[RFC PATCH] __builtin_escape/__builtin_bless

[Uecker, Martin]

Hi Richard and Joseph,

for discussion: here is my simple patch
for __builtin_escape/__builtin_bless.

Maybe it does something stupid. 


Best,
Martin


diff --git a/gcc/builtins.c b/gcc/builtins.c
index e4a8694054e..d0046135213 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -6014,6 +6014,31 @@ expand_builtin_unreachable (void)
   emit_barrier ();
 }
 
+
+static rtx
+expand_builtin_escape (tree exp, rtx target)
+{
+  if (call_expr_nargs (exp) < 1)
+    return const0_rtx;
+
+  target = expand_expr (CALL_EXPR_ARG (exp, 0), target, Pmode,
+			EXPAND_NORMAL);
+
+  return target;
+}
+
+static rtx
+expand_builtin_bless (tree exp, rtx target)
+{
+  if (call_expr_nargs (exp) < 1)
+    return const0_rtx;
+
+  target = expand_expr (CALL_EXPR_ARG (exp, 0), target, Pmode,
+			EXPAND_NORMAL);
+
+  return target;
+}
+
 /* Expand EXP, a call to fabs, fabsf or fabsl.
    Return NULL_RTX if a normal call should be emitted rather than expanding
    the function inline.  If convenient, the result should be placed
@@ -8304,6 +8329,12 @@ expand_builtin (tree exp, rtx target, rtx subtarget, machine_mode mode,
       expand_builtin_unreachable ();
       return const0_rtx;
 
+    case BUILT_IN_ESCAPE:
+      return expand_builtin_escape (exp, target);
+
+    case BUILT_IN_BLESS:
+      return expand_builtin_bless (exp, target);
+
     CASE_FLT_FN (BUILT_IN_SIGNBIT):
     case BUILT_IN_SIGNBITD32:
     case BUILT_IN_SIGNBITD64:
diff --git a/gcc/builtins.def b/gcc/builtins.def
index fa8b0641ab1..9264a0fdaab 100644
--- a/gcc/builtins.def
+++ b/gcc/builtins.def
@@ -865,6 +865,8 @@ DEF_EXT_LIB_BUILTIN        (BUILT_IN_EXECVP, "execvp", BT_FN_INT_CONST_STRING_PT
 DEF_EXT_LIB_BUILTIN        (BUILT_IN_EXECVE, "execve", BT_FN_INT_CONST_STRING_PTR_CONST_STRING_PTR_CONST_STRING, ATTR_NOTHROW_LIST)
 DEF_LIB_BUILTIN        (BUILT_IN_EXIT, "exit", BT_FN_VOID_INT, ATTR_NORETURN_NOTHROW_LIST)
 DEF_GCC_BUILTIN        (BUILT_IN_EXPECT, "expect", BT_FN_LONG_LONG_LONG, ATTR_CONST_NOTHROW_LEAF_LIST)
+DEF_GCC_BUILTIN        (BUILT_IN_ESCAPE, "escape", BT_FN_PTR_PTR, ATTR_NOTHROW_LEAF_LIST)
+DEF_GCC_BUILTIN        (BUILT_IN_BLESS, "bless", BT_FN_PTR_PTR, ATTR_CONST_NOTHROW_LEAF_LIST)
 DEF_GCC_BUILTIN        (BUILT_IN_EXPECT_WITH_PROBABILITY, "expect_with_probability", BT_FN_LONG_LONG_LONG_DOUBLE, ATTR_CONST_NOTHROW_LEAF_LIST)
 DEF_GCC_BUILTIN        (BUILT_IN_ASSUME_ALIGNED, "assume_aligned", BT_FN_PTR_CONST_PTR_SIZE_VAR, ATTR_CONST_NOTHROW_LEAF_LIST)
 DEF_GCC_BUILTIN        (BUILT_IN_EXTEND_POINTER, "extend_pointer", BT_FN_UNWINDWORD_PTR, ATTR_CONST_NOTHROW_LEAF_LIST)
diff --git a/gcc/testsuite/gcc.dg/alias-17.c b/gcc/testsuite/gcc.dg/alias-17.c
new file mode 100644
index 00000000000..c375e4027ca
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/alias-17.c
@@ -0,0 +1,29 @@
+/* { dg-do run } */
+/* { dg-options "-O1" } */
+
+
+static
+int test(int a, int b, int c)
+{
+	int x, y;
+	int d = (&x < &y) ? 1 : -1;
+	if (a) __builtin_escape(&y);
+	y = 0; //!
+	int *q = &x;
+	q += d;
+	int *r = q;
+	if (b) r = __builtin_bless(q);
+	*(c ? r : q) = 1;
+	return y;
+}
+
+int main()
+{
+	if (0 != test(0, 0, 1)) __builtin_abort();
+	if (0 != test(0, 1, 0)) __builtin_abort();
+	if (0 != test(0, 1, 1)) __builtin_abort();
+	if (0 != test(1, 0, 1)) __builtin_abort();
+//	if (0 != test(1, 1, 0)) __builtin_abort();
+	if (0 == test(1, 1, 1)) __builtin_abort();
+	return 0;
+}
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 670676f20c3..d5befff71a6 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -2462,6 +2462,8 @@ ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *ref, bool tbaa_p)
 	  }
 
