With GOAMD64=V3 the canonical isPowerOfTwo function:
func isPowerOfTwo(x uintptr) bool {
return x&(x-1) == 0
}
Used to compile to:
temp := BLSR(x) // x&(x-1)
flags = TEST(temp, temp)
return flags.zf
However the blsr instruction already set ZF according to the result.
So we can remove the TEST instruction if we are just checking ZF.
Such as in multiple pieces of code around memory allocations.
This make the code smaller and faster.
Change-Id: Ia12d5a73aa3cb49188c0b647b1eff7b56c5a7b58
Reviewed-on: https://go-review.googlesource.com/c/go/+/448255
Run-TryBot: Jakub Ciolek <jakub@ciolek.dev>
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Reviewed-by: Cherry Mui <cherryyz@google.com>
make\(\[\][a-zA-Z0-9]+, 0\) is seen 52 times in the go source.
And at least 391 times on internet:
https://grep.app/search?q=make%5C%28%5C%5B%5C%5D%5Ba-zA-Z0-9%5D%2B%2C%200%5C%29®exp=true
This used to compile to calling runtime.makeslice.
However we can copy what we do for []T{}, just use a zerobase pointer.
On my machine this is 10x faster (from 3ns to 0.3ns).
Note that an empty loop also runs in 0.3ns,
so this really is free when you count superscallar execution.
Change-Id: I1cfe7e69f5a7a4dabbc71912ce6a4f8a2d4a7f3c
Reviewed-on: https://go-review.googlesource.com/c/go/+/454036
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The SPanchored opcode is identical to SP, except that it takes a memory
argument so that it (and more importantly, anything that uses it)
must be scheduled at or after that memory argument.
This opcode ensures that a LEAQ of a variable gets scheduled after the
corresponding VARDEF for that variable.
This may lead to less CSE of LEAQ operations. The effect is very small.
The go binary is only 80 bytes bigger after this CL. Usually LEAQs get
folded into load/store operations, so the effect is only for pointerful
types, large enough to need a duffzero, and have their address passed
somewhere. Even then, usually the CSEd LEAQs will be un-CSEd because
the two uses are on different sides of a function call and the LEAQ
ends up being rematerialized at the second use anyway.
Change-Id: Ib893562cd05369b91dd563b48fb83f5250950293
Reviewed-on: https://go-review.googlesource.com/c/go/+/452916
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Reviewed-by: Keith Randall <khr@google.com>
Add a new SSA opcode ISELZ, similar to ISELB to represent a select
of value or 0. Then, merge candidate ISEL opcodes inside the late
lower pass.
This avoids complicating rules within the the lower pass.
Change-Id: I3b14c94b763863aadc834b0e910a85870c131313
Reviewed-on: https://go-review.googlesource.com/c/go/+/442596
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Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
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Reviewed-by: Joedian Reid <joedian@golang.org>
ISEL is roughly equivalent to CMOV on PPC64. Verify ISEL generation
in all reasonable cases.
Note "ISEL test x y z" is the same as "ISEL !test y x z". test is
always one of LT (0), GT (1), EQ (2), SO (3). Sometimes x and y are
swapped if GE/LE/NE is desired.
Change-Id: Ie1bf029224064e004d855099731fe5e8d05aa990
Reviewed-on: https://go-review.googlesource.com/c/go/+/445215
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
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This needs to be as low as possible while not breaking priority
assumptions of other scores to correctly schedule carry chains.
Prior to the arm64 changes, it was set below ReadTuple. At the time,
this prevented the MulHiLo implementation on PPC64 from occluding
the scheduling of a full carry chain.
Memory scores can also prevent better scheduling, as can be observed
with crypto/internal/edwards25519/field.feMulGeneric.
Fixes#56497
Change-Id: Ia4b54e6dffcce584faf46b1b8d7cea18a3913887
Reviewed-on: https://go-review.googlesource.com/c/go/+/447435
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Reviewed-by: Keith Randall <khr@google.com>
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The recently added rule only works before decomposing slices.
Add a rule that works after decomposing slices.
The reason we need the latter is because although the length may
be a constant, it can be hidden inside a slice that is not constant
(its pointer or capacity might be changing). By applying this
optimization after decomposing slices, we can find more cases
where it applies.
Fixes#56440
Change-Id: I0094e59eee3065ab4d210defdda8227a6e897420
Reviewed-on: https://go-review.googlesource.com/c/go/+/446277
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Fixes a performance regression due to CL 418554.
