Commit Graph

83 Commits

Author SHA1 Message Date
Thomas Lively a1d97a960e [WebAssembly] Implement tail calls and unify tablegen call classes
Summary:
Implements direct and indirect tail calls enabled by the 'tail-call'
feature in both DAG ISel and FastISel. Updates existing call tests and
adds new tests including a binary encoding test.

Reviewers: aheejin

Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62877

llvm-svn: 364445
2019-06-26 16:17:15 +00:00
Thomas Lively eafe8ef6f2 [WebAssembly] Add multivalue and tail-call target features
Summary:
These features will both be implemented soon, so I thought I would
save time by adding the boilerplate for both of them at the same time.

Reviewers: aheejin

Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D62047

llvm-svn: 361516
2019-05-23 17:26:47 +00:00
Sam Clegg 492f752969 [WebAssembly] Initial implementation of PIC code generation
This change implements lowering of references global symbols in PIC
mode.

This change implements lowering of global references in PIC mode using a
new @GOT reference type. @GOT references can be used with function or
data symbol names combined with the get_global instruction. In this case
the linker will insert the wasm global that stores the address of the
symbol (either in memory for data symbols or in the wasm table for
function symbols).

For now I'm continuing to use the R_WASM_GLOBAL_INDEX_LEB relocation
type for this type of reference which means that this relocation type
can refer to either a global or a function or data symbol. We could
choose to introduce specific relocation types for GOT entries in the
future.  See the current dynamic linking proposal:

https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md

Differential Revision: https://reviews.llvm.org/D54647

llvm-svn: 357022
2019-03-26 19:46:15 +00:00
Heejin Ahn 4367587fc6 [WebAssembly] Tidy up `let` statements in .td files (NFC)
Summary:
- Delete {} for one-line `let` statements
- Don't indent within `let` blocks
- Add comments after `let` block's closing braces

Reviewers: tlively

Subscribers: dschuff, sbc100, jgravelle-google, sunfish, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57730

llvm-svn: 353248
2019-02-06 00:17:03 +00:00
Thomas Lively d99af23765 [WebAssembly] memory.copy
Summary: Depends on D57495.

Reviewers: aheejin, dschuff

Subscribers: sbc100, jgravelle-google, hiraditya, sunfish

Differential Revision: https://reviews.llvm.org/D57498

llvm-svn: 353127
2019-02-05 00:49:55 +00:00
Thomas Lively 88058d4e1e [WebAssembly] Add bulk memory target feature
Summary: Also clean up some preexisting target feature code.

Reviewers: aheejin

Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, jfb

Differential Revision: https://reviews.llvm.org/D57495

llvm-svn: 352793
2019-01-31 21:02:19 +00:00
Heejin Ahn d6f487863d [WebAssembly] Exception handling: Switch to the new proposal
Summary:
This switches the EH implementation to the new proposal:
https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md
(The previous proposal was
 https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md)

- Instruction changes
  - Now we have one single `catch` instruction that returns a except_ref
    value
  - `throw` now can take variable number of operations
  - `rethrow` does not have 'depth' argument anymore
  - `br_on_exn` queries an except_ref to see if it matches the tag and
    branches to the given label if true.
  - `extract_exception` is a pseudo instruction that simulates popping
    values from wasm stack. This is to make `br_on_exn`, a very special
    instruction, work: `br_on_exn` puts values onto the stack only if it
    is taken, and the # of values can vay depending on the tag.

- Now there's only one `catch` per `try`, this patch removes all special
  handling for terminate pad with a call to `__clang_call_terminate`.
  Before it was the only case there are two catch clauses (a normal
  `catch` and `catch_all` per `try`).

- Make `rethrow` act as a terminator like `throw`. This splits BB after
  `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable`
  after `rethrow` in LateEHPrepare.

- Now we stop at all catchpads (because we add wasm `catch` instruction
  that catches all exceptions), this creates new
  `findWasmUnwindDestinations` function in SelectionDAGBuilder.

- Now we use `br_on_exn` instrution to figure out if an except_ref
  matches the current tag or not, LateEHPrepare generates this sequence
  for catch pads:
```
  catch
  block i32
  br_on_exn $__cpp_exception
  end_block
  extract_exception
```

- Branch analysis for `br_on_exn` in WebAssemblyInstrInfo

- Other various misc. changes to switch to the new proposal.

Reviewers: dschuff

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D57134

llvm-svn: 352598
2019-01-30 03:21:57 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Thomas Lively 64a39a1c4e [WebAssembly] Add unimplemented-simd128 subtarget feature
Summary:
This is a third attempt, but this time we have vetted it on Windows
first. The previous errors were due to an uninitialized class member.

