Currently we only use 1 and 4 as a scale for indexed 4-byte load.
In code generated in #20711 we can use indexed load with scale=8,
to improve performance:
name old time/op new time/op delta
GM-6 108µs ± 0% 95µs ± 0% -12.06% (p=0.000 n=10+10)
So add new ops and combine loadidx1(shift 3..).. into loadidx8,
same for stores.
Change-Id: I5ed1c250ac40960e20606580cf9de221e75b72f1
Reviewed-on: https://go-review.googlesource.com/46134
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Went mainly for the ones that make no sense, such as the ones
mid-sentence or after commas.
Change-Id: Ie245d2c19cc7428a06295635cf6a9482ade25ff0
Reviewed-on: https://go-review.googlesource.com/57293
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Implement int reg <-> fp reg moves on amd64.
If we see a load to int reg followed by an int->fp move, then we can just
load to the fp reg instead. Same for stores.
math.Abs is now:
MOVQ "".x+8(SP), AX
SHLQ $1, AX
SHRQ $1, AX
MOVQ AX, "".~r1+16(SP)
math.Copysign is now:
MOVQ "".x+8(SP), AX
SHLQ $1, AX
SHRQ $1, AX
MOVQ "".y+16(SP), CX
SHRQ $63, CX
SHLQ $63, CX
ORQ CX, AX
MOVQ AX, "".~r2+24(SP)
math.Float64bits is now:
MOVSD "".x+8(SP), X0
MOVSD X0, "".~r1+16(SP)
(it would be nicer to use a non-SSE reg for this, nothing is perfect)
And due to the fix for #21440, the inlined version of these improve as well.
name old time/op new time/op delta
Abs 1.38ns ± 5% 0.89ns ±10% -35.54% (p=0.000 n=10+10)
Copysign 1.56ns ± 7% 1.35ns ± 6% -13.77% (p=0.000 n=9+10)
Fixes#13095
Change-Id: Ibd7f2792412a6668608780b0688a77062e1f1499
Reviewed-on: https://go-review.googlesource.com/58732
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>
We can add a constant to loaction in memory with 1 instruction,
as opposed to load+add+store, so add a new op and relevent ssa rules.
Triggers in e. g. encoding/json isValidNumber:
NumberIsValid-6 36.4ns ± 0% 35.2ns ± 1% -3.32% (p=0.000 n=6+10)
Shaves ~2.5 kb from go tool.
Change-Id: I7ba576676c2522432360f77b290cecb9574a93c3
Reviewed-on: https://go-review.googlesource.com/54431
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
When package ssa was created, Type was in package gc.
To avoid circular dependencies, we used an interface (ssa.Type)
to represent type information in SSA.
In the Go 1.9 cycle, gri extricated the Type type from package gc.
As a result, we can now use it in package ssa.
Now, instead of package types depending on package ssa,
it is the other way.
This is a more sensible dependency tree,
and helps compiler performance a bit.
Though this is a big CL, most of the changes are
mechanical and uninteresting.
Interesting bits:
* Add new singleton globals to package types for the special
SSA types Memory, Void, Invalid, Flags, and Int128.
* Add two new Types, TSSA for the special types,
and TTUPLE, for SSA tuple types.
ssa.MakeTuple is now types.NewTuple.
* Move type comparison result constants CMPlt, CMPeq, and CMPgt
to package types.
* We had picked the name "types" in our rules for the handy
list of types provided by ssa.Config. That conflicted with
the types package name, so change it to "typ".
* Update the type comparison routine to handle tuples and special
types inline.
* Teach gc/fmt.go how to print special types.
* We can now eliminate ElemTypes in favor of just Elem,
and probably also some other duplicated Type methods
designed to return ssa.Type instead of *types.Type.
* The ssa tests were using their own dummy types,
and they were not particularly careful about types in general.
Of necessity, this CL switches them to use *types.Type;
it does not make them more type-accurate.
Unfortunately, using types.Type means initializing a bit
of the types universe.
This is prime for refactoring and improvement.
