Fix a problem in #483

Author: chriselrod

Project.toml

@@ -1,7 +1,7 @@
 name = "LoopVectorization"
 uuid = "bdcacae8-1622-11e9-2a5c-532679323890"
 authors = ["Chris Elrod <elrodc@gmail.com>"]
-version = "0.12.155"
+version = "0.12.156"
 
 [weakdeps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"

src/codegen/lower_threads.jl

@@ -196,7 +196,13 @@ function push_loop_length_expr!(q::Expr, ls::LoopSet)
   if length(ls.loops) == 1
     ndynamic == 0 && push!(q.args, l)
   elseif l == 1
-    push!(q.args, mulexpr)
+    if ndynamic == 1
+      push!(q.args, last(mulexpr.args))
+    elseif ndynamic == 0
+      push!(q.args, l)
+    else
+      push!(q.args, mulexpr)
+    end
   elseif ndynamic == 0
     push!(q.args, l)
   elseif ndynamic == 1

test/threading.jl

@@ -172,4 +172,13 @@ end
   thread_cartesian_indices!(dst, src)
   dst ≈ src
 
+  let a = zeros(3, 2), N = 2
+    @turbo thread = true for i = 1:1, j = 1:N
+      a[i, j] += 1.0
+    end
+    @test all(isone, @view(a[1, :]))
+    @test all(iszero, @view(a[2:end, :]))
+  end
+
+
 end