We've adopted this pattern in Cranelift's instruction definitions where
we let-bind some calls to `Operand::new` and then later use them in one
or more calls to `Inst::new`.
That pattern has two problems:
- It puts the type of each operand somewhere potentially far removed
from the instruction in which it's used.
- We let-bind the same name for many different operands, compounding the
first problem by making it harder to find _which_ definition is used.
So instead this commit removes all let-bindings for operand definitions
and constructs a new `Operand` every time.
Constructing an `Operand` at every use means we duplicate some
documentation strings, but not all that many of them as it turns out.
I've left the let-bound type-sets alone, so those are currently still
shared across many instructions. They have some of the same problems and
should be reviewed as well.
Rework br_table to use BlockCall, allowing us to avoid adding new nodes during ssa construction to hold block arguments. Additionally, many places where we previously matched on InstructionData to extract branch destinations can be replaced with a use of branch_destination or branch_destination_mut.
Remove the boolean parameters from the instruction builder functions, as they were only ever used with true. Additionally, change the returns and branches functions to imply terminates_block.
* Switch duplicate loads w/ dynamic memories test to `min_size = 0`
This test was accidentally hitting a special case for bounds checks for when we
know that `offset + access_size < min_size` and can skip some steps. This
commit changes the `min_size` of the memory to zero so that we are forced to do
fully general bounds checks.
* Cranelift: Mark `uadd_overflow_trap` as okay for GVN
Although this improves our test sequence for duplicate loads with dynamic
memories, it unfortunately doesn't have any effect on sightglass benchmarks:
```
instantiation :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[34448 35607.23 37158] gvn_uadd_overflow_trap.so
[34566 35734.05 36585] main.so
instantiation :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[44101 60449.62 92712] gvn_uadd_overflow_trap.so
[44011 60436.37 92690] main.so
instantiation :: instructions-retired :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[35595 36675.72 38153] gvn_uadd_overflow_trap.so
[35440 36670.42 37993] main.so
compilation :: instructions-retired :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[17370195 17405125.62 17471222] gvn_uadd_overflow_trap.so
[17369324 17404859.43 17470725] main.so
execution :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[7055720520 7055886880.32 7056265930] gvn_uadd_overflow_trap.so
[7055719554 7055843809.33 7056193289] main.so
compilation :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[683589861 683767276.00 684098366] gvn_uadd_overflow_trap.so
[683590024 683767998.02 684097885] main.so
execution :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[46436883 46437135.10 46437823] gvn_uadd_overflow_trap.so
[46436883 46437087.67 46437785] main.so
compilation :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[126522461 126565812.58 126647044] gvn_uadd_overflow_trap.so
[126522176 126565757.75 126647522] main.so
execution :: instructions-retired :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[653010531 653010533.03 653010544] gvn_uadd_overflow_trap.so
[653010531 653010533.18 653010537] main.so
```
* cranelift-codegen-meta: Rename `side_effects_okay_for_gvn` to `side_effects_idempotent`
* cranelift-filetests: Ensure there is a trailing newline for blessed Wasm tests
* Cranelift: Make spectre guards GVN-able
While these instructions have a side effect that is otherwise invisible to the
optimizer, the side effect in question is idempotent, so it can be de-duplicated
by GVN.
* Cranelift: Run redundant load replacement and GVN twice
This allows us to actually replace redundant Wasm loads with dynamic memories.
