Check whether prefetched load is unrolled. Fixes #225.

Author: chriselrod

src/codegen/lower_load.jl

@@ -81,6 +81,7 @@ function add_prefetches!(q::Expr, ls::LoopSet, op::Operation, td::UnrollArgs, pr
         (ind == u₁loopsym) && (i = j)
     end
     push!(q.args, Expr(:call, lv(:prefetch0), gptr, copy(inds)))
+    i == 0 && return
     for u ∈ 1:u₁-1
         # for u ∈ umin:min(umin,U-1)
         # (u₁loopsym === vloopsym && !iszero(u & dontskip)) && continue

src/reconstruct_loopset.jl

@@ -623,7 +623,7 @@ Execute an `@avx` block. The block's code is represented via the arguments:
 @generated function _avx_!(
     ::Val{UNROLL}, ::Val{OPS}, ::Val{ARF}, ::Val{AM}, ::Val{LPSYM}, var"#lv#tuple#args#"::Tuple{LB,V}
 ) where {UNROLL, OPS, ARF, AM, LPSYM, LB, V}
-    # 1 + 1 # Irrelevant line you can comment out/in to force recompilation...
+    1 + 1 # Irrelevant line you can comment out/in to force recompilation...
     ls = _avx_loopset(OPS, ARF, AM, LPSYM, LB.parameters, V.parameters, UNROLL)
     # return @show avx_body(ls, UNROLL)
     if last(UNROLL) > 1