Adjust Operand encoding#13
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The encoding for OperandConstraint is adjusted to free up 2 bits which allows for 2^21 vregs and 2^6 pregs.
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cfallin
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Sep 13, 2021
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Thanks for this!
Just a request for an additional comment below but otherwise LGTM.
| /// about physical registers. This is done by putting the class bit at | ||
| /// the MSB, or equivalently, declaring that indices 0..31 are the 32 | ||
| /// integer registers and indices 32..63 are the 32 float registers. | ||
| /// the MSB, or equivalently, declaring that indices 0..63 are the 64 |
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Pre-existing but a pedantic nit on my own comment: could you adjust to either 0..=63 or 0..64 (and likewise for the second range)? Inconsistency w.r.t. Rust open/cosed-range syntax is bothering me :-)
| OperandConstraint::Any => (0, 0), | ||
| OperandConstraint::Reg => (0, 1), | ||
| OperandConstraint::Stack => (0, 2), | ||
| let constraint_field = match constraint { |
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Could you add a block comment here describing the bit encoding?
lqd
reviewed
Sep 13, 2021
| /// that the conflict (overlap) is properly accounted for. See | ||
| /// comments on the constructors below for more. | ||
| #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] | ||
| //#[repr(packed)] |
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Looks like a stray comment ?
Suggested change
| //#[repr(packed)] |
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Oops that's from an old test I was doing.
cfallin
added a commit
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Nov 10, 2021
Large parts of the code in regalloc2 are currently licensed under the
Mozilla Public License (MPL) 2.0, because they derive in meaningful
ways from the register allocator in IonMonkey, which is part of
Firefox. The relevant source files are marked as such, with references
to the files in the Firefox source tree.
The intent of the regalloc2 project was to port the register allocator
from Firefox to use in Cranelift, borrowing good technology and
improving on it in the spirit of open source.
However, Several use-cases of Cranelift require, or at least strongly
prefer, the Apache-2.0 license with the LLVM exception (matching the
license of Cranelift itself, and Bytecode Alliance projects
generally). While using this license is not strictly necessary for
regalloc2 to be usable (The MPL is an excellent open-source license!),
relicensing fully under this license to harmonize with the rest of
Cranelift and Bytecode Alliance codebases significantly widens
possibilities and reduces friction; then regalloc2 is "just another
part of Cranelift" and doesn't have to be treated specially.
The source in `src/ion/` specifically began as a fairly direct port of
the algorithms in the following files in the `mozilla-central`
repository (Firefox codebase):
* The bulk of the "backtracking allocator" algorithm:
* `js/src/jit/BacktrackingAllocator.{cpp,h}`
* Helpers and definitions in the surrounding infrastructure:
* `js/src/jit/RegisterAllocator.h`
* `js/src/jit/RegisterAllocator.cpp`
* `js/src/jit/StackSlotAllocator.h`
* `js/src/jit/LIR.h`
* A few data structure implementations:
* `js/src/ds/SplayTree.h`
* `js/src/ds/PriorityQueue.h`
Subsequent work in improving regalloc2 has caused it to drift from the
direct port -- for example, it no longer uses splay trees or the
direct port of the priority queue above -- but it is of course very
clearly still a derivative work.
Analysis of the contributors to these files indicates that we need
signoff from the following folks:
* Mozilla Corp, for contributions made by Mozilla employees (the
majority of the code). Communications with Mozilla (thanks
@tschneidereit and @bholley for doing the work here!) indicate that
@ekr is able to sign off when ready here.
* Andy Wingo, specifically for the work done in [Bug
1620197](https://bugzilla.mozilla.org/show_bug.cgi?id=1620197) and
[Bug 1609057](https://bugzilla.mozilla.org/show_bug.cgi?id=1609057) to
generalize the stack allocator for a Wasm feature (multiple returns).
Additionally, since the initial port, we have had three contributions
from @Amanieu:
[bytecodealliance#9](bytecodealliance#9),
[bytecodealliance#11](bytecodealliance#11),
[bytecodealliance#13](bytecodealliance#13).
So, if everyone applicable is happy with this relicensing, this PR
removes the MPL-2.0 license in `src/ion/` and marks all files as
covered under `Apache-2.0 WITH LLVM-exception`. Please let us know if
this is OK!
Signoffs:
- [ ] @ekr, for Mozilla's contributions
- [ ] @Awingo, for contributions to original code in `mozilla-central`
- [ ] @Amanieu, for the three PRs linked above
Thanks!
3 tasks
cfallin
added a commit
to cfallin/regalloc2
that referenced
this pull request
Nov 10, 2021
Large parts of the code in regalloc2 are currently licensed under the
Mozilla Public License (MPL) 2.0, because they derive in meaningful
ways from the register allocator in IonMonkey, which is part of
Firefox. The relevant source files are marked as such, with references
to the files in the Firefox source tree.
The intent of the regalloc2 project was to port the register allocator
from Firefox to use in Cranelift, borrowing good technology and
improving on it in the spirit of open source.
However, Several use-cases of Cranelift require, or at least strongly
prefer, the Apache-2.0 license with the LLVM exception (matching the
license of Cranelift itself, and Bytecode Alliance projects
generally). While using this license is not strictly necessary for
regalloc2 to be usable (The MPL is an excellent open-source license!),
relicensing fully under this license to harmonize with the rest of
Cranelift and Bytecode Alliance codebases significantly widens
possibilities and reduces friction; then regalloc2 is "just another
part of Cranelift" and doesn't have to be treated specially.
