i386: Fix up expander conditions on cbranchbf4 and cstorebf4 [PR107969]

With -msoft-float we ICE on __bf16 comparisons, because the
insns we want to use under the hood (cbranchsf4 and cstoresf4)
after performing the fast extensions aren't available.

The following patch copies the conditions from the c*sf4 expanders
to the corresponding c*bf4 expanders.

2022-12-06  Jakub Jelinek  <[email protected]>

	PR target/107969
	* config/i386/i386.md (cbranchbf4, cstorebf4): Guard expanders
	with the same condition as cbranchsf4 or cstoresf4 expanders.

	* gcc.target/i386/pr107969.c: New test.

Author: jakubjelinek

gcc/config/i386/i386.md

@@ -1667,7 +1667,7 @@
 		(const_int 0)])
 	      (label_ref (match_operand 3))
 	      (pc)))]
-  ""
+  "TARGET_80387 || (SSE_FLOAT_MODE_P (SFmode) && TARGET_SSE_MATH)"
 {
   rtx op1 = ix86_expand_fast_convert_bf_to_sf (operands[1]);
   rtx op2 = ix86_expand_fast_convert_bf_to_sf (operands[2]);
@@ -1702,7 +1702,7 @@
 	(match_operator 1 "comparison_operator"
 	  [(reg:CC FLAGS_REG)
 	   (const_int 0)]))]
-  ""
+  "TARGET_80387 || (SSE_FLOAT_MODE_P (SFmode) && TARGET_SSE_MATH)"
 {
   rtx op1 = ix86_expand_fast_convert_bf_to_sf (operands[2]);
   rtx op2 = ix86_expand_fast_convert_bf_to_sf (operands[3]);

gcc/testsuite/gcc.target/i386/pr107969.c

@@ -0,0 +1,12 @@
+/* PR target/107969 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fexcess-precision=16 -msoft-float -msse2" } */
+
+int i;
+__bf16 f;
+
+void
+bar (void)
+{
+  i *= 0 <= f;
+}