Reviewers: aheejin

Subscribers: dschuff, sbc100, jgravelle-google, sunfish, jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D56560

llvm-svn: 350901
2019-01-10 22:32:11 +00:00
Thomas Lively fdd4999b86 Revert "[WebAssembly] Add simd128-unimplemented subtarget feature"
This reverts rL350791.

llvm-svn: 350795
2019-01-10 04:09:25 +00:00
Thomas Lively eb6f9abd41 [WebAssembly] Add simd128-unimplemented subtarget feature
This is a second attempt at r350778, which was reverted in
r350789. The only change is that the unimplemented-simd128 feature has
been renamed simd128-unimplemented, since naming it
unimplemented-simd128 somehow made the simd128 feature flag enable the
unimplemented-simd128 feature on Windows.

llvm-svn: 350791
2019-01-10 02:55:52 +00:00
Thomas Lively fdca5fab60 Revert "[WebAssembly] Add unimplemented-simd128 subtarget feature"
This reverts L350778.

llvm-svn: 350789
2019-01-10 01:37:44 +00:00
Thomas Lively 2eeade1814 [WebAssembly] Add unimplemented-simd128 subtarget feature
Summary:
This replaces the old ad-hoc -wasm-enable-unimplemented-simd
flag. Also makes the new unimplemented-simd128 feature imply the
simd128 feature.

Reviewers: aheejin, dschuff

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits, alexcrichton

Differential Revision: https://reviews.llvm.org/D56501

llvm-svn: 350778
2019-01-09 23:59:37 +00:00
Thomas Lively 6a87ddac9a [WebAssembly] Massive instruction renaming
Summary:
An automated renaming of all the instructions listed at
https://github.com/WebAssembly/spec/issues/884#issuecomment-426433329
as well as some similarly-named identifiers.

Reviewers: aheejin, dschuff, aardappel

Subscribers: sbc100, jgravelle-google, eraman, sunfish, jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D56338

llvm-svn: 350609
2019-01-08 06:25:55 +00:00
Thomas Lively 8dbf29af95 [WebAssembly] Gate unimplemented SIMD ops on flag
Summary:
Gates v128.const, f32x4.sqrt, f32x4.div, i8x16.extract_lane_u, and
i16x8.extract_lane_u on the --wasm-enable-unimplemented-simd flag,
since these ops are not implemented yet in V8.

Reviewers: aheejin, dschuff

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D55904

llvm-svn: 349720
2018-12-20 02:10:22 +00:00
Heejin Ahn da419bdb5e [WebAssembly] Add support for the event section
Summary:
This adds support for the 'event section' specified in the exception
handling proposal. (This was named 'exception section' first, but later
renamed to 'event section' to take possibilities of other kinds of
events into consideration. But currently we only store exception info in
this section.)

The event section is added between the global section and the export
section. This is for ease of validation per request of the V8 team.

This patch:
- Creates the event symbol type, which is a weak symbol
- Makes 'throw' instruction take the event symbol '__cpp_exception'
- Adds relocation support for events
- Adds WasmObjectWriter / WasmObjectFile (Reader) support
- Adds obj2yaml / yaml2obj support
- Adds '.eventtype' printing support

Reviewers: dschuff, sbc100, aardappel

Subscribers: jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D54096

llvm-svn: 346825
2018-11-14 02:46:21 +00:00
Heejin Ahn 24faf859e5 Reland "[WebAssembly] LSDA info generation"
Summary:
This adds support for LSDA (exception table) generation for wasm EH.
Wasm EH mostly follows the structure of Itanium-style exception tables,
with one exception: a call site table entry in wasm EH corresponds to
not a call site but a landing pad.

In wasm EH, the VM is responsible for stack unwinding. After an
exception occurs and the stack is unwound, the control flow is
transferred to wasm 'catch' instruction by the VM, after which the
personality function is called from the compiler-generated code. (Refer
to WasmEHPrepare pass for more information on this part.)

This patch:
- Changes wasm.landingpad.index intrinsic to take a token argument, to
make this 1:1 match with a catchpad instruction
- Stores landingpad index info and catch type info MachineFunction in
before instruction selection
- Lowers wasm.lsda intrinsic to an MCSymbol pointing to the start of an
exception table
- Adds WasmException class with overridden methods for table generation
- Adds support for LSDA section in Wasm object writer

Reviewers: dschuff, sbc100, rnk

Subscribers: mgorny, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D52748

llvm-svn: 345345
2018-10-25 23:55:10 +00:00
Thomas Lively c63b5fcb2a [WebAssembly][NFC] Remove WebAssemblyStackifier TableGen backend
Summary:
Replace its functionality with a TableGen InstrInfo relational
instruction mapping. Although arguably more complex than the TableGen
backend, the relational mapping is a smaller maintenance burden than a
TableGen backend.