The source in `src/ion/` specifically began as a fairly direct port of
the algorithms in the following files in the `mozilla-central`
repository (Firefox codebase):
* The bulk of the "backtracking allocator" algorithm:
* `js/src/jit/BacktrackingAllocator.{cpp,h}`
* Helpers and definitions in the surrounding infrastructure:
* `js/src/jit/RegisterAllocator.h`
* `js/src/jit/RegisterAllocator.cpp`
* `js/src/jit/StackSlotAllocator.h`
* `js/src/jit/LIR.h`
* A few data structure implementations:
* `js/src/ds/SplayTree.h`
* `js/src/ds/PriorityQueue.h`
Subsequent work in improving regalloc2 has caused it to drift from the
direct port -- for example, it no longer uses splay trees or the
direct port of the priority queue above -- but it is of course very
clearly still a derivative work.
Analysis of the contributors to these files indicates that we need
signoff from the following folks:
* Mozilla Corp, for contributions made by Mozilla employees (the
majority of the code). Communications with Mozilla (thanks
@tschneidereit and @bholley for doing the work here!) indicate that
@ekr is able to sign off when ready here.
* Andy Wingo, specifically for the work done in [Bug
1620197](https://bugzilla.mozilla.org/show_bug.cgi?id=1620197) and
[Bug 1609057](https://bugzilla.mozilla.org/show_bug.cgi?id=1609057) to
generalize the stack allocator for a Wasm feature (multiple returns).
Additionally, since the initial port, we have had three contributions
from @Amanieu:
[bytecodealliance#9](bytecodealliance#9),
[bytecodealliance#11](bytecodealliance#11),
[bytecodealliance#13](bytecodealliance#13).
So, if everyone applicable is happy with this relicensing, this PR
removes the MPL-2.0 license in `src/ion/` and marks all files as
covered under `Apache-2.0 WITH LLVM-exception`. Please let us know if
this is OK!
Signoffs:
- [ ] @ekr, for Mozilla's contributions
- [ ] @Awingo, for contributions to original code in `mozilla-central`
- [ ] @Amanieu, for the three PRs linked above
Thanks!
cfallin
added a commit
to cfallin/regalloc2
that referenced
this pull request
Nov 10, 2021
Large parts of the code in regalloc2 are currently licensed under the
Mozilla Public License (MPL) 2.0, because they derive in meaningful
ways from the register allocator in IonMonkey, which is part of
Firefox. The relevant source files are marked as such, with references
to the files in the Firefox source tree.
The intent of the regalloc2 project was to port the register allocator
from Firefox to use in Cranelift, borrowing good technology and
improving on it in the spirit of open source.
However, Several use-cases of Cranelift require, or at least strongly
prefer, the Apache-2.0 license with the LLVM exception (matching the
license of Cranelift itself, and Bytecode Alliance projects
generally). While using this license is not strictly necessary for
regalloc2 to be usable (The MPL is an excellent open-source license!),
relicensing fully under this license to harmonize with the rest of
Cranelift and Bytecode Alliance codebases significantly widens
possibilities and reduces friction; then regalloc2 is "just another
part of Cranelift" and doesn't have to be treated specially.
The source in `src/ion/` specifically began as a fairly direct port of
the algorithms in the following files in the `mozilla-central`
repository (Firefox codebase):
* The bulk of the "backtracking allocator" algorithm:
* `js/src/jit/BacktrackingAllocator.{cpp,h}`
* Helpers and definitions in the surrounding infrastructure:
* `js/src/jit/RegisterAllocator.h`
* `js/src/jit/RegisterAllocator.cpp`
* `js/src/jit/StackSlotAllocator.h`
* `js/src/jit/LIR.h`
* A few data structure implementations:
* `js/src/ds/SplayTree.h`
* `js/src/ds/PriorityQueue.h`
Subsequent work in improving regalloc2 has caused it to drift from the
direct port -- for example, it no longer uses splay trees or the
direct port of the priority queue above -- but it is of course very
clearly still a derivative work.
Analysis of the contributors to these files indicates that we need
signoff from the following folks:
* Mozilla Corp, for contributions made by Mozilla employees (the
majority of the code). Communications with Mozilla (thanks
@tschneidereit and @bholley for doing the work here!) indicate that
@ekr is able to sign off when ready here.
* Andy Wingo, specifically for the work done in [Bug
1620197](https://bugzilla.mozilla.org/show_bug.cgi?id=1620197) and
[Bug 1609057](https://bugzilla.mozilla.org/show_bug.cgi?id=1609057) to
generalize the stack allocator for a Wasm feature (multiple returns).
Additionally, since the initial port, we have had three contributions
from @Amanieu:
[bytecodealliance#9](bytecodealliance#9),
[bytecodealliance#11](bytecodealliance#11),
[bytecodealliance#13](bytecodealliance#13).
So, if everyone applicable is happy with this relicensing, this PR
removes the MPL-2.0 license in `src/ion/` and marks all files as
covered under `Apache-2.0 WITH LLVM-exception`. Please let us know if
this is OK!
Signoffs:
- [ ] @ekr, for Mozilla's contributions
- [ ] @wingo, for contributions to original code in `mozilla-central`
- [ ] @Amanieu, for the three PRs linked above
Thanks!
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The encoding for OperandConstraint is adjusted to free up 2 bits which
allows for 2^21 vregs and 2^6 pregs.