Re: [COMMITTED] Remove pass counting in VRP.

[Andrew MacLeod <amacleod@redhat.com>]

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On 10/3/23 13:02, David Malcolm wrote:
> On Tue, 2023-10-03 at 10:32 -0400, Andrew MacLeod wrote:
>> Pass counting in VRP is used to decide when to call early VRP, pass
>> the
>> flag to enable warnings, and when the final pass is.
>>
>> If you try to add additional passes, this becomes quite fragile. This
>> patch simply chooses the pass based on the data pointer passed in,
>> and
>> remove the pass counter.   The first FULL VRP pass invokes the
>> warning
>> code, and the flag passed in now represents the FINAL pass of VRP.
>> There is no longer a global flag which, as it turns out, wasn't
>> working
>> well with the JIT compiler, but when undetected.  (Thanks to dmalcolm
>> for helping me sort out what was going on there)
>>
>>
>> Bootstraps  on x86_64-pc-linux-gnu with no regressions.   Pushed.
> [CCing jit mailing list]
>
> I'm worried that this patch may have "papered over" an issue with
> libgccjit.  Specifically:

well, that isnt the patch that was checked in :-P

Im not sure how the old version got into the commit note.

Attached is the version checked in.


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commit 7eb5ce7f58ed4a48641e1786e4fdeb2f7fb8c5ff
Author: Andrew MacLeod <amacleod@redhat.com>
Date:   Thu Sep 28 09:19:32 2023 -0400

    Remove pass counting in VRP.
    
    Rather than using a pass count to decide which parameters are passed to
    VRP, makemit explicit.
    
            * passes.def (pass_vrp): Pass "final pass" flag as parameter.
            * tree-vrp.cc (vrp_pass_num): Remove.
            (pass_vrp::my_pass): Remove.
            (pass_vrp::pass_vrp): Add warn_p as a parameter.
            (pass_vrp::final_p): New.
            (pass_vrp::set_pass_param): Set final_p param.
            (pass_vrp::execute): Call execute_range_vrp with no conditions.
            (make_pass_vrp): Pass additional parameter.
            (make_pass_early_vrp): Ditto.

diff --git a/gcc/passes.def b/gcc/passes.def
index 4110a472914..2bafd60bbfb 100644
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -221,7 +221,7 @@ along with GCC; see the file COPYING3.  If not see
       NEXT_PASS (pass_fre, true /* may_iterate */);
       NEXT_PASS (pass_merge_phi);
       NEXT_PASS (pass_thread_jumps_full, /*first=*/true);
-      NEXT_PASS (pass_vrp, true /* warn_array_bounds_p */);
+      NEXT_PASS (pass_vrp, false /* final_p*/);
       NEXT_PASS (pass_dse);
       NEXT_PASS (pass_dce);
       /* pass_stdarg is always run and at this point we execute
@@ -348,7 +348,7 @@ along with GCC; see the file COPYING3.  If not see
       NEXT_PASS (pass_dominator, false /* may_peel_loop_headers_p */);
       NEXT_PASS (pass_strlen);
       NEXT_PASS (pass_thread_jumps_full, /*first=*/false);
-      NEXT_PASS (pass_vrp, false /* warn_array_bounds_p */);
+      NEXT_PASS (pass_vrp, true /* final_p */);
       /* Run CCP to compute alignment and nonzero bits.  */
       NEXT_PASS (pass_ccp, true /* nonzero_p */);
       NEXT_PASS (pass_warn_restrict);
diff --git a/gcc/tree-vrp.cc b/gcc/tree-vrp.cc
index d7b194f5904..4f8c7745461 100644
--- a/gcc/tree-vrp.cc
+++ b/gcc/tree-vrp.cc
@@ -1120,36 +1120,32 @@ const pass_data pass_data_early_vrp =
   ( TODO_cleanup_cfg | TODO_update_ssa | TODO_verify_all ),
 };
 
-static int vrp_pass_num = 0;
 class pass_vrp : public gimple_opt_pass
 {
 public:
-  pass_vrp (gcc::context *ctxt, const pass_data &data_)
-    : gimple_opt_pass (data_, ctxt), data (data_), warn_array_bounds_p (false),
-      my_pass (vrp_pass_num++)
-  {}
+  pass_vrp (gcc::context *ctxt, const pass_data &data_, bool warn_p)
+    : gimple_opt_pass (data_, ctxt), data (data_),
+      warn_array_bounds_p (warn_p), final_p (false)
+    { }
 
   /* opt_pass methods: */
-  opt_pass * clone () final override { return new pass_vrp (m_ctxt, data); }
+  opt_pass * clone () final override
+    { return new pass_vrp (m_ctxt, data, false); }
   void set_pass_param (unsigned int n, bool param) final override
     {
       gcc_assert (n == 0);
-      warn_array_bounds_p = param;
+      final_p = param;
     }
   bool gate (function *) final override { return flag_tree_vrp != 0; }
   unsigned int execute (function *fun) final override
     {
-      // Early VRP pass.
-      if (my_pass == 0)
-	return execute_ranger_vrp (fun, /*warn_array_bounds_p=*/false, false);
-
-      return execute_ranger_vrp (fun, warn_array_bounds_p, my_pass == 2);
+      return execute_ranger_vrp (fun, warn_array_bounds_p, final_p);
     }
 
  private:
   const pass_data &data;
   bool warn_array_bounds_p;
-  int my_pass;
+  bool final_p;
 }; // class pass_vrp
 
 const pass_data pass_data_assumptions =
@@ -1219,13 +1215,13 @@ public:
 gimple_opt_pass *
 make_pass_vrp (gcc::context *ctxt)
 {
-  return new pass_vrp (ctxt, pass_data_vrp);
+  return new pass_vrp (ctxt, pass_data_vrp, true);
 }
 
 gimple_opt_pass *
 make_pass_early_vrp (gcc::context *ctxt)
 {
-  return new pass_vrp (ctxt, pass_data_early_vrp);
+  return new pass_vrp (ctxt, pass_data_early_vrp, false);
 }
 
 gimple_opt_pass *