Change-Id: I8fd3727763c812297967c8069847833fc8516ff2
Reviewed-on: https://go-review.googlesource.com/14073Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

Instead of trying to delete dead code as soon as we find it, just
mark it as dead using a PlainAndDead block kind.  The deadcode pass
will do the real removal.

This way is somewhat more efficient because we don't need to mess
with successor and predecessor lists of all the dead blocks.

Fixes #12347

Change-Id: Ia42d6b5f9cdb3215a51737b3eb117c00bd439b13
Reviewed-on: https://go-review.googlesource.com/14033Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

This also fixes the encoding/gob TestTopLevelNilPointer failure.

Change-Id: I9b29a6fddffd51af305c685f3a8e2a0594bfeeab
Reviewed-on: https://go-review.googlesource.com/14032Reviewed-by: Keith Randall <khr@golang.org>

addEdge had two identical implementations so make it an exported method
on Block.

Change-Id: I8c21655a9dc5074fefd7f63b2f5b51897571e608
Reviewed-on: https://go-review.googlesource.com/14040Reviewed-by: Keith Randall <khr@golang.org>

Frontend has already rewriten fallthrough statements, we just need to
ignore them.

Change-Id: Iadf89b06a9f8f9e6e2e1e87c934f31add77a19a1
Reviewed-on: https://go-review.googlesource.com/14029Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

Change-Id: I1453ba226376ccd4d79780fc0686876d6dde01ee
Reviewed-on: https://go-review.googlesource.com/14027Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: I8dee400aef07165f911750de2615b8757f826000
Reviewed-on: https://go-review.googlesource.com/13945Reviewed-by: Keith Randall <khr@golang.org>

Fixes build.  There may be no current block.

Change-Id: I0da8bab133dc207124556927698e7cd682e64ef5
Reviewed-on: https://go-review.googlesource.com/13989Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: If7a6ab6b1336dbacb006f562be7f153eb93e7253
Reviewed-on: https://go-review.googlesource.com/14025Reviewed-by: Keith Randall <khr@golang.org>

Add a check to make sure value arguments dominate the value.

Phi elim output used to fail this test.  When eliminating
redundant phis, phi elim was using one of the args and not
the ultimate source.  For example:

          b1: x = ...
          -> b2 b3

b2: y = Copy x        b3: z = Copy x
-> b4                 -> b4

          b4: w = phi y z

Phi elim eliminates w, but it used to replace w with (Copy y).
That's bad as b2 does not dominate b4.  Instead we should
replace w with (Copy x).

Fixes #12347

Change-Id: I9f340cdabcda8e2e90359fb4f9250877b1fffe98
Reviewed-on: https://go-review.googlesource.com/13986Reviewed-by: David Chase <drchase@google.com>

Still to do: arithmetic

Change-Id: I31fd23b34980c9ed4b4e304b8597134b2ba6ca5c
Reviewed-on: https://go-review.googlesource.com/14024Reviewed-by: Keith Randall <khr@golang.org>

Implement len(map) values.

Change-Id: If92be96ec9a7a86aeb3ce566d6758aab01c2fa7d
Reviewed-on: https://go-review.googlesource.com/13961Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: I113c07caf504cee66a81730da8830de6de098e49
Reviewed-on: https://go-review.googlesource.com/13981Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The old backend doesn't like ideal types,
and we want to reuse its stackmap generation.

OOROR and OANDAND expressions have ideal type.
The old backend didn't care,
because those expressions got rewritten away into
jumps before stackmap generation.

Fix the type during conversion.

Change-Id: I488e7499298d9aec71da39c202f6a7235935bc8d
Reviewed-on: https://go-review.googlesource.com/13980Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The code previously always used AX causing errors.  For now, just
switch off the type in order to at least generate valid code.

Change-Id: Iaf13120a24b62456b9b33c04ab31f2d5104b381b
Reviewed-on: https://go-review.googlesource.com/13943Reviewed-by: David Chase <drchase@google.com>

Change-Id: Iacd302350cf0a8a8164d937e5c4ac55e6a07d380
Reviewed-on: https://go-review.googlesource.com/13942Reviewed-by: David Chase <drchase@google.com>

Semi-regular merge of master into dev.ssa.