Fixes#56440
Change-Id: I6ff152e9b83084756363f49ee6b0844a7a284880
Reviewed-on: https://go-review.googlesource.com/c/go/+/445875
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For example:
movb a0, a0
srai $1, a0, a0
the assembler will expand to:
slli $56, a0, a0
srai $56, a0, a0
srai $1, a0, a0
this CL optimize to:
slli $56, a0, a0
srai $57, a0, a0
Remove 270+ instructions from Go binary on linux/riscv64.
Change-Id: I375e19f9d3bd54f2781791d8cbe5970191297dc8
Reviewed-on: https://go-review.googlesource.com/c/go/+/428496
Reviewed-by: Keith Randall <khr@google.com>
Run-TryBot: Wayne Zuo <wdvxdr@golangcn.org>
Reviewed-by: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
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Partial overlaps can only happen for strict sub-pieces of larger arrays.
That's a much stronger condition than the current optimization rules.
Update #54467
Change-Id: I11e539b71099e50175f37ee78fddf69283f83ee5
Reviewed-on: https://go-review.googlesource.com/c/go/+/433056
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Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This CL adds some optimizaion rules:
1, Converts CMP to CMN, or vice versa, when comparing with a negative
number.
2, For equal and not equal comparisons, CMP can be converted to CMN in
some cases. In theory we could do the same optimization for LT, LE, GT
and GE, but need to account for overflow, this CL doesn't handle them.
There are no noticeable performance changes.
Change-Id: Ia49266c019ab7908ebc9510c2f02e121b1607869
Reviewed-on: https://go-review.googlesource.com/c/go/+/429795
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
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When SLTI/SLTIU is used with ANDI/ORI, it may be possible to determine the
outcome based on the values of the immediates. Resolve these cases.
Improves code generation for various shift operations.
While here, sort tests by architecture to improve readability and ease
future maintenance.
Change-Id: I87e71e016a0e396a928e7d6389a2df61583dfd8d
Reviewed-on: https://go-review.googlesource.com/c/go/+/428217
Reviewed-by: Wayne Zuo <wdvxdr@golangcn.org>
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Run-TryBot: Jenny Rakoczy <jenny@golang.org>
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Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Jenny Rakoczy <jenny@golang.org>
This CL adds shiftIsBounded checks for the Lsh* and Rsh* rules in arm64.
There is no need to check the shift value again with CMP + CSEL when the
shift value is valid.
Change-Id: I54620de64f02a1b5a11089add237248ae2de01b4
Reviewed-on: https://go-review.googlesource.com/c/go/+/417714
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
In go.dev/cl/421821, I included a hack to force OCONVNOP back to
OCONVIFACE for conversions involving shape types and non-empty
interfaces. The comment correctly noted that this was only needed for
conversions between non-identical types, but the code was conservative
and applied to even conversions between identical types.
This CL adds an extra bool to record whether the conversion is between
identical types, so we can keep OCONVNOP instead of forcing back to
OCONVIFACE. This has a small improvement to generated code, because we
no longer need a convI2I call (as demonstrated by codegen/ifaces.go).
But more usefully, this is relevant to pruning unnecessary itab slots
in runtime dictionaries (next CL).
Change-Id: I94f89e961cd26629b925037fea58d283140766ff
Reviewed-on: https://go-review.googlesource.com/c/go/+/427678
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This CL changes the heuristic used to determine whether we can inline a
struct equality check or if we must generate a function and call that
function for equality.
The old method was to count struct fields, but this can lead to poor
in lining decisions. We should really be determining the cost of the
equality check and use that to determine if we should inline or generate
a function.
The new benchmark provided in this CL returns the following when compared
against tip:
```
name old time/op new time/op delta
EqStruct-32 2.46ns ± 4% 0.25ns ±10% -89.72% (p=0.000 n=39+39)
```
Fixes#38494
Change-Id: Ie06b80a2b2a03a3fd0978bcaf7715f9afb66e0ab
GitHub-Last-Rev: e9a18d9389
GitHub-Pull-Request: golang/go#53326
Reviewed-on: https://go-review.googlesource.com/c/go/+/411674
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Reviewed-by: Keith Randall <khr@golang.org>
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This CL optimizes RotateLeft8/16 on arm64.
For 16 bits, we form a 32 bits register by duplicating two 16 bits
registers, then use RORW instruction to do the rotate shift.
For 8 bits, we just use LSR and LSL instead of RORW because the code is
simpler.
