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tree-optimization/116902 - vectorizer load hosting breaks UID order #2

Message ID 20241001122843.0F3DD386F47C@sourceware.org
State New
Headers show
Series tree-optimization/116902 - vectorizer load hosting breaks UID order #2 | expand

Commit Message

Richard Biener Oct. 1, 2024, 12:28 p.m. UTC 
This is another case of load hoisting breaking UID order in the
preheader, this time between two hoistings.  The easiest way out is
to do what we do for the main stmt - copy instead of move.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

	PR tree-optimization/116902
	PR tree-optimization/116842
	* tree-vect-stmts.cc (sort_after_uid): Remove again.
	(hoist_defs_of_uses): Copy defs instead of hoisting them so
	we can zero their UID.
	(vectorizable_load): Separate analysis and transform call,
	do transform on the stmt copy.

	* g++.dg/torture/pr116902.C: New testcase.
---
 gcc/testsuite/g++.dg/torture/pr116902.C | 20 +++++++++
 gcc/tree-vect-stmts.cc                  | 54 ++++++++++++-------------
 2 files changed, 45 insertions(+), 29 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/torture/pr116902.C
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Patch

diff --git a/gcc/testsuite/g++.dg/torture/pr116902.C b/gcc/testsuite/g++.dg/torture/pr116902.C
new file mode 100644
index 00000000000..cf195c8ac02
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr116902.C
@@ -0,0 +1,20 @@ 
+// { dg-do compile }
+// { dg-additional-options "-ftree-vectorize" }
+
+template<typename _Tp>
+inline const _Tp&
+min(const _Tp& __a, const _Tp& __b)
+{
+  if (__b < __a)
+    return __b;
+  return __a;
+}
+
+unsigned a;
+void i(long b, char c[][4], long d[][4]) {
+  for (char e; e; e++)
+    for (char f = 0; f < 021; f = b)
+      for (signed char g; g < 7; g += ~0)
+        for (bool h = 0; h < bool(d[f][f]); h = 1)
+          a = c[2][1] - min(c[1][f + 1], c[2][f + 2]);
+}
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index b880f050715..584be52f423 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -9788,20 +9788,6 @@  permute_vec_elements (vec_info *vinfo,
   return data_ref;
 }
 
-/* Comparator for qsort, sorting after GIMPLE UID.  */
-
-static int
-sort_after_uid (const void *a_, const void *b_)
-{
-  const gimple *a = *(const gimple * const *)a_;
-  const gimple *b = *(const gimple * const *)b_;
-  if (gimple_uid (a) < gimple_uid (b))
-    return -1;
-  else if (gimple_uid (a) > gimple_uid (b))
-    return 1;
-  return 0;
-}
-
 /* Hoist the definitions of all SSA uses on STMT_INFO out of the loop LOOP,
    inserting them on the loops preheader edge.  Returns true if we
    were successful in doing so (and thus STMT_INFO can be moved then),
@@ -9809,15 +9795,15 @@  sort_after_uid (const void *a_, const void *b_)
    definitions of all SSA uses, it would be false when we are costing.  */
 
 static bool
-hoist_defs_of_uses (stmt_vec_info stmt_info, class loop *loop, bool hoist_p)
+hoist_defs_of_uses (gimple *stmt, class loop *loop, bool hoist_p)
 {
   ssa_op_iter i;
-  tree op;
-  auto_vec<gimple *, 8> to_hoist;
+  use_operand_p use_p;
+  auto_vec<use_operand_p, 8> to_hoist;
 
-  FOR_EACH_SSA_TREE_OPERAND (op, stmt_info->stmt, i, SSA_OP_USE)
+  FOR_EACH_SSA_USE_OPERAND (use_p, stmt, i, SSA_OP_USE)
     {
-      gimple *def_stmt = SSA_NAME_DEF_STMT (op);
+      gimple *def_stmt = SSA_NAME_DEF_STMT (USE_FROM_PTR (use_p));
       if (!gimple_nop_p (def_stmt)
 	  && flow_bb_inside_loop_p (loop, gimple_bb (def_stmt)))
 	{
@@ -9827,7 +9813,9 @@  hoist_defs_of_uses (stmt_vec_info stmt_info, class loop *loop, bool hoist_p)
 	     dependencies within them.  */
 	  tree op2;
 	  ssa_op_iter i2;
-	  if (gimple_code (def_stmt) == GIMPLE_PHI)
+	  if (gimple_code (def_stmt) == GIMPLE_PHI
+	      || (single_ssa_def_operand (def_stmt, SSA_OP_DEF)
+		  == NULL_DEF_OPERAND_P))
 	    return false;
 	  FOR_EACH_SSA_TREE_OPERAND (op2, def_stmt, i2, SSA_OP_USE)
 	    {
@@ -9836,7 +9824,7 @@  hoist_defs_of_uses (stmt_vec_info stmt_info, class loop *loop, bool hoist_p)
 		  && flow_bb_inside_loop_p (loop, gimple_bb (def_stmt2)))
 		return false;
 	    }
-	  to_hoist.safe_push (def_stmt);
+	  to_hoist.safe_push (use_p);
 	}
     }
 
@@ -9846,14 +9834,21 @@  hoist_defs_of_uses (stmt_vec_info stmt_info, class loop *loop, bool hoist_p)
   if (!hoist_p)
     return true;
 
-  /* Preserve UID order, otherwise we break dominance checks.  */
-  to_hoist.qsort (sort_after_uid);
-
-  for (gimple *def_stmt : to_hoist)
+  /* Instead of moving defs we copy them so we can zero their UID to not
+     confuse dominance queries in the preheader.  */
+  gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
+  for (use_operand_p use_p : to_hoist)
     {
-      gimple_stmt_iterator gsi = gsi_for_stmt (def_stmt);
-      gsi_remove (&gsi, false);
-      gsi_insert_on_edge_immediate (loop_preheader_edge (loop), def_stmt);
+      gimple *def_stmt = SSA_NAME_DEF_STMT (USE_FROM_PTR (use_p));
+      gimple *copy = gimple_copy (def_stmt);
+      gimple_set_uid (copy, 0);
+      def_operand_p def_p = single_ssa_def_operand (def_stmt, SSA_OP_DEF);
+      tree new_def = duplicate_ssa_name (DEF_FROM_PTR (def_p), copy);
+      update_stmt (copy);
+      def_p = single_ssa_def_operand (copy, SSA_OP_DEF);
+      SET_DEF (def_p, new_def);
+      SET_USE (use_p, new_def);
+      gsi_insert_before (&gsi, copy, GSI_SAME_STMT);
     }
 
   return true;
@@ -10227,7 +10222,7 @@  vectorizable_load (vec_info *vinfo,
 	 transform time.  */
       bool hoist_p = (LOOP_VINFO_NO_DATA_DEPENDENCIES (loop_vinfo)
 		      && !nested_in_vect_loop
-		      && hoist_defs_of_uses (stmt_info, loop, !costing_p));
+		      && hoist_defs_of_uses (stmt_info->stmt, loop, false));
       if (costing_p)
 	{
 	  enum vect_cost_model_location cost_loc
@@ -10264,6 +10259,7 @@  vectorizable_load (vec_info *vinfo,
 	  gimple *new_stmt = gimple_build_assign (scalar_dest, rhs);
 	  gimple_set_vuse (new_stmt, vuse);
 	  gsi_insert_on_edge_immediate (pe, new_stmt);
+	  hoist_defs_of_uses (new_stmt, loop, true);
 	}
       /* These copies are all equivalent.  */
       if (hoist_p)