Code movement only.

If someone finds function 'foo' in "foo_linux.go",
they will expect that the Window version of 'foo' exists in "foo_windows.go".

Current code doesn't follow this manner.

For example, 'sameFile' exists in "file_unix.go",
"stat_plan9.go" and "types_windows.go".

The CL address that problem by following rules:

* readdir family => dir.go, dir_$GOOS.go
* stat family => stat.go, stat_$GOOS.go
* path-functions => path_$GOOS.go
* sameFile => types.go, types_$GOOS.go
* process-functions => exec.go, exec_$GOOS.go
* hostname => sys.go, sys_$GOOS.go

Change-Id: Ic3c64663ce0b2a364d7a414351cd3c772e70187b
Reviewed-on: https://go-review.googlesource.com/27035
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Merging from dev.ssa back into master.

Contains complete SSA backends for arm, arm64, 386, amd64p32.
Work in progress for PPC64.

Change-Id: Ifd7075e3ec6f88f776e29f8c7fd55830328897fd

Change-Id: Ieae5831b35768a625bf735a38f3d938f23f0b77b
Reviewed-on: https://go-review.googlesource.com/27057Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Id83e0371b7232b01be83640ef1e47f9026cf2a23
Reviewed-on: https://go-review.googlesource.com/27055Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Fixes #15820.

Change-Id: Ia5d5237754e77774a3a6049765eea163911f41c9
Reviewed-on: https://go-review.googlesource.com/25592Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Passes ssa_test.

Requires a few new instructions and some scratchpad
memory to move data between G and F registers.

Also fixed comparisons to be correct in case of NaN.
Added missing instructions for run.bash.
Removed some FP registers that are apparently "reserved"
(but that are also apparently also unused except for a
gratuitous multiplication by two when y = x+x would work
just as well).

Currently failing stack splits.

Updates #16010.

Change-Id: I73b161bfff54445d72bd7b813b1479f89fc72602
Reviewed-on: https://go-review.googlesource.com/26813
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Add more ARM64 optimizations:
- use hardware zero register when it is possible.
- use shifted ops.
  The assembler supports shifted ops but not documented, nor knows
  how to print it. This CL adds them.
- enable fast division.
  This was disabled because it makes the old backend generate slower
  code. But with SSA it generates faster code.

Turn on SSA by default, also adjust tests.

Change-Id: I7794479954c83bb65008dcb457bc1e21d7496da6
Reviewed-on: https://go-review.googlesource.com/26950
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

We shouldn't issue instructions like MOVL foo(SB), AX directly from the
SSA backend.  Instead we should do LEAL foo(SB), AX; MOVL (AX), AX.

This simplifies obj logic because now only LEAL needs to be treated
specially.  The register allocator uses the LEAL to in effect allocate
the temporary register required for the shared library thunk calls.

Also, the LEALs can now be CSEd.  So code like
    var g int
    func f() { g += 5 }
Requires only one thunk call instead of 2.

Change-Id: Ib87d465f617f73af437445871d0ea91a630b2355
Reviewed-on: https://go-review.googlesource.com/26814
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

In position-independent 386 code, loading floating-point constants from
the constant pool requires two steps: materializing the address of
the constant pool entry (requires calling a thunk) and then loading
from that address.

Before this CL, the materializing happened implicitly in CX, which
clobbered that register.

Change-Id: Id094e0fb2d3be211089f299e8f7c89c315de0a87
Reviewed-on: https://go-review.googlesource.com/26811
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Mostly mirrors ARM, includes:
- constant folding
- simplification of load, store, extension, and arithmetics
- nilcheck removal

Change-Id: Iffaa5fcdce100fe327429ecab316cb395e543469
Reviewed-on: https://go-review.googlesource.com/26710
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

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: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

When ns/op dropped below 1, the old code
ignored benchtime and reverted to 1s.

Change-Id: I59752cef88d8d73bfd5b085f5400ae657f78504e
Reviewed-on: https://go-review.googlesource.com/26664
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

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: Keith Randall <khr@golang.org>

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: Michael Hudson-Doyle <michael.hudson@canonical.com>

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: Keith Randall <khr@golang.org>

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: David Chase <drchase@google.com>

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: David Chase <drchase@google.com>

Updates #15810.

Change-Id: Ifa7d2fd7fbfe58dff8541b18a11f007a5ff5818a
Reviewed-on: https://go-review.googlesource.com/25591Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Merge "[dev.ssa] Merge commit 'f135c326' into mergebranch" into dev.ssa

The Go HTTP/1 client will make as many new TCP connections as the user requests.

The HTTP/2 client tried to have that behavior, but the policy of
whether a connection is re-usable didn't take into account the extra 1
stream counting against SETTINGS_MAX_CONCURRENT_STREAMS so in practice
users were getting errors.

For example, if the server's advertised max concurrent streams is 100
and 200 concurrrent Go HTTP requests ask for a connection at once, all
200 will think they can reuse that TCP connection, but then 100 will
fail later when the number of concurrent streams exceeds 100.

Instead, recognize the "no cached connections" error value in the
shouldRetryRequest method, so those 100 will retry a new connection.

This is the conservative fix for Go 1.7 so users don't get errors, and
to match the HTTP/1 behavior. Issues #13957 and #13774 are the more
involved bugs for Go 1.8.

