Commit Graph

286 Commits

Author SHA1 Message Date
Jaroslav Sevcik
c3af691e72 [turbofan] Remove int32 narrowing during typed lowering.
With Int32Add we lose the int/uint distinction, so later, in simplified lowering we can make a wrong decision. E.g., see the attached test case, where we lower NumberAdd -> Int32Add because inputs are Uint32, but during simplified lowering we change the inputs to Int32, so we get a wrong result.

Simplified lowering will lower the NumberAdd operations anyway, so we should lose performance.

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/721723004

Cr-Commit-Position: refs/heads/master@{#25368}
2014-11-17 09:04:52 +00:00
dcarney
c97a7acf65 [turbofan] refactor pipeline to use hydrogen like Run calls
BUG=

Review URL: https://codereview.chromium.org/727733002

Cr-Commit-Position: refs/heads/master@{#25361}
2014-11-14 16:44:45 +00:00
Benedikt Meurer
27cc3c685c Revert "[turbofan] Smartify the GraphReducer."
This reverts commit 6e148989a4 for
breaking Massive/Embenchen.

TBR=machenbach@chromium.org

Review URL: https://codereview.chromium.org/727743002

Cr-Commit-Position: refs/heads/master@{#25356}
2014-11-14 11:48:50 +00:00
Benedikt Meurer
6e148989a4 [turbofan] Smartify the GraphReducer.
Don't use the generic algorithm, but instead start going into the
direction of ControlReducer, using a stack plus a revisit queue to
not miss any more possibilities for reductions anymore.

TEST=cctest,unittests
R=dcarney@chromium.org

Committed: f047507370

Review URL: https://codereview.chromium.org/726513002

Cr-Commit-Position: refs/heads/master@{#25345}
2014-11-14 08:00:36 +00:00
Michael Starzinger
78332973e2 Revert "[turbofan] Smartify the GraphReducer."
This reverts commit f047507370 due to mjsunit/numops-fuzz-part2 hitting an
assertion in the ARM assembler.

TBR=bmeurer@chromium.org
TEST=mjsunit/numops-fuzz-part2

Review URL: https://codereview.chromium.org/724053002

Cr-Commit-Position: refs/heads/master@{#25327}
2014-11-13 14:07:04 +00:00
Benedikt Meurer
f047507370 [turbofan] Smartify the GraphReducer.
Don't use the generic algorithm, but instead start going into the
direction of ControlReducer, using a stack plus a revisit queue to
not miss any more possibilities for reductions anymore.

TEST=cctest,unittests
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/726513002

Cr-Commit-Position: refs/heads/master@{#25326}
2014-11-13 11:34:15 +00:00
Benedikt Meurer
7205f6ee9b [turbofan] Avoid useless bit masking in typed lowering.
There's no need to apply the 0x1f mask to right hand sides of shifts if
the input is already in range [0,31].

TEST=cctest,unittests
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/718193003

Cr-Commit-Position: refs/heads/master@{#25313}
2014-11-13 07:40:56 +00:00
dcarney@chromium.org
fdab306aa2 [turbofan] add gap move verifier
R=jarin@chromium.org

BUG=

Review URL: https://codereview.chromium.org/704193007

Cr-Commit-Position: refs/heads/master@{#25300}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25300 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-12 14:53:51 +00:00
mstarzinger@chromium.org
5712592331 Fix bug in graph copy while inlining loops.
R=titzer@chromium.org
TEST=cctest/test-run-inlining/InlineLoop

Review URL: https://codereview.chromium.org/712403003

Cr-Commit-Position: refs/heads/master@{#25285}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25285 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-12 09:47:17 +00:00
mstarzinger@chromium.org
434f2ebb5b Fix scheduler for floating non-naked non-empty loops.
R=jarin@chromium.org
TEST=cctest/test-scheduler/NestedFloatingDiamondWithLoop

Review URL: https://codereview.chromium.org/709753002

Cr-Commit-Position: refs/heads/master@{#25283}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25283 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-12 09:39:13 +00:00
mstarzinger@chromium.org
e1c9e732d3 Scheduler checks that end block doesn't have successors.
R=jarin@chromium.org
TEST=cctest/test-scheduler/RPOLoop

Review URL: https://codereview.chromium.org/710333002

Cr-Commit-Position: refs/heads/master@{#25281}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25281 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-12 09:20:22 +00:00
mstarzinger@chromium.org
1d17f826b3 Simplify scheduler API by removing zone scopes.
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/711413002

