tree-ssa-structalias.c (find_func_aliases): For memset use a constraint from…

tree-ssa-structalias.c (find_func_aliases): For memset use a constraint from NULL if we memset to zero.

2009-06-20  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-structalias.c (find_func_aliases): For memset use
	a constraint from NULL if we memset to zero.
	* tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Add builtins
	we explicitly handle that do not read from memory.
	(call_may_clobber_ref_p_1): Properly handle builtins that may
	set errno.

From-SVN: r148747

gcc/ChangeLog

 2009-06-20  Richard Guenther  <rguenther@suse.de>
 
+	* tree-ssa-structalias.c (find_func_aliases): For memset use
+	a constraint from NULL if we memset to zero.
+	* tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Add builtins
+	we explicitly handle that do not read from memory.
+	(call_may_clobber_ref_p_1): Properly handle builtins that may
+	set errno.
+
+2009-06-20  Richard Guenther  <rguenther@suse.de>
+
 	PR tree-optimization/40495
 	* tree-ssa-structalias.c (get_constraint_exp_for_temp): Remove.
 	(new_scalar_tmp_constraint_exp): New function.

gcc/tree-ssa-alias.c

@@ -899,6 +899,29 @@ ref_maybe_used_by_call_p_1 (gimple call, tree ref)
 	    tree src = gimple_call_arg (call, 1);
 	    return ptr_deref_may_alias_ref_p (src, ref);
 	  }
+	/* The following builtins do not read from memory.  */
+	case BUILT_IN_FREE:
+	case BUILT_IN_MEMSET:
+	case BUILT_IN_FREXP:
+	case BUILT_IN_FREXPF:
+	case BUILT_IN_FREXPL:
+	case BUILT_IN_GAMMA_R:
+	case BUILT_IN_GAMMAF_R:
+	case BUILT_IN_GAMMAL_R:
+	case BUILT_IN_LGAMMA_R:
+	case BUILT_IN_LGAMMAF_R:
+	case BUILT_IN_LGAMMAL_R:
+	case BUILT_IN_MODF:
+	case BUILT_IN_MODFF:
+	case BUILT_IN_MODFL:
+	case BUILT_IN_REMQUO:
+	case BUILT_IN_REMQUOF:
+	case BUILT_IN_REMQUOL:
+	case BUILT_IN_SINCOS:
+	case BUILT_IN_SINCOSF:
+	case BUILT_IN_SINCOSL:
+	  return false;
+
 	default:
 	  /* Fallthru to general call handling.  */;
       }
@@ -1060,15 +1083,23 @@ call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
 	    tree ptr = gimple_call_arg (call, 0);
 	    return ptr_deref_may_alias_ref_p_1 (ptr, ref);
 	  }
-	case BUILT_IN_FREXP:
-	case BUILT_IN_FREXPF:
-	case BUILT_IN_FREXPL:
 	case BUILT_IN_GAMMA_R:
 	case BUILT_IN_GAMMAF_R:
 	case BUILT_IN_GAMMAL_R:
 	case BUILT_IN_LGAMMA_R:
 	case BUILT_IN_LGAMMAF_R:
 	case BUILT_IN_LGAMMAL_R:
+	  {
+	    tree out = gimple_call_arg (call, 1);
+	    if (ptr_deref_may_alias_ref_p_1 (out, ref))
+	      return true;
+	    if (flag_errno_math)
+	      break;
+	    return false;
+	  }
+	case BUILT_IN_FREXP:
+	case BUILT_IN_FREXPF:
+	case BUILT_IN_FREXPL:
 	case BUILT_IN_MODF:
 	case BUILT_IN_MODFF:
 	case BUILT_IN_MODFL:
@@ -1081,7 +1112,11 @@ call_may_clobber_ref_p_1 (gimple call, ao_ref *ref)
 	case BUILT_IN_REMQUOL:
 	  {
 	    tree out = gimple_call_arg (call, 2);
-	    return ptr_deref_may_alias_ref_p_1 (out, ref);
+	    if (ptr_deref_may_alias_ref_p_1 (out, ref))
+	      return true;
+	    if (flag_errno_math)
+	      break;
+	    return false;
 	  }
 	case BUILT_IN_SINCOS:
 	case BUILT_IN_SINCOSF:

gcc/tree-ssa-structalias.c

@@ -3674,8 +3674,17 @@ find_func_aliases (gimple origt)
 		}
 	      get_constraint_for_ptr_offset (dest, NULL_TREE, &lhsc);
 	      do_deref (&lhsc);
-	      ac.type = SCALAR;
-	      ac.var = integer_id;
+	      if (flag_delete_null_pointer_checks
+		  && integer_zerop (gimple_call_arg (t, 1)))
+		{
+		  ac.type = ADDRESSOF;
+		  ac.var = nothing_id;
+		}
+	      else
+		{
+		  ac.type = SCALAR;
+		  ac.var = integer_id;
+		}
 	      ac.offset = 0;
 	      for (i = 0; VEC_iterate (ce_s, lhsc, i, lhsp); ++i)
 		process_constraint (new_constraint (*lhsp, ac));