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  1. 10 Aug, 2016 3 commits
    • Cherry Zhang's avatar
      [dev.ssa] cmd/internal/obj/arm64: fix encoding constant into some instructions · 748aa844
      Cherry Zhang authored 
      When a constant can be encoded in a logical instruction (BITCON), do
it this way instead of using the constant pool. The BITCON testing
code runs faster than table lookup (using map):

(on AMD64 machine, with pseudo random input)
BenchmarkIsBitcon-4   	300000000	         4.04 ns/op
BenchmarkTable-4      	50000000	        27.3 ns/op

The equivalent C code of BITCON testing is formally verified with
model checker CBMC against linear search of the lookup table.

Also handle cases when a constant can be encoded in a MOV instruction.
In this case, materializa the constant into REGTMP without using the
constant pool.

When constants need to be added to the constant pool, make sure to
check whether it fits in 32-bit. If not, store 64-bit.

Both legacy and SSA compiler backends are happy with this.

Fixes #16226.

Change-Id: I883e3069dee093a1cdc40853c42221a198a152b0
Reviewed-on: https://go-review.googlesource.com/26631
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: 's avatarDavid Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
      748aa844
    • Keith Randall's avatar
      [dev.ssa] cmd/compile: implement GO386=387 · c069bc49
      Keith Randall authored 
      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 <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarKeith Randall <khr@golang.org>
      c069bc49
    • Keith Randall's avatar
      [dev.ssa] cmd/compile: more fixes for 386 shared libraries · 77ef597f
      Keith Randall authored 
      Use the destination register for materializing the pc
for GOT references also. See https://go-review.googlesource.com/c/25442/
The SSA backend assumes CX does not get clobbered for these instructions.

Mark duffzero as clobbering CX. The linker needs to clobber CX
to materialize the address to call. (This affects the non-shared-library
duffzero also, but hopefully forbidding one register across duffzero
won't be a big deal.)

Hopefully this is all the cases where the linker is clobbering CX
under the hood and SSA assumes it isn't.

Change-Id: I080c938170193df57cd5ce1f2a956b68a34cc886
Reviewed-on: https://go-review.googlesource.com/26611
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarMichael Hudson-Doyle <michael.hudson@canonical.com>
      77ef597f
  3. 09 Aug, 2016 3 commits
    • David Chase's avatar
      [dev.ssa] cmd/compile: PPC: FP load/store/const/cmp/neg; div/mod · ff37d0e6
      David Chase authored 
      FP<->int conversions remain.

Updates #16010.

Change-Id: I38d7a4923e34d0a489935fffc4c96c020cafdba2
Reviewed-on: https://go-review.googlesource.com/25589
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarKeith Randall <khr@golang.org>
      ff37d0e6
    • Keith Randall's avatar
      [dev.ssa] cmd/compile: fix PIC for SSA-generated code · 2cbdd55d
      Keith Randall authored 
      Access to globals requires a 2-instruction sequence on PIC 386.

    MOVL foo(SB), AX

is translated by the obj package into:

    CALL getPCofNextInstructionInTempRegister(SB)
    MOVL (&foo-&thisInstruction)(tmpReg), AX

The call returns the PC of the next instruction in a register.
The next instruction then offsets from that register to get the
address required.  The tricky part is the allocation of the
temp register.  The legacy compiler always used CX, and forbid
the register allocator from allocating CX when in PIC mode.
We can't easily do that in SSA because CX is actually a required
register for shift instructions. (I think the old backend got away
with this because the register allocator never uses CX, only
codegen knows that shifts must use CX.)

Instead, we allow the temp register to be anything.  When the
destination of the MOV (or LEA) is an integer register, we can
use that register.  Otherwise, we make sure to compile the
operation using an LEA to reference the global.  So

    MOVL AX, foo(SB)

is never generated directly.  Instead, SSA generates:

    LEAL foo(SB), DX
    MOVL AX, (DX)

which is then rewritten by the obj package to:

    CALL getPcInDX(SB)
    LEAL (&foo-&thisInstruction)(DX), AX
    MOVL AX, (DX)

So this CL modifies the obj package to use different thunks
to materialize the pc into different registers.  We use the
registers that regalloc chose so that SSA can still allocate
the full set of registers.