Cr-Commit-Position: refs/heads/master@{#25265}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25265 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-11 15:29:42 +00:00
titzer@chromium.org
21cf5bb249 Remove PhiReducer.
R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/684993006

Cr-Commit-Position: refs/heads/master@{#25262}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25262 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-11 12:03:12 +00:00
titzer@chromium.org
b9886ae9ff Fix bugs in simplified lowering relating to int32/uint32 signs.
Lowering of NumberToUint32 and NumberToInt32 was not correctly accounting for the sign of the input and the sign of the output, emitting the wrong representation changes.

Along the way, I've found cases where MachineOperatorBuilder would break if fed a machine type for loads or stores that was not cached, requiring MachineOperatorBuilder to take zone to allocate operators for these cases.

R=bmeurer@chromium.org, jarin@chromium.org
BUG=

Review URL: https://codereview.chromium.org/714613002

Cr-Commit-Position: refs/heads/master@{#25247}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25247 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-10 14:28:42 +00:00
mstarzinger@chromium.org
9e555db8fb Make scheduler handle floating non-naked loops.
R=jarin@chromium.org
TEST=cctest/test-scheduler/NestedFloatingDiamondWithLoop

Review URL: https://codereview.chromium.org/706123003

Cr-Commit-Position: refs/heads/master@{#25217}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25217 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-07 16:01:49 +00:00
mstarzinger@chromium.org
9734f236a3 Revert "Remove workaround for successors on end block from scheduler."
TBR=titzer@chromium.org

Review URL: https://codereview.chromium.org/705043002

Cr-Commit-Position: refs/heads/master@{#25194}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25194 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-06 13:12:16 +00:00
titzer@chromium.org
b309f3d208 [turbofan] (reland) Compute tighter ranges for modulus in Typer.
R=jarin@chromium.org
BUG=

Review URL: https://codereview.chromium.org/694703004

Cr-Commit-Position: refs/heads/master@{#25193}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25193 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-06 13:10:49 +00:00
mstarzinger@chromium.org
f9575cef57 Remove workaround for successors on end block from scheduler.
R=titzer@chromium.org
TEST=cctest/test-scheduler/RPOLoop

Review URL: https://codereview.chromium.org/708763002

Cr-Commit-Position: refs/heads/master@{#25188}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25188 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-06 12:31:52 +00:00
mstarzinger@chromium.org
361d7b0f0e Avoid redundant work in scheduler loop header/depth calculation.
R=jarin@chromium.org

TEST=cctest/test-scheduler/LoopedFloatingDiamond2

Review URL: https://codereview.chromium.org/702683002

Cr-Commit-Position: refs/heads/master@{#25181}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25181 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-06 09:15:42 +00:00
bmeurer@chromium.org
8798c410e1 [turbofan] Turn various diamonds into selects.
TEST=cctest/test-changes-lowering,mjsunit/asm,unittests
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/704463004

Cr-Commit-Position: refs/heads/master@{#25180}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25180 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-06 09:10:32 +00:00
dcarney@chromium.org
57b42dc51f [turbofan] extend register allocator testing with control flow
R=bmeurer@chromium.org, jarin@chromium.org

BUG=

Review URL: https://codereview.chromium.org/699083003

Cr-Commit-Position: refs/heads/master@{#25178}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25178 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-06 08:28:45 +00:00
titzer@chromium.org
0f46c9b46a Revert "[turbofan] Compute tighter ranges for modulus in Typer."
This reverts commit 482586747ca6bc0c94cc23f916fd190931d3a836.

TBR=jarin@chromium.org
BUG=

Review URL: https://codereview.chromium.org/702893002

Cr-Commit-Position: refs/heads/master@{#25164}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25164 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-05 15:19:45 +00:00
titzer@chromium.org
b2800d7d87 [turbofan] Compute tighter ranges for modulus in Typer.
R=jarin@chromium.org
BUG=

Review URL: https://codereview.chromium.org/689133003

Cr-Commit-Position: refs/heads/master@{#25162}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25162 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-05 14:57:15 +00:00
bmeurer@chromium.org
0c1a545a93 [turbofan] Propagate "deferredness" to dominated basic blocks.
TEST=cctest/test-scheduler
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/686273005

