tree-ssa-alias.c (stmt_kills_ref_p_1): Use ao_ref_init_from_ptr_and_size for builtins.

2013-11-11  Marc Glisse  <marc.glisse@inria.fr>
	    Jeff Law  <law@redhat.com>

gcc/
	* tree-ssa-alias.c (stmt_kills_ref_p_1): Use
	ao_ref_init_from_ptr_and_size for builtins.

gcc/testsuite/
	* gcc.dg/tree-ssa/alias-27.c: New testcase.

Co-Authored-By: Jeff Law <law@redhat.com>

From-SVN: r204686

4 files changed, 50 insertions, 17 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a140a62..bc418fe 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2013-11-11  Marc Glisse  <marc.glisse@inria.fr>
+	    Jeff Law  <law@redhat.com>
+
+	* tree-ssa-alias.c (stmt_kills_ref_p_1): Use
+	ao_ref_init_from_ptr_and_size for builtins.
+
 2013-11-11  Uros Bizjak  <ubizjak@gmail.com>
 	    H.J. Lu  <hongjiu.lu@intel.com>
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 74a2d56..9a527e0 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2013-11-11  Marc Glisse  <marc.glisse@inria.fr>
+	    Jeff Law  <law@redhat.com>
+
+	* gcc.dg/tree-ssa/alias-27.c: New testcase.
+
 2013-11-11  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/58853
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/alias-27.c b/gcc/testsuite/gcc.dg/tree-ssa/alias-27.c
new file mode 100644
index 0000000..91c737e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/alias-27.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+
+void f (long *p) {
+  *p = 42;
+  p[4] = 42;
+  __builtin_memset (p, 0, 100);
+}
+
+/* { dg-final { scan-tree-dump-not "= 42" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 2785995..161a66a 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -2008,9 +2008,10 @@ static bool
 stmt_kills_ref_p_1 (gimple stmt, ao_ref *ref)
 {
   /* For a must-alias check we need to be able to constrain
-     the access properly.  */
-  ao_ref_base (ref);
-  if (ref->max_size == -1)
+     the access properly.
+     FIXME: except for BUILTIN_FREE.  */
+  if (!ao_ref_base (ref)
+      || ref->max_size == -1)
     return false;
 
   if (gimple_has_lhs (stmt)
@@ -2097,23 +2098,33 @@ stmt_kills_ref_p_1 (gimple stmt, ao_ref *ref)
 	    {
 	      tree dest = gimple_call_arg (stmt, 0);
 	      tree len = gimple_call_arg (stmt, 2);
-	      tree base = NULL_TREE;
-	      HOST_WIDE_INT offset = 0;
 	      if (!host_integerp (len, 0))
 		return false;
-	      if (TREE_CODE (dest) == ADDR_EXPR)
-		base = get_addr_base_and_unit_offset (TREE_OPERAND (dest, 0),
-						      &offset);
-	      else if (TREE_CODE (dest) == SSA_NAME)
-		base = dest;
-	      if (base
-		  && base == ao_ref_base (ref))
+	      tree rbase = ref->base;
+	      double_int roffset = double_int::from_shwi (ref->offset);
+	      ao_ref dref;
+	      ao_ref_init_from_ptr_and_size (&dref, dest, len);
+	      tree base = ao_ref_base (&dref);
+	      double_int offset = double_int::from_shwi (dref.offset);
+	      double_int bpu = double_int::from_uhwi (BITS_PER_UNIT);
+	      if (!base || dref.size == -1)
+		return false;
+	      if (TREE_CODE (base) == MEM_REF)
+		{
+		  if (TREE_CODE (rbase) != MEM_REF)
+		    return false;
+		  // Compare pointers.
+		  offset += bpu * mem_ref_offset (base);
+		  roffset += bpu * mem_ref_offset (rbase);
+		  base = TREE_OPERAND (base, 0);
+		  rbase = TREE_OPERAND (rbase, 0);
+		}
+	      if (base == rbase)
 		{
-		  HOST_WIDE_INT size = TREE_INT_CST_LOW (len);
-		  if (offset <= ref->offset / BITS_PER_UNIT
-		      && (offset + size
-		          >= ((ref->offset + ref->max_size + BITS_PER_UNIT - 1)
-			      / BITS_PER_UNIT)))
+		  double_int size = bpu * tree_to_double_int (len);
+		  double_int rsize = double_int::from_uhwi (ref->max_size);
+		  if (offset.sle (roffset)
+		      && (roffset + rsize).sle (offset + size))
 		    return true;
 		}
 	      break;