Reviewers: aardappel, aheejin, dschuff

Subscribers: mgorny, sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D53307

llvm-svn: 344962
2018-10-22 21:55:26 +00:00
Krasimir Georgiev 547d824da6 Revert "[WebAssembly] LSDA info generation"
This reverts commit r344575.
Newly introduced test eh-lsda.ll.test fails with use-after-free under
ASAN build.

llvm-svn: 344639
2018-10-16 18:50:09 +00:00
Heejin Ahn 0981eaab47 [WebAssembly] LSDA info generation
Summary:
This adds support for LSDA (exception table) generation for wasm EH.
Wasm EH mostly follows the structure of Itanium-style exception tables,
with one exception: a call site table entry in wasm EH corresponds to
not a call site but a landing pad.

In wasm EH, the VM is responsible for stack unwinding. After an
exception occurs and the stack is unwound, the control flow is
transferred to wasm 'catch' instruction by the VM, after which the
personality function is called from the compiler-generated code. (Refer
to WasmEHPrepare pass for more information on this part.)

This patch:
- Changes wasm.landingpad.index intrinsic to take a token argument, to
make this 1:1 match with a catchpad instruction
- Stores landingpad index info and catch type info MachineFunction in
before instruction selection
- Lowers wasm.lsda intrinsic to an MCSymbol pointing to the start of an
exception table
- Adds WasmException class with overridden methods for table generation
- Adds support for LSDA section in Wasm object writer

Reviewers: dschuff, sbc100, rnk

Subscribers: mgorny, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D52748

llvm-svn: 344575
2018-10-16 00:09:12 +00:00
Thomas Lively 0ff82ac154 [WebAssembly][NFC] Unify ARGUMENT classes
Reviewers: aheejin, dschuff

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D53172

llvm-svn: 344436
2018-10-13 07:09:10 +00:00
Thomas Lively f04bed8e79 [WebAssembly][NFC] Remove repetition of Defs = [ARGUMENTS] (fixed)
llvm-svn: 344287
2018-10-11 20:21:22 +00:00
Thomas Lively ab37189f7e [WebAssembly] Revert rL344180, which was breaking expensive checks
llvm-svn: 344280
2018-10-11 18:45:48 +00:00
Thomas Lively eff0542c56 [WebAssembly][NFC] Remove repetition of Defs = [ARGUMENTS]
Summary:
By moving that line into the `I` multiclass.

Reviewers: aheejin

Subscribers: dschuff, sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D53093

llvm-svn: 344180
2018-10-10 20:40:54 +00:00
Heejin Ahn d9a6de3c38 [WebAssembly] Improve readability of SIMD instructions (NFC)
Summary:
- Categorize instructions into the categories as in the SIMD spec
- Move SIMD-related definition to WebAssemblyInstrSIMD.td
- Put definition and use of patterns together
- Add newlines here and there

Reviewers: tlively

Subscribers: dschuff, sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D53045

llvm-svn: 344086
2018-10-09 22:23:39 +00:00
Thomas Lively 22442924a8 [WebAssembly] v128.const
Summary:
This CL implements v128.const for each vector type. New operand types
are added to ensure the vector contents can be serialized without LEB
encoding. Tests are added for instruction selection, encoding,
assembly and disassembly.

Reviewers: aheejin, dschuff, aardappel

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D50873

llvm-svn: 340336
2018-08-21 21:03:18 +00:00
Derek Schuff 51ed131ed2 [WebAssembly] Update SIMD binary arithmetic
Add missing SIMD types (v2f64) and binary ops. Also adds
tablegen support for automatically prepending prefix byte to SIMD
opcodes.

Differential Revision: https://reviews.llvm.org/D50292

Patch by Thomas Lively

llvm-svn: 339186
2018-08-07 21:24:01 +00:00
Wouter van Oortmerssen 48dac3109e [WebAssembly] Modified tablegen defs to have 2 parallel instuction sets.
Summary:
One for register based, much like the existing definitions,
and one for stack based (suffix _S).

This allows us to use registers in most of LLVM (which works better),
and stack based in MC (which results in a simpler and more readable
assembler / disassembler).

