[PATCH] Support libcall __float{, un}sibf by SF when it is not supported for _bf16

[Jin Ma]

We don't have SI -> BF library functions, use SI -> SF -> BF
instead. Although this can also be implemented in a target
machine description, it is more appropriate to move
into target independent code.

gcc/ChangeLog:

	* optabs.cc (expand_float): Split SI -> BF into SI -> SF -> BF.
---
 gcc/optabs.cc | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/gcc/optabs.cc b/gcc/optabs.cc
index 6a34276c239..c58a0321bbd 100644
--- a/gcc/optabs.cc
+++ b/gcc/optabs.cc
@@ -5727,6 +5727,19 @@ expand_float (rtx to, rtx from, int unsignedp)
       if (is_narrower_int_mode (GET_MODE (from), SImode))
 	from = convert_to_mode (SImode, from, unsignedp);
 
+#ifdef HAVE_SFmode
+      if (REAL_MODE_FORMAT (GET_MODE (to)) == &arm_bfloat_half_format
+	  && REAL_MODE_FORMAT (SFmode) == &ieee_single_format
+	  && GET_MODE (from) == SImode)
+	/* We don't have SI -> BF library functions, use SI -> SF -> BF
+	   instead.  */
+	{
+	  target = gen_reg_rtx (SFmode);
+	  expand_float (target, from, unsignedp);
+	  goto done;
+	}
+#endif
+
       libfunc = convert_optab_libfunc (tab, GET_MODE (to), GET_MODE (from));
       gcc_assert (libfunc);
 
-- 
2.17.1