2018-01-17 Richard Biener <rguenther@suse.de>

	Backport from mainline
	2017-12-18  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/81877
	* tree-ssa-loop-im.c (ref_indep_loop_p): Remove safelen parameters.
	(outermost_indep_loop): Adjust.
	(ref_indep_loop_p_1): Likewise.  Remove safelen handling again.
	(can_sm_ref_p): Adjust.

	* g++.dg/torture/pr81877.C: New testcase.
	* g++.dg/vect/pr70729.cc: XFAIL.
	* g++.dg/vect/pr70729-nest.cc: XFAIL.

	2017-12-08  Richard Biener  <rguenther@suse.de>

	PR middle-end/81782
	* tree-ssa-uninit.c (warn_uninitialized_vars): Properly
	handle accesses outside of zero-sized vars.

	* gcc.dg/uninit-pr81782.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-7-branch@256792 138bc75d-0d04-0410-961f-82ee72b054a4

8 files changed, 82 insertions, 47 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 009b7fcd2f00..ad7f159045af 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,20 @@
+2018-01-17  Richard Biener  <rguenther@suse.de>
+
+	Backport from mainline
+	2017-12-18  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/81877
+	* tree-ssa-loop-im.c (ref_indep_loop_p): Remove safelen parameters.
+	(outermost_indep_loop): Adjust.
+	(ref_indep_loop_p_1): Likewise.  Remove safelen handling again.
+	(can_sm_ref_p): Adjust.
+
+	2017-12-08  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/81782
+	* tree-ssa-uninit.c (warn_uninitialized_vars): Properly
+	handle accesses outside of zero-sized vars.
+
 2018-01-17  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	Backport from mailine
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 533a92fca1c3..f674940a6a90 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,18 @@
+2018-01-17  Richard Biener  <rguenther@suse.de>
+
+	Backport from mainline
+	2017-12-18  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/81877
+	* g++.dg/torture/pr81877.C: New testcase.
+	* g++.dg/vect/pr70729.cc: XFAIL.
+	* g++.dg/vect/pr70729-nest.cc: XFAIL.
+
+	2017-12-08  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/81782
+	* gcc.dg/uninit-pr81782.c: New testcase.
+
 2018-01-17  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	Backport from mainline
diff --git a/gcc/testsuite/g++.dg/torture/pr81877.C b/gcc/testsuite/g++.dg/torture/pr81877.C
new file mode 100644
index 000000000000..dae23a3c0d2e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr81877.C
@@ -0,0 +1,22 @@
+/* { dg-do run } */
+
+void __attribute__((noinline,noclone)) g(int p, int *out)
+{
+  int x = 0, y;
+#pragma GCC ivdep
+  for (int i = 0; i < 100; i++)
+    {
+      int &r = p ? x : y;
+      r = 42;
+      out[i] = x;
+    }
+}
+
+int main()
+{
+  int out[100] = { 0 };
+  g (1, out);
+  if (out[0] != 42)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/vect/pr70729-nest.cc b/gcc/testsuite/g++.dg/vect/pr70729-nest.cc
index 96171e5ec94e..bbe4a5e2dba5 100644
--- a/gcc/testsuite/g++.dg/vect/pr70729-nest.cc
+++ b/gcc/testsuite/g++.dg/vect/pr70729-nest.cc
@@ -76,4 +76,4 @@ void Ss::foo (int n)
     }
 }
  
-// { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" { target x86_64-*-* i?86-*-* } } }
+// { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" { xfail *-*-* } } }
diff --git a/gcc/testsuite/g++.dg/vect/pr70729.cc b/gcc/testsuite/g++.dg/vect/pr70729.cc
index ff868f7a41be..d5bdf49c4194 100644
--- a/gcc/testsuite/g++.dg/vect/pr70729.cc
+++ b/gcc/testsuite/g++.dg/vect/pr70729.cc
@@ -70,4 +70,4 @@ void Ss::foo (float *in, float w)
     }
 }
  
-// { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" { target x86_64-*-* i?86-*-* } } }
+// { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" { xfail *-*-* } } }
diff --git a/gcc/testsuite/gcc.dg/uninit-pr81782.c b/gcc/testsuite/gcc.dg/uninit-pr81782.c
new file mode 100644
index 000000000000..7d1e90203f00
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/uninit-pr81782.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-Wmaybe-uninitialized" } */
+
+int
+foo (void)
+{
+  char empty_array[] = { };
+  int i, ret = 0;
+
+  for (i = 0; i < (int) (sizeof (empty_array) / sizeof (empty_array[0])); i++)
+    ret = empty_array[i]; /* { dg-bogus "uninitialized" } */
+
+  return ret;
+}
diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
index 0d806da2a3ed..b259747481c3 100644
--- a/gcc/tree-ssa-loop-im.c
+++ b/gcc/tree-ssa-loop-im.c
@@ -197,7 +197,7 @@ static struct
 static bitmap_obstack lim_bitmap_obstack;
 static obstack mem_ref_obstack;
 
-static bool ref_indep_loop_p (struct loop *, im_mem_ref *, struct loop *);
+static bool ref_indep_loop_p (struct loop *, im_mem_ref *);
 
