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Commit Graph

330 Commits

Author SHA1 Message Date
Derek Schuff
0c7127a873 [WebAssembly] Generate R_WASM_FUNCTION_OFFSET relocs in debuginfo sections
Debug info sections need R_WASM_FUNCTION_OFFSET_I32 relocs (with FK_Data_4 fixup
kinds) to refer to functions (instead of R_WASM_TABLE_INDEX as is used in data
sections). Usually this is done in a convoluted way, with unnamed temp data
symbols which target the start of the function, in which case
WasmObjectWriter::recordRelocation converts it to use the section symbol
instead. However in some cases the function can actually be undefined; in this
case the dwarf generator uses the function symbol (a named undefined function
symbol) instead. In that case the section-symbol transform doesn't work and we
need to generate the correct reloc type a different way. In this change
WebAssemblyWasmObjectWriter::getRelocType takes the fixup section type into
account to choose the correct reloc type.

Fixes PR50408
Differential Revision: https://reviews.llvm.org/D103557
2021-07-19 14:02:33 -07:00
Wouter van Oortmerssen
8a42745952 [WebAssembly] Support R_WASM_MEMORY_ADDR_TLS_SLEB64 for wasm64
Also fixed TLS tests swapping addr & value in store op
Differential Revision: https://reviews.llvm.org/D106096
2021-07-19 10:22:43 -07:00
Fangrui Song
35af2802d5 [test] Avoid llvm-readelf/llvm-readobj one-dash long options and deprecated aliases (e.g. --file-headers) 2021-07-15 10:26:21 -07:00
Thomas Lively
81bb5f99ad [WebAssembly] Remove datalayout strings from llc tests
The data layout strings do not have any effect on llc tests and will become
misleadingly out of date as we continue to update the canonical data layout, so
remove them from the tests.

Differential Revision: https://reviews.llvm.org/D105842
2021-07-14 11:17:08 -07:00
Wouter van Oortmerssen
538b137e0b [WebAssembly] Added initial type checker to MC Assembler
This to protect against non-sensical instruction sequences being assembled,
which would either cause asserts/crashes further down, or a Wasm module being output that doesn't validate.

Unlike a validator, this type checker is able to give type-errors as part of the parsing process, which makes the assembler much friendlier to be used by humans writing manual input.

Because the MC system is single pass (instructions aren't even stored in MC format, they are directly output) the type checker has to be single pass as well, which means that from now on .globaltype and .functype decls must come before their use. An extra pass is added to Codegen to collect information for this purpose, since AsmPrinter is normally single pass / streaming as well, and would otherwise generate this information on the fly.

A `-no-type-check` flag was added to llvm-mc (and any other tools that take asm input) that surpresses type errors, as a quick escape hatch for tests that were not intended to be type correct.

This is a first version of the type checker that ignores control flow, i.e. it checks that types are correct along the linear path, but not the branch path. This will still catch most errors. Branch checking could be added in the future.

Differential Revision: https://reviews.llvm.org/D104945
2021-07-09 14:07:25 -07:00
Heejin Ahn
f7b0205560 [WebAssembly] Rename event to tag
We recently decided to change 'event' to 'tag', and 'event section' to
'tag section', out of the rationale that the section contains a
generalized tag that references a type, which may be used for something
other than exceptions, and the name 'event' can be confusing in the web
context.

See
- https://github.com/WebAssembly/exception-handling/issues/159#issuecomment-857910130
- https://github.com/WebAssembly/exception-handling/pull/161

Reviewed By: tlively

Differential Revision: https://reviews.llvm.org/D104423
2021-06-17 20:34:19 -07:00
serge-sans-paille
73bc91a5e6 Revert "[NFC] remove explicit default value for strboolattr attribute in tests"
This reverts commit bda6e5bee04c75b1f1332b4fd1ac4e8ef6c3c247.

See https://lab.llvm.org/buildbot/#/builders/109/builds/15424 for instance
2021-05-24 19:43:40 +02:00
serge-sans-paille
1f63b26006 [NFC] remove explicit default value for strboolattr attribute in tests
Since d6de1e1a71406c75a4ea4d5a2fe84289f07ea3a1, no attributes is quivalent to
setting attribute to false.