Change-Id: Ie095644f7164a026c62e95baf9d18a8bcaed0bba
Reviewed-on: https://go-review.googlesource.com/25442
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarDavid Chase <drchase@google.com>
      2cbdd55d
    • Keith Randall's avatar
      [dev.ssa] cmd/compile: port SSA backend to amd64p32 · 69a755b6
      Keith Randall authored 
      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: 's avatarDavid Chase <drchase@google.com>
      69a755b6
  5. 08 Aug, 2016 1 commit
  7. 07 Aug, 2016 1 commit
  9. 06 Aug, 2016 1 commit
  11. 04 Aug, 2016 4 commits
  13. 03 Aug, 2016 1 commit
    • Josh Bleecher Snyder's avatar
      [dev.ssa] cmd/compile: refactor out rulegen value parsing · 6a1153ac
      Josh Bleecher Snyder authored 
      Previously, genMatch0 and genResult0 contained
lots of duplication: locating the op, parsing
the value, validation, etc.
Parsing and validation was mixed in with code gen.

Extract a helper, parseValue. It is responsible
for parsing the value, locating the op, and doing
shared validation.

As a bonus (and possibly as my original motivation),
make op selection pay attention to the number
of args present.
This allows arch-specific ops to share a name
with generic ops as long as there is no ambiguity.
It also detects and reports unresolved ambiguity,
unlike before, where it would simply always
pick the generic op, with no warning.

Also use parseValue when generating the top-level
op dispatch, to ensure its opinion about ops
matches genMatch0 and genResult0.

The order of statements in the generated code used
to depend on the exact rule. It is now somewhat
independent of the rule. That is the source
of some of the generated code changes in this CL.
See rewritedec64 and rewritegeneric for examples.
It is a one-time change.

The op dispatch switch and functions used to be
sorted by opname without architecture. The sort
now includes the architecture, leading to further
generated code changes.
See rewriteARM and rewriteAMD64 for examples.
Again, it is a one-time change.

There are no functional changes.

Change-Id: I22c989183ad5651741ebdc0566349c5fd6c6b23c
Reviewed-on: https://go-review.googlesource.com/24649
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarDavid Chase <drchase@google.com>
Reviewed-by: 's avatarKeith Randall <khr@golang.org>
      6a1153ac
  15. 02 Aug, 2016 10 commits
  17. 01 Aug, 2016 1 commit
  19. 29 Jul, 2016 1 commit
    • Cherry Zhang's avatar
      cmd/compile: fix possible spill of invalid pointer with DUFFZERO on AMD64 · 111d590f
      Cherry Zhang authored 
      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: 's avatarDavid Chase <drchase@google.com>
      111d590f
  21. 28 Jul, 2016 2 commits
  23. 27 Jul, 2016 4 commits
    • Rhys Hiltner's avatar
      runtime: reduce GC assist extra credit · ccca9c9c
      Rhys Hiltner authored 
      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 <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarAustin Clements <austin@google.com>
Reviewed-by: 's avatarRick Hudson <rlh@golang.org>
Reviewed-by: 's avatarChris Broadfoot <cbro@golang.org>
      ccca9c9c
    • Cherry Zhang's avatar
      [dev.ssa] cmd/compile: fix possible invalid pointer spill in large Zero/Move on ARM · 114c0596
      Cherry Zhang authored 
      Instead of comparing the address of the end of the memory to zero/copy,
comparing the address of the last element, which is a valid pointer.
Also unify large and unaligned Zero/Move, by passing alignment as AuxInt.

Fixes #16515 for ARM.

Change-Id: I19a62b31c5acf5c55c16a89bea1039c926dc91e5
Reviewed-on: https://go-review.googlesource.com/25300
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarDavid Chase <drchase@google.com>
      114c0596
    • Cherry Zhang's avatar
      [dev.ssa] cmd/compile: add more on ARM64 SSA · 83208504
      Cherry Zhang authored 
      Support the following:
- Shifts. ARM64 machine instructions only use lowest 6 bits of the
  shift (i.e. mod 64). Use conditional selection instruction to
  ensure Go semantics.
- Zero/Move. Alignment is ensured.
- Hmul, Avg64u, Sqrt.
- reserve R18 (platform register in ARM64 ABI) and R29 (frame pointer
  in ARM64 ABI).

Everything compiles, all.bash passed (with non-SSA test disabled).

Change-Id: Ia8ed58dae5cbc001946f0b889357b258655078b1
Reviewed-on: https://go-review.googlesource.com/25290
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarDavid Chase <drchase@google.com>
      83208504
    • Brad Fitzpatrick's avatar
      net/http: fix data race with concurrent use of Server.Serve · c80e0d37
      Brad Fitzpatrick authored 
      Fixes #16505

Change-Id: I0afabcc8b1be3a5dbee59946b0c44d4c00a28d71
Reviewed-on: https://go-review.googlesource.com/25280
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: 's avatarChris Broadfoot <cbro@golang.org>
      c80e0d37
  25. 26 Jul, 2016 8 commits