delta/go-git.git/test/live.go, branch dev.typeparams

[dev.typeparams] cmd/compile: simplify interface conversions

2021-08-09T16:10:20+00:00

Simplify the implementation of interface conversions in the compiler.
Don't pass fields that aren't needed (the data word, usually) to the runtime.

For generics, we need to put a dynamic type in an interface. The new
dataWord function is exactly what we need (the type word will come
from a dictionary).

Change-Id: Iade5de5c174854b65ad248f35c7893c603f7be3d
Reviewed-on: https://go-review.googlesource.com/c/go/+/340029
Trust: Keith Randall 
Trust: Dan Scales 
Run-TryBot: Keith Randall 
TryBot-Result: Go Bot 
Reviewed-by: Dan Scales

[dev.typeparams] cmd/compile: suppress liveness diagnostics of wrappers

2021-06-24T20:28:44+00:00

Similar to the previous CL to suppress escape analysis diagnostics for
method wrappers, suppress liveness analysis diagnostics too. It's
hardly useful to know that all of a wrapper method's arguments are
live at entry.

Change-Id: I0d1e44552c6334ee3b454adc107430232abcb56a
Reviewed-on: https://go-review.googlesource.com/c/go/+/330749
Trust: Matthew Dempsky 
Run-TryBot: Matthew Dempsky 
TryBot-Result: Go Bot 
Reviewed-by: Cuong Manh Le

[dev.typeparams] cmd/compile, runtime: always enable defer/go wrapping

2021-06-08T17:03:39+00:00

Hardwire regabidefers to true. Remove it from GOEXPERIMENTs.

Fallback paths are not cleaned up in this CL. That will be done
in later CLs.

Change-Id: Iec1112a1e55d5f6ef70232a5ff6e702f649071c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/325913
Trust: Cherry Mui 
Run-TryBot: Cherry Mui 
TryBot-Result: Go Bot 
Reviewed-by: Michael Knyszek 
Reviewed-by: Than McIntosh

[dev.typeparams] test: test regabidefers in live.go

2021-06-04T17:00:48+00:00

Previously, live.go is conditioned on not using regabidefers. Now
we have regabidefers enabled by default everywhere, and we may
remove the fallback path in the near future, test that
configuration instead.

Change-Id: Idf910aee323bdd6478bc7a2062b2052d82ce003f
Reviewed-on: https://go-review.googlesource.com/c/go/+/325111
Trust: Cherry Mui 
Run-TryBot: Cherry Mui 
TryBot-Result: Go Bot 
Reviewed-by: Than McIntosh

test: add liveness test for regabi

2021-04-19T14:42:58+00:00

With defer/go wrapping and register arguments, some liveness info
changed and live.go test was disabled for regabi. This CL adds a
new one for regabi.

Change-Id: I65f03a6ef156366d8b76c62a16251c3e818f4b02
Reviewed-on: https://go-review.googlesource.com/c/go/+/311369
Trust: Cherry Zhang 
Reviewed-by: David Chase

cmd/compile: wrap/desugar defer calls for register abi

2021-03-23T23:08:19+00:00

Adds code to the compiler's "order" phase to rewrite go and defer
statements to always be argument-less. E.g.

 defer f(x,y)       =>     x1, y1 := x, y
			   defer func() { f(x1, y1) }

This transformation is not beneficial on its own, but it helps
simplify runtime defer handling for the new register ABI (when
invoking deferred functions on the panic path, the runtime doesn't
need to manage the complexity of determining which args to pass in
register vs memory).

This feature is currently enabled by default if GOEXPERIMENT=regabi or
GOEXPERIMENT=regabidefer is in effect.

Included in this CL are some workarounds in the runtime to insure that
"go" statement targets in the runtime are argument-less already (since
wrapping them can potentially introduce heap-allocated closures, which
are currently not allowed). The expectation is that these workarounds
will be temporary, and can go away once we either A) change the rules
about heap-allocated closures, or B) implement some other scheme for
handling go statements.

Change-Id: I01060d79a6b140c6f0838d6e6813f807ccdca319
Reviewed-on: https://go-review.googlesource.com/c/go/+/298669
Trust: Than McIntosh 
Run-TryBot: Than McIntosh 
TryBot-Result: Go Bot 
Reviewed-by: Cherry Zhang 
Reviewed-by: David Chase

[dev.regabi] cmd/compile: only save ONAMEs on Curfn.Dcl

2020-12-01T17:16:53+00:00

There's not really any use to tracking function-scoped constants and
types on Curfn.Dcl, and there's sloppy code that assumes all of the
declarations are variables (e.g., cmpstackvarlt).