 	/* The following builtins do not read from memory.  */
+	case BUILT_IN_ESCAPE:
+	case BUILT_IN_BLESS:
 	case BUILT_IN_FREE:
 	case BUILT_IN_MALLOC:
 	case BUILT_IN_POSIX_MEMALIGN:
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index be6647db894..53a38a04ebb 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -1963,6 +1963,8 @@ evaluate_stmt (gimple *stmt)
 	      break;
 
 	    /* These builtins return their first argument, unmodified.  */
+	    case BUILT_IN_ESCAPE:
+	    case BUILT_IN_BLESS:
 	    case BUILT_IN_MEMCPY:
 	    case BUILT_IN_MEMMOVE:
 	    case BUILT_IN_MEMSET:
diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index 416a26c996c..003349c7278 100644
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -4381,6 +4381,24 @@ find_func_aliases_for_builtin_call (struct function *fn, gcall *t)
        in the alias-oracle query functions explicitly!  */
     switch (DECL_FUNCTION_CODE (fndecl))
       {
+      case BUILT_IN_ESCAPE:
+	{
+	   make_escape_constraint (gimple_call_arg (t, 0));
+	   return true;
+	}
+      case BUILT_IN_BLESS:
+	{
+	   tree lhs = gimple_call_lhs (t);
+	   struct constraint_expr rhsc, *lhsp;
+	   unsigned j;
+	   get_constraint_for (lhs, &lhsc);
+	   rhsc.var = nonlocal_id;
+	   rhsc.offset = 0;
+	   rhsc.type = SCALAR;
+	   FOR_EACH_VEC_ELT (lhsc, j, lhsp)
+	      process_constraint (new_constraint (*lhsp, rhsc));
+	   return true;
+	}
       /* All the following functions return a pointer to the same object
 	 as their first argument points to.  The functions do not add
 	 to the ESCAPED solution.  The functions make the first argument
@@ -5257,6 +5275,7 @@ find_func_clobbers (struct function *fn, gimple *origt)
       if (gimple_call_builtin_p (t, BUILT_IN_NORMAL))
 	switch (DECL_FUNCTION_CODE (decl))
 	  {
+
 	  /* The following functions use and clobber memory pointed to
 	     by their arguments.  */
 	  case BUILT_IN_STRCPY:
@@ -5349,6 +5368,9 @@ find_func_clobbers (struct function *fn, gimple *origt)
 	  case BUILT_IN_ASSUME_ALIGNED:
 	  case BUILT_IN_FREE:
 	    return;
+	  case BUILT_IN_ESCAPE:
+	  case BUILT_IN_BLESS:
+	    return;
 	  /* Trampolines are of no interest to us.  */
 	  case BUILT_IN_INIT_TRAMPOLINE:
 	  case BUILT_IN_ADJUST_TRAMPOLINE: