When T is a scalar, there are no runtime calls
required, which makes this a clear win.
encoding/binary:
WriteInts-8 958ns ± 3% 864ns ± 2% -9.80% (p=0.000 n=15+15)
This also considerably shrinks a core fmt
routine:
Before: "".(*pp).printArg t=1 size=3952 args=0x20 locals=0xf0
After: "".(*pp).printArg t=1 size=2624 args=0x20 locals=0x98
Unfortunately, I find it very hard to get stable
numbers out of the fmt benchmarks due to thermal scaling.
Change-Id: I1278006b030253bf8e48dc7631d18985cdaa143d
Reviewed-on: https://go-review.googlesource.com/26659
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
These can be implemented with just a compare and a move instruction.
Do so, avoiding the overhead of a call into the runtime.
These assertions are a significant cost in Go code that uses interface{}
as a safe alternative to C's void* (or unsafe.Pointer), such as the
current version of the Go compiler.
*T here includes pointer to T but also any Go type represented as
a single pointer (chan, func, map). It does not include [1]*T or struct{*int}.
That requires more work in other parts of the compiler; there is a TODO.
Change-Id: I7ff681c20d2c3eb6ad11dd7b3a37b1f3dda23965
Reviewed-on: https://go-review.googlesource.com/7862
Reviewed-by: Rob Pike <r@golang.org>
