… on ARM

Progress on SSA for ARM. Still not complete. Now Fibonacci function compiles
and runs correctly.

The old backend swaps the operands for CMP instruction. This CL does the same
on SSA backend, and uses conditional branch accordingly.

Updates #15365.

Change-Id: I117e17feb22f03d936608bd232f76970e4bbe21a
Reviewed-on: https://go-review.googlesource.com/22187
Reviewed-by: Keith Randall <khr@golang.org>

Progress on SSA backend for ARM. Still not complete. It compiles a
Fibonacci function, but the caller picked the return value from an
incorrect offset. This CL adjusts it to match the stack frame layout
for architectures with link register.

Updates #15365.

Change-Id: I01e03c3e95f5503a185e8ac2b6d9caf4faf3d014
Reviewed-on: https://go-review.googlesource.com/22186
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Progress on SSA backend for ARM. Still not complete. Now "helloworld"
function compiles and runs.

Updates #15365.

Change-Id: I02f66983cefdf07a6aed262fb4af8add464d8e9a
Reviewed-on: https://go-review.googlesource.com/22854
Reviewed-by: Keith Randall <khr@golang.org>

…Barrier check

Use 32-bit load for writeBarrier check on all architectures.
Padding added to runtime structure.

Updates #15365, #15492.

Change-Id: I5d3dadf8609923fe0fe4fcb384a418b7b9624998
Reviewed-on: https://go-review.googlesource.com/22855
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

- generic Ops: Phi, CALL variants, NilCheck
- generic Blocks: Plain, Check
- 32-bit arithmetics
- CMP and conditional branches
- load/store
- zero/sign-extensions (8 to 16, 8 to 32, 16 to 32)

Progress on SSA backend for ARM. Still not complete. Now "errors"
package compiles and tests passed.

Updates #15365.

Change-Id: If126fd17f8695cbf55d64085bb3f1a4a53205701
Reviewed-on: https://go-review.googlesource.com/22856
Reviewed-by: Keith Randall <khr@golang.org>

Fix hardcoded flag register mask in ssa/flagalloc.go by auto-generating
the mask.

Also fix a mistake (in previous CL) about conditional branches.

Progress on SSA backend for ARM. Still not complete. Now "container/ring"
package compiles and tests passed.

Updates #15365.

Change-Id: Id7c8805c30dbb8107baedb485ed0f71f59ed6ea8
Reviewed-on: https://go-review.googlesource.com/23093
Reviewed-by: Keith Randall <khr@golang.org>

Implement shifts and multiplications for up to 32-bit values.

Also handle Exit block.

Progress on SSA backend for ARM. Still not complete.
container/heap, crypto/subtle, hash/adler32 packages compile and
tests passed.

Updates #15365.

Change-Id: I6bee4d5b0051e51d5de97e8a1938c4b87a36cbf8
Reviewed-on: https://go-review.googlesource.com/23096
Reviewed-by: Keith Randall <khr@golang.org>

Generate load/stores for small zeroing/move, DUFFZERO/DUFFCOPY for
medium zeroing/move, and loops for large zeroing/move.

cmd/compile/internal/gc/testdata/{copy_ssa.go,zero_ssa.go} tests
passed.

Progress on SSA backend for ARM. Still not complete. A few packages
in the standard library compile and tests passed, including
container/list, hash/crc32, unicode/utf8, etc.

Updates #15365.

Change-Id: Ieb4b68b44ee7de66bf7b68f5f33a605349fcc6fa
Reviewed-on: https://go-review.googlesource.com/23097
Reviewed-by: Keith Randall <khr@golang.org>

Also fix argument offset for runtime calls.

Also fix LoadReg/StoreReg by generating instructions by type.

Progress on SSA backend for ARM. Still not complete.
Tests append_ssa.go, assert_ssa.go, loadstore_ssa.go, short_ssa.go, and
deferNoReturn.go in cmd/compile/internal/gc/testdata passed.

Updates #15365.

Change-Id: I0f0a2398cab8bbb461772a55241a16a7da2ecedf
Reviewed-on: https://go-review.googlesource.com/23212
Reviewed-by: David Chase <drchase@google.com>

Introduce dec64 rules to (generically) decompose 64-bit integer on
32-bit architectures. 64-bit integer is composed/decomposed with
Int64Make/Hi/Lo ops, as for complex types.

The idea of dealing with Add64 is the following:

(Add64 (Int64Make xh xl) (Int64Make yh yl))
->
(Int64Make
	(Add32withcarry xh yh (Select0 (Add32carry xl yl)))
	(Select1 (Add32carry xl yl)))

where Add32carry returns a tuple (flags,uint32). Select0 and Select1
read the first and the second component of the tuple, respectively.
The two Add32carry will be CSE'd.

