[Bug middle-end/29756] SSE intrinsics hard to use without redundant temporaries appearing

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=29756

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
Like

Index: gcc/config/i386/i386.c
===================================================================
--- gcc/config/i386/i386.c      (revision 236441)
+++ gcc/config/i386/i386.c      (working copy)
@@ -37745,6 +37745,23 @@ ix86_fold_builtin (tree fndecl, int n_ar
          gcc_assert (n_args == 1);
           return fold_builtin_cpu (fndecl, args);
        }
+      if (fn_code == IX86_BUILTIN_SHUFPS
+         && n_args == 3
+         && TREE_CODE (args[2]) == INTEGER_CST)
+       {
+         tree mask[4];
+         tree mtype = build_vector_type (integer_type_node, 4);
+         mask[0] = build_int_cst (integer_type_node,
+                                  TREE_INT_CST_LOW (args[2]) & 3);
+         mask[1] = build_int_cst (integer_type_node,
+                                  (TREE_INT_CST_LOW (args[2]) >> 2) & 3);
+         mask[2] = build_int_cst (integer_type_node,
+                                  ((TREE_INT_CST_LOW (args[2]) >> 4) & 3) +
4);
+         mask[3] = build_int_cst (integer_type_node,
+                                  ((TREE_INT_CST_LOW (args[2]) >> 6) & 3) +
4);
+         return fold_build3 (VEC_PERM_EXPR, TREE_TYPE (TREE_TYPE (fndecl)),
+                             args[0], args[1], build_vector (mtype, mask));
+       }
     }

 #ifdef SUBTARGET_FOLD_BUILTIN


given the plethora of shuffling intrinsics this might be quite tedious work...