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[Ada] Avoid duplicating branches in loop conditions
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Mon, 21 Mar 2011 13:07:26 +0100
- Subject: [Ada] Avoid duplicating branches in loop conditions
This avoids duplicating branches in the generated code at -O0 for complex loop
conditions involving boolean expressions.
Tested on i586-suse-linux, applied on the mainline.
2011-03-21 Eric Botcazou <ebotcazou@adacore.com>
* gcc-interface/decl.c (elaborate_expression_1): When optimization is
disabled, use the variable for bounds of loop iteration scheme.
--
Eric Botcazou
Index: gcc-interface/decl.c
===================================================================
--- gcc-interface/decl.c (revision 171210)
+++ gcc-interface/decl.c (working copy)
@@ -6004,7 +6004,7 @@ elaborate_expression_1 (tree gnu_expr, E
bool definition, bool need_debug)
{
const bool expr_global_p = Is_Public (gnat_entity) || global_bindings_p ();
- bool expr_variable_p;
+ bool expr_variable_p, use_variable;
tree gnu_decl;
/* In most cases, we won't see a naked FIELD_DECL because a discriminant
@@ -6058,8 +6058,18 @@ elaborate_expression_1 (tree gnu_expr, E
&& (TREE_READONLY (inner) || DECL_READONLY_ONCE_ELAB (inner)));
}
- /* Now create the variable if we need it. */
- if (need_debug || (expr_variable_p && expr_global_p))
+ /* We only need to use the variable if we are in a global context since GCC
+ can do the right thing in the local case. However, when not optimizing,
+ use it for bounds of loop iteration scheme to avoid code duplication. */
+ use_variable = expr_variable_p
+ && (expr_global_p
+ || (!optimize
+ && Is_Itype (gnat_entity)
+ && Nkind (Associated_Node_For_Itype (gnat_entity))
+ == N_Loop_Parameter_Specification));
+
+ /* Now create it, possibly only for debugging purposes. */
+ if (use_variable || need_debug)
gnu_decl
= create_var_decl (create_concat_name (gnat_entity,
IDENTIFIER_POINTER (gnu_name)),
@@ -6067,9 +6077,7 @@ elaborate_expression_1 (tree gnu_expr, E
!need_debug, Is_Public (gnat_entity),
!definition, expr_global_p, NULL, gnat_entity);
- /* We only need to use this variable if we are in global context since GCC
- can do the right thing in the local case. */
- if (expr_global_p && expr_variable_p)
+ if (use_variable)
return gnu_decl;
return expr_variable_p ? gnat_save_expr (gnu_expr) : gnu_expr;