Make arm assembler explicitly take both registers for load/store-pair.

Make arm assembler explicitly take both registers for load/store-pair.

R=zra@google.com

Committed: https://github.com/dart-lang/sdk/commit/1a34875064e4fd09bfbdf4448810f05e7461d6ad

[rmacnak, 2015-10-23 01:39:03]

rmacnak@google.com changed reviewers:
+ zra@google.com

[rmacnak, 2015-10-23 01:39:03]

The register renaming for iOS breaks up some pairs. This change makes it easier
to notice and fix these situations.

[zra, 2015-10-23 03:48:44]

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.cc
File runtime/vm/assembler_arm.cc (right):

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.cc...
runtime/vm/assembler_arm.cc:1711: ASSERT(value_odd == value_even + 1);
assert value_even % 2 == 0.

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.cc...
runtime/vm/assembler_arm.cc:2859: case kWordPair: {
To retain the benefits of passing both registers to ldrd, it might make sense to
split this case off into its own function, like LoadPairFromOffset(r1, r2, base,
offset, condition).

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.cc...
runtime/vm/assembler_arm.cc:2893: case kWordPair: {
ditto

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.h
File runtime/vm/assembler_arm.h (right):

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.h#...
runtime/vm/assembler_arm.h:515: // ARMv5TE, so we only support the base + offset
mode.
Maybe add a comment about the restrictions on rd and rd2.

[rmacnak, 2015-10-23 16:29:04]

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.cc
File runtime/vm/assembler_arm.cc (right):

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.cc...
runtime/vm/assembler_arm.cc:1711: ASSERT(value_odd == value_even + 1);
On 2015/10/23 03:48:44, zra wrote:
> assert value_even % 2 == 0.

Done.

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.cc...
runtime/vm/assembler_arm.cc:2859: case kWordPair: {
On 2015/10/23 03:48:44, zra wrote:
> To retain the benefits of passing both registers to ldrd, it might make sense
to
> split this case off into its own function, like LoadPairFromOffset(r1, r2,
base,
> offset, condition).

Deleted this case as it is unused.

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.cc...
runtime/vm/assembler_arm.cc:2893: case kWordPair: {
On 2015/10/23 03:48:44, zra wrote:
> ditto

Deleted

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.h
File runtime/vm/assembler_arm.h (right):

https://codereview.chromium.org/1407393006/diff/1/runtime/vm/assembler_arm.h#...
runtime/vm/assembler_arm.h:515: // ARMv5TE, so we only support the base + offset
mode.
On 2015/10/23 03:48:44, zra wrote:
> Maybe add a comment about the restrictions on rd and rd2.

Added

[zra, 2015-10-23 16:31:53]

lgtm with asserts

https://codereview.chromium.org/1407393006/diff/40001/runtime/vm/assembler_ar...
File runtime/vm/assembler_arm.cc (right):

https://codereview.chromium.org/1407393006/diff/40001/runtime/vm/assembler_ar...
runtime/vm/assembler_arm.cc:2836: Condition cond) {
ASSERT(size != kWordPair);

https://codereview.chromium.org/1407393006/diff/40001/runtime/vm/assembler_ar...
runtime/vm/assembler_arm.cc:2870: Condition cond) {
ASSERT(size != kWordPair);

[rmacnak, 2015-10-23 17:16:20]

https://codereview.chromium.org/1407393006/diff/40001/runtime/vm/assembler_ar...
File runtime/vm/assembler_arm.cc (right):

https://codereview.chromium.org/1407393006/diff/40001/runtime/vm/assembler_ar...
runtime/vm/assembler_arm.cc:2836: Condition cond) {
On 2015/10/23 16:31:53, zra wrote:
> ASSERT(size != kWordPair);

Done.

https://codereview.chromium.org/1407393006/diff/40001/runtime/vm/assembler_ar...
runtime/vm/assembler_arm.cc:2870: Condition cond) {
On 2015/10/23 16:31:53, zra wrote:
> ASSERT(size != kWordPair);

Done.

[rmacnak, 2015-10-23 17:16:36]

Committed patchset #4 (id:60001) manually as
1a34875064e4fd09bfbdf4448810f05e7461d6ad (presubmit successful).