728 Commits

Author SHA1 Message Date
Thomas Lively cc612c2908 [WebAssembly] Fix FastISel address calculation bug
Fixes PR47040, in which an assertion was improperly triggered during
FastISel's address computation. The issue was that an `Address` set to
be relative to the FrameIndex with offset zero was incorrectly
considered to have an unset base. When the left hand side of an add
set the Address to be 0 off the FrameIndex, the right side would not
detect that the Address base had already been set and could try to set
the Address to be relative to a register instead, triggering an
assertion.

This patch fixes the issue by explicitly tracking whether an `Address`
has been set rather than interpreting an offset of zero to mean the
`Address` has not been set.

Differential Revision: https://reviews.llvm.org/D85581
2020-08-08 15:23:11 -07:00
Thomas Lively cb32792210 [WebAssembly] Implement prototype v128.load{32,64}_zero instructions
Specified in https://github.com/WebAssembly/simd/pull/237, these
instructions load the first vector lane from memory and zero the other
lanes. Since these instructions are not officially part of the SIMD
proposal, they are only available on an opt-in basis via LLVM
intrinsics and clang builtin functions. If these instructions are
merged to the proposal, this implementation will change so that the
instructions will be generated from normal IR. At that point the
intrinsics and builtin functions would be removed.

This PR also changes the opcodes for the experimental f32x4.qfm{a,s}
instructions because their opcodes conflicted with those of the
v128.load{32,64}_zero instructions. The new opcodes were chosen to
match those used in V8.

Differential Revision: https://reviews.llvm.org/D84820
2020-08-03 13:54:00 -07:00
Wouter van Oortmerssen ce1eb7af9d [WebAssembly] Fixed 64-bit indices in br_table
LLVM selection dag assumes "switch" indices are pointer sized, which causes problems for our 32-bit br_table. The new function ensures 32-bit operands don't get unnecessarily extended, and 64-bit operands get truncated.

Note that the changes to the existing test test exactly that: the addition of -NEXT in 2 places ensures no extension is inserted (which the test previously ignored) and that the wrap is present (previously omitted in wasm64 mode).

Differential Revision: https://reviews.llvm.org/D84705
2020-07-30 10:52:16 -07:00
Heejin Ahn 276f9e8cfa [WebAssembly] Fix getBottom for loops
When it was first created, CFGSort only made sure BBs in each
`MachineLoop` are sorted together. After we added exception support,
CFGSort now also sorts BBs in each `WebAssemblyException`, which
represents a `catch` block, together, and
`Region` class was introduced to be a thin wrapper for both
`MachineLoop` and `WebAssemblyException`.

But how we compute those loops and exceptions is different.
`MachineLoopInfo` is constructed using the standard loop computation
algorithm in LLVM; the definition of loop is "a set of BBs that are
dominated by a loop header and have a path back to the loop header". So
even if some BBs are semantically contained by a loop in the original
program, or in other words dominated by a loop header, if they don't
have a path back to the loop header, they are not considered a part of
the loop. For example, if a BB is dominated by a loop header but
contains `call abort()` or `rethrow`, it wouldn't have a path back to
the header, so it is not included in the loop.

But `WebAssemblyException` is wasm-specific data structure, and its
algorithm is simple: a `WebAssemblyException` consists of an EH pad and
all BBs dominated by the EH pad. So this scenario is possible: (This is
also the situation in the newly added test in cfg-stackify-eh.ll)

```
Loop L: header, A, ehpad, latch
Exception E: ehpad, latch, B
```
(B contains `abort()`, so it does not have a path back to the loop
header, so it is not included in L.)

And it is sorted in this order:
```
header
A
ehpad
latch
B
```

And when CFGStackify places `end_loop` or `end_try` markers, it
previously used `WebAssembly::getBottom()`, which returns the latest BB
in the sorted order, and placed the marker there. So in this case the
marker placements will be like this:
```
loop
  header
  try
    A
  catch
    ehpad
    latch
end_loop         <-- misplaced!
    B
  end_try
```
in which nesting between the loop and the exception is not correct.
`end_loop` marker has to be placed after `B`, and also after `end_try`.

Maybe the fundamental way to solve this problem is to come up with our
own algorithm for computing loop region too, in which we include all BBs
dominated by a loop header in a loop. But this takes a lot more effort.
The only thing we need to fix is actually, `getBottom()`. If we make it
return the right BB, which means in case of a loop, the latest BB of the
loop itself and all exceptions contained in there, we are good.

This renames `Region` and `RegionInfo` to `SortRegion` and
`SortRegionInfo` and extracts them into their own file. And add
`getBottom` to `SortRegionInfo` class, from which it can access
`WebAssemblyExceptionInfo`, so that it can compute a correct bottom
block for loops.

Reviewed By: dschuff

Differential Revision: https://reviews.llvm.org/D84724
2020-07-29 10:36:32 -07:00
Thomas Lively 11bb7eef41 [WebAssembly] Remove intrinsics for SIMD widening ops
Instead, pattern match extends of extract_subvectors to generate
widening operations. Since extract_subvector is not a legal node, this
is implemented via a custom combine that recognizes extract_subvector
nodes before they are legalized. The combine produces custom ISD nodes
that are later pattern matched directly, just like the intrinsic was.