This shrinks ssa.Value; it now fits in a smaller size class
on 64 bit systems. This doesn't have a giant impact,
though, since most Values are preallocated in a chunk.
name old alloc/op new alloc/op delta
Template 37.9MB ± 0% 37.7MB ± 0% -0.57% (p=0.000 n=10+8)
Unicode 28.9MB ± 0% 28.7MB ± 0% -0.52% (p=0.000 n=10+10)
GoTypes 110MB ± 0% 109MB ± 0% -0.88% (p=0.000 n=10+10)
Flate 24.7MB ± 0% 24.6MB ± 0% -0.66% (p=0.000 n=10+10)
GoParser 31.1MB ± 0% 30.9MB ± 0% -0.61% (p=0.000 n=10+9)
Reflect 73.9MB ± 0% 73.4MB ± 0% -0.62% (p=0.000 n=10+8)
Tar 25.8MB ± 0% 25.6MB ± 0% -0.77% (p=0.000 n=9+10)
XML 41.2MB ± 0% 40.9MB ± 0% -0.80% (p=0.000 n=10+10)
[Geo mean] 40.5MB 40.3MB -0.68%
name old allocs/op new allocs/op delta
Template 385k ± 0% 386k ± 0% ~ (p=0.356 n=10+9)
Unicode 343k ± 1% 344k ± 0% ~ (p=0.481 n=10+10)
GoTypes 1.16M ± 0% 1.16M ± 0% -0.16% (p=0.004 n=10+10)
Flate 238k ± 1% 238k ± 1% ~ (p=0.853 n=10+10)
GoParser 320k ± 0% 320k ± 0% ~ (p=0.720 n=10+9)
Reflect 957k ± 0% 957k ± 0% ~ (p=0.460 n=10+8)
Tar 252k ± 0% 252k ± 0% ~ (p=0.133 n=9+10)
XML 400k ± 0% 400k ± 0% ~ (p=0.796 n=10+10)
[Geo mean] 428k 428k -0.01%
Removing all the interface calls helps non-trivially with CPU, though.
name old time/op new time/op delta
Template 178ms ± 4% 173ms ± 3% -2.90% (p=0.000 n=94+96)
Unicode 85.0ms ± 4% 83.9ms ± 4% -1.23% (p=0.000 n=96+96)
GoTypes 543ms ± 3% 528ms ± 3% -2.73% (p=0.000 n=98+96)
Flate 116ms ± 3% 113ms ± 4% -2.34% (p=0.000 n=96+99)
GoParser 144ms ± 3% 140ms ± 4% -2.80% (p=0.000 n=99+97)
Reflect 344ms ± 3% 334ms ± 4% -3.02% (p=0.000 n=100+99)
Tar 106ms ± 5% 103ms ± 4% -3.30% (p=0.000 n=98+94)
XML 198ms ± 5% 192ms ± 4% -2.88% (p=0.000 n=92+95)
[Geo mean] 178ms 173ms -2.65%
name old user-time/op new user-time/op delta
Template 229ms ± 5% 224ms ± 5% -2.36% (p=0.000 n=95+99)
Unicode 107ms ± 6% 106ms ± 5% -1.13% (p=0.001 n=93+95)
GoTypes 696ms ± 4% 679ms ± 4% -2.45% (p=0.000 n=97+99)
Flate 137ms ± 4% 134ms ± 5% -2.66% (p=0.000 n=99+96)
GoParser 176ms ± 5% 172ms ± 8% -2.27% (p=0.000 n=98+100)
Reflect 430ms ± 6% 411ms ± 5% -4.46% (p=0.000 n=100+92)
Tar 128ms ±13% 123ms ±13% -4.21% (p=0.000 n=100+100)
XML 239ms ± 6% 233ms ± 6% -2.50% (p=0.000 n=95+97)
[Geo mean] 220ms 213ms -2.76%
Change-Id: I15c7d6268347f8358e75066dfdbd77db24e8d0c1
Reviewed-on: https://go-review.googlesource.com/42145
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Type.Size and Type.Alignment are for the front end:
They calculate size and alignment if needed.
Type.MustSize and Type.MustAlignment are for the back end:
They call Fatal if size and alignment are not already calculated.
Most uses are of MustSize and MustAlignment,
but that's because the back end is newer,
and this API was added to support it.
This CL was mostly generated with sed and selective reversion.
The only mildly interesting bit is the change of the ssa.Type interface
and the supporting ssa dummy types.
Follow-up to review feedback on CL 41970.
Passes toolstash-check.
