fix extrema(A,dim) when length(dim)>1

Ref #22118
(cherry picked from commit 4a470cb)

base/multidimensional.jl

@@ -1440,26 +1440,23 @@ function extrema(A::AbstractArray, dims)
     return extrema!(B, A)
 end
 
-@generated function extrema!(B, A::AbstractArray{T,N}) where {T,N}
-    return quote
-        sA = size(A)
-        sB = size(B)
-        @nloops $N i B begin
-            AI = @nref $N A i
-            (@nref $N B i) = (AI, AI)
-        end
-        Bmax = sB
-        Istart = Int[sB[i] == 1 != sA[i] ? 2 : 1 for i = 1:ndims(A)]
-        @inbounds @nloops $N i d->(Istart[d]:size(A,d)) begin
-            AI = @nref $N A i
-            @nexprs $N d->(j_d = min(Bmax[d], i_{d}))
-            BJ = @nref $N B j
-            if AI < BJ[1]
-                (@nref $N B j) = (AI, BJ[2])
-            elseif AI > BJ[2]
-                (@nref $N B j) = (BJ[1], AI)
-            end
+@noinline function extrema!(B, A)
+    sA = size(A)
+    sB = size(B)
+    for I in CartesianRange(sB)
+        AI = A[I]
+        B[I] = (AI, AI)
+    end
+    Bmax = CartesianIndex(sB)
+    @inbounds @simd for I in CartesianRange(sA)
+        J = min(Bmax,I)
+        BJ = B[J]
+        AI = A[I]
+        if AI < BJ[1]
+            B[J] = (AI, BJ[2])
+        elseif AI > BJ[2]
+            B[J] = (BJ[1], AI)
         end
-        return B
     end
+    return B
 end

test/reduce.jl

@@ -197,9 +197,17 @@ prod2(itr) = invoke(prod, Tuple{Any}, itr)
 @test maximum(collect(Int16(1):Int16(100))) === Int16(100)
 @test maximum(Int32[1,2]) === Int32(2)
 
-@test extrema(reshape(1:24,2,3,4),1) == reshape([(1,2),(3,4),(5,6),(7,8),(9,10),(11,12),(13,14),(15,16),(17,18),(19,20),(21,22),(23,24)],1,3,4)
-@test extrema(reshape(1:24,2,3,4),2) == reshape([(1,5),(2,6),(7,11),(8,12),(13,17),(14,18),(19,23),(20,24)],2,1,4)
-@test extrema(reshape(1:24,2,3,4),3) == reshape([(1,19),(2,20),(3,21),(4,22),(5,23),(6,24)],2,3,1)
+A = circshift(reshape(1:24,2,3,4), (0,1,1))
+@test extrema(A,1) == reshape([(23,24),(19,20),(21,22),(5,6),(1,2),(3,4),(11,12),(7,8),(9,10),(17,18),(13,14),(15,16)],1,3,4)
+@test extrema(A,2) == reshape([(19,23),(20,24),(1,5),(2,6),(7,11),(8,12),(13,17),(14,18)],2,1,4)
+@test extrema(A,3) == reshape([(5,23),(6,24),(1,19),(2,20),(3,21),(4,22)],2,3,1)
+@test extrema(A,(1,2)) == reshape([(19,24),(1,6),(7,12),(13,18)],1,1,4)
+@test extrema(A,(1,3)) == reshape([(5,24),(1,20),(3,22)],1,3,1)
+@test extrema(A,(2,3)) == reshape([(1,23),(2,24)],2,1,1)
+@test extrema(A,(1,2,3)) == reshape([(1,24)],1,1,1)
+@test size(extrema(A,1)) == size(maximum(A,1))
+@test size(extrema(A,(1,2))) == size(maximum(A,(1,2)))
+@test size(extrema(A,(1,2,3))) == size(maximum(A,(1,2,3)))
 
 # any & all