Add support for implicit type conversions to ISLE.
This feature allows the DSL user to register to the compiler that a
particular term (used as a constructor or extractor) converts from one
type to another. The compiler will then *automatically* insert this term
whenever a type mismatch involving that specific pair of types occurs.
This significantly cleans up many uses of the ISLE DSL. For example,
when defining the compiler backends, we often have newtypes like `Gpr`
around `Reg` (signifying a particular type of register); we can define
a conversion from Gpr to Reg automatically.
Conversions can also have side-effects, as long as these side-effects
are idempotent. For example, `put_value_in_reg` in a compiler backend
has the effect of marking the value as used, causing codegen to produce
it, and assigns a register to the value; but multiple invocations of
this will return the same register for the same value. Thus it is safe
to use it as an implicit conversion that may be invoked multiple times.
This is documented in the ISLE-Cranelift integration document.
This PR also adds some testing infrastructure to the ISLE compiler,
checking that "pass" tests pass through the DSL compiler, "fail" tests
do not, and "link" tests are able to generate code and link that code
with corresponding Rust code.
This documentation provides details for all of the ISLE language
features, and detailed rationale for why many of them are designed in
the way that they are. It is hopefully both a reasonable tutorial and
reference for someone looking to understand the DSL.
Note that this documentation is separate from and orthogonal to the
work to document the Cranelift bindings and integration work that
@fitzgen has covered well in #3556. This document can link to that one
and vice-versa once they are both in-tree.
This also paves the way for unifying TargetIsa and MachBackend, since now they map one to one. In theory the two traits could be merged, which would be nice to limit the number of total concepts. Also they have quite different responsibilities, so it might be fine to keep them separate.
Interestingly, this PR started as removing RegInfo from the TargetIsa trait since the adapter returned a dummy value there. From the fallout, noticed that all Display implementations didn't needed an ISA anymore (since these were only used to render ISA specific registers). Also the whole family of RegInfo / ValueLoc / RegUnit was exclusively used for the old backend, and these could be removed. Notably, some IR instructions needed to be removed, because they were using RegUnit too: this was the oddball of regfill / regmove / regspill / copy_special, which were IR instructions inserted by the old regalloc. Fare thee well!
* cranelift: Add heap support to filetest infrastructure
* cranelift: Explicit heap pointer placement in filetest annotations
* cranelift: Add documentation about the Heap directive
* cranelift: Clarify that heap filetests pointers must be laid out sequentially
* cranelift: Use wrapping add when computing bound pointer
* cranelift: Better error messages when invalid signatures are found for heap file tests.
see https://github.com/bytecodealliance/wasmtime/pull/1816
DEPRECATION NOTICE: the Cranelift developer team intends to stop maintaining
the `cranelift-faerie` crate and remove it from the `wasmtime` git repository
on or after August 3, 2020. We recommend users use its successor, the
`cranelift-object` crate.
Several links were broken by line-breaks between the link caption and
the link itself. This commit fixes them by moving each on its own line.
Co-authored-by: k.bagrov <k.bagrov@g.nsu.ru>
* Improve output display of RunCommand
The previous use of Debug for displaying `print` and `run` results was less than clear.
* Avoid checking the types of vectors during trampoline construction
Because DataValue only understands `V128` vectors, we avoid type-checking vector values when constructing the trampoline arguments.
* Improve the documentation of the filetest `run` command
Adds an up-to-date example of how to use the `run` and `print` directives and includes an actual use of the new directives in a SIMD arithmetic filetest.
* Add AArch64 tests to CI
This commit enhances our CI with an AArch64 builder. Currently we have
no physical hardware to run on so for now we run all tests in an
emulator. The AArch64 build is cross-compiled from x86_64 from Linux.
Tests all happen in release mode with a recent version of QEMU (recent
version because it's so much faster, and in release mode because debug
mode tests take quite a long time in an emulator).
