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[PATCH/middle-end/diagnostic] Do not warn about unused out of bounds array refs
- From: Dirk Mueller <dmueller at suse dot de>
- To: gcc-patches at gcc dot gnu dot org
- Date: Tue, 20 Mar 2007 14:19:32 +0100
- Subject: [PATCH/middle-end/diagnostic] Do not warn about unused out of bounds array refs
Hi,
Marcus Meissner showed me one case where tree-alias introduced an out of
bounds array reference that wasn't used at all. Hence the patch below to
suppress warnings about such artifically constructed cases.
Bootstrapped, regtested on i686-suse-linux
Thanks,
Dirk
2007-03-20 Dirk Mueller <dmueller@suse.de>
* tree-vrp.c (check_array_bounds): Do not warn about
out of bounds array refs which are not immediately used.
--- tree-vrp.c
+++ tree-vrp.c
@@ -4112,6 +4112,10 @@ check_array_bounds (tree *tp, int *walk_
or
ssa_name = &array[-200]
+
+ or
+
+ ssa_name = &array[-200]
other_name = ssa_name + 300;
which are sometimes
@@ -4123,9 +4127,10 @@ check_array_bounds (tree *tp, int *walk_
if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
&& TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 0)) == SSA_NAME
- && single_imm_use (GIMPLE_STMT_OPERAND (stmt, 0), &op, &use_stmt)
+ && (has_zero_uses (GIMPLE_STMT_OPERAND (stmt, 0))
+ || (single_imm_use (GIMPLE_STMT_OPERAND (stmt, 0), &op, &use_stmt)
&& TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
- && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (use_stmt, 1)))
+ && BINARY_CLASS_P (GIMPLE_STMT_OPERAND (use_stmt, 1)))))
*walk_subtree = FALSE;
while (*walk_subtree && handled_component_p (t))