From ee000f3affad66ecc026240da6cda9057dee4dcc Mon Sep 17 00:00:00 2001
From: Chris Elrod <elrodc@gmail.com>
Date: Tue, 23 Jan 2024 18:45:56 -0500
Subject: [PATCH] findfirstequal for `DenseVector{Int}` only instead of generic
 because YAGNI (probably)

---
 Project.toml              |  2 +-
 src/FindFirstFunctions.jl | 69 ++++++++++++++++++++++++++++++++++++++-
 test/runtests.jl          | 18 +++++++++-
 3 files changed, 86 insertions(+), 3 deletions(-)

diff --git a/Project.toml b/Project.toml
index 85f8cc3..ec0a834 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "FindFirstFunctions"
 uuid = "64ca27bc-2ba2-4a57-88aa-44e436879224"
 authors = ["Chris Elrod <elrodc@gmail.com> and contributors"]
-version = "1.0.0-DEV"
+version = "1.0.0"
 
 [compat]
 julia = "1.8"
diff --git a/src/FindFirstFunctions.jl b/src/FindFirstFunctions.jl
index 27abbb5..16bec72 100644
--- a/src/FindFirstFunctions.jl
+++ b/src/FindFirstFunctions.jl
@@ -1,5 +1,72 @@
 module FindFirstFunctions
 
-# Write your package code here.
+findfirstequal(vpivot, ivars) = findfirst(isequal(vpivot), ivars)
+function findfirstequal(vpivot::Int64, ivars::DenseVector{Int64})
+  GC.@preserve ivars begin
+    ret = Base.llvmcall(("""
+                       declare i8 @llvm.cttz.i8(i8, i1);
+                       define i64 @entry(i64 %0, i64 %1, i64 %2) #0 {
+                       top:
+                         %ivars = inttoptr i64 %1 to i64*
+                         %btmp = insertelement <8 x i64> undef, i64 %0, i64 0
+                         %var = shufflevector <8 x i64> %btmp, <8 x i64> undef, <8 x i32> zeroinitializer
+                         %lenm7 = add nsw i64 %2, -7
+                         %dosimditer = icmp ugt i64 %2, 7
+                         br i1 %dosimditer, label %L9.lr.ph, label %L32
+
+                       L9.lr.ph:
+                         %len8 = and i64 %2, 9223372036854775800
+                         br label %L9
+
+                       L9:
+                         %i = phi i64 [ 0, %L9.lr.ph ], [ %vinc, %L30 ]
+                         %ivarsi = getelementptr inbounds i64, i64* %ivars, i64 %i
+                         %vpvi = bitcast i64* %ivarsi to <8 x i64>*
+                         %v = load <8 x i64>, <8 x i64>* %vpvi, align 8
+                         %m = icmp eq <8 x i64> %v, %var
+                         %mu = bitcast <8 x i1> %m to i8
+                         %matchnotfound = icmp eq i8 %mu, 0
+                         br i1 %matchnotfound, label %L30, label %L17
+
+                       L17:
+                         %tz8 = call i8 @llvm.cttz.i8(i8 %mu, i1 true)
+                         %tz64 = zext i8 %tz8 to i64
+                         %vis = add nuw i64 %i, %tz64
+                         br label %common.ret
+
+                       common.ret:
+                         %retval = phi i64 [ %vis, %L17 ], [ -1, %L32 ], [ %si, %L51 ], [ -1, %L67 ]
+                         ret i64 %retval
+
+                       L30:
+                         %vinc = add nuw nsw i64 %i, 8
+                         %continue = icmp slt i64 %vinc, %lenm7
+                         br i1 %continue, label %L9, label %L32
+
+                       L32:
+                         %cumi = phi i64 [ 0, %top ], [ %len8, %L30 ]
+                         %done = icmp eq i64 %cumi, %2
+                         br i1 %done, label %common.ret, label %L51
+
+                       L51:
+                         %si = phi i64 [ %inc, %L67 ], [ %cumi, %L32 ]
+                         %spi = getelementptr inbounds i64, i64* %ivars, i64 %si
+                         %svi = load i64, i64* %spi, align 8
+                         %match = icmp eq i64 %svi, %0
+                         br i1 %match, label %common.ret, label %L67
+
+                       L67:
+                         %inc = add i64 %si, 1
+                         %dobreak = icmp eq i64 %inc, %2
+                         br i1 %dobreak, label %common.ret, label %L51
+
+                       }
+                       attributes #0 = { alwaysinline }
+    """, "entry"), Int64, Tuple{Int64,Ptr{Int64},Int64}, vpivot, pointer(ivars),
+      length(ivars))
+  end
+  ret < 0 ? nothing : ret + 1
+end
+
 
 end
diff --git a/test/runtests.jl b/test/runtests.jl
index c15a3d4..65c3832 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -2,5 +2,21 @@ using FindFirstFunctions
 using Test
 
 @testset "FindFirstFunctions.jl" begin
-    # Write your tests here.
+
+  for n = 0:128
+    x = unique!(rand(Int, n))
+    for i = eachindex(x)
+      @test FindFirstFunctions.findfirstequal(x[i], x) == i
+    end
+    if length(x) > 0
+      @test FindFirstFunctions.findfirstequal(x[begin], @view(x[begin:end])) === 1
+      @test FindFirstFunctions.findfirstequal(x[begin], @view(x[begin+1:end])) === nothing
+      @test FindFirstFunctions.findfirstequal(x[end], @view(x[begin:end-1])) === nothing
+    end
+    y = rand(Int)
+    @test FindFirstFunctions.findfirstequal(y, x) === findfirst(==(y), x)
+  end
+
 end
+
+