Change-Id: I0d9b9505e57453dae8fb6a236a07a7a02abd459e
Reviewed-on: https://go-review.googlesource.com/42016
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The experiment "clobberdead" clobbers all pointer fields that the
compiler thinks are dead, just before and after every safepoint.
Useful for debugging the generation of live pointer bitmaps.
Helped find the following issues:
Update #15936
Update #16026
Update #16095
Update #18860
Change-Id: Id1d12f86845e3d93bae903d968b1eac61fc461f9
Reviewed-on: https://go-review.googlesource.com/23924
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Popcount instructions on amd64 are not guaranteed to be
present, so we must guard their call. Rewrite rules can't
generate control flow at the moment, so the intrinsifier
needs to generate that code.
name old time/op new time/op delta
OnesCount-8 2.47ns ± 5% 1.04ns ± 2% -57.70% (p=0.000 n=10+10)
OnesCount16-8 1.05ns ± 1% 0.78ns ± 0% -25.56% (p=0.000 n=9+8)
OnesCount32-8 1.63ns ± 5% 1.04ns ± 2% -35.96% (p=0.000 n=10+10)
OnesCount64-8 2.45ns ± 0% 1.04ns ± 1% -57.55% (p=0.000 n=6+10)
Update #18616
Change-Id: I4aff2cc9aa93787898d7b22055fe272a7cf95673
Reviewed-on: https://go-review.googlesource.com/38320
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
We don't need them any more since #15837 was fixed.
Fixes#19718
Change-Id: I13e46c62b321b2c9265f44c977b63bfb23163ca2
Reviewed-on: https://go-review.googlesource.com/38664
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This CL changes the GOARCH.Init functions to take gc.Thearch as a
parameter, which gc.Main supplies.
Additionally, the x86 backend is refactored to decide within Init
whether to use the 387 or SSE2 instruction generators, rather than for
each individual SSA Value/Block.
Passes toolstash-check -all.
Change-Id: Ie6305a6cd6f6ab4e89ecbb3cbbaf5ffd57057a24
Reviewed-on: https://go-review.googlesource.com/38301
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
name old time/op new time/op delta
LeadingZeros-4 2.00ns ± 0% 1.34ns ± 1% -33.02% (p=0.000 n=8+10)
LeadingZeros16-4 1.62ns ± 0% 1.57ns ± 0% -3.09% (p=0.001 n=8+9)
LeadingZeros32-4 2.14ns ± 0% 1.48ns ± 0% -30.84% (p=0.002 n=8+10)
LeadingZeros64-4 2.06ns ± 1% 1.33ns ± 0% -35.08% (p=0.000 n=8+8)
8-bit args is a special case - the Go code is really fast because
it is just a single table lookup. So I've disabled that for now.
Intrinsics were actually slower:
LeadingZeros8-4 1.22ns ± 3% 1.58ns ± 1% +29.56% (p=0.000 n=10+10)
Update #18616
Change-Id: Ia9c289b9ba59c583ea64060470315fd637e814cf
Reviewed-on: https://go-review.googlesource.com/38311
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This abstracts creation of ACALL Progs into package gc. The main
benefit of this today is we can refactor away a lot of common
boilerplate code.
Later, once liveness analysis happens on the SSA graph, this will also
provide an easy insertion point for emitting the PCDATA Progs
immediately before call instructions.
Passes toolstash-check -all.
Change-Id: Ia15108ace97201cd84314f1ca916dfeb4f09d61c
Reviewed-on: https://go-review.googlesource.com/38081
Reviewed-by: Keith Randall <khr@golang.org>
Several SSA ops will always behave identically regardless of target
architecture, so handle those within gc/ssa.go instead.
Passes toolstash-check -all.
Change-Id: I54d514e80ab86723e44332a5a38e3054cbca8c5d
Reviewed-on: https://go-review.googlesource.com/37931
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
On AMD64 Most operation can have one operand in memory.
Combine load and dependand operation into one new operation,
where possible. I've seen no significant performance changes on go1,
but this allows to remove ~1.8kb code from go tool. And in math package
I see e. g.:
Remainder-6 70.0ns ± 0% 64.6ns ± 0% -7.76% (p=0.000 n=9+1
Change-Id: I88b8602b1d55da8ba548a34eb7da4b25d59a297e
Reviewed-on: https://go-review.googlesource.com/36793
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Removes all external uses of Linksym and Pkglookup, which are the only
two exported functions that return Syms.