Change-Id: Ia7f2e29dfdea7618141efcfcf6f6c7c8b5553dfa

Add blocks to remove critical edges, even when it looks like
there's no phi that requires it.  Regalloc still likes to have
critical-edge-free graphs for other reasons.

Change-Id: I69f8eaecbc5d79ab9f2a257c2e289d60b18e43c8
Reviewed-on: https://go-review.googlesource.com/13933Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

The issue 12226 has been caused by the allocation of the same register
for the equality check of two byte values. The code in cgen.go freed the
register for the second operand before the allocation of the register
for the first operand.

Fixes #12226

Change-Id: Ie4dc33a488bd48a17f8ae9b497fd63c1ae390555
Reviewed-on: https://go-review.googlesource.com/13771Reviewed-by: Russ Cox <rsc@golang.org>

Change-Id: I3c598faff8af18530ae863b9e72f0cef379b4a1f
Reviewed-on: https://go-review.googlesource.com/13909Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Add a new function and generic operation to handle
bounds checking for slices. Unlike the index
bounds checking the index can be equal to the upper
bound.

Do gc-friendly slicing that generates proper code for
0-length result slices.

This is a takeover of Alexandru's original change,
(https://go-review.googlesource.com/#/c/12764/)
submittable now that the decompose phase is in.

Change-Id: I17d164cf42ed7839f84ca949c6ad3289269c9160
Reviewed-on: https://go-review.googlesource.com/13903Reviewed-by: David Chase <drchase@google.com>

Basic ops, no particular optimization in the pattern
matching yet (e.g. x!=x for Nan detection, x cmp constant,
etc.)

Change-Id: I0043564081d6dc0eede876c4a9eb3c33cbd1521c
Reviewed-on: https://go-review.googlesource.com/13704Reviewed-by: Keith Randall <khr@golang.org>

A comparison of the form l == r where l is an interface and r is
concrete performs a type assertion on l to convert it to r's type.
However, the compiler fails to zero the temporary where the result of
the type assertion is written, so if the type is a pointer type and a
stack scan occurs while in the type assertion, it may see an invalid
pointer on the stack.

Fix this by zeroing the temporary. This is equivalent to the fix for
type switches from c4092ac3.

Fixes #12253.

Change-Id: Iaf205d456b856c056b317b4e888ce892f0c555b9
Reviewed-on: https://go-review.googlesource.com/13872Reviewed-by: Russ Cox <rsc@golang.org>

Change-Id: I8c17f706a3e0f1fa2d754bfb4ccd1f7a027cb3db
Reviewed-on: https://go-review.googlesource.com/13744Reviewed-by: Keith Randall <khr@golang.org>

MOVXload and MOVXstore opcodes have both an auxint offset
and an aux offset (a symbol name, like a local or arg or global).
Make sure we keep those values during rewrites.

Change-Id: Ic9fd61bf295b5d1457784c281079a4fb38f7ad3b
Reviewed-on: https://go-review.googlesource.com/13849Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

Updates #11336

Follow the lead of amd64 by doing a pointer equality check
before comparing string/byte contents on arm64.

BenchmarkCompareBytesEqual-8               25.8           26.3           +1.94%
BenchmarkCompareBytesToNil-8               9.59           9.59           +0.00%
BenchmarkCompareBytesEmpty-8               9.59           9.17           -4.38%
BenchmarkCompareBytesIdentical-8           26.3           9.17           -65.13%
BenchmarkCompareBytesSameLength-8          16.3           16.3           +0.00%
BenchmarkCompareBytesDifferentLength-8     16.3           16.3           +0.00%
BenchmarkCompareBytesBigUnaligned-8        1132038        1131409        -0.06%
BenchmarkCompareBytesBig-8                 1126758        1128470        +0.15%
BenchmarkCompareBytesBigIdentical-8        1084366        9.17           -100.00%

Change-Id: Id7125c31957eff1ddb78897d4511bd50e79af3f7
Reviewed-on: https://go-review.googlesource.com/13885Reviewed-by: Keith Randall <khr@golang.org>

nmspinning has a value range of [0, 2^31-1].  Update the comment to
indicate this and fix the comparison so it's not always false.

