when compiling f(a, b, c), we do something like:
*(SP+0) = eval(a)
*(SP+8) = eval(b)
*(SP+16) = eval(c)
call f
If one of those evaluations is later determined to unconditionally panic
(say eval(b) in this example), then the call is deadcode eliminated. But
any previous argument write (*(SP+0)=... here) is still around. Becuase
we only compute the size of the outarg area for calls which are still
around at the end of optimization, the space needed for *(SP+0)=v is not
accounted for and thus the outarg area may be too small.
The fix is to make sure that we evaluate any potentially panicing
operation before we write any of the args to the stack. It turns out
that fix is pretty easy, as we already have such a mechanism available
for function args. We just need to extend it to possibly panicing args
as well.
The resulting code (if b and c can panic, but a can't) is:
tmpb = eval(b)
*(SP+16) = eval(c)
*(SP+0) = eval(a)
*(SP+8) = tmpb
call f
This change tickled a bug in how we find the arguments for intrinsic
calls, so that latent bug is fixed up as well.
Update #16760.
Change-Id: I0bf5edf370220f82bc036cf2085ecc24f356d166
Reviewed-on: https://go-review.googlesource.com/32551
Reviewed-by: Cherry Zhang <cherryyz@google.com>
The code to do the conversion is smaller than the
call to the runtime.
The 1-result asserts need to call panic if they fail, but that
code is out of line.
The only conversions left in the runtime are those which
might allocate and those which might need to generate an itab.
Given the following types:
type E interface{}
type I interface { foo() }
type I2 iterface { foo(); bar() }
type Big [10]int
func (b Big) foo() { ... }
This CL inlines the following conversions:
was assertE2T
var e E = ...
b := i.(Big)
was assertE2T2
var e E = ...
b, ok := i.(Big)
was assertI2T
var i I = ...
b := i.(Big)
was assertI2T2
var i I = ...
b, ok := i.(Big)
was assertI2E
var i I = ...
e := i.(E)
was assertI2E2
var i I = ...
e, ok := i.(E)
These are the remaining runtime calls:
convT2E:
var b Big = ...
var e E = b
convT2I:
var b Big = ...
var i I = b
convI2I:
var i2 I2 = ...
var i I = i2
assertE2I:
var e E = ...
i := e.(I)
assertE2I2:
var e E = ...
i, ok := e.(I)
assertI2I:
var i I = ...
i2 := i.(I2)
assertI2I2:
var i I = ...
i2, ok := i.(I2)
Fixes#17405Fixes#8422
Change-Id: Ida2367bf8ce3cd2c6bb599a1814f1d275afabe21
Reviewed-on: https://go-review.googlesource.com/32313
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>
We generate an OpKeepAlive for the idata portion of the interface
for a runtime.KeepAlive call. But given such an op, we need to keep
the entire containing variable alive, not just the range that was
passed to the OpKeepAlive operation.
Fixes#17710
Change-Id: I90de66ec8065e22fb09bcf9722999ddda289ae6e
Reviewed-on: https://go-review.googlesource.com/32477
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
We used to have to keep on-stack copies of these types.
Now they can be registerized.
[0]T is kind of trivial but might as well handle it.
This change enables another change I'm working on to improve how x.(T)
expressions are handled (#17405). This CL helps because now all
types that are direct interface types are registerizeable (e.g. [1]*byte).
No higher-degree arrays for now because non-constant indexes are hard.
Update #17405
Change-Id: I2399940965d17b3969ae66f6fe447a8cefdd6edd
Reviewed-on: https://go-review.googlesource.com/32416
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This is an extension of
https://go-review.googlesource.com/c/31662/
to mark all the temporaries, not just the ssa-generated ones.
Before-and-after ls -l `go tool -n compile` shows a 3%
reduction in size (or rather, a prior 3% inflation for
failing to filter temps out properly.)
Replaced name-dependent "is it a temp?" tests with calls to
*Node.IsAutoTmp(), which depends on AutoTemp. Also replace
calls to istemp(n) with n.IsAutoTmp(), to reduce duplication
and clean up function name space. Generated temporaries
now come with a "." prefix to avoid (apparently harmless)
clashes with legal Go variable names.
Fixes#17644.
