn
Change-Id: If70ae18cb86f4cc83ab6213f88ced03cc4986156
Reviewed-on: https://go-review.googlesource.com/21514
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
2016-04-07 13:28:13 +00:00
Alexandru Moșoi
1747788c56
cmd/compile: add a pass to print bound checks
...
Since BCE happens over several passes (opt, loopbce, prove)
it's easy to regress especially with rewriting.
The pass is only activated with special debug flag.
Change-Id: I46205982e7a2751156db8e875d69af6138068f59
Reviewed-on: https://go-review.googlesource.com/21510
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
2016-04-05 12:46:59 +00:00
