Declare a function's arguments as having already been
spilled so their use just requires a restore.

Allow spill locations to be portions of larger objects the stack.
Required to load portions of compound input arguments.

Rename the memory input to InputMem.  Use Arg for the
pre-spilled argument values.

Change-Id: I8fe2a03ffbba1022d98bfae2052b376b96d32dda
Reviewed-on: https://go-review.googlesource.com/16536
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Be more consistent about this.  There's no reason to do the
pointer arithmetic on a different type, as sizeof(int) >=
sizeof(ptr) on all of our platforms.  It simplifies our
rewrite rules also, except for a few that need duplication.

Add some more constant folding to get constant indexing and
slicing to fold down to nothing.

Change-Id: I3e56cdb14b3dc1a6a0514f0333e883f92c19e3c7
Reviewed-on: https://go-review.googlesource.com/16586
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

For the statement

    if a && b { target }

the old code allocated a new variable v and did:

    v = a
    if a {
       v = b
    }
    if v { goto target }

The new code does:

    if a {
      if b { goto target }
    }

The new arrangement tends to generate much more efficient code.  In
particular, there is no temporary variable and there is only one join
point instead of two.

The old code is still used for ANDAND and OROR which are not
direct descendents of IF or FOR statements.

Change-Id: I082f246d27c823c6f32d1287300e4b0911607507
Reviewed-on: https://go-review.googlesource.com/16584
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Some tests disabled, some bifurcated into _ssa and not,
with appropriate logging added to compiler.

"tests/live.go" in particular needs attention.

SSA-specific testing removed, since it's all SSA now.

Added "-run_skips" option to tests/run.go to simplify
checking whether a test still fails (or how it fails)
on a skipped platform.

The compiler now compiles with SSA by default.
If you don't want SSA, specify GOSSAHASH=n (or N) as
an environment variable.  Function names ending in "_ssa"
are always SSA-compiled.

GOSSAFUNC=fname retains its "SSA for fname, log to ssa.html"
GOSSAPKG=pkg only has an effect when GOSSAHASH=n
GOSSAHASH=10101 etc retains its name-hash-matching behavior
for purposes of debugging.

See #13068

Change-Id: I8217bfeb34173533eaeb391b5f6935483c7d6b43
Reviewed-on: https://go-review.googlesource.com/16299Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: David Chase <drchase@google.com>

Shaves ~8k off the go binary on darwin x64.

Change-Id: I73396af44ae28cd4cfc675290d6858f304d45b76
Reviewed-on: https://go-review.googlesource.com/16456
Run-TryBot: Todd Neal <todd@tneal.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

We "spill" flag values by recomputing them from their original
inputs.  The "find original inputs" part of the algorithm was
a hack.  It was broken by rematerialization.  This change does
the real job of keeping track of original values for each
spill/restore/flagrecompute/rematerialization we issue.

Change-Id: I95088326a4ee4958c98148b063e518c80e863e4c
Reviewed-on: https://go-review.googlesource.com/16500
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This improves cse and works correctly now that divide by zero is checked
explicitly.

Change-Id: If54fbe403ed5230b897afc5def644ba9f0056dfd
Reviewed-on: https://go-review.googlesource.com/16454
Run-TryBot: Todd Neal <todd@tneal.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

The single value rewrite function is too big.  Some compilers
fail on it (out of memory, branch offset too large).  Break it
up into a rewrite function per op.

Change-Id: Iede697c8a1a3a22b485cd0dc85d3e233160c89c2
Reviewed-on: https://go-review.googlesource.com/16347
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Todd Neal <todd@tneal.org>

SSA generates ACALL assembly with the target in a *Sym.
The old compiler generates both that *Sym and a *Node.
Use the *Sym to print the live info so it works with both compilers.

Change-Id: I0b12a161f83e76638604358c21b9f5abb31ce950
Reviewed-on: https://go-review.googlesource.com/16432
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Added an explicit compare-zero and branch-to-panic for
integer division and mod so that other optimizations will
not be fooled by their implicit panics.

Change-Id: Ibf96f636b541c0088861907c537a6beb4b99fa4c
Reviewed-on: https://go-review.googlesource.com/16450Reviewed-by: Keith Randall <khr@golang.org>

For debugging, spill values to named variables instead of autotmp_
variables if possible.  We do this by keeping a name -> value map
for each function, keep it up-to-date during deadcode elim, and use
it to override spill decisions in stackalloc.

It might even make stack frames a bit smaller, as it makes it easy
to identify a set of spills which are likely not to interfere.

