Re: [PATCH] TREE-SSA remove redundant condition checks in get_default_value

[Jeff Law <law at redhat dot com>]

On 08/12/2013 12:46 AM, Zhouyi Zhou wrote:
> In function get_default_value of tree-ssa-ccp.c,
> 261   else if (is_gimple_assign (stmt)
> 262            /* Value-returning GIMPLE_CALL statements assign to
> 263               a variable, and are treated similarly to GIMPLE_ASSIGN.  */
> 264            || (is_gimple_call (stmt)
> 265                && gimple_call_lhs (stmt) != NULL_TREE)
> 266            || gimple_code (stmt) == GIMPLE_PHI)
> 267     {
> 268       tree cst;
> 269       if (gimple_assign_single_p (stmt)
> 270           && DECL_P (gimple_assign_rhs1 (stmt))
> 271           && (cst = get_symbol_constant_value (gimple_assign_rhs1 (stmt))))
> 272         {
> 273           val.lattice_val = CONSTANT;
> 274           val.value = cst;
> 275         }
> 276       else
> 277         /* Any other variable defined by an assignment or a PHI node
> 278            is considered UNDEFINED.  */
> 279         val.lattice_val = UNDEFINED;
> if the stmt is a gimple call node or a gimple phi node, it will never satisfy
> the condition gimple_assign_single_p (stmt). so there exists redundant condition
> checks. The patch attached try to remove this.
>
>
> Bootstrap passed. Regression tested on x86_64-unknown-linux-gnu (pc).
>
> ChangeLog:
> 2013-08-13  Zhouyi Zhou  <yizhouzhou@ict.ac.cn>
> 	* tree-ssa-ccp.c (get_default_value): remove redundant condition checks	
Thanks.  I fixed some minor formatting issues and committed your change 
after another bootstrap & regression test.

Jeff