Also removes the clang builtins for these operations since the
instructions can now be generated from portable code sequences.

Differential Revision: https://reviews.llvm.org/D84556
2020-07-28 18:25:55 -07:00
Thomas Lively ffd8c23ccb [WebAssembly] Implement truncating vector stores
Rather than expanding truncating stores so that vectors are stored one
lane at a time, lower them to a sequence of instructions using
narrowing operations instead, when possible. Since the narrowing
operations have saturating semantics, but truncating stores require
truncation, mask the stored value to manually truncate it before
narrowing. Also, since narrowing is a binary operation, pass in the
original vector as the unused second argument.

Differential Revision: https://reviews.llvm.org/D84377
2020-07-28 17:46:45 -07:00
Thomas Lively a459459248 [WebAssembly] Fix store_unfolded_offset tests in simd-offset.ll
These tests were previously duplicates of the
unfolded_gep_negative_offset tests, and this change updates them to
test what they were meant to test.

Differential Revision: https://reviews.llvm.org/D84365
2020-07-23 16:05:20 -07:00
Thomas Lively 51cd326f99 [WebAssembly] Autogenerate checks in simd-offset.ll
Implementing new functionality tested in this file requires adding new
tests for many IR addressing patterns, which can be a large
maintenance burden. This patch makes adding tests easier by switching
to using autogenerated checks. This patch also removes the testing
mode that has simd128 disabled because it would produce very large
checks and is not particularly interesting.

Differential Revision: https://reviews.llvm.org/D84288
2020-07-22 10:12:26 -07:00
Wouter van Oortmerssen cc1b9b680f [WebAssembly] 64-bit (function) pointer fixes.
Accounting for the fact that Wasm function indices are 32-bit, but in wasm64 we want uniform 64-bit pointers.
Includes reloc types for 64-bit table indices.

Differential Revision: https://reviews.llvm.org/D83729
2020-07-16 14:10:22 -07:00
Thomas Lively ecb2e5bcd7 [WebAssembly] Implement v128.select
Although the SIMD spec proposal does not specifically include a
select instruction, the select instruction in MVP WebAssembly is
polymorphic over the selected types, so it is able to work on v128
values when they are enabled. This patch introduces a new variant of
the select instruction for each legal vector type. Additional ISel
patterns are adapted from the SELECT_I32 and SELECT_I64 patterns.

Depends on D83736.

Differential Revision: https://reviews.llvm.org/D83737
2020-07-16 11:37:25 -07:00
Thomas Lively f7868f87ac [WebAssembly] Autogenerate tests for simd-select.ll
Updating the simd-select.ll tests manually with consistent named
regexps for the register numbers was taking more time than it was
worth, so this patch updates that test file to have autogenerated
output. This is not a significant readability regression because the
tests in that file are all very small.

Depends on D83734.

Differential Revision: https://reviews.llvm.org/D83736
2020-07-16 11:19:09 -07:00
Thomas Lively f0f9787646 [WebAssembly] Lower vselect to v128.bitselect
We were previously expanding vselect and matching on the expansion to
generate bitselects, but in some cases the expansion would be further
combined and a bitselect would not get generated. This patch improves
codegen in those cases by legalizing vselect and lowering it to
v128.bitselect. The old pattern that matches the expansion is still
useful for lowering IR that already uses the expansion rather than a
select operation.

Differential Revision: https://reviews.llvm.org/D83734
2020-07-16 11:11:19 -07:00
Roger Ferrer Ibanez 14bc5e149d [DAGCombiner] Rebuild (setcc x, y, ==) from (xor (xor x, y), 1)
The existing code already considered this case. Unfortunately a typo in
the condition prevents it from triggering. Also the existing code, had
it run, forgot to do the folding.

This fixes PR42876.

Differential Revision: https://reviews.llvm.org/D65802
2020-07-15 07:34:22 +00:00
Thomas Lively b59c6fcaf3 [WebAssembly] Prefer v128.const for constant splats
In BUILD_VECTOR lowering, we used to generally prefer using splats
over v128.const instructions because v128.const has a very large
encoding. However, in d5b7a4e2e8 we switched to preferring consts
because they are expected to be more efficient in engines. This patch
updates the ISel patterns to match this current preference.

Differential Revision: https://reviews.llvm.org/D83581
2020-07-10 18:27:52 -07:00
Thomas Lively 043eaa9a4a [WebAssembly][NFC] Simplify vector shift lowering and add tests
This patch builds on 0d7286a652 by simplifying the code for detecting
splat values and adding new tests demonstrating the lowering of
splatted absolute value shift amounts, which are common in code
generated by Halide. The lowering is very bad right now, but
subsequent patches will improve it considerably. The tests will be
useful for evaluating the improvements in those patches.