Similarly for multiplication, Mul32uhilo returns a tuple (hi, lo).

Also add support of KeepAlive, to fix build after merge.

Tests addressed_ssa.go, array_ssa.go, break_ssa.go, chan_ssa.go,
cmp_ssa.go, ctl_ssa.go, map_ssa.go, and string_ssa.go in
cmd/compile/internal/gc/testdata passed.

Progress on SSA for ARM. Still not complete.

Updates #15365.

Change-Id: I7867c76785a456312de5d8398a6b3f7ca5a4f7ec
Reviewed-on: https://go-review.googlesource.com/23213
Reviewed-by: Keith Randall <khr@golang.org>

Auto-generate register masks and load them through Config.

Passed toolstash -cmp on AMD64.

Tests phi_ssa.go and regalloc_ssa.go in cmd/compile/internal/gc/testdata
passed on ARM.

Updates #15365.

Change-Id: I393924d68067f2dbb13dab82e569fb452c986593
Reviewed-on: https://go-review.googlesource.com/23292
Reviewed-by: David Chase <drchase@google.com>

Also fix a mistake in previous CL about x8 and x16 shifts:
the shift needs ZeroExt.

Progress on SSA for ARM. Still not complete.

Updates #15365.

Change-Id: Ibc352760023d38bc6b9c5251e929fe26e016637a
Reviewed-on: https://go-review.googlesource.com/23486
Reviewed-by: David Chase <drchase@google.com>

SSA treats SP as constant throughout a function, so as OffPtr [off] SP.
When the stack moves, spilled OffPtr values become invalid, if they are
not pointer-typed.

(Currently it is fine because of the optimization rules that folds OffPtr
into Load/Store. But it'd better be "optimization", not requirement.)

Updates #15365.

Change-Id: I76cf4008dfdc169e1cb5a55a2605b6678efc915d
Reviewed-on: https://go-review.googlesource.com/23941
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Introduce an op MOVWaddr for addresses on ARM, instead of overuse
ADDconst.

Mark MOVWaddr as rematerializable. This fixes a liveness problem: if
it were not rematerializable, the address of a variable may be spilled
and later use of the address may just load the spilled value without
mentioning the variable, and the liveness code may think it is dead
prematurely.

Update #15365.

Change-Id: Ib0b0fa826bdb75c9e6bb362b95c6cf132cc6b1c0
Reviewed-on: https://go-review.googlesource.com/23942
Reviewed-by: David Chase <drchase@google.com>

Use hardware g register (R10) for GetG, allow g to appear at LHS of
some ops.

Progress on SSA backend for ARM. Now everything compiles and runs.

Updates #15365.

Change-Id: Icdf93585579faa86cc29b1e17ab7c90f0119fc4e
Reviewed-on: https://go-review.googlesource.com/23952
Reviewed-by: David Chase <drchase@google.com>

CSE may substitute a tuple generator with another one in a different
block. In this case, since we want tuple selectors to stay together
with the tuple generator, copy the selector to the new generator's
block and rewrite its use.

Op.isTupleGenerator and Op.isTupleSelector are introduced to assert
tuple ops. Use it in tighten as well.

Updates #15365.

Change-Id: Ia9e8c734b9cc3bc9fca4a2750041eef9cdfac5a5
Reviewed-on: https://go-review.googlesource.com/24137
Reviewed-by: David Chase <drchase@google.com>

Like AMD64, don't issue NilCheck instruction if the subsequent block
has a load or store at the same address.

Pass test/nilptr3_ssa.go.

Updates #15365.

Change-Id: Ic88780dab8c4893c57d1c95f663760cc185fe51e
Reviewed-on: https://go-review.googlesource.com/24451
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>

Encode the size and the alignment into AuxInt of Zero and Move ops.
On AMD64, we simply don't look at the alignment. On ARM and PPC64, we
only generate aligned stores.

Updates #15365.

Change-Id: Ifdcc205c364f67c4516b9adebfe7d50d223b6863
Reviewed-on: https://go-review.googlesource.com/24511
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

As Josh mentioned in CL 24716, there has been requests for using SSA
for ARM. SSA can still be disabled by setting -ssa=0 for cmd/compile,
or partially enabled with GOSSAFUNC, GOSSAPKG, and GOSSAHASH.

Not enable SSA by default on NaCl, which is not supported yet.

Enable SSA-specific tests on ARM: live_ssa.go and nilptr3_ssa.go;
disable non-SSA tests: live.go, nilptr3.go, and slicepot.go.

Updates #15365.

Change-Id: Ic2ca8d166aeca8517b9d262a55e92f2130683a16
Reviewed-on: https://go-review.googlesource.com/23953
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: David Chase <drchase@google.com>

Mostly constant folding rules, analogous to AMD64 ones. Along with
some simplifications.