Benchmark Old ThisCL delta
RotateLeft8-46 2.16 ns/op 1.73 ns/op -19.70%
RotateLeft16-46 2.16 ns/op 1.54 ns/op -28.53%
Change-Id: I09cde4383d12e31876a57f8cdfd3bb4f324fadb0
Reviewed-on: https://go-review.googlesource.com/c/go/+/420976
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Keith Randall <khr@golang.org>
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For the following code case:
var x uint64
x >> (shift & 63)
We can directly genereta `x >> shift` on arm64, since the hardware will
only use the bottom 6 bits of the shift amount.
Benchmark old time/op new time/op delta
ShiftArithmeticRight-8 0.40ns 0.31ns -21.7%
Change-Id: Id58c8a5b2f6dd5c30c3876f4a36e11b4d81e2dc9
Reviewed-on: https://go-review.googlesource.com/c/go/+/425294
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
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Rotating by c, then by d, is the same as rotating by c+d.
Change-Id: I36df82261460ff80f7c6d39bcdf0e840cef1c91a
Reviewed-on: https://go-review.googlesource.com/c/go/+/424894
Reviewed-by: Wayne Zuo <wdvxdr@golangcn.org>
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Reviewed-by: Heschi Kreinick <heschi@google.com>
Currently we use a full cmpstring to do the comparison for each
split in the binary search for a string switch.
Instead, split by comparing a single byte of the input string with a
constant. That will give us a much faster split (although it might be
not quite as good a split).
Fixes#53333
R=go1.20
Change-Id: I28c7209342314f367071e4aa1f2beb6ec9ff7123
Reviewed-on: https://go-review.googlesource.com/c/go/+/414894
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The prove pass will mark some shifts bounded, and then we can use that
information to generate better code on riscv64.
Change-Id: Ia22f43d0598453c9417adac7017db28d7240948b
Reviewed-on: https://go-review.googlesource.com/c/go/+/422616
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This is a follow up of CL 425101 on RISCV64.
According to RISCV Volume 1, Unprivileged Spec v. 20191213 Chapter 7.1:
If both the high and low bits of the same product are required, then the
recommended code sequence is: MULH[[S]U] rdh, rs1, rs2; MUL rdl, rs1, rs2
(source register specifiers must be in same order and rdh cannot be the
same as rs1 or rs2). Microarchitectures can then fuse these into a single
multiply operation instead of performing two separate multiplies.
So we should not split Muluhilo to separate instructions.
Updates #54607
Change-Id: If47461f3aaaf00e27cd583a9990e144fb8bcdb17
Reviewed-on: https://go-review.googlesource.com/c/go/+/425203
Auto-Submit: Keith Randall <khr@golang.org>
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Detect rotate instructions while still in architecture-independent form.
It's easier to do here, and we don't need to repeat it in each
architecture file.
Change-Id: I9396954b3f3b3bfb96c160d064a02002309935bb
Reviewed-on: https://go-review.googlesource.com/c/go/+/421195
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Reviewed-by: Joedian Reid <joedian@golang.org>
Reviewed-by: Ruinan Sun <Ruinan.Sun@arm.com>
Run-TryBot: Keith Randall <khr@golang.org>
Previously we convert $0 to the ZR register for some reasons, which causes
two problems:
1. Confusion, the special case of the ZR register needs to be considered
when dealing with constants. For encoding, some places we encode ZR, and
some places we encode $0, although we have converted $0 to ZR.
2. Unexpected instruction format. All instructions that support ZR register
operands can be replaced by $0.
This patch removes this conversion. Note that this patch may cause previously
unintendedly supported instruction formats to no longer be supported.
Change-Id: I3d8d2c06711b7614a38191397da7776417f1861c
Reviewed-on: https://go-review.googlesource.com/c/go/+/404316
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Eric Fang <eric.fang@arm.com>
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On ARM64 we use two separate instructions to compute the hi and lo
results of a 64x64->128 multiplication. Lower to two separate ops
so if only one result is needed we can deadcode the other.
Fixes#54607.
Change-Id: Ib023e77eb2b2b0bcf467b45471cb8a294bce6f90
Reviewed-on: https://go-review.googlesource.com/c/go/+/425101
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
With the introduction of stack objects, VARKILL information is
no longer needed.
With stack objects, an object is dead when there are no more static
references to it, and the stack scanner can't find any live pointers
to it. VARKILL information isn't used to establish live ranges for
address-taken variables any more. In effect, the last static reference
*is* the VARKILL, and there's an additional dynamic liveness check
during stack scanning.
