This removes an odd restriction in lookup_tmp_vars helper create_tmp_from_val. That conditionalizes whether vector and complex variables get to have a register based on whether the tmp var is a formal one or not. But that can't matter for correctness, either all temporaries can get a register or none.
The only case is prepare_gimple_addressable which is used to avoid marking a register as addressable by creating a new temporary (otherwise previous other gimplifications could need revisiting). But here we can safely un-set DECL_GIMPLE_REG_P before the new temporary gets further uses. This improves initial code-gen for gcc.dg/tree-ssa/forwprop-19.c for example when gimplfying vec z = VEC_PERM_EXPR < SAVE_EXPR <y> , SAVE_EXPR <y> , m > ; creating y.0 = y; z = VEC_PERM_EXPR <y.0, y.0, m>; instead of two extra loads from y.0 for the uses in the VEC_PERM_EXPR. Thus the following, bootstrapped on x86_64-unknown-linux-gnu, testing in progress. Richard. 2014-06-04 Richard Biener <rguent...@suse.de> * gimplify.c (create_tmp_from_val): Remove is_formal parameter and set DECL_GIMPLE_REG_P unconditionally if appropriate. (lookup_tmp_var): Adjust. (prepare_gimple_addressable): Unset DECL_GIMPLE_REG_P here. Index: gcc/gimplify.c =================================================================== --- gcc/gimplify.c (revision 211227) +++ gcc/gimplify.c (working copy) @@ -451,14 +451,13 @@ is_gimple_mem_rhs_or_call (tree t) lookup_tmp_var; nobody else should call this function. */ static inline tree -create_tmp_from_val (tree val, bool is_formal) +create_tmp_from_val (tree val) { /* Drop all qualifiers and address-space information from the value type. */ tree type = TYPE_MAIN_VARIANT (TREE_TYPE (val)); tree var = create_tmp_var (type, get_name (val)); - if (is_formal - && (TREE_CODE (TREE_TYPE (var)) == COMPLEX_TYPE - || TREE_CODE (TREE_TYPE (var)) == VECTOR_TYPE)) + if (TREE_CODE (TREE_TYPE (var)) == COMPLEX_TYPE + || TREE_CODE (TREE_TYPE (var)) == VECTOR_TYPE) DECL_GIMPLE_REG_P (var) = 1; return var; } @@ -477,7 +476,7 @@ lookup_tmp_var (tree val, bool is_formal work in reload and final and poorer code generation, outweighing the extra memory allocation here. */ if (!optimize || !is_formal || TREE_SIDE_EFFECTS (val)) - ret = create_tmp_from_val (val, is_formal); + ret = create_tmp_from_val (val); else { elt_t elt, *elt_p; @@ -491,7 +490,7 @@ lookup_tmp_var (tree val, bool is_formal { elt_p = XNEW (elt_t); elt_p->val = val; - elt_p->temp = ret = create_tmp_from_val (val, is_formal); + elt_p->temp = ret = create_tmp_from_val (val); *slot = elt_p; } else @@ -3154,7 +3153,11 @@ prepare_gimple_addressable (tree *expr_p while (handled_component_p (*expr_p)) expr_p = &TREE_OPERAND (*expr_p, 0); if (is_gimple_reg (*expr_p)) - *expr_p = get_initialized_tmp_var (*expr_p, seq_p, NULL); + { + tree var = get_initialized_tmp_var (*expr_p, seq_p, NULL); + DECL_GIMPLE_REG_P (var) = 0; + *expr_p = var; + } } /* A subroutine of gimplify_modify_expr. Replace a MODIFY_EXPR with