[RISCV] Add support for Zawrs extension

[sunshaoce]

Summary

Zawrs spec: https://github.com/riscv/riscv-zawrs/blob/main/Zawrs.pdf

[sunshaoce]

I didn't notice that Zawrs had committed to D128235.

llvm/lib/Support/RISCVISAInfo.cpp

static const RISCVSupportedExtension SupportedExtensions[] = {
     {"zve64d", RISCVExtensionVersion{1, 0}},
 
     {"zicbom", RISCVExtensionVersion{1, 0}},
     {"zicboz", RISCVExtensionVersion{1, 0}},
     {"zicbop", RISCVExtensionVersion{1, 0}},
 };
 
 static const RISCVSupportedExtension SupportedExperimentalExtensions[] = {
+    {"zawrs", RISCVExtensionVersion{1, 0}},
     {"zbe", RISCVExtensionVersion{0, 93}},
     {"zbf", RISCVExtensionVersion{0, 93}},
     {"zbm", RISCVExtensionVersion{0, 93}},
     {"zbp", RISCVExtensionVersion{0, 93}},
     {"zbr", RISCVExtensionVersion{0, 93}},
     {"zbt", RISCVExtensionVersion{0, 93}},
     {"zvfh", RISCVExtensionVersion{0, 1}},
 };

llvm/lib/Target/RISCV/RISCV.td

 
 def FeatureStdExtC
     : SubtargetFeature<"c", "HasStdExtC", "true",
                        "'C' (Compressed Instructions)">;
 def HasStdExtC : Predicate<"Subtarget->hasStdExtC()">,
                            AssemblerPredicate<(all_of FeatureStdExtC),
                            "'C' (Compressed Instructions)">;
 
+def FeatureStdExtZawrs
+    : SubtargetFeature<"experimental-zawrs", "HasStdExtZawrs", "true",
+                       "'Zawrs' (Wait on Reservation Set)">;
+def HasStdExtZawrs : Predicate<"Subtarget->hasStdExtZawrs()">,
+                             AssemblerPredicate<(all_of FeatureStdExtZawrs),
+                             "'Zawrs' (Wait on Reservation Set)">;
+
 def FeatureStdExtZba
     : SubtargetFeature<"zba", "HasStdExtZba", "true",
                        "'Zba' (Address Generation Instructions)">;
 def HasStdExtZba : Predicate<"Subtarget->hasStdExtZba()">,
                              AssemblerPredicate<(all_of FeatureStdExtZba),
                              "'Zba' (Address Generation Instructions)">;
 def NotHasStdExtZba : Predicate<"!Subtarget->hasStdExtZba()">;
 

llvm/lib/Target/RISCV/RISCVInstrInfo.td

 // instruction (i.e., it should always trap, if your implementation has invalid
 // instruction traps).
 def UNIMP : RVInstI<0b001, OPC_SYSTEM, (outs), (ins), "unimp", "">,
             Sched<[]> {
   let rs1 = 0;
   let rd = 0;
   let imm12 = 0b110000000000;
 }
+
+let Predicates = [HasStdExtZawrs] in {
+def WRS_NTO : RVInstI<0b000, OPC_SYSTEM, (outs), (ins), "wrs.nto", "">,
+              Sched<[]> {
+  let rs1 = 0;
+  let rd = 0;
+  let imm12 = 0b000000001101;
+}
+
+def WRS_STO : RVInstI<0b000, OPC_SYSTEM, (outs), (ins), "wrs.sto", "">,
+              Sched<[]> {
+  let rs1 = 0;
+  let rd = 0;
+  let imm12 = 0b000000011101;
+}
+} // Predicates = [HasStdExtZawrs]
+
 } // hasSideEffects = 1, mayLoad = 0, mayStore = 0
 
 def CSRRW : CSR_ir<0b001, "csrrw">;
 def CSRRS : CSR_ir<0b010, "csrrs">;
 def CSRRC : CSR_ir<0b011, "csrrc">;
 
 def CSRRWI : CSR_ii<0b101, "csrrwi">;
 def CSRRSI : CSR_ii<0b110, "csrrsi">;

llvm/lib/Target/RISCV/RISCVSubtarget.h

private:
   RISCVProcFamilyEnum RISCVProcFamily = Others;
 
   bool HasStdExtM = false;
   bool HasStdExtA = false;
   bool HasStdExtF = false;
   bool HasStdExtD = false;
   bool HasStdExtC = false;
   bool HasStdExtZihintpause = false;
+  bool HasStdExtZawrs = false;
   bool HasStdExtZba = false;
   bool HasStdExtZbb = false;
   bool HasStdExtZbc = false;
   bool HasStdExtZbe = false;
   bool HasStdExtZbf = false;
   bool HasStdExtZbm = false;
   bool HasStdExtZbp = false;
   bool HasStdExtZbr = false;
public:
 
   bool hasStdExtM() const { return HasStdExtM; }
   bool hasStdExtA() const { return HasStdExtA; }
   bool hasStdExtF() const { return HasStdExtF; }
   bool hasStdExtD() const { return HasStdExtD; }
   bool hasStdExtC() const { return HasStdExtC; }
   bool hasStdExtV() const { return HasStdExtV; }
   bool hasStdExtZihintpause() const { return HasStdExtZihintpause; }
+  bool hasStdExtZawrs() const { return HasStdExtZawrs; }
   bool hasStdExtZba() const { return HasStdExtZba; }
   bool hasStdExtZbb() const { return HasStdExtZbb; }
   bool hasStdExtZbc() const { return HasStdExtZbc; }
   bool hasStdExtZbe() const { return HasStdExtZbe; }
   bool hasStdExtZbf() const { return HasStdExtZbf; }
   bool hasStdExtZbm() const { return HasStdExtZbm; }
   bool hasStdExtZbp() const { return HasStdExtZbp; }
   bool hasStdExtZbr() const { return HasStdExtZbr; }

llvm/test/MC/RISCV/rv32zawrs-valid.s

+# RUN: llvm-mc %s -triple=riscv32 -mattr=+experimental-zawrs -riscv-no-aliases -show-encoding \
+# RUN:     | FileCheck -check-prefixes=CHECK-ASM,CHECK-ASM-AND-OBJ %s
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+experimental-zawrs -riscv-no-aliases -show-encoding \
+# RUN:     | FileCheck -check-prefixes=CHECK-ASM,CHECK-ASM-AND-OBJ %s
+# RUN: llvm-mc -filetype=obj -triple=riscv32 -mattr=+experimental-zawrs < %s \
+# RUN:     | llvm-objdump --mattr=+experimental-zawrs -M no-aliases -d -r - \
+# RUN:     | FileCheck --check-prefix=CHECK-ASM-AND-OBJ %s
+# RUN: llvm-mc -filetype=obj -triple=riscv64 -mattr=+experimental-zawrs < %s \
+# RUN:     | llvm-objdump --mattr=+experimental-zawrs -M no-aliases -d -r - \
+# RUN:     | FileCheck --check-prefix=CHECK-ASM-AND-OBJ %s
+
+# CHECK-ASM-AND-OBJ: wrs.nto
+# CHECK-ASM: encoding: [0x73,0x00,0xd0,0x00]
+wrs.nto
+
+# CHECK-ASM-AND-OBJ: wrs.sto
+# CHECK-ASM: encoding: [0x73,0x00,0xd0,0x01]
+wrs.sto