delta/go-git.git/src/runtime, branch dev.ssa

[dev.ssa] cmd/compile: implement GO386=387

2016-08-10T17:41:01+00:00

Last part of the 386 SSA port.

Modify the x86 backend to simulate SSE registers and
instructions with 387 registers and instructions.
The simulation isn't terribly performant, but it works,
and the old implementation wasn't very performant either.
Leaving to people who care about 387 to optimize if they want.

Turn on SSA backend for 386 by default.

Fixes #16358

Change-Id: I678fb59132620b2c47e993c1c10c4c21135f70c0
Reviewed-on: https://go-review.googlesource.com/25271
Run-TryBot: Keith Randall 
TryBot-Result: Gobot Gobot 
Reviewed-by: Keith Randall

[dev.ssa] Merge commit 'f135c326402aaa757aa96aad283a91873d4ae124' into mergebranch

2016-08-04T17:52:24+00:00

Pick up shared library fix in dev.ssa.

Change-Id: I5bdd0e9e0f1d6f7c14b518343ee323ed9a894b9c

runtime: initialize hash algs before typemap

2016-08-04T17:39:05+00:00

When compiling with -buildmode=shared, a map[int32]*_type is created for
each extra module mapping duplicate types back to a canonical object.
This is done in the function typelinksinit, which is called before the
init function that sets up the hash functions for the map
implementation. The result is typemap becomes unusable after
runtime initialization.

The fix in this CL is to move algorithm init before typelinksinit in
the runtime setup process. (For 1.8, we may want to turn typemap into
a sorted slice of types and use binary search.)

Manually tested on GOOS=linux with:

	GOHOSTARCH=386 GOARCH=386 ./make.bash && \
		go install -buildmode=shared std && \
		cd ../test && \
		go run run.go -linkshared

Fixes #16590

Change-Id: Idc08c50cc70d20028276fbf564509d2cd5405210
Reviewed-on: https://go-review.googlesource.com/25469
Run-TryBot: David Crawshaw 
Reviewed-by: Keith Randall

[dev.ssa] Merge remote-tracking branch 'origin/master' into mergebranch

2016-08-04T17:08:20+00:00

Semi-regular merge from tip into dev.ssa.

Change-Id: Iadb60e594ef65a99c0e1404b14205fa67c32a9e9

runtime: fix nanotime for macOS Sierra, again.

2016-08-02T20:17:50+00:00

macOS Sierra beta4 changed the kernel interface for getting time.
DX now optionally points to an address for additional info.
Set it to zero to avoid corrupting memory.

Fixes #16570

Change-Id: I9f537e552682045325cdbb68b7d0b4ddafade14a
Reviewed-on: https://go-review.googlesource.com/25400
Reviewed-by: David Crawshaw 
Reviewed-by: Ian Lance Taylor 
Reviewed-by: Quentin Smith 
Run-TryBot: Brad Fitzpatrick 
Reviewed-by: Austin Clements 
TryBot-Result: Gobot Gobot

runtime: reduce GC assist extra credit

2016-07-27T18:56:04+00:00

Mutator goroutines that allocate memory during the concurrent mark
phase are required to spend some time assisting the garbage
collector. The magnitude of this mandatory assistance is proportional
to the goroutine's allocation debt and subject to the assistance
ratio as calculated by the pacer.

When assisting the garbage collector, a mutator goroutine will go
beyond paying off its allocation debt. It will build up extra credit
to amortize the overhead of the assist.

In fast-allocating applications with high assist ratios, building up
this credit can take the affected goroutine's entire time slice.
Reduce the penalty on each goroutine being selected to assist the GC
in two ways, to spread the responsibility more evenly.

First, do a consistent amount of extra scan work without regard for
the pacer's assistance ratio. Second, reduce the magnitude of the
extra scan work so it can be completed within a few hundred
microseconds.