Cr-Commit-Position: refs/heads/master@{#25141}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25141 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-05 10:44:12 +00:00
mstarzinger@chromium.org
b0aa81f30d Make special RPO computation iterative during scheduling.
This contains the following changes squashed together:
- Switch BasicBlock::loop_end to be a basic block instead of an RPO.
- Switch ScheduleLate to use dominator depth instead of RPO.
- Switch ScheduleEarly to use dominator depth instead of RPO.
- Push out absolute RPO ordering everywhere else in the scheduler.
- Keep linked list of blocks in RPO order while scheduling.
- Switch from RPO number to depth for dominator calculation.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/696363002

Cr-Commit-Position: refs/heads/master@{#25138}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25138 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-05 10:10:54 +00:00
titzer@chromium.org
faa71f966a Introduce Diamond, a helper for building diamond-shaped control patterns.
R=mstarzinger@chromium.org, bmeurer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/694063005

Cr-Commit-Position: refs/heads/master@{#25110}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25110 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-04 14:37:44 +00:00
dcarney@chromium.org
7cb25f5020 [turbofan] add RegisterConfiguration to decouple arch specific register layouts from compiler
R=bmeurer@chromium.org

BUG=

Review URL: https://codereview.chromium.org/694313002

Cr-Commit-Position: refs/heads/master@{#25097}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25097 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-04 09:22:32 +00:00
titzer@chromium.org
5bba6b20e6 Make visualizer robust to graphs with NULL inputs.
R=mstarzinger@chromium.org, jarin@chromium.org
BUG=

Review URL: https://codereview.chromium.org/652263002

Cr-Commit-Position: refs/heads/master@{#25084}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25084 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-03 17:42:17 +00:00
dcarney@chromium.org
273a9ad200 build fix after 25072
TBR=bmeurer@chromium.org

BUG=

Review URL: https://codereview.chromium.org/688323005

Cr-Commit-Position: refs/heads/master@{#25073}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25073 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-03 13:55:44 +00:00
dcarney@chromium.org
e17194ba52 build fix after r25071
TBR=bmeurer@chromium.org

BUG=

Review URL: https://codereview.chromium.org/684523003

Cr-Commit-Position: refs/heads/master@{#25072}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25072 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-03 13:42:13 +00:00
dcarney@chromium.org
0d1cdebad2 [turbofan] initial framework for unittesting of register allocator
BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/683133005

Cr-Commit-Position: refs/heads/master@{#25071}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25071 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-03 13:27:23 +00:00
mstarzinger@chromium.org
c63deb9b56 Make generic algorithm less generic.
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/701473002

Cr-Commit-Position: refs/heads/master@{#25064}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25064 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-03 10:31:11 +00:00
titzer@chromium.org
c62bb3e2eb Now with more checkings! Skip the CallFunctionStub when the callee function can be statically determined.
R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/696223002

Cr-Commit-Position: refs/heads/master@{#25062}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25062 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-03 10:22:44 +00:00
bmeurer@chromium.org
498920f91c [turbofan] Also optimize unsigned division by constant.
TEST=cctest,mjsunit,unittests
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/697663003

Cr-Commit-Position: refs/heads/master@{#25061}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25061 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-11-03 10:05:46 +00:00
jarin@chromium.org
4a9579feeb [turbofan] Avoid unnecessary (u)int32<->float64 changes in simplified lowering.
BUG=
R=bmeurer@chromium.org, titzer@chromium.org

Review URL: https://codereview.chromium.org/683873002

Cr-Commit-Position: refs/heads/master@{#25045}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25045 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-31 19:53:48 +00:00
jarin@chromium.org
6935e0131c Revert "Skip the CallFunctionStub when the callee function can be statically determined."
This reverts commit 9845dfadd2 (r25042) for failing tests.

TBR=titzer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/693103004

Cr-Commit-Position: refs/heads/master@{#25044}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25044 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-31 19:06:18 +00:00
titzer@chromium.org
9845dfadd2 Skip the CallFunctionStub when the callee function can be statically determined.
R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/694773002

Cr-Commit-Position: refs/heads/master@{#25042}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25042 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-31 16:36:13 +00:00
bmeurer@chromium.org
28b683630e [turbofan] Lower NumberModulus to Uint32Mod if both inputs are Unsigned32.
TEST=cctest/test-simplified-lowering
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/685993003

Cr-Commit-Position: refs/heads/master@{#25025}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25025 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-31 07:59:18 +00:00
bmeurer@chromium.org
948ce2141e [turbofan] First step towards correctified 64-bit addressing.
Also remove the LEA matching from x64, since it was never really
effective. We'll optimize that once we're correct.