This is a preliminary commit for https://reviews.llvm.org/D99080
2021-05-24 19:31:04 +02:00
Wouter van Oortmerssen
1184fb03b6 [WebAssembly] Fix PIC/GOT codegen for wasm64
__table_base is know 64-bit, since in LLVM it represents a function pointer offset
__table_base32 is a copy in wasm32 for use in elem init expr, since no truncation may be used there.
New reloc R_WASM_TABLE_INDEX_REL_SLEB64 added

Differential Revision: https://reviews.llvm.org/D101784
2021-05-20 09:59:31 -07:00
Sam Clegg
6e585563bc [WebAssembly] Add TLS data segment flag: WASM_SEG_FLAG_TLS
Previously the linker was relying solely on the name of the segment
to imply TLS.

Differential Revision: https://reviews.llvm.org/D102202
2021-05-12 13:31:02 -07:00
Sam Clegg
b94988cc08 Reland: "[lld][WebAssembly] Initial support merging string data"
This change was originally landed in: 5000a1b4b9edeb9e994f2a5b36da8d48599bea49
It was reverted in: 061e071d8c9b98526f35cad55a918a4f1615afd4

This change adds support for a new WASM_SEG_FLAG_STRINGS flag in
the object format which works in a similar fashion to SHF_STRINGS
in the ELF world.

Unlike the ELF linker this support is currently limited:
- No support for SHF_MERGE (non-string merging)
- Always do full tail merging ("lo" can be merged with "hello")
- Only support single byte strings (p2align 0)

Like the ELF linker merging is only performed at `-O1` and above.

This fixes part of https://bugs.llvm.org/show_bug.cgi?id=48828,
although crucially it doesn't not currently support debug sections
because they are not represented by data segments (they are custom
sections)

Differential Revision: https://reviews.llvm.org/D97657
2021-05-10 16:03:38 -07:00
Nico Weber
f766faca78 Revert "[lld][WebAssembly] Initial support merging string data"
This reverts commit 5000a1b4b9edeb9e994f2a5b36da8d48599bea49.
Breaks tests, see https://reviews.llvm.org/D97657#2749151

Easily repros locally with `ninja check-llvm-mc-webassembly`.
2021-05-10 18:28:28 -04:00
Sam Clegg
fcb19b5df4 [lld][WebAssembly] Initial support merging string data
This change adds support for a new WASM_SEG_FLAG_STRINGS flag in
the object format which works in a similar fashion to SHF_STRINGS
in the ELF world.

Unlike the ELF linker this support is currently limited:
- No support for SHF_MERGE (non-string merging)
- Always do full tail merging ("lo" can be merged with "hello")
- Only support single byte strings (p2align 0)

Like the ELF linker merging is only performed at `-O1` and above.

This fixes part of https://bugs.llvm.org/show_bug.cgi?id=48828,
although crucially it doesn't not currently support debug sections
because they are not represented by data segments (they are custom
sections)

Differential Revision: https://reviews.llvm.org/D97657
2021-05-10 13:15:12 -07:00
Thomas Lively
fee114b476 [WebAssembly] Test i64x2.abs encoding
This test was disabled despite the instruction having been implemented for a
long time. This commit just enables the test.

Differential Revision: https://reviews.llvm.org/D100345
2021-04-13 00:06:25 -07:00
Thomas Lively
a397d1a74f [WebAssembly] Update v128.any_true
In the final SIMD spec, there is only a single v128.any_true instruction, rather
than one for each lane interpretation because the semantics do not depend on the
lane interpretation.

Differential Revision: https://reviews.llvm.org/D100241
2021-04-11 11:13:16 -07:00
Thomas Lively
a9b1f02ebd [WebAssembly] Implement i64x2 comparisons
Removes the prototype builtin and intrinsic for i64x2.eq and implements that
instruction as well as the other i64x2 comparison instructions in the final SIMD
spec. Unsigned comparisons were not included in the final spec, so they still
need to be scalarized via a custom lowering.

Differential Revision: https://reviews.llvm.org/D99623
2021-03-31 10:46:17 -07:00
Heejin Ahn
ac42de94f4 [WebAssembly] Raname a test and fix comments
D99627 fixed a decoding bug, not an encoding bug. This renames the test
to correct it and fix comments.

Reviewed By: dschuff

Differential Revision: https://reviews.llvm.org/D99644
2021-03-31 09:13:08 -07:00
Alex Richardson
e6f3a5b86f [WebAssembly] Fix incorrect DW_TAG_pointer_type size in test
It should be 64 bits not 32 for wasm64-unknown-unknown. I noticed this
because this test was failing in our CHERI fork of LLVM due to a larger
.debug_abbrev section size. It turns out this happens because we add
DW_AT_byte_size for non-default pointer sizes to allow debugging our
hybrid compilation mode where we can have two different kinds of pointers.

