[PATCH] Fix reassociation with -g (PR tree-optimization/60844)

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

The (admittedly ugly) reassoc stmt positioning stuff requires that
we maintain uids in ascending order within each bb (equal uid for several
adjacent stmts is ok), including debug stmts.
We assign those initially, and for stmts we add we make sure to copy the
uid from some adjacent insn.

But, as the following testcase shows, we don't take into account that
gsi_remove can add debug stmts, and those don't have uid set.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
ok for trunk/4.9.1?

2014-04-15  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/60844
	* tree-ssa-reassoc.c (reassoc_remove_stmt): New function.
	(propagate_op_to_single_use, remove_visited_stmt_chain,
	linearize_expr, repropagate_negates, reassociate_bb): Use it
	instead of gsi_remove.

	* gcc.dg/pr60844.c: New test.

--- gcc/tree-ssa-reassoc.c.jj	2014-03-13 10:38:09.000000000 +0100
+++ gcc/tree-ssa-reassoc.c	2014-04-15 13:59:14.511383249 +0200
@@ -221,6 +221,35 @@ static struct pointer_map_t *operand_ran
 static long get_rank (tree);
 static bool reassoc_stmt_dominates_stmt_p (gimple, gimple);
 
+/* Wrapper around gsi_remove, which adjusts gimple_uid of debug stmts
+   possibly added by gsi_remove.  */
+
+bool
+reassoc_remove_stmt (gimple_stmt_iterator *gsi)
+{
+  gimple stmt = gsi_stmt (*gsi);
+
+  if (!MAY_HAVE_DEBUG_STMTS || gimple_code (stmt) == GIMPLE_PHI)
+    return gsi_remove (gsi, true);
+
+  gimple_stmt_iterator prev = *gsi;
+  gsi_prev (&prev);
+  unsigned uid = gimple_uid (stmt);
+  basic_block bb = gimple_bb (stmt);
+  bool ret = gsi_remove (gsi, true);
+  if (!gsi_end_p (prev))
+    gsi_next (&prev);
+  else
+    prev = gsi_start_bb (bb);
+  gimple end_stmt = gsi_stmt (*gsi);
+  while ((stmt = gsi_stmt (prev)) != end_stmt)
+    {
+      gcc_assert (stmt && is_gimple_debug (stmt) && gimple_uid (stmt) == 0);
+      gimple_set_uid (stmt, uid);
+      gsi_next (&prev);
+    }
+  return ret;
+}
 
 /* Bias amount for loop-carried phis.  We want this to be larger than
    the depth of any reassociation tree we can see, but not larger than
@@ -1123,7 +1152,7 @@ propagate_op_to_single_use (tree op, gim
     update_stmt (use_stmt);
   gsi = gsi_for_stmt (stmt);
   unlink_stmt_vdef (stmt);
-  gsi_remove (&gsi, true);
+  reassoc_remove_stmt (&gsi);
   release_defs (stmt);
 }
 
@@ -3072,7 +3101,7 @@ remove_visited_stmt_chain (tree var)
 	{
 	  var = gimple_assign_rhs1 (stmt);
 	  gsi = gsi_for_stmt (stmt);
-	  gsi_remove (&gsi, true);
+	  reassoc_remove_stmt (&gsi);
 	  release_defs (stmt);
 	}
       else
@@ -3494,7 +3523,7 @@ linearize_expr (gimple stmt)
   update_stmt (stmt);
 
   gsi = gsi_for_stmt (oldbinrhs);
-  gsi_remove (&gsi, true);
+  reassoc_remove_stmt (&gsi);
   release_defs (oldbinrhs);
 
   gimple_set_visited (stmt, true);
@@ -3896,7 +3925,7 @@ repropagate_negates (void)
 	      gimple_assign_set_rhs_with_ops (&gsi2, NEGATE_EXPR, x, NULL);
 	      user = gsi_stmt (gsi2);
 	      update_stmt (user);
-	      gsi_remove (&gsi, true);
+	      reassoc_remove_stmt (&gsi);
 	      release_defs (feed);
 	      plus_negates.safe_push (gimple_assign_lhs (user));
 	    }
@@ -4413,7 +4442,7 @@ reassociate_bb (basic_block bb)
 		 reassociations.  */
 	      if (has_zero_uses (gimple_get_lhs (stmt)))
 		{
-		  gsi_remove (&gsi, true);
+		  reassoc_remove_stmt (&gsi);
 		  release_defs (stmt);
 		  /* We might end up removing the last stmt above which
 		     places the iterator to the end of the sequence.
--- gcc/testsuite/gcc.dg/pr60844.c.jj	2014-04-15 14:01:27.561689401 +0200
+++ gcc/testsuite/gcc.dg/pr60844.c	2014-04-15 14:01:10.000000000 +0200
@@ -0,0 +1,16 @@
+/* PR tree-optimization/60844 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -g" } */
+/* { dg-additional-options "-mtune=atom" { target { i?86-*-* x86_64-*-* } } } */
+
+void
+foo (int *x, int y, int z)
+{
+  int b, c = x[0], d = x[1];
+  for (b = 0; b < 1; b++)
+    {
+      int e = (y ? 1 : 0) | (d ? 2 : 0) | (z ? 1 : 0);
+      e |= (c ? 2 : 0) | ((1 >> b) ? 1 : 0);
+      x[2 + b] = e;
+    }
+}

	Jakub