Prior to this CL, the function's position was used.
The dottype Node's position is clearly better.
I'm not thrilled about introducing a reference to
lineno in the middle of SSA construction;
I will have to remove it later.
My immediate goal is stability and correctness of positions,
though, since that aids refactoring, so this is an improvement.
An example from package io:
func (t *multiWriter) WriteString(s string) (n int, err error) {
var p []byte // lazily initialized if/when needed
for _, w := range t.writers {
if sw, ok := w.(stringWriter); ok {
n, err = sw.WriteString(s)
The w.(stringWriter) type assertion includes loading
the address of static type data for stringWriter:
LEAQ type."".stringWriter(SB), R10
Prior to this CL, this instruction was given the line number
of the function declaration.
After this CL, this instruction is given the line number
of the type assertion itself.
Change-Id: Ifcca274b581a5a57d7e3102c4d7b7786bf307210
Reviewed-on: https://go-review.googlesource.com/38389
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Tested by fixedbugs/issue3705.go.
This removes a dependency on lineno
from near the backend.
Change-Id: I228bd0ad7295cf881b9bdeb0df9d18483fb96821
Reviewed-on: https://go-review.googlesource.com/38382
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This eliminates an old TODO,
and stabilizes the position information
for init functions.
Change-Id: Idf2d9a16a60e097ee08f42541b87e170da2f9d3a
Reviewed-on: https://go-review.googlesource.com/38388
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Previously, we handled recursive interfaces by deferring typechecking
of interface methods, while eagerly expanding interface embeddings.
This CL switches to eagerly evaluating interface methods, and
deferring expanding interface embeddings to dowidth. This allows us to
detect recursive interface embeddings with the same mechanism used for
detecting recursive struct embeddings.
Updates #16369.
Change-Id: If4c0320058047f8a2d9b52b9a79de47eb9887f95
Reviewed-on: https://go-review.googlesource.com/38391
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This CL changes the order that liveness analysis visits CFG blocks to
PC order, rather than RPO. This doesn't meaningfully change anything
except that the PCDATA_StackMapIndex values will be assigned in PC
order too.
However, this does have the benefit that the subsequent CL to port
liveness analysis to the SSA CFG (which has blocks in PC order) will
now pass toolstash-check.
Change-Id: I1de5a2eecb8027723a6e422d46186d0c63d48c8d
Reviewed-on: https://go-review.googlesource.com/38086
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Teach the backend to recognize that the address of a symbol
is equal with itself, and that the addresses of two different
symbols are different.
Some examples of where this rule hits in the standard library:
- inlined uses of (*time.Time).setLoc (e.g. time.UTC)
- inlined uses of bufio.NewReader (via type assertion)
Change-Id: I23dcb068c2ec333655c1292917bec13bbd908c24
Reviewed-on: https://go-review.googlesource.com/38338
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
When optimizations are disabled, the compiler
cannot eliminate enough write barriers to satisfy
the runtime's nowritebarrier and nowritebarrierrec
annotations.
Enforce that requirement, and for convenience,
have cmd/go elide -N when compiling the runtime.
This came up in practice for me when running
toolstash -cmp. When toolstash -cmp detected
mismatches, it recompiled with -N, which caused
runtime compilation failures.
Change-Id: Ifcdef22c725baf2c59a09470f00124361508a8f3
Reviewed-on: https://go-review.googlesource.com/38380
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Instead we can use t.nod.Pos.
Change-Id: I643ee3226e402e38d4c77e8f328cbe83e55eac5c
Reviewed-on: https://go-review.googlesource.com/38309
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
CL 27254 changed a constant string to a byte array
in encoding/hex and got significant performance
improvements.
hex.Encode used the string twice in a single function.
The rewrite rules lower constant strings into components.
The pointer component requires an aux symbol.
The existing implementation created a new aux symbol every time.
As a result, constant string pointers were never CSE'd.
Tighten then moved the pointer calculation next to the uses, i.e.
into the loop.
The re-use of aux syms enabled by this CL
occurs 3691 times during make.bash.
This CL should not go in without CL 38338
or something like it.
Change-Id: Ibbf5b17283c0e31821d04c7e08d995c654de5663
Reviewed-on: https://go-review.googlesource.com/28219
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This makes the overall naming and use of the functions
to create a Type more consistent.
Passes toolstash -cmp.
Change-Id: Ie0d40b42cc32b5ecf5f20502675a225038ea40e4
Reviewed-on: https://go-review.googlesource.com/38354
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Mapping all empty interfaces onto the same Type
allows better reuse of the ptrTo and sliceOf
Type caches for *interface{} and []interface{}.
This has little compiler performance impact now,
but it will be helpful in the future,
when we will eagerly populate some of those caches.
Passes toolstash-check.
Change-Id: I17daee599a129b0b2f5f3025c1be43d569d6782c
Reviewed-on: https://go-review.googlesource.com/38344
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This reduces the number of calls back into the
gc Type routines, which will help performance
in a concurrent backend.