Reviewed By: aardappel

Differential Revision: https://reviews.llvm.org/D99410
2021-03-31 09:17:45 +01:00
Heejin Ahn
86cb95ac54 [WebAssembly] Encode numbers in ULEB128 in event section
The number of events and the type index should be encoded in ULEB128,
but they were incorrctly encoded in LEB128. The smallest number with
which its LEB128 and ULEB128 encodings are different is 64.
There's no way we can generate 64 events in the C++ toolchain
implementation so we can't test that, but the attached test tests when
the type index is 64.

Reviewed By: dschuff

Differential Revision: https://reviews.llvm.org/D99627
2021-03-30 16:21:58 -07:00
Thomas Lively
4fea92a98b [WebAssembly] Fix i8x16.popcnt opcode
When I updated the SIMD opcodes in f5764a8654e3, I accidentally missed updating
i8x16.popcnt. This patch fixes the omission.

Differential Revision: https://reviews.llvm.org/D99536
2021-03-29 17:23:15 -07:00
Andy Wingo
87799a4429 [WebAssembly][MC] Record limit constraints for table sizes
This commit adds a full WasmTableType to MCSymbolWasm, differing from
the current situation (just an ElemType) in that it additionally records
a WasmLimits.

We add support for specifying the limits in .S files also, via the
following syntax variations:

  .tabletype SYM, ELEMTYPE
  .tabletype SYM, ELEMTYPE, MINSIZE
  .tabletype SYM, ELEMTYPE, MINSIZE, MAXSIZE

Depends on D99186.

Differential Revision: https://reviews.llvm.org/D99191
2021-03-24 09:44:22 +01:00
Andy Wingo
0ac187d2cf [WebAssembly] Rename WasmLimits::Initial to ::Minimum. NFC.
This patch renames the "Initial" member of WasmLimits to the name used
in the spec, "Minimum".

In the core WebAssembly specification, the Limits data type has one
required "min" member and one optional "max" member, indicating the
minimum required size of the corresponding table or memory, and the
maximum size, if any.

Although the WebAssembly spec does instantiate locally-defined tables
and memories with the initial size being equal to the minimum size, it
can't impose such a requirement for imports.  It doesn't make sense to
require an initial size for a memory import, for example.  The compiler
can only sensibly express the minimum and maximum sizes.

See
https://github.com/WebAssembly/js-types/blob/master/proposals/js-types/Overview.md#naming-of-size-limits
for a related discussion that agrees that the right name of "initial" is
"minimum" when querying the type of a table or memory from JavaScript.
(Of course it still makes sense for JS to speak in terms of an initial
size when it explicitly instantiates memories and tables.)

Differential Revision: https://reviews.llvm.org/D99186
2021-03-24 09:10:11 +01:00
Thomas Lively
6bcfb98bcc [WebAssembly] Finalize SIMD names and opcodes
Updates the names (e.g. widen => extend, saturate => sat) and opcodes of all
SIMD instructions to match the finalized SIMD spec. Deliberately does not change
the public interface in wasm_simd128.h yet; that will require more care.

Depends on D98466.

Differential Revision: https://reviews.llvm.org/D98676
2021-03-18 11:21:25 -07:00
Thomas Lively
7742bff518 [WebAssembly] Remove experimental SIMD instructions
Removes the instruction definitions, intrinsics, and builtins for qfma/qfms,
signselect, and prefetch instructions, which were not included in the final
WebAssembly SIMD spec.

Depends on D98457.

Differential Revision: https://reviews.llvm.org/D98466
2021-03-18 11:21:24 -07:00
Thomas Lively
f8ea4e377b [WebAssembly] Remove unimplemented-simd target feature
Now that the WebAssembly SIMD specification is finalized and engines are
generally up-to-date, there is no need for a separate target feature for gating
SIMD instructions that engines have not implemented. With this change,
v128.const is now enabled by default with the simd128 target feature.

Differential Revision: https://reviews.llvm.org/D98457
2021-03-18 10:23:12 -07:00
Yuta Saito
9526edaf68 [WebAssembly] Add new relocation for location relative data
This `R_WASM_MEMORY_ADDR_SELFREL_I32` relocation represents an offset
between its relocating address and the symbol address. It's very similar
to `R_X86_64_PC32` but restricted to be used for only data segments.

```
S + A - P
```

A: Represents the addend used to compute the value of the relocatable
field.
P: Represents the place of the storage unit being relocated.
S: Represents the value of the symbol whose index resides in the
relocation entry.

