aarch64: Initial work to transition backend to ISLE #3541
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| ;; First up some special cases for constants which match certain custom | ||
| ;; conditions. Note that these have explicit priorities to explicitly list | ||
| ;; that we prefer instructions in the order that they're listed here. Otherwise | ||
| ;; ISLE has no way of determining which is the more relevant matcher. |
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Someone more familiar with AArch64 may want to confirm this, I'm respecting the original ordering that's implemented today, but I'm not sure if it matters matching it precisely or if any of the three one-instruction forms is fine to materialize a constant with.
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Since they're all 1-instruction lowerings, it should be fine (and equal cost) to use any that fit, I think. (Though at least MOVZ and MOVN should be completely mutually exclusive, since all the other bits except the shifted 16-bit field are all 0 or all 1 respectively, but ORI's range overlaps with MOVZ.)
So I think it's slightly better to exclude the priorities here so the decision trie build has more freedom to merge and reorder.
Excellent attention to preserving original behavior though, thanks for taking care with that!
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| ;; First up some special cases for constants which match certain custom | ||
| ;; conditions. Note that these have explicit priorities to explicitly list | ||
| ;; that we prefer instructions in the order that they're listed here. Otherwise | ||
| ;; ISLE has no way of determining which is the more relevant matcher. |
There was a problem hiding this comment.
Since they're all 1-instruction lowerings, it should be fine (and equal cost) to use any that fit, I think. (Though at least MOVZ and MOVN should be completely mutually exclusive, since all the other bits except the shifted 16-bit field are all 0 or all 1 respectively, but ORI's range overlaps with MOVZ.)
So I think it's slightly better to exclude the priorities here so the decision trie build has more freedom to merge and reorder.
Excellent attention to preserving original behavior though, thanks for taking care with that!
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This commit is what is hoped to be the initial commit towards migrating the aarch64 backend to ISLE. There's seemingly a lot of changes here but it's intended to largely be code motion. The current thinking is to closely follow the x64 backend for how all this is handled and organized. Major changes in this PR are: * The `Inst` enum is now defined in ISLE. This avoids having to define it in two places (once in Rust and once in ISLE). I've preserved all the comments in the ISLE and otherwise this isn't actually a functional change from the Rust perspective, it's still the same enum according to Rust. * Lots of little enums and things were moved to ISLE as well. As with `Inst` their definitions didn't change, only where they're defined. This will give future ISLE PRs access to all these operations. * Initial code for lowering `iconst`, `null`, and `bconst` are implemented. Ironically none of this is actually used right now because constant lowering is handled in `put_input_in_regs` which specially handles constants. Nonetheless I wanted to get at least something simple working which shows off how to special case various things that are specific to AArch64. In a future PR I plan to hook up const-lowering in ISLE to this path so even though `iconst`-the-clif-instruction is never lowered this should use the const lowering defined in ISLE rather than elsewhere in the backend (eventually leading to the deletion of the non-ISLE lowering). * The `IsleContext` skeleton is created and set up for future additions. * Some code for ISLE that's shared across all backends now lives in `isle_prelude_methods!()` and is deduplicated between the AArch64 backend and the x64 backend. * Register mapping is tweaked to do the same thing for AArch64 that it does for x64. Namely mapping virtual registers is supported instead of just virtual to machine registers. My main goal with this PR was to get AArch64 into a place where new instructions can be added with relative ease. Additionally I'm hoping to figure out as part of this change how much to share for ISLE between AArch64 and x64 (and other backends).
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This commit is what is hoped to be the initial commit towards migrating
the aarch64 backend to ISLE. There's seemingly a lot of changes here but
it's intended to largely be code motion. The current thinking is to
closely follow the x64 backend for how all this is handled and
organized.
Major changes in this PR are:
The
Instenum is now defined in ISLE. This avoids having to defineit in two places (once in Rust and once in ISLE). I've preserved all
the comments in the ISLE and otherwise this isn't actually a
functional change from the Rust perspective, it's still the same enum
according to Rust.
Lots of little enums and things were moved to ISLE as well. As with
Insttheir definitions didn't change, only where they're defined.This will give future ISLE PRs access to all these operations.
Initial code for lowering
iconst,null, andbconstareimplemented. Ironically none of this is actually used right now
because constant lowering is handled in
put_input_in_regswhichspecially handles constants. Nonetheless I wanted to get at least
something simple working which shows off how to special case various
things that are specific to AArch64. In a future PR I plan to hook up
const-lowering in ISLE to this path so even though
iconst-the-clif-instruction is never lowered this should use theconst lowering defined in ISLE rather than elsewhere in the backend
(eventually leading to the deletion of the non-ISLE lowering).
The
IsleContextskeleton is created and set up for future additions.Some code for ISLE that's shared across all backends now lives in
isle_prelude_methods!()and is deduplicated between the AArch64backend and the x64 backend.
Register mapping is tweaked to do the same thing for AArch64 that it
does for x64. Namely mapping virtual registers is supported instead of
just virtual to machine registers.
My main goal with this PR was to get AArch64 into a place where new
instructions can be added with relative ease. Additionally I'm hoping to
figure out as part of this change how much to share for ISLE between
AArch64 and x64 (and other backends).