 /* Minimum cost of an expensive expression.  */
 #define LIM_EXPENSIVE ((unsigned) PARAM_VALUE (PARAM_LIM_EXPENSIVE))
@@ -545,10 +545,10 @@ outermost_indep_loop (struct loop *outer, struct loop *loop, im_mem_ref *ref)
        aloop != loop;
        aloop = superloop_at_depth (loop, loop_depth (aloop) + 1))
     if ((!ref->stored || !bitmap_bit_p (ref->stored, aloop->num))
-	&& ref_indep_loop_p (aloop, ref, loop))
+	&& ref_indep_loop_p (aloop, ref))
       return aloop;
 
-  if (ref_indep_loop_p (loop, ref, loop))
+  if (ref_indep_loop_p (loop, ref))
     return loop;
   else
     return NULL;
@@ -2111,20 +2111,13 @@ record_dep_loop (struct loop *loop, im_mem_ref *ref, bool stored_p)
 }
 
 /* Returns true if REF is independent on all other memory
-   references in LOOP.  REF_LOOP is where REF is accessed, SAFELEN is the
-   safelen to apply.  */
+   references in LOOP.  */
 
 static bool
-ref_indep_loop_p_1 (int safelen, struct loop *loop, im_mem_ref *ref,
-		    bool stored_p, struct loop *ref_loop)
+ref_indep_loop_p_1 (struct loop *loop, im_mem_ref *ref, bool stored_p)
 {
   stored_p |= (ref->stored && bitmap_bit_p (ref->stored, loop->num));
 
-  if (loop->safelen > safelen
-      /* Check that REF is accessed inside LOOP.  */
-      && (loop == ref_loop || flow_loop_nested_p (loop, ref_loop)))
-    safelen = loop->safelen;
-
   bool indep_p = true;
   bitmap refs_to_check;
 
@@ -2135,32 +2128,6 @@ ref_indep_loop_p_1 (int safelen, struct loop *loop, im_mem_ref *ref,
 
   if (bitmap_bit_p (refs_to_check, UNANALYZABLE_MEM_ID))
     indep_p = false;
-  else if (safelen > 1)
-    {
-      if (dump_file && (dump_flags & TDF_DETAILS))
-	{
-	  fprintf (dump_file,"REF is independent due to safelen %d\n",
-		   safelen);
-	  print_generic_expr (dump_file, ref->mem.ref, TDF_SLIM);
-	  fprintf (dump_file, "\n");
-	}
-
-      /* We need to recurse to properly handle UNANALYZABLE_MEM_ID.  */
-      struct loop *inner = loop->inner;
-      while (inner)
-	{
-	  if (!ref_indep_loop_p_1 (safelen, inner, ref, stored_p, ref_loop))
-	    {
-	      indep_p = false;
-	      break;
-	    }
-	  inner = inner->next;
-	}
-
-      /* Avoid caching here as safelen depends on context and refs
-         are shared between different contexts.  */
-      return indep_p;
-    }
   else
     {
       if (bitmap_bit_p (&ref->indep_loop, LOOP_DEP_BIT (loop->num, stored_p)))
@@ -2171,7 +2138,7 @@ ref_indep_loop_p_1 (int safelen, struct loop *loop, im_mem_ref *ref,
       struct loop *inner = loop->inner;
       while (inner)
 	{
-	  if (!ref_indep_loop_p_1 (safelen, inner, ref, stored_p, ref_loop))
+	  if (!ref_indep_loop_p_1 (inner, ref, stored_p))
 	    {
 	      indep_p = false;
 	      break;
@@ -2225,14 +2192,14 @@ ref_indep_loop_p_1 (int safelen, struct loop *loop, im_mem_ref *ref,
 }
 
 /* Returns true if REF is independent on all other memory references in
-   LOOP.  REF_LOOP is the loop where REF is accessed.  */
+   LOOP.  */
 
 static bool
-ref_indep_loop_p (struct loop *loop, im_mem_ref *ref, struct loop *ref_loop)
+ref_indep_loop_p (struct loop *loop, im_mem_ref *ref)
 {
   gcc_checking_assert (MEM_ANALYZABLE (ref));
 
-  return ref_indep_loop_p_1 (0, loop, ref, false, ref_loop);
+  return ref_indep_loop_p_1 (loop, ref, false);
 }
 
 /* Returns true if we can perform store motion of REF from LOOP.  */
@@ -2268,7 +2235,7 @@ can_sm_ref_p (struct loop *loop, im_mem_ref *ref)
 
   /* And it must be independent on all other memory references
      in LOOP.  */
-  if (!ref_indep_loop_p (loop, ref, loop))
+  if (!ref_indep_loop_p (loop, ref))
     return false;
 
   return true;
diff --git a/gcc/tree-ssa-uninit.c b/gcc/tree-ssa-uninit.c
index e019ecc9d29e..90d2636b12a8 100644
--- a/gcc/tree-ssa-uninit.c
+++ b/gcc/tree-ssa-uninit.c
@@ -290,8 +290,8 @@ warn_uninitialized_vars (bool warn_possibly_uninitialized)
 	      /* Do not warn if the access is fully outside of the
 	         variable.  */
 	      if (ref.size != -1
-		  && ref.max_size == ref.size
-		  && (ref.offset + ref.size <= 0
+		  && ((ref.max_size == ref.size
+		       && ref.offset + ref.size <= 0)
 		      || (ref.offset >= 0
 			  && TREE_CODE (DECL_SIZE (base)) == INTEGER_CST
 			  && compare_tree_int (DECL_SIZE (base),