While this improves our hand-crafted test sequences, it doesn't seem to have any
improvement on sightglass benchmarks run with dynamic memories, however it also
isn't a hit to compilation times, so seems generally good to land anyways:
```
$ cargo run --release -- benchmark -e ~/scratch/once.so -e ~/scratch/twice.so -m insts-retired --processes 20 --iterations-per-process 3 --engine-flags="--static-memory-maximum-size 0" -- benchmarks/default.suite
compilation :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[683595240 683768610.53 684097577] once.so
[683597068 700115966.83 1664907164] twice.so
instantiation :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[44107 60411.07 92785] once.so
[44138 59552.32 92097] twice.so
compilation :: instructions-retired :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[17369916 17404839.78 17471458] once.so
[17369935 17625713.87 30700150] twice.so
compilation :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[126523640 126566170.80 126648265] once.so
[126523076 127174580.30 163145149] twice.so
instantiation :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[34569 35686.25 36513] once.so
[34651 35749.97 36953] twice.so
instantiation :: instructions-retired :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[35146 36639.10 37707] once.so
[34472 36580.82 38431] twice.so
execution :: instructions-retired :: benchmarks/spidermonkey/benchmark.wasm
No difference in performance.
[7055720115 7055841324.82 7056180024] once.so
[7055717681 7055877095.85 7056225217] twice.so
execution :: instructions-retired :: benchmarks/pulldown-cmark/benchmark.wasm
No difference in performance.
[46436881 46437081.28 46437691] once.so
[46436883 46437127.68 46437766] twice.so
execution :: instructions-retired :: benchmarks/bz2/benchmark.wasm
No difference in performance.
[653010530 653010533.27 653010539] once.so
[653010531 653010532.95 653010538] twice.so
```
All instructions using the CPU flags types (IFLAGS/FFLAGS) were already
removed. This patch completes the cleanup by removing all remaining
instructions that define values of CPU flags types, as well as the
types themselves.
Specifically, the following features are removed:
- The IFLAGS and FFLAGS types and the SpecialType category.
- Special handling of IFLAGS and FFLAGS in machinst/isle.rs and
machinst/lower.rs.
- The ifcmp, ifcmp_imm, ffcmp, iadd_ifcin, iadd_ifcout, iadd_ifcarry,
isub_ifbin, isub_ifbout, and isub_ifborrow instructions.
- The writes_cpu_flags instruction property.
- The flags verifier pass.
- Flags handling in the interpreter.
All of these features are currently unused; no functional change
intended by this patch.
This addresses https://github.com/bytecodealliance/wasmtime/issues/3249.
* Fix some nightly dead code warnings
Looks like the "struct field not used" lint has improved on nightly and
caught a few more instances of fields that were never actually read.
* Fix windows
* 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.
And replace it by constructors in OperandKind. There's a single optional
parameter function `set_doc` that remains, and didn't justify the whole
OperandKindBuilder concept to exist.
This does a lot at once, since there was no clear way to split the three
commits:
- Instruction need to be passed an explicit InstructionFormat,
- InstructionFormat deduplication is checked once all entities have been
defined;
This avoids a lot of dereferences, and InstructionFormat are immutable
once they're created. It removes a lot of code that was keeping the
FormatRegistry around, just in case we needed the format. This is more
in line with the way we create Instructions, and make it easy to
reference InstructionFormats in general.
Previously, ConstantData was a type alias for `Vec<u8>` which prevented it from having an implementation; this meant that `V128Imm` and `&[u8; 16]` were used in places that otherwise could have accepted types of different byte lengths.
This avoids doing multiple unpacking of the InstructionData for a single
legalization, improving readability and reducing size of the generated
code. For instance, icmp had to unpack the format once per IntCC
condition code.
This change should make the code more clear (and less code) when adding encodings for instructions with specific immediates; e.g., a constant with a 0 immediate could be encoded as an XOR with something like `const.bind(...)` without explicitly creating the necessary predicates. It has several parts:
* Introduce Bindable trait to instructions
* Convert all instruction bindings to use Bindable::bind()
* Add ability to bind immediates to BoundInstruction
This is an attempt to reduce some of the issues in #955.
Instead of using MOVUPS to expensively load bits from memory, this change uses a predicate to optimize vconst without a memory access:
- when the 128-bit immediate is all zeroes in all bits, use PXOR to zero out an XMM register
- when the 128-bit immediate is all ones in all bits, use PCMPEQB to set an XMM register to all ones
This leaves the constant data in the constant pool, which may increase code size (TODO)