This just works for one-word variables for now.  Strings/slices
will be a separate CL.

Change-Id: Ie89eba8cab16bcd41b311c479ec46dd7e64cdb67
Reviewed-on: https://go-review.googlesource.com/16336
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Introduce opcodes that store a constant value.
AuxInt now needs to hold both the value to be stored and the
constant offset at which to store it.  Introduce a StoreConst
type to help encode/decode these parts to/from an AuxInt.

Change-Id: I1631883abe035cff4b16368683e1eb3d2ccb674d
Reviewed-on: https://go-review.googlesource.com/16170Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

deadstore elimination currently works in a block, fusing before
performing dse eliminates ~1% more stores for make.bash

Change-Id: If5bbddac76bf42616938a8e8e84cb7441fa02f73
Reviewed-on: https://go-review.googlesource.com/16350Reviewed-by: Keith Randall <khr@golang.org>

If the closure pointer gets spilled, we need to spill it with
pointer type to make stack copy and GC happy.

Change-Id: Ic108748e6b9caecd45522141f02c9422567376e3
Reviewed-on: https://go-review.googlesource.com/16363
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Replace REP MOVSB with all the copying techniques used by the
old compiler.  Copy in chunks, DUFFCOPY, etc.

Introduces MOVO opcodes and an Int128 type to move around
16 bytes at a time.

Change-Id: I1e73e68ca1d8b3dd58bb4af2f4c9e5d9bf13a502
Reviewed-on: https://go-review.googlesource.com/16174Reviewed-by: Todd Neal <todd@tneal.org>
Run-TryBot: Keith Randall <khr@golang.org>

Use faulting loads instead of test/jeq to do nil checks.
Fold nil checks into a following load/store if possible.

Makes binaries about 2% smaller.

Change-Id: I54af0f0a93c853f37e34e0ce7e3f01dd2ac87f64
Reviewed-on: https://go-review.googlesource.com/16287Reviewed-by: David Chase <drchase@google.com>

unsafe.Pointer->uintptr, add, then uintptr->unsafe.Pointer.
Do the add directly on the pointer type instead.

Change-Id: I5a3a32691d0a000e16975857974ed9a1039c6d28
Reviewed-on: https://go-review.googlesource.com/16281
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Modified GOSSA{HASH.PKG} environment variable filters to
make it easier to make/run with all SSA for testing.
Disable attempts at SSA for architectures that are not
amd64 (avoid spurious errors/unimplementeds.)

Removed easy out for unimplemented features.

Add convert op for proper liveness in presence of uintptr
to/from unsafe.Pointer conversions.

Tweaked stack sizes to get a pass on windows;
1024 instead 768, was observed to pass at least once.

Change-Id: Ida3800afcda67d529e3b1cf48ca4a3f0fa48b2c5
Reviewed-on: https://go-review.googlesource.com/16201Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: David Chase <drchase@google.com>

Calls to NewConfig required an extra parameter that
sometimes could not be nil.

Change-Id: I806dd53c045056a0c2d30d641a20fe27fb790539
Reviewed-on: https://go-review.googlesource.com/16272Reviewed-by: Keith Randall <khr@golang.org>

BP for framepointer experiment
R15 for dynamic linking

Change-Id: I28e48be461d04a4d5c9b013f48fce5c0e58d6a08
Reviewed-on: https://go-review.googlesource.com/16231
Run-TryBot: Todd Neal <todd@tneal.org>
Reviewed-by: Todd Neal <todd@tneal.org>

Register phis are better than stack phis.  If we have
unused registers available, use them for phis.

Change-Id: I3045711c65caa1b6d0be29131b87b57466320cc2
Reviewed-on: https://go-review.googlesource.com/16080
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

It confuses live variable analysis to have a bunch of unreachable
no-ops at the end of a function.  Symptom is:
    gc/plive.go:483 panic: interface conversion: interface {} is nil, not *gc.BasicBlock

I don't see any reason why the old compiler needs these no-ops either.
all.bash passes with the equivalent code removed on master.

Change-Id: Ifcd2c3e139aa16314f08aebc9079b2fb7aa60556
Reviewed-on: https://go-review.googlesource.com/16132Reviewed-by: David Chase <drchase@google.com>

getg reads from memory, so it should really have a
memory arg.  It is critical in functions which call setg
to make sure getg gets ordered correctly with setg.

Change-Id: Ief4875421f741fc49c07b0e1f065ce2535232341
Reviewed-on: https://go-review.googlesource.com/16100
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>

It isn't safe, the place where we're moving the value to
might have a different live memory.  Moving will introduce
two simultaneously live memories.

