Computed collections: simple count check (dotnet#16947)

* Use count = 0 instead of count < 1 * The count < 1 check was a vestige of an older approach for computing the count that could result in a negative count. * Update baselines * Update release notes
vzarytovskii · Apr 4, 2024 · 71442c8 · 71442c8
1 parent 06c85f0
commit 71442c8
Show file tree

Hide file tree

Showing 5 changed files with 2,205 additions and 2,320 deletions.
diff --git a/docs/release-notes/.FSharp.Compiler.Service/8.0.300.md b/docs/release-notes/.FSharp.Compiler.Service/8.0.300.md
@@ -54,4 +54,4 @@
 * Reverted [#16348](https://github.com/dotnet/fsharp/pull/16348) `ThreadStatic` `CancellationToken` changes to improve test stability and prevent potential unwanted cancellations. ([PR #16536](https://github.com/dotnet/fsharp/pull/16536))
 * Refactored parenthesization API. ([PR #16461])(https://github.com/dotnet/fsharp/pull/16461))
 * Optimize some interpolated strings by lowering to string concatenation. ([PR #16556](https://github.com/dotnet/fsharp/pull/16556))
-* Integral range optimizations. ([PR #16650](https://github.com/dotnet/fsharp/pull/16650), [PR #16832](https://github.com/dotnet/fsharp/pull/16832))
+* Integral range optimizations. ([PR #16650](https://github.com/dotnet/fsharp/pull/16650), [PR #16832](https://github.com/dotnet/fsharp/pull/16832), [PR #16947](https://github.com/dotnet/fsharp/pull/16947))
diff --git a/src/Compiler/Optimize/LowerComputedCollections.fs b/src/Compiler/Optimize/LowerComputedCollections.fs
@@ -393,14 +393,7 @@ module Array =
                     mkCompGenLetIn m (nameof count) (tyOfExpr g count) count (fun (_, count) ->
                         let countTy = tyOfExpr g count
 
-                        // count < 1
-                        let countLtOne =
-                            if isSignedIntegerTy g countTy then
-                                mkILAsmClt g m count (mkTypedOne g m countTy)
-                            else
-                                mkAsmExpr ([AI_clt_un], [], [count; mkTypedOne g m countTy], [g.bool_ty], m)
-
-                        // if count < 1 then
+                        // if count = 0 then
                         //     [||]
                         // else
                         //     let array = (# "newarr !0" type ('T) count : 'T array #) in
@@ -410,7 +403,7 @@ module Array =
                             DebugPointAtBinding.NoneAtInvisible
                             m
                             arrayTy
-                            countLtOne
+                            (mkILAsmCeq g m count (mkTypedZero g m countTy))
                             (mkArray (overallElemTy, [], m))
                             (mkArrayInit count mkLoop)
                     )