On 7/29/25 7:41 PM, KuanLin Chen wrote:
+
+;;
+;; ....................
+;;
+;; String Extension
+;;
+;; ....................
+;;
+
+(define_insn "riscv_nds_ffb<mode>"
+ [(set (match_operand:GPR 0 "register_operand" "=r")
+ (unspec:GPR [(match_operand:GPR 1 "reg_or_0_operand" "rJ")
+ (match_operand:GPR 2 "nonmemory_operand" "rJ")]
UNSPEC_NDS_FFB))]
+ ""
+ "nds.ffb\t%0, %z1, %z2"
+ [(set_attr "mode" "<MODE>")
+ (set_attr "type" "arith")])
+
+(define_insn "riscv_nds_ffzmism<mode>"
+ [(set (match_operand:GPR 0 "register_operand" "=r")
+ (unspec:GPR [(match_operand:GPR 1 "reg_or_0_operand" "rJ")
+ (match_operand:GPR 2 "reg_or_0_operand" "rJ")]
UNSPEC_NDS_FFZMISM))]
+ ""
+ "nds.ffzmism\t%0, %z1, %z2"
+ [(set_attr "mode" "<MODE>")
+ (set_attr "type" "arith")])
+
+(define_insn "riscv_nds_ffmism<mode>"
+ [(set (match_operand:GPR 0 "register_operand" "=r")
+ (unspec:GPR [(match_operand:GPR 1 "reg_or_0_operand" "rJ")
+ (match_operand:GPR 2 "reg_or_0_operand" "rJ")]
UNSPEC_NDS_FFMISM))]
+ ""
+ "nds.ffmism\t%0, %z1, %z2"
+ [(set_attr "mode" "<MODE>")
+ (set_attr "type" "arith")])
+
+(define_insn "riscv_nds_flmism<mode>"
+ [(set (match_operand:GPR 0 "register_operand" "=r")
+ (unspec:GPR [(match_operand:GPR 1 "reg_or_0_operand" "rJ")
+ (match_operand:GPR 2 "reg_or_0_operand" "rJ")]
UNSPEC_NDS_FLMISM))]
+ ""
+ "nds.flmism\t%0, %z1, %z2"
+ [(set_attr "mode" "<MODE>")
+ (set_attr "type" "arith")])
What are the semantics of these UNSPECs? Do they match existing RTL
code, and if so wouldn't it be better to use the existing RTL codes?
These UNPSECs are for string processing instructions and we only
provide intrinsic functions for users.
There seems no existing RTL codes about string operations.
It'd still be useful to know the semantics. Even if we don't have a
mapping to RTL now, understanding what kinds of target specific
operations folks are wiring up via UNSPECs can help guide adding new RTL
codes.
Feel free to just point me at an ISA specification if that's easier than
describing them. I didn't see one after some quick google searching.
Thanks,
Jeff