Next CL will actually rip out the VARKILL opcodes.
Change-Id: I030a2ab867445cf4e0e69397911f8a2e2f0ed07b
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Updated multiple tests in test/codegen: math.go, mathbits.go, shift.go
and slices.go to verify on ppc64/ppc64le as well
Change-Id: Id88dd41569b7097819fb4d451b615f69cf7f7a94
Reviewed-on: https://go-review.googlesource.com/c/go/+/412115
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Reviewed-by: Ian Lance Taylor <iant@google.com>
For signed comparisons, the following four optimization rules hold:
(CMPconst [0] z:(AND x y)) && z.Uses == 1 => (TST x y)
(CMPWconst [0] z:(AND x y)) && z.Uses == 1 => (TSTW x y)
(CMPconst [0] x:(ANDconst [c] y)) && x.Uses == 1 => (TSTconst [c] y)
(CMPWconst [0] x:(ANDconst [c] y)) && x.Uses == 1 => (TSTWconst [int32(c)] y)
But currently they only apply to jump instructions, not to conditional
instructions within a block, such as cset, csel, etc. This CL extends
the above rules into blocks so that conditional instructions can also be
optimized.
name old time/op new time/op delta
DivisiblePow2constI64-160 1.04ns ± 0% 0.86ns ± 0% -17.30% (p=0.008 n=5+5)
DivisiblePow2constI32-160 1.04ns ± 0% 0.87ns ± 0% -16.16% (p=0.016 n=4+5)
DivisiblePow2constI16-160 1.04ns ± 0% 0.87ns ± 0% -16.03% (p=0.008 n=5+5)
DivisiblePow2constI8-160 1.04ns ± 0% 0.86ns ± 0% -17.15% (p=0.008 n=5+5)
Change-Id: I6bc34bff30862210e8dd001e0340b8fe502fe3de
Reviewed-on: https://go-review.googlesource.com/c/go/+/420434
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As it can't appear in user package paths.
There is a hack for handling "go:buildid" and "type:*" on windows/386.
Previously, windows/386 requires underscore prefix on external symbols,
but that's only applied for SHOSTOBJ/SUNDEFEXT or cgo export symbols.
"go.buildid" is STEXT, "type.*" is STYPE, thus they are not prefixed
with underscore.
In external linking mode, the external linker can't resolve them as
external symbols. But we are lucky that they have "." in their name,
so the external linker see them as Forwarder RVA exports. See:
- https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#export-address-table
- https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=ld/pe-dll.c;h=e7b82ba6ffadf74dc1b9ee71dc13d48336941e51;hb=HEAD#l972)
This CL changes "." to ":" in symbols name, so theses symbols can not be
found by external linker anymore. So a hacky way is adding the
underscore prefix for these 2 symbols. I don't have enough knowledge to
verify whether adding the underscore for all STEXT/STYPE symbols are
fine, even if it could be, that would be done in future CL.
Fixes#37762
Change-Id: I92eaaf24c0820926a36e0530fdb07b07af1fcc35
Reviewed-on: https://go-review.googlesource.com/c/go/+/317917
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Currently there is a an ANDconst and an ANDCCconst op in PPC64,
which is confusing since they map onto the same instruction.
One of these ops sets the result of the AND operation, and the
other sets the flag (condition register).
This converts ANDCCconst into an op with the 2 expected results:
the integer result of the AND and the flag setting. The ANDconst
op has been removed.
Note that in the PPC64 ISA the only variation of the 'and immediate'
is the one that sets the condition bit, which probably led to the
original (confusing) implementation.
This also adds a few rules to improve the use of ANDCCconst with
ISELB and some testcases to verify those improvements.
Change-Id: I523703fa4da2098eb995dc3ba744d36fa28e41d4
Reviewed-on: https://go-review.googlesource.com/c/go/+/422015
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Paul Murphy <murp@ibm.com>
We don't need a multiply when the element type is size 0 or 1.
The panic functions don't return, so we don't need any post-call
code (register restores, etc.).
Change-Id: I0dcea5df56d29d7be26554ddca966b3903c672e5
Reviewed-on: https://go-review.googlesource.com/c/go/+/419754
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Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Since CL 391014, cmd/compile now requires the -p flag to be set the
build system. This CL changes it to initialize LocalPkg.Path to the
provided path, rather than relying on writing out `"".` into object
files and expecting cmd/link to substitute them.