Fixes #11280

Change-Id: Iedaf0654dcba5e2c800645f26b26a1a781ea1991
Reviewed-on: https://go-review.googlesource.com/13877Reviewed-by: Minux Ma <minux@golang.org>

gobuf.g is a guintptr, so without hex(), it will be printed as
a decimal, which is not very helpful and inconsistent with how
other pointers are printed.

Change-Id: I7c0432e9709e90a5c3b3e22ce799551a6242d017
Reviewed-on: https://go-review.googlesource.com/13879Reviewed-by: Ian Lance Taylor <iant@golang.org>

Simplify slice/map literal expressions.
Caught with gofmt -d -s, fixed with gofmt -w -s
Reformatted some expressions to improve readability.

Change-Id: Iaf123e6bd49162ec45c59297ad3b002ca59443bc
Reviewed-on: https://go-review.googlesource.com/13850Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

While we're at it, also fix a typo.

Change-Id: Id436f33cffa5683e2a8450cce5b545960cf2877e
Reviewed-on: https://go-review.googlesource.com/13878Reviewed-by: Ian Lance Taylor <iant@golang.org>

This is not a functional change. nr is a uint64 and can never be less
than zero, remove the no-op comparison.

Fixes #11279

Change-Id: Iebb36cc8fe97428b503e65d01b5e67d2b2bc7369
Reviewed-on: https://go-review.googlesource.com/13876
Run-TryBot: Todd Neal <todd@tneal.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The nohup command doesn't work in tmux on darwin.

Fixes #5135.

Change-Id: I1c21073d8bd54b49dd6b0bad86ef088d6d8e7a5f
Reviewed-on: https://go-review.googlesource.com/13883Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This aids in making sense of the aggregate set of work outstanding.
Interest in the details of any particular implementation failure
is better handled locally anyway.

In my local tree, running make.bash after this CL yields:

