ifcvt: Support bitfield lowering of multiple-exit loops

diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1-not.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1-not.c
new file mode 100644
index 0000000000000000000000000000000000000000..0d91067ebb27b1db2b2352975c43bce8b4171e3f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1-not.c
@@ -0,0 +1,60 @@ 
+/* { dg-require-effective-target vect_shift } */
+/* { dg-require-effective-target vect_long_long } */
+/* { dg-additional-options { "-fdump-tree-ifcvt-all" } } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    char a : 4;
+};
+
+#define N 32
+#define ELT0 {0}
+#define ELT1 {1}
+#define ELT2 {2}
+#define ELT3 {3}
+#define RES 56
+struct s A[N]
+  = { ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3};
+
+int __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    int res = 0;
+    for (int i = 0; i < n; ++i)
+      {
+	switch (ptr[i].a)
+	  {
+	  case 0:
+	    res += ptr[i].a + 1;
+	    break;
+	  case 1:
+	  case 2:
+	  case 3:
+	    res += ptr[i].a;
+	    break;
+	  default:
+	    return 0;
+	  }
+      }
+    return res;
+}
+
+int main (void)
+{
+  check_vect ();
+
+  if (f(&A[0], N) != RES)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-not "Bitfield OK to lower." "ifcvt" } } */
+
+
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-2-not.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-2-not.c
new file mode 100644
index 0000000000000000000000000000000000000000..4ac7b3fc0dfd1c9d0b5e94a2ba6a745545577ec1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-2-not.c
@@ -0,0 +1,49 @@ 
+/* { dg-require-effective-target vect_shift } */
+/* { dg-require-effective-target vect_long_long } */
+/* { dg-additional-options { "-fdump-tree-ifcvt-all" } } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    char a : 4;
+};
+
+#define N 32
+#define ELT0 {0}
+#define ELT1 {1}
+#define ELT2 {2}
+#define ELT3 {3}
+#define RES 48
+struct s A[N]
+  = { ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3};
+
+int __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    int res = 0;
+    for (int i = 0; i < n; ++i)
+      {
+	asm volatile ("" ::: "memory");
+	res += ptr[i].a;
+      }
+    return res;
+}
+
+int main (void)
+{
+  check_vect ();
+
+  if (f(&A[0], N) != RES)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-not "Bitfield OK to lower." "ifcvt" } } */
+
+
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-8.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-8.c
new file mode 100644
index 0000000000000000000000000000000000000000..52cfd33d937ae90f3fe9556716c90e098b768ac8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-8.c
@@ -0,0 +1,49 @@ 
+/* { dg-require-effective-target vect_int } */
+/* { dg-require-effective-target vect_shift } */
+/* { dg-additional-options { "-fdump-tree-ifcvt-all" } } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s { int i : 31; };
+
+#define ELT0 {0}
+#define ELT1 {1}
+#define ELT2 {2}
+#define ELT3 {3}
+#define ELT4 {4}
+#define N 32
+#define RES 25
+struct s A[N]
+  = { ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT4, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3};
+
+int __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    int res = 0;
+    for (int i = 0; i < n; ++i)
+      {
+	if (ptr[i].i == 4)
+	  return res;
+	res += ptr[i].i;
+      }
+
+    return res;
+}
+
+int main (void)
+{
+  check_vect ();
+
+  if (f(&A[0], N) != RES)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump "Bitfield OK to lower." "ifcvt" } } */
+
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-9.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-9.c
new file mode 100644
index 0000000000000000000000000000000000000000..ab814698131a5905def181eeed85d8a3c62b924b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-9.c
@@ -0,0 +1,51 @@ 
+/* { dg-require-effective-target vect_shift } */
+/* { dg-require-effective-target vect_long_long } */
+/* { dg-additional-options { "-fdump-tree-ifcvt-all" } } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    unsigned i : 31;
+    char a : 4;
+};
+
+#define N 32
+#define ELT0 {0x7FFFFFFFUL, 0}
+#define ELT1 {0x7FFFFFFFUL, 1}
+#define ELT2 {0x7FFFFFFFUL, 2}
+#define ELT3 {0x7FFFFFFFUL, 3}
+#define ELT4 {0x7FFFFFFFUL, 4}
+#define RES 9
+struct s A[N]
+  = { ELT0, ELT4, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3};
+
+int __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    int res = 0;
+    for (int i = 0; i < n; ++i)
+      {
+	if (ptr[i].a)
+	  return 9;
+	res += ptr[i].a;
+      }
+    return res;
+}
+
+int main (void)
+{
+  check_vect ();
+
+  if (f(&A[0], N) != RES)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump "Bitfield OK to lower." "ifcvt" } } */
+
diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index a83b013d2ad3d9066b1c2bc62282ec054483598f..639cd91f61517b4cadd50cca253eec3ccdf79b8d 100644
--- a/gcc/tree-if-conv.cc
+++ b/gcc/tree-if-conv.cc
@@ -1257,6 +1257,31 @@  get_loop_body_in_if_conv_order (const class loop *loop)
     }
   free (blocks_in_bfs_order);
   BITMAP_FREE (visited);
+
+  /* Go through loop and reject if-conversion or lowering of bitfields if we
+     encounter statements we do not believe the vectorizer will be able to
+     handle.  If adding a new type of statement here, make sure
+     'ifcvt_local_dce' is also able to handle it propertly.  */
+  for (index = 0; index < loop->num_nodes; index++)
+    {
+      basic_block bb = blocks[index];
+      gimple_stmt_iterator gsi;
+
+      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+	switch (gimple_code (gsi_stmt (gsi)))
+	  {
+	  case GIMPLE_LABEL:
+	  case GIMPLE_ASSIGN:
+	  case GIMPLE_CALL:
+	  case GIMPLE_DEBUG:
+	  case GIMPLE_COND:
+	    gimple_set_uid (gsi_stmt (gsi), 0);
+	    break;
+	  default:
+	    free (blocks);
+	    return NULL;
+	  }
+    }
   return blocks;
 }
 