TEST=cctest,unittests
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/652363006

Cr-Commit-Position: refs/heads/master@{#25024}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25024 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-31 06:41:41 +00:00
sigurds@chromium.org
75ac43928b Add floor, ceil, round (truncate) instructions for ia32, x64 (if SSE4.1) and
add floor, ceil, round (truncate and away from zero) for arm64.

R=bmeurer@chromium.org, dcarney@chromium.org, mstarzinger@chromium.org, rodolph.perfetta@arm.com
TEST=test/mjsunit/asm/math-floor.js,test/mjsunit/asm/math-ceil.js,test/unittest/compiler/js-builtin-reducer-unittest.cc

Review URL: https://codereview.chromium.org/677433002

Cr-Commit-Position: refs/heads/master@{#25018}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25018 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-30 14:16:15 +00:00
dcarney@chromium.org
ee9de33075 [turbofan] move Node to vreg mapping to InstructionSelector
BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/683933004

Cr-Commit-Position: refs/heads/master@{#25010}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25010 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-30 09:50:41 +00:00
dcarney@chromium.org
7f94583f79 [turbofan] add configuration parameters for register allocator
T=jarin@chromium.org

BUG=
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/688633002

Cr-Commit-Position: refs/heads/master@{#25008}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25008 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-30 09:01:47 +00:00
jarin@chromium.org
5d54e89ad6 [turbofan] Fix input count in Uint32Mod/Div reduction.
BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/684193002

Cr-Commit-Position: refs/heads/master@{#24997}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24997 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-29 21:07:47 +00:00
titzer@chromium.org
5c25fdb65e Inline trivial OperatorProperties methods.
R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/686213002

Cr-Commit-Position: refs/heads/master@{#24995}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24995 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-29 18:47:14 +00:00
titzer@chromium.org
2a57f036b2 Run ControlReducer early after graph building, then again later.
The justification for doing this is to reduce the size of the graph and
therefore speedup later phases of compilation. The control reducer also
obviates the need to run the PhiReducer, since it subsumes it.

R=mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/681263004

Cr-Commit-Position: refs/heads/master@{#24986}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24986 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-29 15:27:58 +00:00
titzer@chromium.org
6c6a71b3f7 Move input/output counts directly into Operators, simplying OperatorProperties.
This is a first step to refactoring OperatorProperties out of existence.
The next step is to inline OperatorProperties::GetXXXCount into the callers.

R=rossberg@chromium.org
BUG=

Review URL: https://codereview.chromium.org/680313003

Cr-Commit-Position: refs/heads/master@{#24983}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24983 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-29 14:41:18 +00:00
dcarney@chromium.org
60909d1eaf [turbofan] cleanup register allocator interface a little
BUG=
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/671043004

Cr-Commit-Position: refs/heads/master@{#24978}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24978 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-29 12:35:16 +00:00
titzer@chromium.org
1ddcb4b16d Fix windows build.
TBR=ishell@chromium.org
BUG=

Review URL: https://codereview.chromium.org/669663003

Cr-Commit-Position: refs/heads/master@{#24958}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24958 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-28 17:54:57 +00:00
titzer@chromium.org
90a7f07489 Implement loop variable assignment analysis.
This analysis computes the set of variables that are assigned in each loop. This is useful to avoid creating redundant loop phis when building an SSA graph, which just waste memory and require analysis to get rid of.

This CL implements an AST walk for the analysis and plugs the result into the TurboFan graph builder. I left this analysis under a flag for A/B testing and until sufficient unit tests can be developed.

R=danno@chromium.org, mstarzinger@chromium.org
BUG=

Review URL: https://codereview.chromium.org/656123005

Cr-Commit-Position: refs/heads/master@{#24957}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24957 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-28 17:30:14 +00:00
bmeurer@chromium.org
81aaeb476d [turbofan] Complete support for integer division/modulus in simplified lowering.
Also add backend flags that tell whether integer division/modulus is
generally safe, i.e. does not trap on overflow or divide by zero.

TEST=unittests
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/681133004

Cr-Commit-Position: refs/heads/master@{#24942}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24942 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-10-28 13:56:46 +00:00