It also reduces the number of callsites
that must be considered in making the transition.
Passes toolstash-check -all. No compiler performance changes.
Updates #15756
Change-Id: Ic7a8f1daac7e01a21658ae61ac118b2a70804117
Reviewed-on: https://go-review.googlesource.com/38340
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Prior to this CL, the ssa.Frontend field was responsible
for providing types to the backend during compilation.
However, the types needed by the backend are few and static.
It makes more sense to use a struct for them
and to hang that struct off the ssa.Config,
which is the correct home for readonly data.
Now that Types is a struct, we can clean up the names a bit as well.
This has the added benefit of allowing early construction
of all types needed by the backend.
This will be useful for concurrent backend compilation.
Passes toolstash-check -all. No compiler performance change.
Updates #15756
Change-Id: I021658c8cf2836d6a22bbc20cc828ac38c7da08a
Reviewed-on: https://go-review.googlesource.com/38336
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
While we're here, also eliminate a few more Curfn uses.
Passes toolstash -cmp. No compiler performance impact.
Updates #15756
Change-Id: Ib8db9e23467bbaf16cc44bf62d604910f733d6b8
Reviewed-on: https://go-review.googlesource.com/38331
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This is a first step towards eliminating the
Curfn global in the backend.
There's more to do.
Passes toolstash -cmp. No compiler performance impact.
Updates #15756
Change-Id: Ib09f550a001e279a5aeeed0f85698290f890939c
Reviewed-on: https://go-review.googlesource.com/38232
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Suggested by mdempsky in CL 38232.
This allows us to use the Frontend field
to associate frontend state and information
with a function.
See the following CL in the series for examples.
This is a giant CL, but it is almost entirely routine refactoring.
The ssa test API is starting to feel a bit unwieldy.
I will clean it up separately, once the dust has settled.
Passes toolstash -cmp.
Updates #15756
Change-Id: I71c573bd96ff7251935fce1391b06b1f133c3caf
Reviewed-on: https://go-review.googlesource.com/38327
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.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>
I don't know that it exists for any other architectures.
Update #18616
Change-Id: Idfe5dee251764d32787915889ec0be4bebc5be24
Reviewed-on: https://go-review.googlesource.com/38323
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This makes ssa.Func, ssa.Cache, and ssa.Config fulfill
the roles laid out for them in CL 38160.
The only non-trivial change in this CL is how cached
values and blocks get IDs. Prior to this CL, their IDs were
assigned as part of resetting the cache, and only modified
IDs were reset. This required knowing how many values and
blocks were modified, which required a tight coupling between
ssa.Func and ssa.Config. To eliminate that coupling,
we now zero values and blocks during reset,
and assign their IDs when they are used.
Since unused values and blocks have ID == 0,
we can efficiently find the last used value/block,
to avoid zeroing everything.
Bulk zeroing is efficient, but not efficient enough
to obviate the need to avoid zeroing everything every time.
As a happy side-effect, ssa.Func.Free is no longer necessary.
DebugHashMatch and friends now belong in func.go.
They have been left in place for clarity and review.
I will move them in a subsequent CL.
Passes toolstash -cmp. No compiler performance impact.
No change in 'go test cmd/compile/internal/ssa' execution time.
Change-Id: I2eb7af58da067ef6a36e815a6f386cfe8634d098
Reviewed-on: https://go-review.googlesource.com/38167
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
See https://go-review.googlesource.com/#/c/38313/ for background.
It turns out that only a few tests checked for this.
The new error message is shorter and very clear.
Change-Id: I8ab4ad59fb023c8b54806339adc23aefd7dc7b07
Reviewed-on: https://go-review.googlesource.com/38314
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This is an evolution of https://go-review.googlesource.com/33616, as discussed
via email with Robert (gri):
$ cat foobar.go
package main
func main() {
a := "foo", "bar"
}
before:
./foobar.go:4:4: assignment count mismatch: want 1 values, got 2
after:
./foobar.go:4:4: assignment count mismatch: cannot assign 2 values to 1 variables
We could likely also eliminate the "assignment count mismatch" prefix now
without losing any information, but that string is matched by a number of
tests.
Change-Id: Ie6fc8a7bbd0ebe841d53e66e5c2f49868decf761
Reviewed-on: https://go-review.googlesource.com/38313
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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>
Remove size AuxInt in Store, and alignment in Move/Zero. We still
pass size AuxInt to Move/Zero, as it is used for partial Move/Zero
lowering (e.g. cmd/compile/internal/ssa/gen/386.rules:288).
SizeAndAlign is gone.
Passes "toolstash -cmp" on std.
Change-Id: I1ca34652b65dd30de886940e789fcf41d521475d
Reviewed-on: https://go-review.googlesource.com/38150
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Now that the write barrier insertion is moved to SSA, the SSA
building code can be simplified.
