Index: gcc/tree-cfg.c
===================================================================
--- gcc/tree-cfg.c	(revision 192041)
+++ gcc/tree-cfg.c	(working copy)
@@ -6322,6 +6322,7 @@ move_block_to_fn (struct function *dest_cfun, basi
       use_operand_p use;
       tree op = PHI_RESULT (phi);
       ssa_op_iter oi;
+      unsigned i;
 
       if (virtual_operand_p (op))
 	{
@@ -6340,6 +6341,23 @@ move_block_to_fn (struct function *dest_cfun, basi
 	    SET_USE (use, replace_ssa_name (op, d->vars_map, dest_cfun->decl));
 	}
 
+      for (i = 0; i < EDGE_COUNT (bb->preds); i++)
+	{
+	  location_t locus = gimple_phi_arg_location (phi, i);
+	  tree block = LOCATION_BLOCK (locus);
+
+	  if (locus == UNKNOWN_LOCATION)
+	    continue;
+	  if (d->orig_block == NULL_TREE || block == d->orig_block)
+	    {
+	      if (d->new_block == NULL_TREE)
+		locus = LOCATION_LOCUS (locus);
+	      else
+		locus = COMBINE_LOCATION_DATA (line_table, locus, d->new_block);
+	      gimple_phi_arg_set_location (phi, i, locus);
+	    }
+	}
+
       gsi_next (&si);
     }
 
Index: gcc/testsuite/gcc.dg/pr54782.c
===================================================================
--- gcc/testsuite/gcc.dg/pr54782.c	(revision 0)
+++ gcc/testsuite/gcc.dg/pr54782.c	(revision 0)
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O -ffast-math -ftree-parallelize-loops=2 -g" } */
+
+struct S
+{
+  int n;
+  float *a;
+};
+
+int
+foo (struct S *s)
+{
+  float sum = 0;
+  int i;
+  for (i = 0; i < s->n; i++)
+    sum += s->a[i];
+  return sum;
+}