[AArch64][SME] Add rdsvl instruction

[HsiangKai]

Summary

This patch adds support for the following SME instruction:

• RDSVL

The reference can be found here:
https://developer.arm.com/documentation/ddi0602/2021-12

llvm/lib/Target/AArch64/AArch64SMEInstrInfo.td

 //
 //===----------------------------------------------------------------------===//
 
 //===----------------------------------------------------------------------===//
 // Add vector elements horizontally or vertically to ZA tile.
 //===----------------------------------------------------------------------===//
 
 let Predicates = [HasSME] in {
+def RDSVLI_XI  : sve_int_read_vl_a<0b0, 0b11111, "rdsvl", /*streaming_sve=*/0b1>;
 def ADDSPL_XXI : sve_int_arith_vl<0b1, "addspl", /*streaming_sve=*/0b1>;
 def ADDSVL_XXI : sve_int_arith_vl<0b0, "addsvl", /*streaming_sve=*/0b1>;
 
 def ADDHA_MPPZ_S : sme_add_vector_to_tile_u32<0b0, "addha">;
 def ADDVA_MPPZ_S : sme_add_vector_to_tile_u32<0b1, "addva">;
 }
 
 let Predicates = [HasSMEI64] in {

llvm/lib/Target/AArch64/SVEInstrFormats.td

: I<(outs GPR64sp:$Rd), (ins GPR64sp:$Rn, simm6_32b:$imm6),
   let Inst{21}    = 0b1;
   let Inst{20-16} = Rn;
   let Inst{15-12} = 0b0101;
   let Inst{11}    = streaming_sve;
   let Inst{10-5}  = imm6;
   let Inst{4-0}   = Rd;
 }
 
-class sve_int_read_vl_a<bit op, bits<5> opc2, string asm>
+class sve_int_read_vl_a<bit op, bits<5> opc2, string asm, bit streaming_sve = 0b0>
 : I<(outs GPR64:$Rd), (ins simm6_32b:$imm6),
   asm, "\t$Rd, $imm6",
   "",
   []>, Sched<[]> {
   bits<5> Rd;
   bits<6> imm6;
   let Inst{31-23} = 0b000001001;
   let Inst{22}    = op;
   let Inst{21}    = 0b1;
   let Inst{20-16} = opc2{4-0};
-  let Inst{15-11} = 0b01010;
+  let Inst{15-12} = 0b0101;
+  let Inst{11}    = streaming_sve;
   let Inst{10-5}  = imm6;
   let Inst{4-0}   = Rd;
 }
 
 //===----------------------------------------------------------------------===//
 // SVE Permute - In Lane Group
 //===----------------------------------------------------------------------===//
 

llvm/test/MC/AArch64/SME/rdsvl-diagnostics.s

+// RUN: not llvm-mc -triple=aarch64 -show-encoding -mattr=+sme  2>&1 < %s| FileCheck %s
+
+// Immediate out of upper bound [-32, 31].
+rdsvl x9, #32
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: index must be an integer in range [-32, 31].
+// CHECK-NEXT: rdsvl x9, #32
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:
+
+// rdsvl requires an immediate, not a register.
+rdsvl x9, x10
+// CHECK: [[@LINE-1]]:{{[0-9]+}}: error: index must be an integer in range [-32, 31].
+// CHECK-NEXT: rdsvl x9, x10
+// CHECK-NOT: [[@LINE-1]]:{{[0-9]+}}:

llvm/test/MC/AArch64/SME/rdsvl.s

+// RUN: llvm-mc -triple=aarch64 -show-encoding -mattr=+sme < %s \
+// RUN:        | FileCheck %s --check-prefixes=CHECK-ENCODING,CHECK-INST
+// RUN: not llvm-mc -triple=aarch64 -show-encoding < %s 2>&1 \
+// RUN:        | FileCheck %s --check-prefix=CHECK-ERROR
+// RUN: llvm-mc -triple=aarch64 -filetype=obj -mattr=+sme < %s \
+// RUN:        | llvm-objdump -d --mattr=+sme - | FileCheck %s --check-prefix=CHECK-INST
+// RUN: llvm-mc -triple=aarch64 -filetype=obj -mattr=+sme < %s \
+// RUN:        | llvm-objdump -d - | FileCheck %s --check-prefix=CHECK-UNKNOWN
+
+rdsvl    x0, #0
+// CHECK-INST: rdsvl    x0, #0
+// CHECK-ENCODING: [0x00,0x58,0xbf,0x04]
+// CHECK-ERROR: instruction requires: sme
+// CHECK-UNKNOWN: 00 58 bf 04 <unknown>
+
+rdsvl    xzr, #-1
+// CHECK-INST: rdsvl    xzr, #-1
+// CHECK-ENCODING: [0xff,0x5f,0xbf,0x04]
+// CHECK-ERROR: instruction requires: sme
+// CHECK-UNKNOWN: ff 5f bf 04 <unknown>
+
+rdsvl    x23, #31
+// CHECK-INST: rdsvl    x23, #31
+// CHECK-ENCODING: [0xf7,0x5b,0xbf,0x04]
+// CHECK-ERROR: instruction requires: sme
+// CHECK-UNKNOWN: f7 5b bf 04 <unknown>
+
+rdsvl    x21, #-32
+// CHECK-INST: rdsvl    x21, #-32
+// CHECK-ENCODING: [0x15,0x5c,0xbf,0x04]
+// CHECK-ERROR: instruction requires: sme
+// CHECK-UNKNOWN: 15 5c bf 04 <unknown>