Change-Id: I5d10dc681dac2c161c7b73ba808403052ca0608e
Reviewed-on: https://go-review.googlesource.com/c/go/+/274436
Reviewed-by: Russ Cox 
Trust: Matthew Dempsky

cmd/compile,cmd/link: fix and re-enable open-coded defers on riscv64

2020-01-29T16:34:44+00:00

The R_CALLRISCV relocation marker is on the JALR instruction, however the actual
relocation is currently two instructions previous for the AUIPC+ADDI sequence.
Adjust the platform dependent offset accordingly and re-enable open-coded defers.

Fixes #36786.

Change-Id: I71597c193c447930fbe94ce44b7355e89ae877bb
Reviewed-on: https://go-review.googlesource.com/c/go/+/216797
Run-TryBot: Joel Sing 
TryBot-Result: Gobot Gobot 
Reviewed-by: Cherry Zhang

test: disable the live test on riscv64

2020-01-29T02:43:35+00:00

This test expects that open-coded defers are enabled, which is not currently
the case on riscv64.

Updates issue #27532 and #36786.

Change-Id: I94bb558c5b0734b4cfe5ae12873be81026009bcf
Reviewed-on: https://go-review.googlesource.com/c/go/+/216777
Reviewed-by: Brad Fitzpatrick 
Run-TryBot: Brad Fitzpatrick 
TryBot-Result: Gobot Gobot

cmd/compile, cmd/link, runtime: make defers low-cost through inline code and extra funcdata

2019-10-24T13:54:11+00:00

Generate inline code at defer time to save the args of defer calls to unique
(autotmp) stack slots, and generate inline code at exit time to check which defer
calls were made and make the associated function/method/interface calls. We
remember that a particular defer statement was reached by storing in the deferBits
variable (always stored on the stack). At exit time, we check the bits of the
deferBits variable to determine which defer function calls to make (in reverse
order). These low-cost defers are only used for functions where no defers
appear in loops. In addition, we don't do these low-cost defers if there are too
many defer statements or too many exits in a function (to limit code increase).

When a function uses open-coded defers, we produce extra
FUNCDATA_OpenCodedDeferInfo information that specifies the number of defers, and
for each defer, the stack slots where the closure and associated args have been
stored. The funcdata also includes the location of the deferBits variable.
Therefore, for panics, we can use this funcdata to determine exactly which defers
are active, and call the appropriate functions/methods/closures with the correct
arguments for each active defer.

In order to unwind the stack correctly after a recover(), we need to add an extra
code segment to functions with open-coded defers that simply calls deferreturn()
and returns. This segment is not reachable by the normal function, but is returned
to by the runtime during recovery. We set the liveness information of this
deferreturn() to be the same as the liveness at the first function call during the
last defer exit code (so all return values and all stack slots needed by the defer
calls will be live).

I needed to increase the stackguard constant from 880 to 896, because of a small
amount of new code in deferreturn().

The -N flag disables open-coded defers. '-d defer' prints out the kind of defer
being used at each defer statement (heap-allocated, stack-allocated, or
open-coded).

Cost of defer statement  [ go test -run NONE -bench BenchmarkDefer$ runtime ]
  With normal (stack-allocated) defers only:         35.4  ns/op
  With open-coded defers:                             5.6  ns/op
  Cost of function call alone (remove defer keyword): 4.4  ns/op

Text size increase (including funcdata) for go binary without/with open-coded defers:  0.09%

The average size increase (including funcdata) for only the functions that use
open-coded defers is 1.1%.

The cost of a panic followed by a recover got noticeably slower, since panic
processing now requires a scan of the stack for open-coded defer frames. This scan
is required, even if no frames are using open-coded defers:

Cost of panic and recover [ go test -run NONE -bench BenchmarkPanicRecover runtime ]
  Without open-coded defers:        62.0 ns/op
  With open-coded defers:           255  ns/op

A CGO Go-to-C-to-Go benchmark got noticeably faster because of open-coded defers:

CGO Go-to-C-to-Go benchmark [cd misc/cgo/test; go test -run NONE -bench BenchmarkCGoCallback ]
  Without open-coded defers:        443 ns/op
  With open-coded defers:           347 ns/op

Updates #14939 (defer performance)
Updates #34481 (design doc)

Change-Id: I63b1a60d1ebf28126f55ee9fd7ecffe9cb23d1ff
Reviewed-on: https://go-review.googlesource.com/c/go/+/202340
Reviewed-by: Austin Clements