Introduce can_vcond_compare_p function

z13 supports only non-signaling vector comparisons.  This means we
cannot vectorize LT, LE, GT, GE and LTGT when compiling for z13.
However, we cannot express this restriction today: the code only checks
whether vcond$a$b optab exists, but this does not say anything about the
operation.

Introduce a function that checks whether back-end supports vector
comparisons with individual rtx codes by matching vcond expander's third
argument with a fake comparison with the corresponding rtx code.

gcc/ChangeLog:

2019-10-07  Ilya Leoshkevich  <iii@linux.ibm.com>

	PR target/77918
	* optabs-tree.c (vcond_icode_p): New function.
	(vcond_eq_icode_p): Likewise.
	(expand_vec_cond_expr_p): Use vcond_icode_p and
	vcond_eq_icode_p.
	* optabs.c (can_vcond_compare_p): New function.
	* optabs.h (can_vcond_compare_p): Likewise.

From-SVN: r276660

1 files changed, 19 insertions, 0 deletions

diff --git a/gcc/optabs.c b/gcc/optabs.c
index 35921e6..d6701df 100644
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -3819,6 +3819,25 @@ can_compare_p (enum rtx_code code, machine_mode mode,
   return 0;
 }
 
+/* Return whether the backend can emit a vector comparison for code CODE,
+   comparing operands of mode CMP_OP_MODE and producing a result with
+   VALUE_MODE.  */
+
+bool
+can_vcond_compare_p (enum rtx_code code, machine_mode value_mode,
+		     machine_mode cmp_op_mode)
+{
+  enum insn_code icode;
+  bool unsigned_p = (code == LTU || code == LEU || code == GTU || code == GEU);
+  rtx reg1 = alloca_raw_REG (cmp_op_mode, LAST_VIRTUAL_REGISTER + 1);
+  rtx reg2 = alloca_raw_REG (cmp_op_mode, LAST_VIRTUAL_REGISTER + 2);
+  rtx test = alloca_rtx_fmt_ee (code, value_mode, reg1, reg2);
+
+  return (icode = get_vcond_icode (value_mode, cmp_op_mode, unsigned_p))
+	 != CODE_FOR_nothing
+	 && insn_operand_matches (icode, 3, test);
+}
+
 /* This function is called when we are going to emit a compare instruction that
    compares the values found in X and Y, using the rtl operator COMPARISON.