http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50213
--- Comment #4 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-09-07
08:59:01 UTC ---
With
Index: gcc/tree-ssa-forwprop.c
===================================================================
--- gcc/tree-ssa-forwprop.c (revision 178628)
+++ gcc/tree-ssa-forwprop.c (working copy)
@@ -34,6 +34,7 @@ along with GCC; see the file COPYING3.
#include "flags.h"
#include "gimple.h"
#include "expr.h"
+#include "cfgloop.h"
/* This pass propagates the RHS of assignment statements into use
sites of the LHS of the assignment. It's basically a specialized
@@ -1069,10 +1070,11 @@ forward_propagate_addr_expr (tree name,
continue;
}
- /* If the use is in a deeper loop nest, then we do not want
- to propagate non-invariant ADDR_EXPRs into the loop as that
- is likely adding expression evaluations into the loop. */
- if (gimple_bb (use_stmt)->loop_depth > stmt_loop_depth
+ /* If the use is in a different loop nest, then we do not want
+ to propagate non-invariant ADDR_EXPRs into or out of the loop
+ as that is likely adding expression evaluations into the loop
+ or extends register lifetimes across loop boundaries. */
+ if (gimple_bb (use_stmt)->loop_depth != stmt_loop_depth
&& !is_gimple_min_invariant (rhs))
{
all = false;
@@ -2322,6 +2324,13 @@ ssa_forward_propagate_and_combine (void)
{
basic_block bb;
unsigned int todoflags = 0;
+ bool cleanup_loops = false;
+
+ if (!current_loops)
+ {
+ loop_optimizer_init (LOOPS_NORMAL);
+ cleanup_loops = true;
+ }
cfg_changed = false;
@@ -2517,6 +2526,9 @@ ssa_forward_propagate_and_combine (void)
}
}
+ if (cleanup_loops)
+ loop_optimizer_finalize ();
+
if (cfg_changed)
todoflags |= TODO_cleanup_cfg;
This is fixed. Of course computing loops all over the place is ... not
the cheapest thing.
I'll see if we can easily avoid some of them.
