re PR tree-optimization/19831 (Missing DSE/malloc/free optimization)

2013-10-29  Marc Glisse  <marc.glisse@inria.fr>

	PR tree-optimization/19831
gcc/
	* tree-ssa-alias.c (stmt_kills_ref_p_1): Handle BUILT_IN_FREE.

gcc/testsuite/
	* gcc.dg/tree-ssa/alias-25.c: New file.

From-SVN: r204160

gcc/ChangeLog

+2013-10-29  Marc Glisse  <marc.glisse@inria.fr>
+
+	PR tree-optimization/19831
+	* tree-ssa-alias.c (stmt_kills_ref_p_1): Handle BUILT_IN_FREE.
+
 2013-10-29  Andrew MacLeod  <amacleod@redhat.com>
 
 	* tree-outof-ssa.h: Remove include files.

gcc/testsuite/ChangeLog

+2013-10-29  Marc Glisse  <marc.glisse@inria.fr>
+
+	PR tree-optimization/19831
+	* gcc.dg/tree-ssa/alias-25.c: New file.
+
 2013-10-29  Richard Biener  <rguenther@suse.de>
 
 	* g++.dg/vect/slp-pr56812.cc: Adjust with respect to -fvect-cost-model

gcc/testsuite/gcc.dg/tree-ssa/alias-25.c

+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+
+void f (long *p) {
+  *p = 42;
+  p[4] = 42;
+  __builtin_free (p);
+}
+
+/* { dg-final { scan-tree-dump-not "= 42" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
+

gcc/tree-ssa-alias.c

@@ -2057,6 +2057,16 @@ stmt_kills_ref_p_1 (gimple stmt, ao_ref *ref)
 	  && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
 	switch (DECL_FUNCTION_CODE (callee))
 	  {
+	  case BUILT_IN_FREE:
+	    {
+	      tree ptr = gimple_call_arg (stmt, 0);
+	      tree base = ao_ref_base (ref);
+	      if (base && TREE_CODE (base) == MEM_REF
+		  && TREE_OPERAND (base, 0) == ptr)
+		return true;
+	      break;
+	    }
+
 	  case BUILT_IN_MEMCPY:
 	  case BUILT_IN_MEMPCPY:
 	  case BUILT_IN_MEMMOVE: