The following patch partially reverts r212352 to restore bootstrap
on i585-linux (where I reproduced and verified the fix). It makes
phicprop honor that loop-depth condition again which doing not
seems to cause a latent bug to pop up which miscompiles the stage2
compiler which in turn miscompiles stage3 genmodes.
I don't have time to track down the failure thus the revert below.
Also bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard.
2014-07-10 Richard Biener <rguent...@suse.de>
PR tree-optimization/61757
* tree-ssa-dom.c (loop_depth_of_name): Restore.
(propagate_rhs_into_lhs): Revert part of last change.
Index: gcc/tree-ssa-dom.c
===================================================================
--- gcc/tree-ssa-dom.c (revision 212352)
+++ gcc/tree-ssa-dom.c (working copy)
@@ -2639,6 +2639,33 @@ get_lhs_or_phi_result (gimple stmt)
gcc_unreachable ();
}
+/* Return the loop depth of the basic block of the defining statement of X.
+ This number should not be treated as absolutely correct because the loop
+ information may not be completely up-to-date when dom runs. However, it
+ will be relatively correct, and as more passes are taught to keep loop info
+ up to date, the result will become more and more accurate. */
+
+static int
+loop_depth_of_name (tree x)
+{
+ gimple defstmt;
+ basic_block defbb;
+
+ /* If it's not an SSA_NAME, we have no clue where the definition is. */
+ if (TREE_CODE (x) != SSA_NAME)
+ return 0;
+
+ /* Otherwise return the loop depth of the defining statement's bb.
+ Note that there may not actually be a bb for this statement, if the
+ ssa_name is live on entry. */
+ defstmt = SSA_NAME_DEF_STMT (x);
+ defbb = gimple_bb (defstmt);
+ if (!defbb)
+ return 0;
+
+ return bb_loop_depth (defbb);
+}
+
/* Propagate RHS into all uses of LHS (when possible).
RHS and LHS are derived from STMT, which is passed in solely so
@@ -2654,7 +2681,8 @@ static void
propagate_rhs_into_lhs (gimple stmt, tree lhs, tree rhs, bitmap
interesting_names)
{
/* First verify that propagation is valid. */
- if (may_propagate_copy (lhs, rhs))
+ if (may_propagate_copy (lhs, rhs)
+ && loop_depth_of_name (lhs) >= loop_depth_of_name (rhs))
{
use_operand_p use_p;
imm_use_iterator iter;