Fixes#17240.
Change-Id: If1417f29c79a7275d7303ddf859b51472890fd43
Reviewed-on: https://go-review.googlesource.com/32255
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Currently, zeroing generates an ssa.OpZero, which never has write
barriers, even if the assignment is an OASWB. The hybrid barrier
requires write barriers on zeroing, so change OASWB to generate an
ssa.OpZeroWB when assigning the zero value, which turns into a
typedmemclr.
Updates #17503.
Change-Id: Ib37ac5e39f578447dbd6b36a6a54117d5624784d
Reviewed-on: https://go-review.googlesource.com/31451
Reviewed-by: Cherry Zhang <cherryyz@google.com>
- removes the runtime function stringtoslicebytetmp
- removes the generation of calls to stringtoslicebytetmp from the frontend
- adds handling of OSTRARRAYBYTETMP in the backend
This reduces binary sizes and avoids function call overhead.
Change-Id: Ib9988d48549cee663b685b4897a483f94727b940
Reviewed-on: https://go-review.googlesource.com/32158
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Martin Möhrmann <martisch@uos.de>
TryBot-Result: Gobot Gobot <gobot@golang.org>
When we do
var x []byte = ...
y := x[i:]
We can't just use y.ptr = x.ptr + i, as the new pointer may point to the
next object in memory after the backing array.
We used to fix this by doing:
y.cap = x.cap - i
delta := i
if y.cap == 0 {
delta = 0
}
y.ptr = x.ptr + delta
That generates a branch in what is otherwise straight-line code.
Better to do:
y.cap = x.cap - i
mask := (y.cap - 1) >> 63 // -1 if y.cap==0, 0 otherwise
y.ptr = x.ptr + i &^ mask
It's about the same number of instructions (~4, depending on what
parts are constant, and the target architecture), but it is all
inline. It plays nicely with CSE, and the mask can be computed
in parallel with the index (in cases where a multiply is required).
It is a minor win in both speed and space.
Change-Id: Ied60465a0b8abb683c02208402e5bb7ac0e8370f
Reviewed-on: https://go-review.googlesource.com/32022
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
When the compiler insert write barriers, the frontend makes
conservative decisions at an early stage. This may have false
positives which result in write barriers for stack writes.
A new phase, writebarrier, is added to the SSA backend, to delay
the decision and eliminate false positives. The frontend still
makes conservative decisions. When building SSA, instead of
emitting runtime calls directly, it emits WB ops (StoreWB,
MoveWB, etc.), which will be expanded to branches and runtime
calls in writebarrier phase. Writes to static locations on stack
are detected and write barriers are removed.
All write barriers of stack writes found by the script from
issue #17330 are eliminated (except two false positives).
Fixes#17330.
Change-Id: I9bd66333da9d0ceb64dcaa3c6f33502798d1a0f8
Reviewed-on: https://go-review.googlesource.com/31131
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Adapt old test for prove's bounds check elimination.
Added missing rule to generic rules that lead to differences
between 32 and 64 bit platforms on sliceopt test.
Added debugging to prove.go that was helpful-to-necessary to
discover that missing rule.
Lowered debugging level on prove.go from 3 to 1; no idea
why it was previously 3.
Change-Id: I09de206aeb2fced9f2796efe2bfd4a59927eda0c
Reviewed-on: https://go-review.googlesource.com/23290
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This pragma cancels the effect of go:nowritebarrierrec. This is useful
in the scheduler because there are places where we enter a function
without a valid P (and hence cannot have write barriers), but then
obtain a P. This allows us to annotate the function with
go:nowritebarrierrec and split out the part after we've obtained a P
into a go:yeswritebarrierrec function.
Change-Id: Ic8ce4b6d3c074a1ecd8280ad90eaf39f0ffbcc2a
Reviewed-on: https://go-review.googlesource.com/30938
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
"abc"[1] is not like 'b', in that -"abc"[1] is uint8 math, not ideal constant math.
Delay the constantification until after ideal constant folding is over.
Fixes#11370.