However, this actually involved a rather long tail of fixes. Many have
already been submitted, but a few notable ones that have to land
simultaneously with changing LocalPkg:
1. When compiling package runtime, there are really two "runtime"
packages: types.LocalPkg (the source package itself) and
ir.Pkgs.Runtime (the compiler's internal representation, for synthetic
references). Previously, these ended up creating separate link
symbols (`"".xxx` and `runtime.xxx`, respectively), but now they both
end up as `runtime.xxx`, which causes lsym collisions (notably
inittask and funcsyms).
2. test/codegen tests need to be updated to expect symbols to be named
`command-line-arguments.xxx` rather than `"".foo`.
3. The issue20014 test case is sensitive to the sort order of field
tracking symbols. In particular, the local package now sorts to its
natural place in the list, rather than to the front.
Thanks to David Chase for helping track down all of the fixes needed
for this CL.
Updates #51734.
Change-Id: Iba3041cf7ad967d18c6e17922fa06ba11798b565
Reviewed-on: https://go-review.googlesource.com/c/go/+/393715
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
math/bits.Add64 and math/bits.Sub64 now lower and optimize
directly in SSA form.
The optimization of carry chains focuses around eliding
XER<->GPR transfers of the CA bit when used exclusively as an
input to a single carry operations, or when the CA value is
known.
This also adds support for handling XER spills in the assembler
which could happen if carry chains contain inter-dependencies
on each other (which seems very unlikely with practical usage),
or a clobber happens (SRAW/SRAD/SUBFC operations clobber CA).
With PPC64 Add64/Sub64 lowering into SSA and this patch, the net
performance difference in crypto/elliptic benchmarks on P9/ppc64le
are:
name old time/op new time/op delta
ScalarBaseMult/P256 46.3µs ± 0% 46.9µs ± 0% +1.34%
ScalarBaseMult/P224 356µs ± 0% 209µs ± 0% -41.14%
ScalarBaseMult/P384 1.20ms ± 0% 0.57ms ± 0% -52.14%
ScalarBaseMult/P521 3.38ms ± 0% 1.44ms ± 0% -57.27%
ScalarMult/P256 199µs ± 0% 199µs ± 0% -0.17%
ScalarMult/P224 357µs ± 0% 212µs ± 0% -40.56%
ScalarMult/P384 1.20ms ± 0% 0.58ms ± 0% -51.86%
ScalarMult/P521 3.37ms ± 0% 1.44ms ± 0% -57.32%
MarshalUnmarshal/P256/Uncompressed 2.59µs ± 0% 2.52µs ± 0% -2.63%
MarshalUnmarshal/P256/Compressed 2.58µs ± 0% 2.52µs ± 0% -2.06%
MarshalUnmarshal/P224/Uncompressed 1.54µs ± 0% 1.40µs ± 0% -9.42%
MarshalUnmarshal/P224/Compressed 1.54µs ± 0% 1.39µs ± 0% -9.87%
MarshalUnmarshal/P384/Uncompressed 2.40µs ± 0% 1.80µs ± 0% -24.93%
MarshalUnmarshal/P384/Compressed 2.35µs ± 0% 1.81µs ± 0% -23.03%
MarshalUnmarshal/P521/Uncompressed 3.79µs ± 0% 2.58µs ± 0% -31.81%
MarshalUnmarshal/P521/Compressed 3.80µs ± 0% 2.60µs ± 0% -31.67%
Note, P256 uses an asm implementation, thus, little variation is expected.
Change-Id: I88a24f6bf0f4f285c649e40243b1ab69cc452b71
Reviewed-on: https://go-review.googlesource.com/c/go/+/346870
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Paul Murphy <murp@ibm.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
It is hit ~70k times building go.
This make the go binary, 0.04% smaller.
I didn't included benchmarks because this is just constant foldings
and is hard to mesure objectively.
For example, this enable rewriting things like:
if x == 20 {
return x + 30 + z
}
Into:
if x == 20 {
return 50 + z
}
It's not just fixing programer's code,
the ssa generator generate code like this sometimes.
Change-Id: I0861f342b27f7227b5f1c34d8267fa0057b1bbbc
GitHub-Last-Rev: 4c2f9b5216
GitHub-Pull-Request: golang/go#52669
Reviewed-on: https://go-review.googlesource.com/c/go/+/403735
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This shows up in a few crypto functions, and other
assorted places.
Change-Id: I5a7f4c25ddd4a6499dc295ef693b9fe43d2448ab
Reviewed-on: https://go-review.googlesource.com/c/go/+/404057
Run-TryBot: Paul Murphy <murp@ibm.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