Change-Id: I07e61a6db8ef285088c530dc2e5d5768d27871ff
Reviewed-on: https://go-review.googlesource.com/16099Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>

It isn't safe in functions that also call setg.

Change-Id: I76a7bf0401b4b6c8a129c245b15a2d6f06080e94
Reviewed-on: https://go-review.googlesource.com/16095Reviewed-by: Todd Neal <todd@tneal.org>

The only major fixup is that duffzero changed from
8-byte writes to 16-byte writes.

Change-Id: I1762b74ce67a8e4b81c11568027cdb3572f7f87c

I cannot find any documentation for this, but these tests no longer run
on the device I have since upgrading to Android L. Presumably it still
works for root, but standard Android programs to not have root access.

Change-Id: I001c8fb5ce22f9ff8d7433f881d0dccbf6ab969d
Reviewed-on: https://go-review.googlesource.com/16056Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

Rematerialize constants instead of spilling and loading them.
"Constants" includes constant offsets from SP and SB.

Should help somewhat with stack frame sizes.  I'm not sure
exactly how much yet.

Change-Id: I44dbad97aae870cf31cb6e89c92fe4f6a2b9586f
Reviewed-on: https://go-review.googlesource.com/16029
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

These functions are always called together and perform logically
related state resets, so combine them in to just gcResetMarkState.

Fixes #11427.

Change-Id: I06c17ef65f66186494887a767b3993126955b5fe
Reviewed-on: https://go-review.googlesource.com/16041Reviewed-by: Rick Hudson <rlh@golang.org>

Currently gcResetGState is called by func gcscan_m for concurrent GC
and directly by func gc for STW GC. Simplify this by consolidating
these two calls in to one call by func gc above where it splits for
concurrent and STW GC.

As a consequence, gcResetGState and gcResetMarkState are always called
together, so the next commit will consolidate these.

Change-Id: Ib62d404c7b32b28f7d3080d26ecf3966cbc4aca0
Reviewed-on: https://go-review.googlesource.com/16040Reviewed-by: Rick Hudson <rlh@golang.org>

This work queue is no longer used (there are many reads of
work.partial, but the only write is in putpartial, which is never
called).

Fixes #11922.

Change-Id: I08b76c0c02a0867a9cdcb94783e1f7629d44249a
Reviewed-on: https://go-review.googlesource.com/15892Reviewed-by: Rick Hudson <rlh@golang.org>

fmt docs say:

  If the operand is a reflect.Value, the concrete value it
  holds is printed as if it was the operand.

It implies recursive application of this rule, which is not the case.
Clarify the docs.

Change-Id: I019277c7c6439095bab83e5536aa06403638aa51
Reviewed-on: https://go-review.googlesource.com/15952Reviewed-by: Ian Lance Taylor <iant@golang.org>

Also make PIE executables the default build mode, as PIE executables
are required as of Android L.

For #10807

Change-Id: I86b7556b9792105cd2531df1b8f3c8f7a8c5d25c
Reviewed-on: https://go-review.googlesource.com/16055Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>

For #10807

Change-Id: Ied826d06cb622edf6413b6f2cdcc46987ab0b05a
Reviewed-on: https://go-review.googlesource.com/16054Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #12945.

Change-Id: I08b44795fcd7ec59371aea8111f7febead54720b
Reviewed-on: https://go-review.googlesource.com/15900Reviewed-by: Robert Griesemer <gri@golang.org>

Change-Id: Ib424e14cfaab35d37ebdd084d41151928bfd645e
Reviewed-on: https://go-review.googlesource.com/16051Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>

It was generating the wrong error message, always defaulting to "500
Internal Server Error", since the err variable used was always nil.

Fixes #12991

Change-Id: I94b0e516409c131ff3b878bcb91e65f0259ff077
Reviewed-on: https://go-review.googlesource.com/16060Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

It appears this was made possible by commit 89f185fe; before that, g was
not dereferenced above.

Change-Id: I70bc571d924b36351392fd4c13d681e938cfb573
Reviewed-on: https://go-review.googlesource.com/16033Reviewed-by: Andrew Gerrand <adg@golang.org>

Reuse the ArgSymbol for nodes so that the Aux values will be equal for cse.

Change-Id: Iaae80bd19ff2d3f51b6c9049fd860e04baa6f175
Reviewed-on: https://go-review.googlesource.com/15930Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Todd Neal <todd@tneal.org>