Tried to keep this change as small as possible while passing tests,
follow-up commit will:
- Add reg->stack conversion in MI.
- Fix asm/disasm in MC to be stack based.
- Fix emitter to be stack based.

tests passing:
llvm-lit -v `find test -name WebAssembly`

test/CodeGen/WebAssembly
test/MC/WebAssembly
test/MC/Disassembler/WebAssembly
test/DebugInfo/WebAssembly
test/CodeGen/MIR/WebAssembly
test/tools/llvm-objdump/WebAssembly

Reviewers: dschuff, sbc100, jgravelle-google, sunfish

Subscribers: aheejin, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D48183

llvm-svn: 334985
2018-06-18 21:22:44 +00:00
Sam Clegg 537afe6f0e [WebAssembly] Fix .td files after rL333900
Differential Revision: https://reviews.llvm.org/D47727

llvm-svn: 333928
2018-06-04 16:59:26 +00:00
Adrian Prantl 5f8f34e459 Remove \brief commands from doxygen comments.
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.

Patch produced by

  for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done

Differential Revision: https://reviews.llvm.org/D46290

llvm-svn: 331272
2018-05-01 15:54:18 +00:00
Heejin Ahn 0de587296e [WebAssembly] Add except_ref as a first-class type
Summary: Add except_ref as a first-class type, according to the [[https://github.com/WebAssembly/exception-handling/blob/master/proposals/Level-1.md | Level 1 exception handling proposal ]].

Reviewers: dschuff

Subscribers: jfb, sbc100, llvm-commits

Differential Revision: https://reviews.llvm.org/D43706

llvm-svn: 326985
2018-03-08 04:05:37 +00:00
Heejin Ahn 9386bde11b [WebAssembly] Add exception handling option and feature
Summary:
Add a llc command line option and WebAssembly architecture feature for
exception handling.

Reviewers: dschuff

Subscribers: jfb, sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D43683

llvm-svn: 326004
2018-02-24 00:40:50 +00:00
Dan Gohman 5d2b9354b1 [WebAssembly] Make sign-extension opcodes a distinct feature.
Sign-extension opcodes have been split into a separate proposal from
the main threads proposal, so switch them to their own target
feature. See:

https://github.com/WebAssembly/sign-extension-ops

llvm-svn: 322966
2018-01-19 17:16:24 +00:00
Dan Gohman cdd48b8a6b [WebAssembly] Fix trapping behavior in fptosi/fptoui.
This adds code to protect WebAssembly's `trunc_s` family of opcodes
from values outside their domain. Even though such conversions have
full undefined behavior in C/C++, LLVM IR's `fptosi` and `fptoui` do
not, and only return undef.

This also implements the proposed non-trapping float-to-int conversion
feature and uses that instead when available.

llvm-svn: 319128
2017-11-28 01:13:40 +00:00
Derek Schuff 18ba192843 [WebAssembly] Add target feature for atomics
Summary:
This tracks the WebAssembly threads feature proposal at
https://github.com/WebAssembly/threads/blob/master/proposals/threads/Overview.md

Differential Revision: https://reviews.llvm.org/D37300

llvm-svn: 312145
2017-08-30 18:07:45 +00:00
Serge Pavlov d526b13e61 Add extra operand to CALLSEQ_START to keep frame part set up previously
Using arguments with attribute inalloca creates problems for verification
of machine representation. This attribute instructs the backend that the
argument is prepared in stack prior to  CALLSEQ_START..CALLSEQ_END
sequence (see http://llvm.org/docs/InAlloca.htm for details). Frame size
stored in CALLSEQ_START in this case does not count the size of this
argument. However CALLSEQ_END still keeps total frame size, as caller can
be responsible for cleanup of entire frame. So CALLSEQ_START and
CALLSEQ_END keep different frame size and the difference is treated by
MachineVerifier as stack error. Currently there is no way to distinguish
this case from actual errors.

This patch adds additional argument to CALLSEQ_START and its
target-specific counterparts to keep size of stack that is set up prior to
the call frame sequence. This argument allows MachineVerifier to calculate
actual frame size associated with frame setup instruction and correctly
process the case of inalloca arguments.

The changes made by the patch are:
- Frame setup instructions get the second mandatory argument. It
  affects all targets that use frame pseudo instructions and touched many
  files although the changes are uniform.
- Access to frame properties are implemented using special instructions
  rather than calls getOperand(N).getImm(). For X86 and ARM such
  replacement was made previously.
- Changes that reflect appearance of additional argument of frame setup
  instruction. These involve proper instruction initialization and
  methods that access instruction arguments.
- MachineVerifier retrieves frame size using method, which reports sum of
  frame parts initialized inside frame instruction pair and outside it.

