[gcc r8-10471] phiopt: Avoid -fcompare-debug bug in phiopt [PR94211]

[Jakub Jelinek]

https://gcc.gnu.org/g:2b0aaa4970a8d174b00fb98b4d24550d1c9a4e3a

commit r8-10471-g2b0aaa4970a8d174b00fb98b4d24550d1c9a4e3a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Mar 19 10:24:16 2020 +0100

    phiopt: Avoid -fcompare-debug bug in phiopt [PR94211]
    
    Two years ago, I've added support for up to 2 simple preparation statements
    in value_replacement, but the
    -      && estimate_num_insns (assign, &eni_time_weights)
    +      && estimate_num_insns (bb_seq (middle_bb), &eni_time_weights)
    change, meant that we compute the cost of all those statements rather than
    just the single assign that has been the single supported non-debug
    statement in the bb before, doesn't do what I thought would do, gimple_seq
    is just gimple * and thus it can't be really overloaded depending on whether
    we pass a single gimple * or a whole sequence.  Which means in the last
    two years it doesn't count all the statements, but only the first one.
    With -g that happens to be a DEBUG_STMT, or it could be e.g. the first
    preparation statement which could be much cheaper than the actual assign.
    
    2020-03-19  Jakub Jelinek  <jakub@redhat.com>
    
            PR tree-optimization/94211
            * tree-ssa-phiopt.c (value_replacement): Use estimate_num_insns_seq
            instead of estimate_num_insns for bb_seq (middle_bb).  Rename
            emtpy_or_with_defined_p variable to empty_or_with_defined_p, adjust
            all uses.
    
            * gcc.dg/pr94211.c: New test.
    
    (cherry picked from commit 8db876e9c045c57d2dc5bd08a6e250f822efaad0)

Diff:
---
 gcc/testsuite/gcc.dg/pr94211.c | 12 ++++++++++++
 gcc/tree-ssa-phiopt.c          | 10 +++++-----
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/pr94211.c b/gcc/testsuite/gcc.dg/pr94211.c
new file mode 100644
index 00000000000..3e160e457fe
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr94211.c
@@ -0,0 +1,12 @@
+/* PR tree-optimization/94211 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fcompare-debug" } */
+
+long
+foo (long a, long b)
+{
+  if (__builtin_expect (b == 1, 1))
+    return a;
+  int e = a + 1;
+  return a / b;
+}
diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
index 53f46dc0350..c6826cb87a2 100644
--- a/gcc/tree-ssa-phiopt.c
+++ b/gcc/tree-ssa-phiopt.c
@@ -890,7 +890,7 @@ value_replacement (basic_block cond_bb, basic_block middle_bb,
   gimple *cond;
   edge true_edge, false_edge;
   enum tree_code code;
-  bool emtpy_or_with_defined_p = true;
+  bool empty_or_with_defined_p = true;
 
   /* If the type says honor signed zeros we cannot do this
      optimization.  */
@@ -907,7 +907,7 @@ value_replacement (basic_block cond_bb, basic_block middle_bb,
       gsi_next_nondebug (&gsi);
       if (!is_gimple_assign (stmt))
 	{
-	  emtpy_or_with_defined_p = false;
+	  empty_or_with_defined_p = false;
 	  continue;
 	}
       /* Now try to adjust arg0 or arg1 according to the computation
@@ -917,7 +917,7 @@ value_replacement (basic_block cond_bb, basic_block middle_bb,
 	     && jump_function_from_stmt (&arg0, stmt))
 	    || (lhs == arg1
 		&& jump_function_from_stmt (&arg1, stmt)))
-	emtpy_or_with_defined_p = false;
+	empty_or_with_defined_p = false;
     }
 
   cond = last_stmt (cond_bb);
@@ -969,7 +969,7 @@ value_replacement (basic_block cond_bb, basic_block middle_bb,
       /* If the middle basic block was empty or is defining the
 	 PHI arguments and this is a single phi where the args are different
 	 for the edges e0 and e1 then we can remove the middle basic block. */
-      if (emtpy_or_with_defined_p
+      if (empty_or_with_defined_p
 	  && single_non_singleton_phi_for_edges (phi_nodes (gimple_bb (phi)),
 						 e0, e1) == phi)
 	{
@@ -1087,7 +1087,7 @@ value_replacement (basic_block cond_bb, basic_block middle_bb,
       && profile_status_for_fn (cfun) != PROFILE_ABSENT
       && EDGE_PRED (middle_bb, 0)->probability < profile_probability::even ()
       /* If assign is cheap, there is no point avoiding it.  */
-      && estimate_num_insns (bb_seq (middle_bb), &eni_time_weights)
+      && estimate_num_insns_seq (bb_seq (middle_bb), &eni_time_weights)
 	 >= 3 * estimate_num_insns (cond, &eni_time_weights))
     return 0;