Also add Duffcopy and Duffzero since they're used often enough across
SSA backends.
Passes toolstash -cmp.
Change-Id: I8d3fd048ad5cd676fc46378f09a917569ffc9b2c
Reviewed-on: https://go-review.googlesource.com/36418
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Gc's Sym type represents a package-qualified identifier, which is a
frontend concept and doesn't belong in SSA. Bonus: we can replace some
interface{} types with *obj.LSym.
Passes toolstash -cmp.
Change-Id: I456eb9957207d80f99f6eb9b8eab4a1f3263e9ed
Reviewed-on: https://go-review.googlesource.com/36415
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This is a mostly mechanical rename followed by manual fixes where necessary.
Change-Id: Ie5c670b133db978f15dc03e50dc2da0c80fc8842
Reviewed-on: https://go-review.googlesource.com/34137
Reviewed-by: David Lazar <lazard@golang.org>
Various minor adjustments.
Change-Id: Iedfb97989f7bedaa3e9e8993b167e05f162434a7
Reviewed-on: https://go-review.googlesource.com/34136
Reviewed-by: David Lazar <lazard@golang.org>
Adjust cmd/compile accordingly.
This will make it easier to replace the underlying implementation.
Change-Id: I33645850bb18c839b24785b6222a9e028617addb
Reviewed-on: https://go-review.googlesource.com/34133
Reviewed-by: David Lazar <lazard@golang.org>
Identify live stack variables during SSA and compute the stack frame
layout earlier so that we can emit instructions with the correct
offsets upfront.
Passes toolstash/buildall.
Change-Id: I191100dba274f1e364a15bdcfdc1d1466cdd1db5
Reviewed-on: https://go-review.googlesource.com/30216
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Teach SSA about the cmd/internal/obj/$ARCH register numbering.
It can then return that numbering when requested. Each architecture
now does not need to know anything about the internal SSA numbering
of registers.
Change-Id: I34472a2736227c15482e60994eebcdd2723fa52d
Reviewed-on: https://go-review.googlesource.com/29249
Reviewed-by: David Chase <drchase@google.com>
Get rid of BlockCheck. Josh goaded me into it, and I went
down a rabbithole making it happen.
NilCheck now panics if the pointer is nil and returns void, as before.
BlockCheck is gone, and NilCheck is no longer a Control value for
any block. It just exists (and deadcode knows not to throw it away).
I rewrote the nilcheckelim pass to handle this case. In particular,
there can now be multiple NilCheck ops per block.
I moved all of the arch-dependent nil check elimination done as
part of ssaGenValue into its own proper pass, so we don't have to
duplicate that code for every architecture.
Making the arch-dependent nil check its own pass means I needed
to add a bunch of flags to the opcode table so I could write
the code without arch-dependent ops everywhere.
Change-Id: I419f891ac9b0de313033ff09115c374163416a9f
Reviewed-on: https://go-review.googlesource.com/29120
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Rip out the code that allows SSA to be used conditionally.
No longer exists:
ssa=0 flag
GOSSAHASH
GOSSAPKG
SSATEST
GOSSAFUNC now only controls the printing of the IR/html.
Still need to rip out all of the old backend. It should no longer be
callable after this CL.
Update #16357
Change-Id: Ib30cc18fba6ca52232c41689ba610b0a94aa74f5
Reviewed-on: https://go-review.googlesource.com/29155
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
No need for it, we can treat calls as (mostly) normal values
that take a memory and return a memory.
Lowers the number of basic blocks needed to represent a function.
"go test -c net/http" uses 27% fewer basic blocks.
Probably doesn't affect generated code much, but should help
various passes whose running time and/or space depends on
the number of basic blocks.
Fixes#15631
Change-Id: I0bf21e123f835e2cfa382753955a4f8bce03dfa6
Reviewed-on: https://go-review.googlesource.com/28950
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reduce the duplication in every arch by moving the code into package gc.
Change-Id: Ia111add8316492571825431ecd4f0154c8792ae1
Reviewed-on: https://go-review.googlesource.com/28481
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Atomic add rules were depending on CSE to combine duplicate atomic ops.
