Make HSA resilient to side-effects of split_edge

2017-09-11  Martin Jambor  <mjambor@suse.cz>

	PR hsa/82119
	* hsa-gen.c (gen_hsa_phi_from_gimple_phi): Process ADDR_EXPRs in
	arguments in advance.
	* hsa-regalloc.c (naive_process_phi): New parameter predecessors,
	use it to find predecessor edges.
	(naive_outof_ssa): Collect vector of predecessors.

From-SVN: r251964

gcc/ChangeLog

+2017-09-11  Martin Jambor  <mjambor@suse.cz>
+
+	PR hsa/82119
+	* hsa-gen.c (gen_hsa_phi_from_gimple_phi): Process ADDR_EXPRs in
+	arguments in advance.
+	* hsa-regalloc.c (naive_process_phi): New parameter predecessors,
+	use it to find predecessor edges.
+	(naive_outof_ssa): Collect vector of predecessors.
+
 2017-09-08  Jason Merrill  <jason@redhat.com>
 
 	PR c++/70029 - ICE with ref-qualifier and -flto

gcc/hsa-gen.c

@@ -5657,8 +5657,37 @@ gen_hsa_phi_from_gimple_phi (gimple *phi_stmt, hsa_bb *hbb)
   hphi = new hsa_insn_phi (count, dest);
   hphi->m_bb = hbb->m_bb;
 
-  tree lhs = gimple_phi_result (phi_stmt);
+  auto_vec <tree, 8> aexprs;
+  auto_vec <hsa_op_reg *, 8> aregs;
+
+  /* Calling split_edge when processing a PHI node messes up with the order of
+     gimple phi node arguments (it moves the one associated with the edge to
+     the end).  We need to keep the order of edges and arguments of HSA phi
+     node arguments consistent, so we do all required splitting as the first
+     step, and in reverse order as to not be affected by the re-orderings.  */
+  for (unsigned j = count; j != 0; j--)
+    {
+      unsigned i = j - 1;
+      tree op = gimple_phi_arg_def (phi_stmt, i);
+      if (TREE_CODE (op) != ADDR_EXPR)
+	continue;
 
+      edge e = gimple_phi_arg_edge (as_a <gphi *> (phi_stmt), i);
+      hsa_bb *hbb_src = hsa_init_new_bb (split_edge (e));
+      hsa_op_address *addr = gen_hsa_addr (TREE_OPERAND (op, 0),
+					   hbb_src);
+
+      hsa_op_reg *dest
+	= new hsa_op_reg (hsa_get_segment_addr_type (BRIG_SEGMENT_FLAT));
+      hsa_insn_basic *insn
+	= new hsa_insn_basic (2, BRIG_OPCODE_LDA, BRIG_TYPE_U64,
+			      dest, addr);
+      hbb_src->append_insn (insn);
+      aexprs.safe_push (op);
+      aregs.safe_push (dest);
+    }
+
+  tree lhs = gimple_phi_result (phi_stmt);
   for (unsigned i = 0; i < count; i++)
     {
       tree op = gimple_phi_arg_def (phi_stmt, i);
@@ -5684,18 +5713,14 @@ gen_hsa_phi_from_gimple_phi (gimple *phi_stmt, hsa_bb *hbb)
 	    }
 	  else if (TREE_CODE (op) == ADDR_EXPR)
 	    {
-	      edge e = gimple_phi_arg_edge (as_a <gphi *> (phi_stmt), i);
-	      hsa_bb *hbb_src = hsa_init_new_bb (split_edge (e));
-	      hsa_op_address *addr = gen_hsa_addr (TREE_OPERAND (op, 0),
-						   hbb_src);
-
-	      hsa_op_reg *dest
-		= new hsa_op_reg (hsa_get_segment_addr_type (BRIG_SEGMENT_FLAT));
-	      hsa_insn_basic *insn
-		= new hsa_insn_basic (2, BRIG_OPCODE_LDA, BRIG_TYPE_U64,
-				      dest, addr);
-	      hbb_src->append_insn (insn);
-
+	      hsa_op_reg *dest = NULL;
+	      for (unsigned a_idx = 0; a_idx < aexprs.length (); a_idx++)
+		if (aexprs[a_idx] == op)
+		  {
+		    dest = aregs[a_idx];
+		    break;
+		  }
+	      gcc_assert (dest);
 	      hphi->set_op (i, dest);
 	    }
 	  else

gcc/hsa-regalloc.c

@@ -42,7 +42,7 @@ along with GCC; see the file COPYING3.  If not see
 /* Process a PHI node PHI of basic block BB as a part of naive out-f-ssa.  */
 
 static void
-naive_process_phi (hsa_insn_phi *phi)
+naive_process_phi (hsa_insn_phi *phi, const vec<edge> &predecessors)
 {
   unsigned count = phi->operand_count ();
   for (unsigned i = 0; i < count; i++)
@@ -55,7 +55,7 @@ naive_process_phi (hsa_insn_phi *phi)
       if (!op)
 	break;
 
-      e = EDGE_PRED (phi->m_bb, i);
+      e = predecessors[i];
       if (single_succ_p (e->src))
 	hbb = hsa_bb_for_bb (e->src);
       else
@@ -89,10 +89,18 @@ naive_outof_ssa (void)
     hsa_bb *hbb = hsa_bb_for_bb (bb);
     hsa_insn_phi *phi;
 
+    /* naive_process_phi can call split_edge on an incoming edge which order if
+       the incoming edges to the basic block and thus make it inconsistent with
+       the ordering of PHI arguments, so we collect them in advance.  */
+    auto_vec<edge, 8> predecessors;
+    unsigned pred_count = EDGE_COUNT (bb->preds);
+    for (unsigned i = 0; i < pred_count; i++)
+      predecessors.safe_push (EDGE_PRED (bb, i));
+
     for (phi = hbb->m_first_phi;
 	 phi;
 	 phi = phi->m_next ? as_a <hsa_insn_phi *> (phi->m_next) : NULL)
-      naive_process_phi (phi);
+      naive_process_phi (phi, predecessors);
 
     /* Zap PHI nodes, they will be deallocated when everything else will.  */
     hbb->m_first_phi = NULL;