image/jpeg: reduce bound checks from idct and fdct
Before -
$gotip build -gcflags="-d=ssa/check_bce/debug=1" fdct.go idct.go
./fdct.go:89:10: Found IsInBounds
./fdct.go:90:10: Found IsInBounds
./fdct.go:91:10: Found IsInBounds
./fdct.go:92:10: Found IsInBounds
./fdct.go:93:10: Found IsInBounds
./fdct.go:94:10: Found IsInBounds
./fdct.go:95:10: Found IsInBounds
./fdct.go:96:10: Found IsInBounds
./idct.go:77:9: Found IsInBounds
./idct.go:77:27: Found IsInBounds
./idct.go:77:45: Found IsInBounds
./idct.go:78:7: Found IsInBounds
./idct.go:78:25: Found IsInBounds
./idct.go:78:43: Found IsInBounds
./idct.go:78:61: Found IsInBounds
./idct.go:79:13: Found IsInBounds
./idct.go:92:13: Found IsInBounds
./idct.go:93:12: Found IsInBounds
./idct.go:94:12: Found IsInBounds
./idct.go:95:12: Found IsInBounds
./idct.go:97:12: Found IsInBounds
./idct.go:98:12: Found IsInBounds
./idct.go:99:12: Found IsInBounds
After -
$gotip build -gcflags="-d=ssa/check_bce/debug=1" fdct.go idct.go
./fdct.go:90:9: Found IsSliceInBounds
./idct.go:76:11: Found IsSliceInBounds
./idct.go:145:11: Found IsSliceInBounds
name old time/op new time/op delta
FDCT-4 1.85µs ± 2% 1.74µs ± 1% -5.95% (p=0.000 n=10+10)
IDCT-4 1.94µs ± 2% 1.89µs ± 1% -2.67% (p=0.000 n=10+9)
DecodeBaseline-4 1.45ms ± 2% 1.46ms ± 1% ~ (p=0.156 n=9+10)
DecodeProgressive-4 2.21ms ± 1% 2.21ms ± 1% ~ (p=0.796 n=10+10)
EncodeRGBA-4 24.9ms ± 1% 25.0ms ± 1% ~ (p=0.075 n=10+10)
EncodeYCbCr-4 26.1ms ± 1% 26.2ms ± 1% ~ (p=0.573 n=8+10)
name old speed new speed delta
DecodeBaseline-4 42.5MB/s ± 2% 42.4MB/s ± 1% ~ (p=0.162 n=9+10)
DecodeProgressive-4 27.9MB/s ± 1% 27.9MB/s ± 1% ~ (p=0.796 n=10+10)
EncodeRGBA-4 49.4MB/s ± 1% 49.1MB/s ± 1% ~ (p=0.066 n=10+10)
EncodeYCbCr-4 35.3MB/s ± 1% 35.2MB/s ± 1% ~ (p=0.586 n=8+10)
name old alloc/op new alloc/op delta
DecodeBaseline-4 63.0kB ± 0% 63.0kB ± 0% ~ (all equal)
DecodeProgressive-4 260kB ± 0% 260kB ± 0% ~ (all equal)
EncodeRGBA-4 4.40kB ± 0% 4.40kB ± 0% ~ (all equal)
EncodeYCbCr-4 4.40kB ± 0% 4.40kB ± 0% ~ (all equal)
name old allocs/op new allocs/op delta
DecodeBaseline-4 5.00 ± 0% 5.00 ± 0% ~ (all equal)
DecodeProgressive-4 13.0 ± 0% 13.0 ± 0% ~ (all equal)
EncodeRGBA-4 4.00 ± 0% 4.00 ± 0% ~ (all equal)
EncodeYCbCr-4 4.00 ± 0% 4.00 ± 0% ~ (all equal)
Updates #24499
Change-Id: I6828d077b851817503a7c1a08235763f81bdadf9
Reviewed-on: https://go-review.googlesource.com/c/go/+/167417
Run-TryBot: Agniva De Sarker <agniva.quicksilver@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>