optimize identity splat of a tuple, (t...,) (JuliaLang#30571)

simeonschaub · Jan 4, 2019 · a153fea · a153fea
1 parent 0b7f689
commit a153fea
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diff --git a/base/compiler/ssair/inlining.jl b/base/compiler/ssair/inlining.jl
@@ -837,6 +837,12 @@ function assemble_inline_todo!(ir::IRCode, linetable::Vector{LineInfoNode}, sv::
  # Independent of whether we can inline, the above analysis allows us to rewrite
  # this apply call to a regular call
  ft = atypes[2]
+ if length(atypes) == 3 && ft isa Const && ft.val === Core.tuple && atypes[3] ⊑ Tuple
+ # rewrite `((t::Tuple)...,)` to `t`
+ ir.stmts[idx] = stmt.args[3]
+ ok = false
+ break
+ end
  stmt.args, atypes = rewrite_apply_exprargs!(ir, idx, stmt.args, atypes, sv)
  ok = !has_free_typevars(ft)
  ok || break

diff --git a/src/builtins.c b/src/builtins.c
@@ -462,6 +462,9 @@ JL_CALLABLE(jl_f__apply)
  return (jl_value_t*)t;
  }
  }
+ else if (f == jl_builtin_tuple && jl_is_tuple(args[1])) {
+ return args[1];
+ }
  }
  size_t n=0, i, j;
  for(i=1; i < nargs; i++) {

diff --git a/test/compiler/inline.jl b/test/compiler/inline.jl
@@ -217,3 +217,6 @@ function f_div(x, y)
  return x
 end
 @test length(code_typed(f_div, (Int, Int))[1][1].code) > 1
+
+f_identity_splat(t) = (t...,)
+@test length(code_typed(f_identity_splat, (Tuple{Int,Int},))[1][1].code) == 1