 14.85%  1811 SSA unimplemented: unhandled expr SLICEARR
 13.84%  1687 SSA unimplemented: unhandled expr CALLINTER
 11.84%  1444 SSA unimplemented: unhandled stmt RETJMP
 10.24%  1249 SSA unimplemented: unhandled expr EFACE
  8.52%  1039 SSA unimplemented: unhandled expr SLICE
  4.92%   600 SSA unimplemented: local variable with class PAUTO,heap unimplemented
  4.90%   598 SSA unimplemented: unhandled expr SLICESTR
  3.91%   477 SSA unimplemented: local variable with class PFUNC unimplemented
  3.45%   421 SSA unimplemented: not lowered: IMake INTER PTR64 PTR64
  3.42%   417 SSA unimplemented: unhandled expr APPEND
  3.21%   391 SSA unimplemented: unhandled expr CLOSUREVAR
  3.06%   373 SSA unimplemented: unhandled stmt DEFER
  3.04%   371 SSA unimplemented: unhandled stmt AS2DOTTYPE
  1.61%   196 SSA unimplemented: unhandled expr DOTTYPE
  1.56%   190 SSA unimplemented: not lowered: Load STRUCT PTR64 mem
  0.79%    96 SSA unimplemented: not lowered: StringMake STRING PTR64 UINTPTR
  0.69%    84 SSA unimplemented: unhandled binary op NE FLOAT64
  0.53%    65 SSA unimplemented: unhandled expr STRUCTLIT
  0.50%    61 SSA unimplemented: not lowered: SliceMake ARRAY PTR64 UINTPTR UINTPTR
  0.45%    55 SSA unimplemented: zero for type float64 not implemented
  0.44%    54 SSA unimplemented: unhandled addr CLOSUREVAR
  0.38%    46 SSA unimplemented: unhandled binary op EQ FLOAT64
  0.35%    43 SSA unimplemented: unhandled binary op LT FLOAT64
  0.34%    42 SSA unimplemented: unhandled len(map)
  0.33%    40 SSA unimplemented: unhandled stmt FALL
  0.23%    28 SSA unimplemented: CONVNOP closure
  0.21%    25 SSA unimplemented: local variable with class PPARAM,heap unimplemented
  0.21%    25 SSA unimplemented: unhandled binary op GT FLOAT64
  0.18%    22 SSA unimplemented: unhandled OCONV FLOAT32 -> FLOAT64
  0.18%    22 SSA unimplemented: unhandled expr REAL
  0.16%    20 SSA unimplemented: unhandled stmt PROC
  0.16%    19 SSA unimplemented: unhandled closure arg
  0.15%    18 SSA unimplemented: unhandled OCONV INT64 -> FLOAT64
  0.12%    15 SSA unimplemented: unhandled expr CFUNC
  0.10%    12 SSA unimplemented: unhandled OCONV UINT64 -> FLOAT64
  0.09%    11 SSA unimplemented: unhandled OLITERAL 4
  0.09%    11 SSA unimplemented: unhandled expr IMAG
  0.07%     9 SSA unimplemented: unhandled binary op GE FLOAT64
  0.07%     9 SSA unimplemented: unhandled binary op MINUS FLOAT64
  0.06%     7 SSA unimplemented: unhandled OCONV FLOAT64 -> FLOAT32
  0.06%     7 SSA unimplemented: unhandled binary op NE FLOAT32
  0.06%     7 SSA unimplemented: variable address class 5 not implemented
  0.05%     6 SSA unimplemented: not lowered: Load COMPLEX128 PTR64 mem
  0.05%     6 SSA unimplemented: unhandled expr SLICE3ARR
  0.04%     5 SSA unimplemented: unhandled binary op LE FLOAT64
  0.03%     4 SSA unimplemented: unhandled OCONV UINTPTR -> FLOAT64
  0.03%     4 SSA unimplemented: unhandled binary op EQ COMPLEX128
  0.03%     4 SSA unimplemented: unhandled binary op EQ FLOAT32
  0.03%     4 SSA unimplemented: unhandled expr COMPLEX
  0.02%     3 SSA unimplemented: local variable with class PPARAMOUT,heap unimplemented
  0.02%     3 SSA unimplemented: not lowered: Load ARRAY PTR64 mem
  0.02%     3 SSA unimplemented: unhandled OCONV INT32 -> FLOAT64
  0.02%     3 SSA unimplemented: unhandled OCONV INT64 -> FLOAT32
  0.02%     3 SSA unimplemented: unhandled expr SLICE3
  0.02%     2 SSA unimplemented: unhandled OCONV COMPLEX64 -> COMPLEX128
  0.02%     2 SSA unimplemented: unhandled OCONV FLOAT64 -> INT64
  0.02%     2 SSA unimplemented: unhandled OCONV FLOAT64 -> UINT64
  0.02%     2 SSA unimplemented: unhandled OCONV INT -> FLOAT64
  0.02%     2 SSA unimplemented: unhandled OCONV UINT64 -> FLOAT32
  0.02%     2 SSA unimplemented: unhandled binary op EQ COMPLEX64
  0.02%     2 SSA unimplemented: unhandled binary op MINUS FLOAT32
  0.02%     2 SSA unimplemented: zero for type complex128 not implemented
  0.02%     2 SSA unimplemented: zero for type complex64 not implemented
  0.02%     2 SSA unimplemented: zero for type float32 not implemented
  0.01%     1 SSA unimplemented: not lowered: EqFat BOOL INTER INTER
  0.01%     1 SSA unimplemented: not lowered: Store mem UINTPTR COMPLEX128 mem
  0.01%     1 SSA unimplemented: unhandled OCONV UINT32 -> FLOAT64
  0.01%     1 SSA unimplemented: unhandled cap(chan)
  0.01%     1 SSA unimplemented: unhandled expr ARRAYLIT
  0.01%     1 SSA unimplemented: unhandled expr PLUS
  0.01%     1 SSA unimplemented: unhandled stmt CHECKNIL

Change-Id: I43474fe6d6ec22a9f57239090136f6e97eebfdf2
Reviewed-on: https://go-review.googlesource.com/13848Reviewed-by: Keith Randall <khr@golang.org>

This CL takes a simple approach to spilling and loading flags.
We never spill. When a load is needed, we recalculate,
loading the arguments as needed.