Commentary on gcOverAssistWork is by Austin Clements, originally in
https://golang.org/cl/24704

Updates #14812
Fixes #16432

Change-Id: I436f899e778c20daa314f3e9f0e2a1bbd53b43e1
Reviewed-on: https://go-review.googlesource.com/25155
Run-TryBot: Austin Clements 
TryBot-Result: Gobot Gobot 
Reviewed-by: Austin Clements 
Reviewed-by: Rick Hudson 
Reviewed-by: Chris Broadfoot

runtime/pprof: document use of pprof package

2016-07-26T22:16:55+00:00

Currently the pprof package gives almost no guidance for how to use it
and, despite the standard boilerplate used to create CPU and memory
profiles, this boilerplate appears nowhere in the pprof documentation.

Update the pprof package documentation to give the standard
boilerplate in a form people can copy, paste, and tweak. This
boilerplate is based on rsc's 2011 blog post on profiling Go programs
at https://blog.golang.org/profiling-go-programs, which is where I
always go when I need to copy-paste the boilerplate.

Change-Id: I74021e494ea4dcc6b56d6fb5e59829ad4bb7b0be
Reviewed-on: https://go-review.googlesource.com/25182
Reviewed-by: Rick Hudson

[dev.ssa] cmd/compile: 386 port now works

2016-07-21T20:41:18+00:00

GOARCH=386 SSATEST=1 ./all.bash passes

Caveat: still needs changes to test/ files to use *_ssa.go versions.  I
won't check those changes in with this CL because the builders will
complain as they don't have SSATEST=1.

Mostly minor fixes.

Implement float <-> uint32 in assembly.  It seems the simplest option
for now.

GO386=387 does not work.  That's why I can't make SSA the default for
386 yet.

Change-Id: Ic4d4402104d32bcfb1fd612f5bb6539f9acb8ae0
Reviewed-on: https://go-review.googlesource.com/25119
Reviewed-by: Cherry Zhang

runtime: add explicit `INT $3` at end of Darwin amd64 sigtramp

2016-07-21T01:04:22+00:00

The omission of this instruction could confuse the traceback code if a
SIGPROF occurred during a signal handler.  The traceback code would
trace up to sigtramp, but would then get confused because it would see a
PC address that did not appear to be in the function.

Fixes #16453.

Change-Id: I2b3d53e0b272fb01d9c2cb8add22bad879d3eebc
Reviewed-on: https://go-review.googlesource.com/25104
Reviewed-by: Josh Bleecher Snyder

runtime: support smaller physical pages than PhysPageSize

2016-07-20T18:28:43+00:00

Most operations need an upper bound on the physical page size, which
is what sys.PhysPageSize is for (this is checked at runtime init on
Linux). However, a few operations need a *lower* bound on the physical
page size. Introduce a "minPhysPageSize" constant to act as this lower
bound and use it where it makes sense:

1) In addrspace_free, we have to query each page in the given range.
   Currently we increment by the upper bound on the physical page
   size, which means we may skip over pages if the true size is
   smaller. Worse, we currently pass a result buffer that only has
   enough room for one page. If there are actually multiple pages in
   the range passed to mincore, the kernel will overflow this buffer.
   Fix these problems by incrementing by the lower-bound on the
   physical page size and by passing "1" for the length, which the
   kernel will round up to the true physical page size.

2) In the write barrier, the bad pointer check tests for pointers to
   the first physical page, which are presumably small integers
   masquerading as pointers. However, if physical pages are smaller
   than we think, we may have legitimate pointers below
   sys.PhysPageSize. Hence, use minPhysPageSize for this test since
   pointers should never fall below that.

In particular, this applies to ARM64 and MIPS. The runtime is
configured to use 64kB pages on ARM64, but by default Linux uses 4kB
pages. Similarly, the runtime assumes 16kB pages on MIPS, but both 4kB
and 16kB kernel configurations are common. This also applies to ARM on
systems where the runtime is recompiled to deal with a larger page
size. It is also a step toward making the runtime use only a
dynamically-queried page size.

Change-Id: I1fdfd18f6e7cbca170cc100354b9faa22fde8a69
Reviewed-on: https://go-review.googlesource.com/25020
Reviewed-by: Ian Lance Taylor 
Reviewed-by: Cherry Zhang 
Run-TryBot: Austin Clements