This fixes PR50213 by adding a heuristic to tree forwprop to not
propagate simple IV counter increments (similar as how to DOM
avoids to CSE them).
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard.
2011-09-07 Richard Guenther <rguent...@suse.de>
PR tree-optimization/50213
* tree-flow.h (simple_iv_increment_p): Declare.
* tree-ssa-dom.c (simple_iv_increment_p): Export. Also handle
POINTER_PLUS_EXPR.
* tree-ssa-forwprop.c (ssa_forward_propagate_and_combine): Do
not propagate simple IV counter increments.
Index: gcc/tree-flow.h
===================================================================
*** gcc/tree-flow.h (revision 178628)
--- gcc/tree-flow.h (working copy)
*************** extern void dump_dominator_optimization_
*** 597,602 ****
--- 597,603 ----
extern void debug_dominator_optimization_stats (void);
int loop_depth_of_name (tree);
tree degenerate_phi_result (gimple);
+ bool simple_iv_increment_p (gimple);
/* In tree-ssa-copy.c */
extern void propagate_value (use_operand_p, tree);
Index: gcc/tree-ssa-dom.c
===================================================================
*** gcc/tree-ssa-dom.c (revision 178628)
--- gcc/tree-ssa-dom.c (working copy)
*************** record_equality (tree x, tree y)
*** 1409,1417 ****
i_1 = phi (..., i_2)
i_2 = i_1 +/- ... */
! static bool
simple_iv_increment_p (gimple stmt)
{
tree lhs, preinc;
gimple phi;
size_t i;
--- 1409,1418 ----
i_1 = phi (..., i_2)
i_2 = i_1 +/- ... */
! bool
simple_iv_increment_p (gimple stmt)
{
+ enum tree_code code;
tree lhs, preinc;
gimple phi;
size_t i;
*************** simple_iv_increment_p (gimple stmt)
*** 1423,1434 ****
if (TREE_CODE (lhs) != SSA_NAME)
return false;
! if (gimple_assign_rhs_code (stmt) != PLUS_EXPR
! && gimple_assign_rhs_code (stmt) != MINUS_EXPR)
return false;
preinc = gimple_assign_rhs1 (stmt);
-
if (TREE_CODE (preinc) != SSA_NAME)
return false;
--- 1424,1436 ----
if (TREE_CODE (lhs) != SSA_NAME)
return false;
! code = gimple_assign_rhs_code (stmt);
! if (code != PLUS_EXPR
! && code != MINUS_EXPR
! && code != POINTER_PLUS_EXPR)
return false;
preinc = gimple_assign_rhs1 (stmt);
if (TREE_CODE (preinc) != SSA_NAME)
return false;
Index: gcc/tree-ssa-forwprop.c
===================================================================
*** gcc/tree-ssa-forwprop.c (revision 178628)
--- gcc/tree-ssa-forwprop.c (working copy)
*************** ssa_forward_propagate_and_combine (void)
*** 2377,2397 ****
else
gsi_next (&gsi);
}
! else if (code == POINTER_PLUS_EXPR && can_propagate_from (stmt))
{
! if (TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST
/* ??? Better adjust the interface to that function
instead of building new trees here. */
&& forward_propagate_addr_expr
! (lhs,
! build1 (ADDR_EXPR,
! TREE_TYPE (rhs),
! fold_build2 (MEM_REF,
! TREE_TYPE (TREE_TYPE (rhs)),
! rhs,
! fold_convert
! (ptr_type_node,
! gimple_assign_rhs2 (stmt))))))
{
release_defs (stmt);
todoflags |= TODO_remove_unused_locals;
--- 2377,2399 ----
else
gsi_next (&gsi);
}
! else if (code == POINTER_PLUS_EXPR)
{
! tree off = gimple_assign_rhs2 (stmt);
! if (TREE_CODE (off) == INTEGER_CST
! && can_propagate_from (stmt)
! && !simple_iv_increment_p (stmt)
/* ??? Better adjust the interface to that function
instead of building new trees here. */
&& forward_propagate_addr_expr
! (lhs,
! build1_loc (gimple_location (stmt),
! ADDR_EXPR, TREE_TYPE (rhs),
! fold_build2 (MEM_REF,
! TREE_TYPE (TREE_TYPE (rhs)),
! rhs,
! fold_convert (ptr_type_node,
! off)))))
{
release_defs (stmt);
todoflags |= TODO_remove_unused_locals;