Updates #15365.

Change-Id: If83bc1188bb05acb982ef3a1c21704c187e3eb24
Reviewed-on: https://go-review.googlesource.com/24210
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

This CL implements the following optimizations for ARM:
- use shifted ops (e.g. ADD R1<<2, R2) and indexed load/stores
- break up shift ops. Shifts used to be one SSA op that generates
  multiple instructions. We break them up to multiple ops, which
  allows constant folding and CSE for comparisons. Conditional moves
  are introduced for this.
- simplify zero/sign-extension ops.

Updates #15365.

Change-Id: I55e262a776a7ef2a1505d75e04d1208913c35d39
Reviewed-on: https://go-review.googlesource.com/24512
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

The argument size for runtime call was incorrectly includes the size
of LR (FixedFrameSize in general). This makes the stack frame
sometimes unnecessarily 4 bytes larger on ARM.
For example,
	func f(b []byte) byte { return b[0] }
compiles to
	0x0000 00000 (h.go:6)	TEXT	"".f(SB), $4-16 // <-- framesize = 4
	0x0000 00000 (h.go:6)	MOVW	8(g), R1
	0x0004 00004 (h.go:6)	CMP	R1, R13
	0x0008 00008 (h.go:6)	BLS	52
	0x000c 00012 (h.go:6)	MOVW.W	R14, -8(R13)
	0x0010 00016 (h.go:6)	FUNCDATA	$0, gclocals·8355ad952265fec823c17fcf739bd009(SB)
	0x0010 00016 (h.go:6)	FUNCDATA	$1, gclocals·69c1753bd5f81501d95132d08af04464(SB)
	0x0010 00016 (h.go:6)	MOVW	"".b+4(FP), R0
	0x0014 00020 (h.go:6)	CMP	$0, R0
	0x0018 00024 (h.go:6)	BLS	44
	0x001c 00028 (h.go:6)	MOVW	"".b(FP), R0
	0x0020 00032 (h.go:6)	MOVBU	(R0), R0
	0x0024 00036 (h.go:6)	MOVB	R0, "".~r1+12(FP)
	0x0028 00040 (h.go:6)	MOVW.P	8(R13), R15
	0x002c 00044 (h.go:6)	PCDATA	$0, $1
	0x002c 00044 (h.go:6)	CALL	runtime.panicindex(SB)
	0x0030 00048 (h.go:6)	UNDEF
	0x0034 00052 (h.go:6)	NOP
	0x0034 00052 (h.go:6)	MOVW	R14, R3
	0x0038 00056 (h.go:6)	CALL	runtime.morestack_noctxt(SB)
	0x003c 00060 (h.go:6)	JMP	0

Note that the frame size is 4, but there is actually no local. It
incorrectly thinks call to runtime.panicindex needs 4 bytes space
for argument.

This CL fixes it.

Updates #15365.

Change-Id: Ic65d55283a6aa8a7861d7a3fbc7b63c35785eeec
Reviewed-on: https://go-review.googlesource.com/24909
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

Add some simplification rules for floating point ops.

cmd/internal/obj/arm supports instructions that compare FP register
to 0, but runtime softfloat simulator does not. This CL adds these
instructions to softfloat simulator as well.

Updates #15365.

Change-Id: I29405b2bfcb4c8cf106cb7a1a811409fec91b170
Reviewed-on: https://go-review.googlesource.com/24790
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

NaCl code runs in sandbox and there are restrictions for its
instruction uses
(https://developer.chrome.com/native-client/reference/sandbox_internals/arm-32-bit-sandbox).

Like the legacy backend, on NaCl,
- don't use R9, which is used as NaCl's "thread pointer".
- don't use Duff's device.
- don't use indexed load/stores.
- the assembler rewrites DIV/MOD to runtime calls, which on NaCl
  clobbers R12, so R12 is marked as clobbered for DIV/MOD.
- other restrictions are satisfied by the assembler.

Enable SSA specific tests on nacl/arm, and disable non-SSA ones.

Updates #15365.

Change-Id: I9262693ec6756b89ca29d3ae4e52a96fe5403b02
Reviewed-on: https://go-review.googlesource.com/24859
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

… on ARM

Updates #15365.

Change-Id: I372a5617c2c7d91de545cac0464809b96711b63a
Reviewed-on: https://go-review.googlesource.com/24646
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>

For register-register move, if there is only one use, allocate it in
the same register so we don't need to emit an instruction.

Updates #15365.

Change-Id: Iad41843854a506c521d577ad93fcbe73e8de8065
Reviewed-on: https://go-review.googlesource.com/25059
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>