The patch implements approach proposed by Quentin Colombet in
https://bugs.llvm.org/show_bug.cgi?id=27481#c1.
It fixes 9 tests failed with machine verifier enabled and listed
in PR27481.

Differential Revision: https://reviews.llvm.org/D32394

llvm-svn: 302527
2017-05-09 13:35:13 +00:00
Dan Gohman d934cb8806 [WebAssembly] Basic support for Wasm object file encoding.
With the "wasm32-unknown-unknown-wasm" triple, this allows writing out
simple wasm object files, and is another step in a larger series toward
migrating from ELF to general wasm object support. Note that this code
and the binary format itself is still experimental.

llvm-svn: 296190
2017-02-24 23:18:00 +00:00
Dan Gohman b89f2d3d92 [WebAssembly] Add instruction definitions for drop and get/set_global.
llvm-svn: 293922
2017-02-02 19:29:44 +00:00
Dan Gohman 00d734d89b [WebAssembly] Annotate call and load/store immediates.
These will be used to guide the binary encoding of these immediates.

llvm-svn: 290412
2016-12-23 03:23:52 +00:00
Dan Gohman 3acb187d95 [WebAssembly] Implement more WebAssembly binary encoding.
This changes locals from being declared by the emitLocal hook in
WebAssemblyTargetStreamer, rather than with an instruction. After exploring
the infastructure in LLVM more, this seems to make more sense since
declaring locals doesn't use an encoded opcode.

This also adds more 0xd opcodes, type encodings, and miscellaneous
binary encoding bits.

llvm-svn: 285040
2016-10-24 23:27:49 +00:00
Dan Gohman c968297b95 [WebAssembly] Update opcode values according to recent spec changes.
This corresponds to the "0xd" opcode renumbering.

llvm-svn: 285014
2016-10-24 20:21:49 +00:00
Dan Gohman 4fc4e42dea [WebAssembly] Add an option to make get_local/set_local explicit.
This patch adds a pass, controlled by an option and off by default for
now, for making implicit get_local/set_local explicit. This simplifies
emitting wasm with MC.

Differential Revision: https://reviews.llvm.org/D25836

llvm-svn: 285009
2016-10-24 19:49:43 +00:00
Dan Gohman 2726b88c03 [WebAssemby] Implement block signatures.
Per spec changes, this implements block signatures, and adds just enough
logic to produce correct block signatures at the ends of functions.

Differential Revision: https://reviews.llvm.org/D25144

llvm-svn: 283503
2016-10-06 22:29:32 +00:00
Dan Gohman 5a68ec7f09 [WebAssembly] Add binary-encoding opcode values to instruction descriptions.
llvm-svn: 283389
2016-10-05 21:24:08 +00:00
Dan Gohman 4b8e8becf6 [WebAssembly] Rename OPERAND_FP32IMM to OPERAND_F32IMM.
WebAssembly documentation consistently says "f32" rather than "fp32" to
describe 32-bit floating-point.

llvm-svn: 283146
2016-10-03 21:31:31 +00:00
Derek Schuff 39bf39f35c [WebAssembly] Initial SIMD128 support.
Kicks off the implementation of wasm SIMD128 support (spec:
https://github.com/stoklund/portable-simd/blob/master/portable-simd.md),
adding support for add, sub, mul for i8x16, i16x8, i32x4, and f32x4.

The spec is WIP, and might change in the near future.

Patch by João Porto

Differential Revision: https://reviews.llvm.org/D22686

llvm-svn: 277543
2016-08-02 23:16:09 +00:00
Dan Gohman 4817a7577c [WebAssembly] Mark COPY_LOCAL and TEE_LOCAL instructions has having no side effects.
llvm-svn: 269683
2016-05-16 19:16:32 +00:00
Dan Gohman 1402606477 [WebAssembly] Update for spec change from tableswitch to br_table.
Also note that the operand order changed; the default label is now listed
after the regular labels.

llvm-svn: 262903
2016-03-08 03:18:12 +00:00
Dan Gohman aa7429112e [WebAssembly] Implement support for custom NaN bit patterns.
llvm-svn: 260968
2016-02-16 15:14:23 +00:00
Dan Gohman adf28177eb [WebAssembly] Enhanced register stackification
This patch revamps the RegStackifier pass with a new tree traversal mechanism,
enabling three major new features:

 - Stackification of values with multiple uses, using the result value of set_local
 - More aggressive stackification of instructions with side effects
 - Reordering operands in commutative instructions to enable more stackification.

llvm-svn: 259009
2016-01-28 01:22:44 +00:00