Reviewed By: aheejin

Differential Revision: https://reviews.llvm.org/D83493
2020-07-10 00:18:59 -07:00
Heejin Ahn 7e6793aa33 [WebAssembly] Generate unreachable after __stack_chk_fail
`__stack_chk_fail` does not return, but `unreachable` was not generated
following `call __stack_chk_fail`. This had a possibility to generate an
invalid binary for functions with a return type, because
`__stack_chk_fail`'s return type is void and `call __stack_chk_fail` can
be the last instruction in the function whose return type is non-void.
Generating `unreachable` after it makes sure CFGStackify's
`fixEndsAtEndOfFunction` handles it correctly.

Reviewed By: tlively

Differential Revision: https://reviews.llvm.org/D83277
2020-07-08 01:02:05 -07:00
Thomas Lively 0d7286a652 [WebAssembly] Avoid scalarizing vector shifts in more cases
Since WebAssembly's vector shift instructions take a scalar shift
amount rather than a vector shift amount, we have to check in ISel
that the vector shift amount is a splat. Previously, we were checking
explicitly for splat BUILD_VECTOR nodes, but this change uses the
standard utilities for detecting splat values that can handle more
complex splat patterns. Since the C++ ISel lowering is now more
general than the ISel patterns, this change also simplifies shift
lowering by using the C++ lowering for all SIMD shifts rather than
mixing C++ and normal pattern-based lowering.

This change improves ISel for shifts to the point that the
simd-shift-unroll.ll regression test no longer tests the code path it
was originally meant to test. The bug corresponding to that regression
test is no longer reproducible with its original reported reproducer,
so rather than try to fix the regression test, this change just
removes it.

Differential Revision: https://reviews.llvm.org/D83278
2020-07-07 10:45:26 -07:00
Wouter van Oortmerssen 16d83c395a [WebAssembly] Added 64-bit memory.grow/size/copy/fill
This covers both the existing memory functions as well as the new bulk memory proposal.
Added new test files since changes where also required in the inputs.

Also removes unused init/drop intrinsics rather than trying to make them work for 64-bit.

Differential Revision: https://reviews.llvm.org/D82821
2020-07-06 12:49:50 -07:00
Thomas Lively 8df30d988e [WebAssembly] Do not omit range checks for i64 switches
Summary:
Since the br_table instruction takes an i32, switches over i64s (and
larger integers) must use the i32.wrap_i64 instruction to truncate the
table index. This truncation makes numbers just over 2^32
indistinguishable from small numbers, so it was a miscompilation to
omit the range check preceding these br_tables. This change fixes the
problem by skipping the "fixing" of the br_table when the range check
is an i64 instruction.

Fixes PR46447.

Reviewers: aheejin, dschuff, kripken

Reviewed By: kripken

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D83017
2020-07-03 17:15:39 -07:00
Qiu Chaofan aa4fd7d848 [NFC] Fix typo in triples from unkown to unknown 2020-07-02 16:21:54 +08:00
Wouter van Oortmerssen b9a539c010 [WebAssembly] Adding 64-bit versions of __stack_pointer and other globals
We have 6 globals, all of which except for __table_base are 64-bit under wasm64.

Differential Revision: https://reviews.llvm.org/D82130
2020-06-25 15:52:44 -07:00
Eric Christopher cf23852587 [Target] As part of using inclusive language within the llvm project,
migrate away from the use of blacklist and whitelist.

This change affects an internal llvm command line option.
2020-06-20 00:06:39 -07:00
Heejin Ahn 83c26eae23 [WebAssembly] Remove TEEs when dests are unstackified
When created in RegStackify pass, `TEE` has two destinations, where
op0 is stackified and op1 is not. But it is possible that
op0 becomes unstackified in `fixUnwindMismatches` function in
CFGStackify pass when a nested try-catch-end is introduced, violating
the invariant of `TEE`s destinations.

In this case we convert the `TEE` into two `COPY`s, which will
eventually be resolved in ExplicitLocals.

Reviewed By: dschuff

Differential Revision: https://reviews.llvm.org/D81851
2020-06-19 14:55:21 -07:00
Sam Clegg 7ee758d691 [WebAssembly] MC: Fix for data aliases with offsets (getelementptr)
For some reason we hadn't seen such cases in the wild which makes
me think that clang and rustc don't generate these.  In the bug which
reproduces it only occurs with LTO so my guess is that some LTO pass
is creating this alias + gep.

See: https://github.com/emscripten-core/emscripten/issues/8731

Differential Revision: https://reviews.llvm.org/D79462
2020-06-17 16:25:50 -07:00
Thomas Lively 49754dcf22 [WebAssembly] Fix bug in FixBrTables and use branch analysis utils
Summary:
This commit fixes a bug in the FixBrTables pass in which an
unconditional branch from the switch header block to the jump table
block was not removed before the blocks were combined. The result was
an invalid CFG in the MachineFunction. This commit also switches from
using bespoke branch analysis and deletion code to using the standard
utilities for the same.

Reviewers: aheejin, dschuff

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81909
2020-06-17 12:34:45 -07:00