The goal here was not to get all tests passing on CI, but rather to get
AArch64 running on CI and get it green at the same time. To achieve that
goal many tests are now ignored on aarch64 platforms. Many tests fail
due to unimplemented functionality in the aarch64 backend (#1521), and
all wasmtime tests involving compilation are also disabled due to
panicking attempting to generate generate instruction offset information
for trap symbolication (#1523).
Despite this, though, all Cranelift tests and other wasmtime tests
should be runnin on AArch64 through QEMU with this PR. Additionally
we'll have an AArch64 binary release of Wasmtime for Linux, although it
won't be too useful just yet since it will panic on almost all wasm
modules.
* Review comments
Update the documentation for the merger, and also for various changes in
Cranelift. Remove some old obsolete documentation, and convert the remaining
Sphinx files to Markdown. Some of the remaining content is still out of
date, but this is a step forward.
* Manually rename BasicBlock to BlockPredecessor
BasicBlock is a pair of (Ebb, Inst) that is used to represent the
basic block subcomponent of an Ebb that is a predecessor to an Ebb.
Eventually we will be able to remove this struct, but for now it
makes sense to give it a non-conflicting name so that we can start
to transition Ebb to represent a basic block.
I have not updated any comments that refer to BasicBlock, as
eventually we will remove BlockPredecessor and replace with Block,
which is a basic block, so the comments will become correct.
* Manually rename SSABuilder block types to avoid conflict
SSABuilder has its own Block and BlockData types. These along with
associated identifier will cause conflicts in a later commit, so
they are renamed to be more verbose here.
* Automatically rename 'Ebb' to 'Block' in *.rs
* Automatically rename 'EBB' to 'block' in *.rs
* Automatically rename 'ebb' to 'block' in *.rs
* Automatically rename 'extended basic block' to 'basic block' in *.rs
* Automatically rename 'an basic block' to 'a basic block' in *.rs
* Manually update comment for `Block`
`Block`'s wikipedia article required an update.
* Automatically rename 'an `Block`' to 'a `Block`' in *.rs
* Automatically rename 'extended_basic_block' to 'basic_block' in *.rs
* Automatically rename 'ebb' to 'block' in *.clif
* Manually rename clif constant that contains 'ebb' as substring to avoid conflict
* Automatically rename filecheck uses of 'EBB' to 'BB'
'regex: EBB' -> 'regex: BB'
'$EBB' -> '$BB'
* Automatically rename 'EBB' 'Ebb' to 'block' in *.clif
* Automatically rename 'an block' to 'a block' in *.clif
* Fix broken testcase when function name length increases
Test function names are limited to 16 characters. This causes
the new longer name to be truncated and fail a filecheck test. An
outdated comment was also fixed.
Also, say "guard-offset pages" rather than just "guard pages" to describe the
region of a heap which is never accessible and which exists to support
optimizations for heap accesses with offsets.
And, introduce a `Uimm64` immediate type, and make all heap fields use
`Uimm64` instead of `Imm64` since they really are unsigned.
* Clarify Cranelift's design with respect to mid-level optimization.
Cranelift doesn't currently do much mid-level optimization, however it
is something we're thinking about, so remove text describing it as out of
scope, and add more text explaining the vision for how it would fit into
the overall system.
WebAssembly doesn't have non-dense jump tables, and higher-level users
are better served by the facilities in lib/frontend/src/switch.rs for
working with non-dense switches.
This eliminates the concept of "absent" jump table entries, which
were represented as "0" in the text format.
Also, jump table contents are now enclosed in `[` and `]`, so that
we can unambiguously display empty jump tables. Previously, empty jump
tables were displayed as if they had a single absent entry.
* Reorganize the global value kinds.
This:
- renames "deref" global values to "load" and gives it a offset that works
like the "load" instructions' does
- adds an explicit "iadd_imm" global value kind, which replaces the
builtin iadd in "vmctx" and "deref" global values.
- also renames "globalsym" to "symbol"
