https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24574
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at gcc dot gnu.org
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Only for -Os, it's better to avoid the expensive division otherwise. Maybe
if we can predict the division to be likely executed it is profitable to
make it unconditional.
Missing GIMPLE phiopt.
absorbing_element_p needs to handle division for this.
Index: gcc/tree-ssa-phiopt.c
===================================================================
--- gcc/tree-ssa-phiopt.c (revision 238242)
+++ gcc/tree-ssa-phiopt.c (working copy)
@@ -812,7 +812,7 @@ neutral_element_p (tree_code code, tree
/* Returns true if ARG is an absorbing element for operation CODE. */
static bool
-absorbing_element_p (tree_code code, tree arg)
+absorbing_element_p (tree_code code, tree arg, bool right)
{
switch (code)
{
@@ -823,6 +823,13 @@ absorbing_element_p (tree_code code, tre
case BIT_AND_EXPR:
return integer_zerop (arg);
+ case TRUNC_DIV_EXPR:
+ case CEIL_DIV_EXPR:
+ case FLOOR_DIV_EXPR:
+ case ROUND_DIV_EXPR:
+ case EXACT_DIV_EXPR:
+ return !right && integer_zerop (arg);
+
default:
return false;
}
@@ -994,9 +1001,10 @@ value_replacement (basic_block cond_bb,
&& operand_equal_for_phi_arg_p (rhs1, cond_lhs)
&& neutral_element_p (code_def, cond_rhs, false))
|| (operand_equal_for_phi_arg_p (arg1, cond_rhs)
- && (operand_equal_for_phi_arg_p (rhs2, cond_lhs)
- || operand_equal_for_phi_arg_p (rhs1, cond_lhs))
- && absorbing_element_p (code_def, cond_rhs))))
+ && ((operand_equal_for_phi_arg_p (rhs2, cond_lhs)
+ && absorbing_element_p (code_def, cond_rhs, true))
+ || (operand_equal_for_phi_arg_p (rhs1, cond_lhs)
+ && absorbing_element_p (code_def, cond_rhs, false))))))
{
gsi = gsi_for_stmt (cond);
if (INTEGRAL_TYPE_P (TREE_TYPE (lhs)))