Updates #16582
Updates #13957

Change-Id: I1f15a7ce60c07a4baebca87675836d6fe03993e8
Reviewed-on: https://go-review.googlesource.com/25580
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

Reg allocator skips flag-typed values. Flag allocator uses the type
and whether the op has "clobberFlags" set.

Tested on AMD64, ARM, ARM64, 386. Passed 'toolstash -cmp' on AMD64.
PPC64 is coded blindly.

Change-Id: Ib1cc27efecef6a1bb27f7d7ed035a582660d244f
Reviewed-on: https://go-review.googlesource.com/25480
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Updates #16625

Change-Id: Icac6705828bd9b29379596ba64b34d922b9002c3
Reviewed-on: https://go-review.googlesource.com/25548Reviewed-by: Ian Lance Taylor <iant@golang.org>

Updates #16010.

Change-Id: Ie520d64fd1c4f881f45623303ed0b7cbdf0e4764
Reviewed-on: https://go-review.googlesource.com/25493
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Fixes #16618.

Change-Id: Iffada12e8672bbdbcf2e787782c497e2c45701b1
Reviewed-on: https://go-review.googlesource.com/25550
Run-TryBot: Minux Ma <minux@golang.org>
Reviewed-by: Arjan Van De Ven <arjan.van.de.ven@intel.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #16570 on iOS.

Thanks Daniel Burhans for reporting the bug and testing the fix.

Change-Id: I43ae7b78c8f85a131ed3d93ea59da9f32a02cd8f
Reviewed-on: https://go-review.googlesource.com/25481Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Reportedly waitid is not available for Ubuntu on Windows.

Fixes #16610.

Change-Id: Ia724f45a85c6d3467b847da06d8c65d280781dcd
Reviewed-on: https://go-review.googlesource.com/25507
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates bundled http2 to x/net/http2 git rev 075e191 for:

   http2: adjust flow control on open streams when processing SETTINGS
   https://golang.org/cl/25508

Fixes #16612

Change-Id: Ib0513201bff44ab747a574ae6894479325c105d2
Reviewed-on: https://go-review.googlesource.com/25543
Run-TryBot: Chris Broadfoot <cbro@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #16606

Change-Id: I57465061b90e901293cd8b6ef756d6aa84ebd4a3
Reviewed-on: https://go-review.googlesource.com/25495Reviewed-by: Quentin Smith <quentin@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Quentin Smith <quentin@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Includes hmul (all widths)
compare for boolean result and simplifications
shift operations plus changes/additions for implementation
(ORN, ADDME, ADDC)

Also fixed a backwards-operand CMP.

Change-Id: Id723c4e25125c38e0d9ab9ec9448176b75f4cdb4
Reviewed-on: https://go-review.googlesource.com/25410
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

Pick up shared library fix in dev.ssa.

Change-Id: I5bdd0e9e0f1d6f7c14b518343ee323ed9a894b9c

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 <crawshaw@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Semi-regular merge from tip into dev.ssa.

Change-Id: Iadb60e594ef65a99c0e1404b14205fa67c32a9e9

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: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: I1134a4758b7e1a7da243c56f12ad9d2200c8ba41
Reviewed-on: https://go-review.googlesource.com/25414Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I177856ea2bc9943cbde28ca9afa145b6ea5b0942

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/25400Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Quentin Smith <quentin@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The commit in golang.org/cl/22354 groups constructors functions under
the type that they construct to. However, this caused a minor regression
where functions that had unexported return values were not being printed
at all. Thus, we forgo the grouping logic if the type the constructor falls
under is not going to be printed.

Fixes #16568

Change-Id: Idc14f5d03770282a519dc22187646bda676af612
Reviewed-on: https://go-review.googlesource.com/25369
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Icf861dd28bfe29a2e4b90529e53644b43b6f7969
Reviewed-on: https://go-review.googlesource.com/25368Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Changes made:
* Disallow star expression on interfaces as this is not possible.
* Show an embedded "error" in an interface as public similar to
how godoc does it.
* Properly handle selector expressions in both structs and interfaces.
This is possible since a type may refer to something defined in
another package (e.g. io.Reader).

Before:
<<<
$ go doc runtime.Error
type Error interface {

    // RuntimeError is a no-op function but
    // serves to distinguish types that are run time
    // errors from ordinary errors: a type is a
    // run time error if it has a RuntimeError method.
    RuntimeError()
    // Has unexported methods.
}

$ go doc compress/flate Reader
doc: invalid program: unexpected type for embedded field
doc: invalid program: unexpected type for embedded field
type Reader interface {
    io.Reader
    io.ByteReader
}
>
> After:
> <<<
> $ go doc runtime.Error
> type Error interface {
>     error
>
>     // RuntimeError is a no-op function but
>     // serves to distinguish types that are run time
>     // errors from ordinary errors: a type is a
>     // run time error if it has a RuntimeError method.
>     RuntimeError()
> }
>
> $ go doc compress/flate Reader
> type Reader interface {
>     io.Reader
>     io.ByteReader
> }

Fixes #16567

Change-Id: I272dede971eee9f43173966233eb8810e4a8c907
Reviewed-on: https://go-review.googlesource.com/25365Reviewed-by: Rob Pike <r@golang.org>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>