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4 Commits

Author SHA1 Message Date
Cherry Zhang
1b15c7f102 cmd/compile: debug rewrite
If -d=ssa/PASS/debug=N is specified (N >= 2) for a rewrite pass
(e.g. lower), when a Value (or Block) is rewritten, print the
Value (or Block) before and after.

For #31915.
Updates #19013.

Change-Id: I80eadd44302ae736bc7daed0ef68529ab7a16776
Reviewed-on: https://go-review.googlesource.com/c/go/+/176718
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2020-04-13 21:56:15 +00:00
philhofer
295307ae78 cmd/compile: de-virtualize interface calls
With this change, code like

    h := sha1.New()
    h.Write(buf)
    sum := h.Sum()

gets compiled into static calls rather than
interface calls, because the compiler is able
to prove that 'h' is really a *sha1.digest.

The InterCall re-write rule hits a few dozen times
during make.bash, and hundreds of times during all.bash.

The most common pattern identified by the compiler
is a constructor like

    func New() Interface { return &impl{...} }

where the constructor gets inlined into the caller,
and the result is used immediately. Examples include
{sha1,md5,crc32,crc64,...}.New, base64.NewEncoder,
base64.NewDecoder, errors.New, net.Pipe, and so on.

Some existing benchmarks that change on darwin/amd64:

Crc64/ISO4KB-8        2.67µs ± 1%    2.66µs ± 0%  -0.36%  (p=0.015 n=10+10)
Crc64/ISO1KB-8         694ns ± 0%     690ns ± 1%  -0.59%  (p=0.001 n=10+10)
Adler32KB-8            473ns ± 1%     471ns ± 0%  -0.39%  (p=0.010 n=10+9)

On architectures like amd64, the reduction in code size
appears to contribute more to benchmark improvements than just
removing the indirect call, since that branch gets predicted
accurately when called in a loop.

Updates #19361

Change-Id: I57d4dc21ef40a05ec0fbd55a9bb0eb74cdc67a3d
Reviewed-on: https://go-review.googlesource.com/38139
Run-TryBot: Philip Hofer <phofer@umich.edu>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
2017-03-14 18:49:23 +00:00
David Chase
b59a405656 Revert "cmd/compile: de-virtualize interface calls"
This reverts commit 4e0c7c3f61.

Reason for revert: The presence-of-optimization test program is fragile, breaks under noopt, and might break if the Go libraries are tweaked.  It needs to be (re)written without reference to other packages.

Change-Id: I3aaf1ab006a1a255f961a978e9c984341740e3c7
Reviewed-on: https://go-review.googlesource.com/38097
Reviewed-by: Keith Randall <khr@golang.org>
2017-03-13 21:15:32 +00:00
Philip Hofer
4e0c7c3f61 cmd/compile: de-virtualize interface calls
With this change, code like

    h := sha1.New()
    h.Write(buf)
    sum := h.Sum()

gets compiled into static calls rather than
interface calls, because the compiler is able
to prove that 'h' is really a *sha1.digest.

The InterCall re-write rule hits a few dozen times
during make.bash, and hundreds of times during all.bash.

The most common pattern identified by the compiler
is a constructor like

    func New() Interface { return &impl{...} }

where the constructor gets inlined into the caller,
and the result is used immediately. Examples include
{sha1,md5,crc32,crc64,...}.New, base64.NewEncoder,
base64.NewDecoder, errors.New, net.Pipe, and so on.

Some existing benchmarks that change on darwin/amd64:

Crc64/ISO4KB-8        2.67µs ± 1%    2.66µs ± 0%  -0.36%  (p=0.015 n=10+10)
Crc64/ISO1KB-8         694ns ± 0%     690ns ± 1%  -0.59%  (p=0.001 n=10+10)
Adler32KB-8            473ns ± 1%     471ns ± 0%  -0.39%  (p=0.010 n=10+9)

On architectures like amd64, the reduction in code size
appears to contribute more to benchmark improvements than just
removing the indirect call, since that branch gets predicted
accurately when called in a loop.

Updates #19361

Change-Id: Ia9d30afdd5f6b4d38d38b14b88f308acae8ce7ed
Reviewed-on: https://go-review.googlesource.com/37751
Run-TryBot: Philip Hofer <phofer@umich.edu>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2017-03-13 18:24:57 +00:00