Currently these builtins use float compare instructions which require
FP flags to be saved/restored which could be costly in uarch.
RV Base ISA already has FCLASS.{d,s,h} instruction to compare/identify FP
values w/o disturbing FP exception flags.
Now that upstream supports the corresponding optabs, wire them up in the
backend.
gcc/ChangeLog:
* config/riscv/riscv.md: define_insn for fclass insn.
define_expand for isfinite, isnormal, isinf.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/fclass.c: New tests.
Tested-by: Edwin Lu <e...@rivosinc.com> # pre-commit-CI #2060
Signed-off-by: Vineet Gupta <vine...@rivosinc.com>
---
gcc/config/riscv/riscv.md | 63 +++++++++++++++++++++++++
gcc/testsuite/gcc.target/riscv/fclass.c | 38 +++++++++++++++
2 files changed, 101 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/riscv/fclass.c
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index 5e3ef789e42e..f8d8162c0f91 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -68,6 +68,7 @@
UNSPEC_FMAX
UNSPEC_FMINM
UNSPEC_FMAXM
+ UNSPEC_FCLASS
;; Stack tie
UNSPEC_TIE
@@ -3478,6 +3479,68 @@
(set_attr "mode" "<UNITMODE>")
(set (attr "length") (const_int 16))])
+;; fclass instruction output bitmap
+;; 0 negative infinity
+;; 1 negative normal number.
+;; 2 negative subnormal number.
+;; 3 -0
+;; 4 +0
+;; 5 positive subnormal number.
+;; 6 positive normal number.
+;; 7 positive infinity
+;; 8 signaling NaN.
+;; 9 quiet NaN
+
+(define_insn "fclass<ANYF:mode><X:mode>"
+ [(set (match_operand:X 0 "register_operand" "=r")
+ (unspec [(match_operand:ANYF 1 "register_operand" " f")]
+ UNSPEC_FCLASS))]
+ "TARGET_HARD_FLOAT"
+ "fclass.<fmt>\t%0,%1";
+ [(set_attr "type" "fcmp")
+ (set_attr "mode" "<UNITMODE>")])
+
+;; Implements optab for isfinite, isnormal, isinf
+
+(define_int_iterator FCLASS_MASK [126 66 129])
+(define_int_attr fclass_optab
+ [(126 "isfinite")
+ (66 "isnormal")
+ (129 "isinf")])
+
+(define_expand "<FCLASS_MASK:fclass_optab><ANYF:mode>2"
+ [(match_operand 0 "register_operand" "=r")
+ (match_operand:ANYF 1 "register_operand" " f")
+ (const_int FCLASS_MASK)]
+ "TARGET_HARD_FLOAT"
+{
+ if (GET_MODE (operands[0]) != SImode
+ && GET_MODE (operands[0]) != word_mode)
+ FAIL;
+
+ rtx t = gen_reg_rtx (word_mode);
+ rtx t_op0 = gen_reg_rtx (word_mode);
+
+ if (TARGET_64BIT)
+ emit_insn (gen_fclass<ANYF:mode>di (t, operands[1]));
+ else
+ emit_insn (gen_fclass<ANYF:mode>si (t, operands[1]));
+
+ riscv_emit_binary (AND, t, t, GEN_INT (<FCLASS_MASK>));
+ rtx cmp = gen_rtx_NE (word_mode, t, const0_rtx);
+ emit_insn (gen_cstore<mode>4 (t_op0, cmp, t, const0_rtx));
+
+ if (TARGET_64BIT)
+ {
+ t_op0 = gen_lowpart (SImode, t_op0);
+ SUBREG_PROMOTED_VAR_P (t_op0) = 1;
+ SUBREG_PROMOTED_SET (t_op0, SRP_SIGNED);
+ }
+
+ emit_move_insn (operands[0], t_op0);
+ DONE;
+})
+
(define_insn "*seq_zero_<X:mode><GPR:mode>"
[(set (match_operand:GPR 0 "register_operand" "=r")
(eq:GPR (match_operand:X 1 "register_operand" " r")
diff --git a/gcc/testsuite/gcc.target/riscv/fclass.c
b/gcc/testsuite/gcc.target/riscv/fclass.c
new file mode 100644
index 000000000000..ea0f173ecf4b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/fclass.c
@@ -0,0 +1,38 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target hard_float } */
+/* { dg-options "-march=rv64gc -mabi=lp64d -ftrapping-math" { target { rv64 }
} } */
+/* { dg-options "-march=rv32gc -mabi=ilp32d -ftrapping-math" { target { rv32 }
} } */
+
+int d_isfinite(double a)
+{
+ return __builtin_isfinite(a);
+}
+
+int d_isnormal(double a)
+{
+ return __builtin_isnormal(a);
+}
+
+int d_isinf(double a)
+{
+ return __builtin_isinf(a);
+}
+
+int f_isfinite(float a)
+{
+ return __builtin_isfinite(a);
+}
+
+int f_isnormal(float a)
+{
+ return __builtin_isnormal(a);
+}
+
+int f_isinf(float a)
+{
+ return __builtin_isinf(a);
+}
+
+/* { dg-final { scan-assembler-not {\mfrflags} } } */
+/* { dg-final { scan-assembler-not {\mfsflags} } } */
+/* { dg-final { scan-assembler-times {\tfclass} 6 } } */
--
2.43.0