@@ -1429,26 +1454,6 @@  if_convertible_loop_p_1 (class loop *loop, vec<data_reference_p> *refs)
 	exit_bb = bb;
     }
 
-  for (i = 0; i < loop->num_nodes; i++)
-    {
-      basic_block bb = ifc_bbs[i];
-      gimple_stmt_iterator gsi;
-
-      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
-	switch (gimple_code (gsi_stmt (gsi)))
-	  {
-	  case GIMPLE_LABEL:
-	  case GIMPLE_ASSIGN:
-	  case GIMPLE_CALL:
-	  case GIMPLE_DEBUG:
-	  case GIMPLE_COND:
-	    gimple_set_uid (gsi_stmt (gsi), 0);
-	    break;
-	  default:
-	    return false;
-	  }
-    }
-
   data_reference_p dr;
 
   innermost_DR_map
@@ -1560,14 +1565,6 @@  if_convertible_loop_p (class loop *loop, vec<data_reference_p> *refs)
       return false;
     }
 
-  /* More than one loop exit is too much to handle.  */
-  if (!single_exit (loop))
-    {
-      if (dump_file && (dump_flags & TDF_DETAILS))
-	fprintf (dump_file, "multiple exits\n");
-      return false;
-    }
-
   /* If one of the loop header's edge is an exit edge then do not
      apply if-conversion.  */
   FOR_EACH_EDGE (e, ei, loop->header->succs)
@@ -3510,9 +3507,6 @@  tree_if_conversion (class loop *loop, vec<gimple *> *preds)
 	aggressive_if_conv = true;
     }
 
-  if (!single_exit (loop))
-    goto cleanup;
-
   /* If there are more than two BBs in the loop then there is at least one if
      to convert.  */
   if (loop->num_nodes > 2
@@ -3532,15 +3526,25 @@  tree_if_conversion (class loop *loop, vec<gimple *> *preds)
 
   if (loop->num_nodes > 2)
     {
-      need_to_ifcvt = true;
+      /* More than one loop exit is too much to handle.  */
+      if (!single_exit (loop))
+	{
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    fprintf (dump_file, "Can not ifcvt due to multiple exits\n");
+	}
+      else
+	{
+	  need_to_ifcvt = true;
 
-      if (!if_convertible_loop_p (loop, &refs) || !dbg_cnt (if_conversion_tree))
-	goto cleanup;
+	  if (!if_convertible_loop_p (loop, &refs)
+	      || !dbg_cnt (if_conversion_tree))
+	    goto cleanup;
 
-      if ((need_to_predicate || any_complicated_phi)
-	  && ((!flag_tree_loop_vectorize && !loop->force_vectorize)
-	      || loop->dont_vectorize))
-	goto cleanup;
+	  if ((need_to_predicate || any_complicated_phi)
+	      && ((!flag_tree_loop_vectorize && !loop->force_vectorize)
+		  || loop->dont_vectorize))
+	    goto cleanup;
+	}
     }
 
   if ((flag_tree_loop_vectorize || loop->force_vectorize)
@@ -3631,7 +3635,8 @@  tree_if_conversion (class loop *loop, vec<gimple *> *preds)
      PHIs, those are to be kept in sync with the non-if-converted copy.
      ???  We'll still keep dead stores though.  */
   exit_bbs = BITMAP_ALLOC (NULL);
-  bitmap_set_bit (exit_bbs, single_exit (loop)->dest->index);
+  for (edge exit : get_loop_exit_edges (loop))
+    bitmap_set_bit (exit_bbs, exit->dest->index);
   bitmap_set_bit (exit_bbs, loop->latch->index);
 
   std::pair <tree, tree> *name_pair;