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Optimizations to egraph framework (#5391)

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* Optimizations to egraph framework:

- Save elaborated results by canonical value, not latest value (union
  value). Previously we were artificially skipping and re-elaborating
  some values we already had because we were not finding them in the
  map.

- Make some changes to handling of icmp results: when icmp became
  I8-typed (when bools went away), many uses became `(uextend $I32 (icmp
  $I8 ...))`, and so patterns in lowering backends were no longer
  matching.

  This PR includes an x64-specific change to match `(brz (uextend (icmp
  ...)))` and similarly for `brnz`, but it also takes advantage of the
  ability to write rules easily in the egraph mid-end to rewrite selects
  with icmp inputs appropriately.

- Extend constprop to understand selects in the egraph mid-end.

With these changes, bz2.wasm sees a ~1% speedup, and spidermonkey.wasm
with a fib.js input sees a 16.8% speedup:

```
$ time taskset 1 target/release/wasmtime run --allow-precompiled --dir=. ./spidermonkey.base.cwasm ./fib.js
1346269
taskset 1 target/release/wasmtime run --allow-precompiled --dir=.  ./fib.js  2.14s user 0.01s system 99% cpu 2.148 total
$ time taskset 1 target/release/wasmtime run --allow-precompiled --dir=. ./spidermonkey.egraphs.cwasm ./fib.js
1346269
taskset 1 target/release/wasmtime run --allow-precompiled --dir=.  ./fib.js  1.78s user 0.01s system 99% cpu 1.788 total
```

* Review feedback.
This commit is contained in:
Chris Fallin
2022-12-07 13:23:13 -08:00
committed by GitHub
parent c5379051c4
commit 8c55b81300
8 changed files with 90 additions and 41 deletions
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17
cranelift/codegen/src/prelude_lower.isle
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@@ -308,23 +308,6 @@
;;;; Helpers for Working with Flags ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Reverse an IntCC flag.
(decl intcc_reverse (IntCC) IntCC)
(extern constructor intcc_reverse intcc_reverse)
;; Invert an IntCC flag.
(decl intcc_inverse (IntCC) IntCC)
(extern constructor intcc_inverse intcc_inverse)
;; Reverse an FloatCC flag.
(decl floatcc_reverse (FloatCC) FloatCC)
(extern constructor floatcc_reverse floatcc_reverse)
;; Invert an FloatCC flag.
(decl floatcc_inverse (FloatCC) FloatCC)
(extern constructor floatcc_inverse floatcc_inverse)
;; Newtype wrapper around `MInst` for instructions that are used for their
;; effect on flags.
;;