Change-Id: Iba2fc00ca2455959e7bab8f4b8b4aac14b1f9858
Reviewed-on: https://go-review.googlesource.com/15740
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This, along with CL 30140, removes ~50% of stack write barriers
mentioned in issue #17330. The remaining are most due to Phi and
FwdRef, which is not resolved when building SSA. We might be
able to do it at a later stage where Phi and Copy propagations
are done, but matching an if-(store-store-call)+ sequence seems
not very pleasant.
Updates #17330.
Change-Id: Iaa36c7b1f4c4fc3dc10a27018a3b0e261094cb21
Reviewed-on: https://go-review.googlesource.com/30290
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
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>
Probably a holdover from linked list vs. slice.
Change-Id: Ib2540b08ef0ae48707d44a5d57bc23f8d65c760d
Reviewed-on: https://go-review.googlesource.com/30256
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Should be more asymptotically happy.
We process each variable in turn to find all the
locations where it needs a phi (the dominance frontier
of all of its definitions). Then we add all those phis.
This takes O(n * #variables), although hopefully much less.
Then we do a single tree walk to match all the
FwdRefs with the nearest definition or phi.
This takes O(n) time.
The one remaining inefficiency is that we might end up
introducing a bunch of dead phis in the first step.
A TODO is to introduce phis only where they might be
used by a read.
The old algorithm is still faster on small functions,
so there's a cutover size (currently 500 blocks).
This algorithm supercedes the David's sparse phi
placement algorithm for large functions.
Lowers compile time of example from #14934 from
~10 sec to ~4 sec.
Lowers compile time of example from #16361 from
~4.5 sec to ~3 sec.
Lowers #16407 from ~20 min to ~30 sec.
Update #14934
Update #16361Fixes#16407
Change-Id: I1cff6364e1623c143190b6a924d7599e309db58f
Reviewed-on: https://go-review.googlesource.com/30163
Reviewed-by: David Chase <drchase@google.com>
At this point in the compiler we haven't assigned Xoffset values for
PAUTO variables anyway, so just immediately store the stack offsets
into Xoffset rather than into a global map.
Change-Id: I61eb471c857c8b145fd0895cbd98fd4e8d3c3365
Reviewed-on: https://go-review.googlesource.com/30081
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
var x *X = ...
defer x.foo()
As part of the defer, we need to calculate &(*X).foo·f. This expression
is the address of the static closure that will call (*X).foo when a
pointer to that closure is used in a call/defer/go. This pointer is not
currently properly typed in SSA. It is a pointer type, but the base
type is nil, not a proper type.
This turns out not to be a problem currently because we never use the
type of these SSA values. But I'm trying to change that (to be able to
spill them) in CL 28391. To fix, use uint8 as the fake type of the
closure.
Change-Id: Ieee388089c9af398ed772ee8c815122c347cb633
Reviewed-on: https://go-review.googlesource.com/29444
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Also adds the 'find leftmost one' instruction (FLOGR) and replaces the
WORD-encoded use of FLOGR in math/big with it.
Change-Id: I18e7cd19e75b8501a6ae8bd925471f7e37ded206
Reviewed-on: https://go-review.googlesource.com/29372
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Michael Munday <munday@ca.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
We're dropping this behavior in favor of runtime.KeepAlive.
Implement runtime.KeepAlive as an intrinsic.
Update #15843
Change-Id: Ib60225bd30d6770ece1c3c7d1339a06aa25b1cbc
Reviewed-on: https://go-review.googlesource.com/28310
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
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>
Follow up to CL 29134. Generated with gofmt -r 'Nod -> nod', plus
three manual adjustments to the comments in syntax/parser.go
Change-Id: I02920f7ab10c70b6e850457b42d5fe35f1f3821a
Reviewed-on: https://go-review.googlesource.com/29136
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Binary search remains our friend.
Suppose you add an ought-to-be-benign pattern to PPC64.rules,
and make.bash starts crashing. You can guard the pattern(s)
with config.DebugTest:
(Eq8 x y) && config.DebugTest && isSigned(x.Type) &&
isSigned(y.Type) ->
(Equal (CMPW (SignExt8to32 x) (SignExt8to32 y)))
and then
gossahash -s ./make.bash
...
(go drink beer while silicon minions toil)
...