With -N, CSE doesn't run.
Redo the rules for atomic add so there's only one atomic op.
Introduce an add-to-first-part-of-tuple pseudo-ops to make the atomic add result correct.
Change-Id: Ib132247051abe5f80fefad6c197db8df8ee06427
Reviewed-on: https://go-review.googlesource.com/27991
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Atomic swap, add/and/or, compare and swap.
Also works on amd64p32.
Change-Id: Idf2d8f3e1255f71deba759e6e75e293afe4ab2ba
Reviewed-on: https://go-review.googlesource.com/27813
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Inline atomic reads and writes on amd64. There's no reason
to pay the overhead of a call for these.
To keep atomic loads from being reordered, we make them
return a <value,memory> tuple.
Change the meaning of resultInArg0 for tuple-generating ops
to mean the first part of the result tuple, not the second.
This means we can always put the store part of the tuple last,
matching how arguments are laid out. This requires reordering
the outputs of add32carry and sub32carry and their descendents
in various architectures.
benchmark old ns/op new ns/op delta
BenchmarkAtomicLoad64-8 2.09 0.26 -87.56%
BenchmarkAtomicStore64-8 7.54 5.72 -24.14%
TBD (in a different CL): Cas, Or8, ...
Change-Id: I713ea88e7da3026c44ea5bdb56ed094b20bc5207
Reviewed-on: https://go-review.googlesource.com/27641
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Now that we have ops that can return 2 results, have BSF return a result
and flags. We can then get rid of the redundant comparison and use CMOV
instead of CMOVconst ops.
Get rid of a bunch of the ops we don't use. Ctz{8,16}, plus all the Clzs,
and CMOVNEs. I don't think we'll ever use them, and they would be easy
to add back if needed.
Change-Id: I8858a1d017903474ea7e4002fc76a6a86e7bd487
Reviewed-on: https://go-review.googlesource.com/27630
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
It's not a new backend, just a PtrSize==4 modification
of the existing AMD64 backend.
Change-Id: Icc63521a5cf4ebb379f7430ef3f070894c09afda
Reviewed-on: https://go-review.googlesource.com/25586
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
SSA compiler on AMD64 may spill Duff-adjusted address as scalar. If
the object is on stack and the stack moves, the spilled address become
invalid.
Making the spill pointer-typed does not work. The Duff-adjusted address
points to the memory before the area to be zeroed and may be invalid.
This may cause stack scanning code panic.
Fix it by doing Duff-adjustment in genValue, so the intermediate value
is not seen by the reg allocator, and will not be spilled.
Add a test to cover both cases. As it depends on allocation, it may
be not always triggered.
Fixes#16515.
Change-Id: Ia81d60204782de7405b7046165ad063384ede0db
Reviewed-on: https://go-review.googlesource.com/25309
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
We now allow Values to have 2 outputs. Use that ability for amd64.
This allows x,y := a/b,a%b to use just a single divide instruction.
Update #6815
Change-Id: Id70bcd20188a2dd8445e631a11d11f60991921e4
Reviewed-on: https://go-review.googlesource.com/25004
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
The comments were mostly duplicated; unify them.
Add a check that the required invariant holds.
Change-Id: I42fe09dcd1fac76d3c4e191f7a58c591c5ce429b
Reviewed-on: https://go-review.googlesource.com/24719
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
This will be used verbatim in other architectures.
Change-Id: I307891ae597d797fd45f296b6a38ffe9fac6b975
Reviewed-on: https://go-review.googlesource.com/24155
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Introduce a KeepAlive op which makes sure that its argument is kept
live until the KeepAlive. Use KeepAlive to mark pointer input
arguments as live after each function call and at each return.
We do this change only for pointer arguments. Those are the
critical ones to handle because they might have finalizers.
Doing compound arguments (slices, structs, ...) is more complicated
because we would need to track field liveness individually (we do
that for auto variables now, but inputs requires extra trickery).
Turn off the automatic marking of args as live. That way, when args
are explicitly nulled, plive will know that the original argument is
dead.
The KeepAlive op will be the eventual implementation of
runtime.KeepAlive.
Fixes#15277
Change-Id: I5f223e65d99c9f8342c03fbb1512c4d363e903e5
Reviewed-on: https://go-review.googlesource.com/22365
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