Proposal: https://github.com/WebAssembly/tool-conventions/issues/162

Differential Revision: https://reviews.llvm.org/D96659
2021-03-08 11:34:10 -08:00
Andy Wingo
159bb43ce8 [WebAssembly] Swap operand order of call_indirect in text format
The WebAssembly text and binary formats have different operand orders
for the "type" and "table" fields of call_indirect (and
return_call_indirect).  In LLVM we use the binary order for the MCInstr,
but when we produce or consume the text format we should use the text
order.  For compilation units targetting WebAssembly 1.0 (without the
reference types feature), we omit the table operand entirely.

Differential Revision: https://reviews.llvm.org/D97761
2021-03-03 08:51:21 +01:00
Wouter van Oortmerssen
f423ca3286 [WebAssembly] Fix split-dwarf not emitting DW_OP_WASM_location correctly
It was using the regular path for target indices that uses uleb, but TI_GLOBAL_RELOC needs to be uint32_t.
Introduced here: https://reviews.llvm.org/D85685
Fixes: https://github.com/emscripten-core/emscripten/issues/13240

Differential Revision: https://reviews.llvm.org/D97564
2021-03-01 11:53:30 -08:00
Andy Wingo
d9c224e71b [WebAssembly] call_indirect issues table number relocs
If the reference-types feature is enabled, call_indirect will explicitly
reference its corresponding function table via TABLE_NUMBER
relocations against a table symbol.

Also, as before, address-taken functions can also cause the function
table to be created, only with reference-types they additionally cause a
symbol table entry to be emitted.

Differential Revision: https://reviews.llvm.org/D90948
2021-03-01 16:49:00 +01:00
Andy Wingo
e4dd319951 Revert "[WebAssembly] call_indirect issues table number relocs"
This reverts commit 861dbe1a021e6439af837b72b219fb9c449a57ae.  It broke
emscripten -- see https://reviews.llvm.org/D90948#2578843.
2021-02-23 11:48:08 +01:00
Andy Wingo
4c62f39d2f [WebAssembly] call_indirect issues table number relocs
If the reference-types feature is enabled, call_indirect will explicitly
reference its corresponding function table via `TABLE_NUMBER`
relocations against a table symbol.

Also, as before, address-taken functions can also cause the function
table to be created, only with reference-types they additionally cause a
symbol table entry to be emitted.

We abuse the used-in-reloc flag on symbols to indicate which tables
should end up in the symbol table.  We do this because unfortunately
older wasm-ld will carp if it see a table symbol.

Differential Revision: https://reviews.llvm.org/D90948
2021-02-22 10:13:36 +01:00
Wouter van Oortmerssen
c0b486e8f3 [WebAssembly] Fix assert in lookup of section symbols
Fixes assert in: https://bugs.llvm.org/show_bug.cgi?id=49036

getWasmSection creates sections if they don't exist, but doesn't add them to the Symbols table. This may cause problems in subsequent calls to getOrCreateSymbol which checks this table, the calls createSymbol assuming it doesn't exist, which then checks UsedNames and finds out it does exist, causing an assert on trying to rename a non-temp symbol.

I tried also fixing the somewhat unintuitive forced suffixing (adding `0`), but it turns out that WasmObjectWriter currently assumes these section symbols are unique, so that may have to be a separate fix: https://bugs.llvm.org/show_bug.cgi?id=49252

Also worth noting is that getWasmSection calling createSymbol may not be correct to start with, given that createSymbol seems to assume it is creating non-section symbols. But again, for a future fix.

Related: where some of this was introduced: 8d396acac3

Differential Revision: https://reviews.llvm.org/D96473
2021-02-18 11:50:14 -08:00
Sam Clegg
4cf94ad9e7 [WebAssembly] Use data sections by default
This allows data sections that don't start with `.data` to be
used/created.

Without this, clang's `__attribute__((section("foo")))` would
generate assembly that would not parse.

Differential Revision: https://reviews.llvm.org/D96233
2021-02-09 11:03:06 -08:00
Sam Clegg
0c7ce7206a [MC][WebAssembly] Fix provisional values for data alias relocations
When calculating the symbol offsets to write as provisitonal values
in object files we are only interested in the offset of the symbol
itself.  For aliases this offset already includes the offset of the
base symbol.

The testin question was added back in https://reviews.llvm.org/D87407
but I believe the expectations here were incorrect.   sym_a lives
at offset 4 and sym_b lives 4 bytes into that (should be 8).