Updates #17583.
Change-Id: I5cacc034b11aa90b0abe6f8dd97e4e3994e2bc25
Reviewed-on: https://go-review.googlesource.com/36840
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
When the compiler insert write barriers, the frontend makes
conservative decisions at an early stage. This sometimes have
false positives because of the lack of information, for example,
writes on stack. SSA's writebarrier pass identifies writes on
stack and eliminates write barriers for them.
This CL moves write barrier insertion into SSA. The frontend no
longer makes decisions about write barriers, and simply does
normal assignments and emits normal Store ops when building SSA.
SSA writebarrier pass inserts write barrier for Stores when needed.
There, it has better information about the store because Phi and
Copy propagation are done at that time.
This CL only changes StoreWB to Store in gc/ssa.go. A followup CL
simplifies SSA building code.
Updates #17583.
Change-Id: I4592d9bc0067503befc169c50b4e6f4765673bec
Reviewed-on: https://go-review.googlesource.com/36839
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
For SSA Store/Move/Zero ops, attach the type of the value being
stored to the op as the Aux field. This type will be used for
write barrier insertion (in a followup CL). Since SSA passes
do not accurately propagate types of values (because of type
casting), we can't simply use type of the store's arguments
for write barrier insertion.
Passes "toolstash -cmp" on std.
Updates #17583.
Change-Id: I051d5e5c482931640d1d7d879b2a6bb91f2e0056
Reviewed-on: https://go-review.googlesource.com/36838
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Implement math/bits.TrailingZerosX using intrinsics.
Generally reorganize the intrinsic spec a bit.
The instrinsics data structure is now built at init time.
This will make doing the other functions in math/bits easier.
Update sys.CtzX to return int instead of uint{64,32} so it
matches math/bits.TrailingZerosX.
Improve the intrinsics a bit for amd64. We don't need the CMOV
for <64 bit versions.
Update #18616
Change-Id: Ic1c5339c943f961d830ae56f12674d7b29d4ff39
Reviewed-on: https://go-review.googlesource.com/38155
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Interface wrapper functions now get compiled eagerly in some cases.
Consequently, they may be present in multiple translation units.
Mark them as DUPOK, just like closures.
Fixes#19548Fixes#19550
Change-Id: Ibe74adb5a62dbf6447db37fde22dcbb3479969ef
Reviewed-on: https://go-review.googlesource.com/38156
Reviewed-by: David Chase <drchase@google.com>
In the SSA CFG, TEXT, RET, and JMP instructions correspond to Blocks,
not Values. Rework liveness analysis so that progeffects only cares
about Progs that result from Values, and handle Blocks separately.
Passes toolstash-check -all.
Change-Id: Ic23719c75b0421fdb51382a08dac18c3ba042b32
Reviewed-on: https://go-review.googlesource.com/38085
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
The fmtmode and fmtpkgpfx globals stand in the
way of making the compiler more concurrent (#15756).
This CL removes them.
The natural way to eliminate a global is to explicitly
thread it as a parameter through all function calls.
However, most of the functions in gc/fmt.go
get called indirectly, by way of fmt format strings,
so there's nowhere natural to add a parameter.
Since there are only a few fmtmode modes,
use named types to distinguish between modes.
For example, fmtNodeErr, fmtNodeDbg, and fmtNodeTypeId
are all gc.Node, but they print in different modes.
Varying the type allows us to thread mode through fmt.
Handle fmtpkgpfx by converting it to a printing mode,
FTypeIdName, and using the same type-based approach.
To avoid a loss of readability and danger of bugs
from introducing conversions at all call sites,
instead add a helper that systematically modifies the args.
The only remaining gc/fmt.go global is dumpdepth.
Since that is used for debugging only,
it that can be handled with a global mutex,
or some similarly basic, if inefficient, protection.
Passes toolstash -cmp. No compiler performance impact.
For future reference, other options for threading state
that were considered and rejected:
* Wrapping values in structs, such as:
type fmtNode struct {
n *Node
mode fmtMode
}
This reduces the proliferation of types, and supports
easily adding extra local parameters.
However, putting such a struct into an interface{} allocates.
This is unacceptable in this particular area of code.
* Passing state via precision, such as:
fmt.Fprintf("%*v", mode, n)
where mode is the state encoded as an integer.
This avoids extra allocations, but it is out of keeping
with the intended semantics of precision, and is less readable.
* Modify the fmt package to support setting/getting context
via fmt.State. Unavailable due to Go 1 compatibility,
and probably the wrong solution anyway.
* Give up on package fmt. This would be a huge readability
regression and cause high code churn.
* Attempt a de-novo rewrite that circumvents these problems.
Too high a risk of bugs, with insufficient reward for the effort,
particularly since long term plans call for elimination
of gc.Node.
Change-Id: Iea2440d5a34a938e64273707de27e3a897cb41d1
Reviewed-on: https://go-review.googlesource.com/38147
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
