diff options
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/tree-ssa-propagate.c | 15 |
2 files changed, 17 insertions, 4 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index fa19176659c..2f3578696b9 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2011-07-21 Kai Tietz <ktietz@redhat.com> + + * tree-ssa-propagate.c (substitute_and_fold): Use + do_dce flag to deside, if BB's statements are scanned + in last to first, or first to last order. + 2011-07-21 Georg-Johann Lay <avr@gjlay.de> * config/avr/avr.c (avr_rtx_costs): Set cost of CONST, LABEL_REF to 0. diff --git a/gcc/tree-ssa-propagate.c b/gcc/tree-ssa-propagate.c index 64c3fdfe570..7741db88686 100644 --- a/gcc/tree-ssa-propagate.c +++ b/gcc/tree-ssa-propagate.c @@ -966,6 +966,9 @@ replace_phi_args_in (gimple phi, ssa_prop_get_value_fn get_value) DO_DCE is true if trivially dead stmts can be removed. + If DO_DCE is true, the statements within a BB are walked from + last to first element. Otherwise we scan from first to last element. + Return TRUE when something changed. */ bool @@ -1046,9 +1049,10 @@ substitute_and_fold (ssa_prop_get_value_fn get_value_fn, for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i)) replace_phi_args_in (gsi_stmt (i), get_value_fn); - /* Propagate known values into stmts. Do a backward walk to expose - more trivially deletable stmts. */ - for (i = gsi_last_bb (bb); !gsi_end_p (i);) + /* Propagate known values into stmts. Do a backward walk if + do_dce is true. In some case it exposes + more trivially deletable stmts to walk backward. */ + for (i = (do_dce ? gsi_last_bb (bb) : gsi_start_bb (bb)); !gsi_end_p (i);) { bool did_replace; gimple stmt = gsi_stmt (i); @@ -1057,7 +1061,10 @@ substitute_and_fold (ssa_prop_get_value_fn get_value_fn, gimple_stmt_iterator oldi; oldi = i; - gsi_prev (&i); + if (do_dce) + gsi_prev (&i); + else + gsi_next (&i); /* Ignore ASSERT_EXPRs. They are used by VRP to generate range information for names and they are discarded |