This is simple and architecture-independent.
It is not very efficient, but as of this CL,
there are fewer than 200 flag spills during make.bash.

This was tested by manually reverting CLs 13813 and 13843,
causing SETcc, MOV, and LEA instructions to clobber flags,
which dramatically increases the number of flags spills.
With that done, all stdlib tests that used to pass
still pass.

For future reference, here are some other, more efficient
amd64-only schemes that we could adapt in the future if needed.

(1) Spill exactly the flags needed.

For example, if we know that the flags will be needed
by a SETcc or Jcc op later, we could use SETcc to
extract just the relevant flag. When needed,
we could use TESTB and change the op to JNE/SETNE.
(Alternatively, we could leave the op unaltered
and prepare an appropriate CMPB instruction
to produce the desired flag.)

However, this requires separate handling for every
instruction that uses the flags register,
including (say) SBBQcarrymask.

We could enable this on an ad hoc basis for common cases
and fall back to recalculation for other cases.

(2) Spill all flags with PUSHF and POPF

This modifies SP, which the runtime won't like.
It also requires coordination with stackalloc to
make sure that we have a stack slot ready for use.

(3) Spill almost all flags with LAHF, SETO, and SAHF

See http://blog.freearrow.com/archives/396
for details. This would handle all the flags we currently
use. However, LAHF and SAHF are not universally available
and it requires arranging for AX to be free.

Change-Id: Ie36600fd8e807ef2bee83e2e2ae3685112a7f276
Reviewed-on: https://go-review.googlesource.com/13844Reviewed-by: Keith Randall <khr@golang.org>

This further reduces the number of flags spills
during make.bash by about 50%.

Note that GetG is implemented by one or two MOVs,
which is why it does not clobber flags.

Change-Id: I6fede8c027b7dc340e00d1e15df1b87bf2b2d9ec
Reviewed-on: https://go-review.googlesource.com/13843Reviewed-by: Keith Randall <khr@golang.org>

Change-Id: I4ae38440a33574421c9e3e350701e86e8a224b92
Reviewed-on: https://go-review.googlesource.com/13842Reviewed-by: Todd Neal <todd@tneal.org>
Reviewed-by: Keith Randall <khr@golang.org>

The URL is shown on go docs and is an eye-sore.

For go1.6.

Change-Id: I8b8ea3751200d06ed36acfe22f47ebb38107f8db
Reviewed-on: https://go-review.googlesource.com/13282Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates #11336

Follow the lead of amd64 do a pointer equality check
before comparing string/byte contents on arm.

BenchmarkCompareBytesEqual-4               208             211             +1.44%
BenchmarkCompareBytesToNil-4               83.6            81.8            -2.15%
BenchmarkCompareBytesEmpty-4               80.2            75.2            -6.23%
BenchmarkCompareBytesIdentical-4           208             75.2            -63.85%
BenchmarkCompareBytesSameLength-4          126             128             +1.59%
BenchmarkCompareBytesDifferentLength-4     128             130             +1.56%
BenchmarkCompareBytesBigUnaligned-4        14192804        14060971        -0.93%
BenchmarkCompareBytesBig-4                 12277313        12128193        -1.21%
BenchmarkCompareBytesBigIdentical-4        9385046         78.5            -100.00%

Change-Id: I5b24620018688c5fe04b6ff6743a24c4ce225788
Reviewed-on: https://go-review.googlesource.com/13881Reviewed-by: Keith Randall <khr@golang.org>

In short, %c should just give you the next rune, period.
Apparently this is the design. I use the term loosely.

Fixes #12275

Change-Id: I6f30bed442c0e88eac2244d465c7d151b29cf393
Reviewed-on: https://go-review.googlesource.com/13821Reviewed-by: Andrew Gerrand <adg@golang.org>

Fixes #12299

Change-Id: Id7b73d2935c9f7c0952f833613973ef455d02b0d
Reviewed-on: https://go-review.googlesource.com/13858Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>