On Mon, Sep 7, 2015 at 4:55 AM, Kugan <[email protected]> wrote:
>
> This patch adds support for new tree code SEXT_EXPR.
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index d567a87..bbc3c10 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -5071,6 +5071,10 @@ expand_debug_expr (tree exp)
case FMA_EXPR:
return simplify_gen_ternary (FMA, mode, inner_mode, op0, op1, op2);
+ case SEXT_EXPR:
+ return op0;
that looks wrong. Generate (sext:... ) here?
+ case SEXT_EXPR:
+ {
+ rtx op0 = expand_normal (treeop0);
+ rtx temp;
+ if (!target)
+ target = gen_reg_rtx (TYPE_MODE (TREE_TYPE (treeop0)));
+
+ machine_mode inner_mode
+ = smallest_mode_for_size (tree_to_shwi (treeop1),
+ MODE_INT);
+ temp = convert_modes (inner_mode,
+ TYPE_MODE (TREE_TYPE (treeop0)), op0, 0);
+ convert_move (target, temp, 0);
+ return target;
+ }
Humm - is that really how we expand sign extensions right now? No helper
that would generate (sext ...) directly? I wouldn't try using 'target' btw but
simply return (sext:mode op0 op1) or so. But I am no way an RTL expert.
Note that if we don't disallow arbitrary precision SEXT_EXPRs we have to
fall back to using shifts (and smallest_mode_for_size is simply wrong).
+ case SEXT_EXPR:
+ {
+ if (!INTEGRAL_TYPE_P (lhs_type)
+ || !INTEGRAL_TYPE_P (rhs1_type)
+ || TREE_CODE (rhs2) != INTEGER_CST)
please constrain this some more, with
|| !useless_type_conversion_p (lhs_type, rhs1_type)
+ {
+ error ("invalid operands in sext expr");
+ return true;
+ }
+ return false;
+ }
@@ -3414,6 +3422,9 @@ op_symbol_code (enum tree_code code)
case MIN_EXPR:
return "min";
+ case SEXT_EXPR:
+ return "sext from bit";
+
just "sext" please.
+/* Sign-extend operation. It will sign extend first operand from
+ the sign bit specified by the second operand. */
+DEFTREECODE (SEXT_EXPR, "sext_expr", tcc_binary, 2)
"from the INTEGER_CST sign bit specified"
Also add "The type of the result is that of the first operand."
Otherwise looks good to me - of course the two RTL expansion related
parts need auditing by somebody speaking more RTL than me.
Richard.
> gcc/ChangeLog:
>
> 2015-09-07 Kugan Vivekanandarajah <[email protected]>
>
> * cfgexpand.c (expand_debug_expr): Handle SEXT_EXPR.
> * expr.c (expand_expr_real_2): Likewise.
> * fold-const.c (int_const_binop_1): Likewise.
> * tree-cfg.c (verify_gimple_assign_binary): Likewise.
> * tree-inline.c (estimate_operator_cost): Likewise.
> * tree-pretty-print.c (dump_generic_node): Likewise.
> (op_symbol_code): Likewise.
> * tree.def: Define new tree code SEXT_EXPR.