The addresses of the 3 symbosl in this object file are:

foo  : 0
sym_a: 4
sym_b: 8

Differential Revision: https://reviews.llvm.org/D96234
2021-02-08 16:56:57 -08:00
Heejin Ahn
91168a9374 [WebAssembly] Update InstPrinter and AsmParser for new EH instructions
This updates InstPrinter and AsmParser for `delegate` and `catch_all`
instructions. Both will reject programs with multiple `catch_all`s per a
single `try`. And InstPrinter uses `EHInstStack` to figure out whether
to print catch label comments: It does not print catch label comments
for second `catch` or `catch_all` in a `try`.

Reviewed By: aardappel

Differential Revision: https://reviews.llvm.org/D94051
2021-02-06 08:54:56 -08:00
Wouter van Oortmerssen
57815b21fc [WebAssembly] ensure .functype applies to right label in assembler
We used to require .functype immediately follows the label it sets the type of, but not all Clang output follows this rule.

Now we simply allow it on any symbol, but only assume its a function start for a defined symbol, which is simpler and more general.

Fixes (part of) https://bugs.llvm.org/show_bug.cgi?id=49036

Differential Revision: https://reviews.llvm.org/D96165
2021-02-05 15:36:15 -08:00
Wouter van Oortmerssen
59520b4419 [WebAssembly] Prevent data inside text sections in assembly
This is not supported in Wasm, unless the data was encoded instructions, but that wouldn't work with the assembler's other functionality (enforcing nesting etc.).

Fixes: https://bugs.llvm.org/show_bug.cgi?id=48971

Differential Revision: https://reviews.llvm.org/D95838
2021-02-05 13:48:25 -08:00
Wouter van Oortmerssen
47865bd5df [WebAssembly] locals can now be indirect in DWARF
This for example to indicate that byval args are represented by a pointer to a struct.
Followup to https://reviews.llvm.org/D94140

Differential Revision: https://reviews.llvm.org/D94347
2021-02-05 11:14:42 -08:00
Wouter van Oortmerssen
c4485ed951 [WebAssembly] fixed wasm64 data segment init exp not 64-bit
As defined in the spec:
https://github.com/WebAssembly/memory64/blob/master/proposals/memory64/Overview.md

Differential Revision: https://reviews.llvm.org/D95651
2021-02-01 11:32:50 -08:00
Thomas Lively
30175dd5d9 [WebAssembly] Prototype i8x16 to i32x4 widening instructions
As proposed in https://github.com/WebAssembly/simd/pull/395 and matching the
opcodes used in V8:
https://chromium-review.googlesource.com/c/v8/v8/+/2617385/4/src/wasm/wasm-opcodes.h

Differential Revision: https://reviews.llvm.org/D95557
2021-01-28 10:59:32 -08:00
Sam Clegg
2c5fef6eea Revert "[WebAssembly] MC layer writes table symbols to object files"
This reverts commit d806618636f8a82bfc3f620e1fad83af4d2a2575.
Review: https://reviews.llvm.org/D92215

We had issues where older versions of wasm-ld were crashing on object
files containing a table symbol.  We decided that the best strategy
going forward is to only generate these symbol if refernece types is
enabled.  Without reference types enabled we should never geneate a
table symbol or a TABLE_NUMBER relocation.

This revert is in addition to the one already reverted in
https://reviews.llvm.org/D95005.

The plan is to re-land these in updated form after the llvm 12 branch.

Differential Revision: https://reviews.llvm.org/D95420
2021-01-25 22:32:36 -08:00
Thomas Lively
652dd89674 [WebAssembly] Prototype new f64x2 conversions
As proposed in https://github.com/WebAssembly/simd/pull/383.

Differential Revision: https://reviews.llvm.org/D95012
2021-01-20 11:28:06 -08:00
Sam Clegg
a3e0bfc296 Revert "[WebAssembly] call_indirect issues table number relocs"
This reverts commit 418df4a6ab35d343cc0f2608c90a73dd9b8d0ab1.

This change broke emscripten tests, I believe because it started
generating 5-byte a wide table index in the call_indirect instruction.
Neither v8 nor wabt seem to be able to handle that.  The spec
currently says that this is single 0x0 byte and:

"In future versions of WebAssembly, the zero byte occurring in the
encoding of the call_indirectcall_indirect instruction may be used to
index additional tables."

So we need to revisit this change.  For backwards compat I guess
we need to guarantee that __indirect_function_table is always at
address zero.   We could also consider making this a single-byte
relocation with and assert if have more than 127 tables (for now).

Differential Revision: https://reviews.llvm.org/D95005
2021-01-19 15:06:07 -08:00
Andy Wingo
6ddb7e7525 [WebAssembly] call_indirect issues table number relocs
This patch changes to make call_indirect explicitly refer to the
corresponding function table, residualizing TABLE_NUMBER relocs against
it.

With this change, wasm-ld now sees all references to tables, and can
link multiple tables.

Differential Revision: https://reviews.llvm.org/D90948
2021-01-19 09:32:45 +01:00
Andy Wingo
1d534b8dce [WebAssembly] MC layer writes table symbols to object files
Now that the linker handles table symbols, we can allow the frontend to
produce them.

Depends on D91870.

Differential Revision: https://reviews.llvm.org/D92215
2021-01-18 16:57:18 +01:00
Derek Schuff
89e4eef882 Revert "[WebAssembly] MC layer writes table symbols to object files"
This reverts commit e9f1ed2306b1b3aedcb1acef2b50e252a77a04b9.

Reverting because it depends on 38dfce706f
2021-01-15 15:50:22 -08:00
Andy Wingo
29cfe36e3d [WebAssembly] MC layer writes table symbols to object files
Now that the linker handles table symbols, we can allow the frontend to
produce them.

Depends on D91870.

Differential Revision: https://reviews.llvm.org/D92215
2021-01-15 14:55:55 +01:00
Heejin Ahn
3017c7dd86 [WebAssembly] Update InstPrinter support for EH
- Updates InstPrinter to handle `catch_all`.
- Makes `rethrow` condition an early exit from the function to make the
  rest simpler.
- Unify label and catch counters. They don't need to be counted
  separately and this will help `delegate` instruction later.
- Removes `LastSeenEHInst` field. This was first introduced to handle
  when there are more than one `catch` blocks per `try`, but this was
  not implemented correctly and not being used at the moment anyway.
- Reenables all tests in cfg-stackify-eh.ll that don't deal with unwind
  destination mismatches, which will be handled in a later CL.

Reviewed By: dschuff, tlively, aardappel

Differential Revision: https://reviews.llvm.org/D94043
2021-01-09 02:42:35 -08:00
Heejin Ahn
ecf1f07299 [WebAssembly] Remove exnref and br_on_exn
This removes `exnref` type and `br_on_exn` instruction. This is
effectively NFC because most uses of these were already removed in the
previous CLs.

Reviewed By: dschuff, tlively

Differential Revision: https://reviews.llvm.org/D94041
2021-01-09 02:02:54 -08:00
Heejin Ahn
3675555b63 [WebAssembly] Update basic EH instructions for the new spec
This implements basic instructions for the new spec.

- Adds new versions of instructions: `catch`, `catch_all`, and `rethrow`
- Adds support for instruction selection for the new instructions
 - `catch` needs a custom routine for the same reason `throw` needs one,
   to encode `__cpp_exception` tag symbol.
- Updates `WebAssembly::isCatch` utility function to include `catch_all`
  and Change code that compares an instruction's opcode with `catch` to
  use that function.
- LateEHPrepare
  - Previously in LateEHPrepare we added `catch` instruction to both
    `catchpad`s (for user catches) and `cleanuppad`s (for destructors).
    In the new version `catch` is generated from `llvm.catch` intrinsic
    in instruction selection phase, so we only need to add `catch_all`
    to the beginning of cleanup pads.
  - `catch` is generated from instruction selection, but we need to
    hoist the `catch` instruction to the beginning of every EH pad,
    because `catch` can be in the middle of the EH pad or even in a
    split BB from it after various code transformations.
  - Removes `addExceptionExtraction` function, which was used to
    generate `br_on_exn` before.
- CFGStackfiy: Deletes `fixUnwindMismatches` function. Running this
  function on the new instruction causes crashes, and the new version
  will be added in a later CL, whose contents will be completely
  different. So deleting the whole function will make the diff easier to
  read.
- Reenables all disabled tests in exception.ll and eh-lsda.ll and a
  single basic test in cfg-stackify-eh.ll.
- Updates existing tests to use the new assembly format. And deletes
  `br_on_exn` instructions from the tests and FileCheck lines.

Reviewed By: dschuff, tlively

Differential Revision: https://reviews.llvm.org/D94040
2021-01-09 01:48:06 -08:00