Trying ./make.bash args=[], env=[GOSSAHASH=100110010111110]
./make.bash failed (1 distinct triggers): exit status 1
Trigger string is 'GOSSAHASH triggered (*importReader).readByte',
repeated 1 times
Review GSHS_LAST_FAIL.0.log for failing run
Finished with GOSSAHASH=100110010111110
Change-Id: I4eff46ebaf496baa2acedd32e217005cb3ac1c62
Reviewed-on: https://go-review.googlesource.com/29273
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
GOSSAFUNC=foo had previously only done printing for the
single function foo, and didn't quite clean up after itself
properly. Changes ensures that Config.HTML != nil iff
GOSSAFUNC==name-of-current-function.
Change-Id: I255e2902dfc64f715d93225f0d29d9525c06f764
Reviewed-on: https://go-review.googlesource.com/29250
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
After the removal of the old backend many types are no longer referenced
outside internal/gc. Make these functions private so that tools like
honnef.co/go/unused can spot when they become dead code. In doing so
this CL identified several previously public helpers which are no longer
used, so removes them.
This should be the last of the public functions.
Change-Id: I7e9c4e72f86f391b428b9dddb6f0d516529706c3
Reviewed-on: https://go-review.googlesource.com/29134
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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>
when not instrumenting:
- Intrinsify uses of slicebytetostringtmp within the runtime package
in the ssa backend.
- Pass OARRAYBYTESTRTMP nodes to the compiler backends for lowering
instead of generating calls to slicebytetostringtmp.
name old time/op new time/op delta
ConcatStringAndBytes-4 27.9ns ± 2% 24.7ns ± 2% -11.52% (p=0.000 n=43+43)
Fixes#17044
Change-Id: I51ce9c3b93284ce526edd0234f094e98580faf2d
Reviewed-on: https://go-review.googlesource.com/29017
Run-TryBot: Martin Möhrmann <martisch@uos.de>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
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>
It passed tests once, if anything's wrong, better to fail
sooner than later.
Change-Id: Ibb1c5db3f4c5535a4ff4681fd157db77082c5041
Reviewed-on: https://go-review.googlesource.com/28982
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
The new SSA backend modifies the ABI slightly: R0 is now a usable
general purpose register.
Fixes#16677.
Change-Id: I367435ce921e0c7e79e021c80cf8ef5d1d1466cf
Reviewed-on: https://go-review.googlesource.com/28978
Run-TryBot: Michael Munday <munday@ca.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Also add assembly implementation, in case intrinsics is disabled.
Change-Id: Iff0a8a8ce326651bd29f6c403f5ec08dd3629993
Reviewed-on: https://go-review.googlesource.com/28979
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
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>
- also consistently use %v instead of %s when we have a (gc) Formatter
- rewrite done automatically using Formats test in -u (update) mode
- manual update of format strings that were not single string constants
- updated fmt.go, fmt_test.go accordingly
- fmt_test: permit "%T" always
Change-Id: I8f0704286aba5704600ad0c4a4484005b79b905d
Reviewed-on: https://go-review.googlesource.com/28954
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Atomic ops on ARM are implemented with kernel calls, so they are
not intrinsified.
Change-Id: I0e7cc2e5526ae1a3d24b4b89be1bd13db071f8ef
Reviewed-on: https://go-review.googlesource.com/28977
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This list now matches the one in popt.go.
Change-Id: Ib24de531cc35252f0ef276e5c6d247654b021533
Reviewed-on: https://go-review.googlesource.com/28965
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
When the divisor is known to be a constant
non-zero, don't insert panicdivide calls
that will just be eliminated later.
The main benefit here is readability of the SSA
form for compiler developers.
Change-Id: Icb7d07fc996941fbaff84524ac3e4b53d8e75fda
Reviewed-on: https://go-review.googlesource.com/28530
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
It should alias to Xchg instead of Swap. Found when testing #16985.
Change-Id: If9fd734a1f89b8b2656f421eb31b9d1b0d95a49f
Reviewed-on: https://go-review.googlesource.com/28512
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Does not pass toolstash -cmp due to changed export data,
but the cmd/go binary (which doesn't contain export data)
is bit-for-bit identical.
Change-Id: I6b12f9de18cf7da528e9207dccbf8f08c969f142
Reviewed-on: https://go-review.googlesource.com/26753
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
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>
