ARM: implement MRS/MSR (banked reg) system instructions.

These are system-only instructions for CPUs with virtualization
extensions, allowing a hypervisor easy access to all of the various
different AArch32 registers.

rdar://problem/17861345

llvm-svn: 215700

7 files changed, 241 insertions, 4 deletions

diff --git a/llvm/lib/Target/ARM/ARMInstrFormats.td b/llvm/lib/Target/ARM/ARMInstrFormats.td
index 59e9260b81e..7d27cf3fcdc 100644
--- a/llvm/lib/Target/ARM/ARMInstrFormats.td
+++ b/llvm/lib/Target/ARM/ARMInstrFormats.td
@@ -203,6 +203,16 @@ def msr_mask : Operand<i32> {
   let ParserMatchClass = MSRMaskOperand;
 }
 
+def BankedRegOperand : AsmOperandClass {
+  let Name = "BankedReg";
+  let ParserMethod = "parseBankedRegOperand";
+}
+def banked_reg : Operand<i32> {
+  let PrintMethod = "printBankedRegOperand";
+  let DecoderMethod = "DecodeBankedReg";
+  let ParserMatchClass = BankedRegOperand;
+}
+
 // Shift Right Immediate - A shift right immediate is encoded differently from
 // other shift immediates. The imm6 field is encoded like so:
 //
diff --git a/llvm/lib/Target/ARM/ARMInstrInfo.td b/llvm/lib/Target/ARM/ARMInstrInfo.td
index f6cf69a2fbb..e7640f0e98f 100644
--- a/llvm/lib/Target/ARM/ARMInstrInfo.td
+++ b/llvm/lib/Target/ARM/ARMInstrInfo.td
@@ -241,6 +241,9 @@ def HasDB            : Predicate<"Subtarget->hasDataBarrier()">,
 def HasMP            : Predicate<"Subtarget->hasMPExtension()">,
                                  AssemblerPredicate<"FeatureMP",
                                                     "mp-extensions">;
+def HasVirtualization: Predicate<"false">,
+                                 AssemblerPredicate<"FeatureVirtualization",
+                                                   "virtualization-extensions">;
 def HasTrustZone     : Predicate<"Subtarget->hasTrustZone()">,
                                  AssemblerPredicate<"FeatureTrustZone",
                                                     "TrustZone">;
@@ -5066,12 +5069,31 @@ def MRSsys : ABI<0b0001, (outs GPRnopc:$Rd), (ins), NoItinerary,
   let Unpredictable{11-0} = 0b110100001111;
 }
 
+// However, the MRS (banked register) system instruction (ARMv7VE) *does* have a
+// separate encoding (distinguished by bit 5.
+def MRSbanked : ABI<0b0001, (outs GPRnopc:$Rd), (ins banked_reg:$banked),
+                    NoItinerary, "mrs", "\t$Rd, $banked", []>,
+                Requires<[IsARM, HasVirtualization]> {
+  bits<6> banked;
+  bits<4> Rd;
+
+  let Inst{23} = 0;
+  let Inst{22} = banked{5}; // R bit
+  let Inst{21-20} = 0b10;
+  let Inst{19-16} = banked{3-0};
+  let Inst{15-12} = Rd;
+  let Inst{11-9} = 0b001;
+  let Inst{8} = banked{4};
+  let Inst{7-0} = 0b00000000;
+}
+
 // Move from ARM core register to Special Register
 //
-// No need to have both system and application versions, the encodings are the
-// same and the assembly parser has no way to distinguish between them. The mask
-// operand contains the special register (R Bit) in bit 4 and bits 3-0 contains
-// the mask with the fields to be accessed in the special register.
+// No need to have both system and application versions of MSR (immediate) or
+// MSR (register), the encodings are the same and the assembly parser has no way
+// to distinguish between them. The mask operand contains the special register
+// (R Bit) in bit 4 and bits 3-0 contains the mask with the fields to be
+// accessed in the special register.
 def MSR : ABI<0b0001, (outs), (ins msr_mask:$mask, GPR:$Rn), NoItinerary,
               "msr", "\t$mask, $Rn", []> {
   bits<5> mask;
@@ -5099,6 +5121,25 @@ def MSRi : ABI<0b0011, (outs), (ins msr_mask:$mask,  so_imm:$a), NoItinerary,
   let Inst{11-0} = a;
 }
 
+// However, the MSR (banked register) system instruction (ARMv7VE) *does* have a
+// separate encoding (distinguished by bit 5.
+def MSRbanked : ABI<0b0001, (outs), (ins banked_reg:$banked, GPRnopc:$Rn),
+                    NoItinerary, "msr", "\t$banked, $Rn", []>,
+                Requires<[IsARM, HasVirtualization]> {
+  bits<6> banked;
+  bits<4> Rn;
+
+  let Inst{23} = 0;
+  let Inst{22} = banked{5}; // R bit
+  let Inst{21-20} = 0b10;
+  let Inst{19-16} = banked{3-0};
+  let Inst{15-12} = 0b1111;
+  let Inst{11-9} = 0b001;
+  let Inst{8} = banked{4};
+  let Inst{7-4} = 0b0000;
+  let Inst{3-0} = Rn;
+}
+
 // Dynamic stack allocation yields a _chkstk for Windows targets.  These calls
 // are needed to probe the stack when allocating more than
 // 4k bytes in one go. Touching the stack at 4K increments is necessary to
diff --git a/llvm/lib/Target/ARM/ARMInstrThumb2.td b/llvm/lib/Target/ARM/ARMInstrThumb2.td
index 46dbd8c95ed..e6d17e88755 100644
--- a/llvm/lib/Target/ARM/ARMInstrThumb2.td
+++ b/llvm/lib/Target/ARM/ARMInstrThumb2.td
@@ -3991,6 +3991,23 @@ def t2MRSsys_AR: T2I<(outs GPR:$Rd), (ins), NoItinerary, "mrs", "\t$Rd, spsr",
   let Inst{7-0} = 0b00000000;
 }
 
+def t2MRSbanked : T2I<(outs rGPR:$Rd), (ins banked_reg:$banked),
+                      NoItinerary, "mrs", "\t$Rd, $banked", []>,
+                  Requires<[IsThumb, HasVirtualization]> {
+  bits<6> banked;
+  bits<4> Rd;
+
+  let Inst{31-21} = 0b11110011111;
+  let Inst{20} = banked{5}; // R bit
+  let Inst{19-16} = banked{3-0};
+  let Inst{15-12} = 0b1000;
+  let Inst{11-8} = Rd;
+  let Inst{7-5} = 0b001;
+  let Inst{4} = banked{4};
+  let Inst{3-0} = 0b0000;
+}
+
+
 // M class MRS.
 //
 // This MRS has a mask field in bits 7-0 and can take more values than
@@ -4028,6 +4045,25 @@ def t2MSR_AR : T2I<(outs), (ins msr_mask:$mask, rGPR:$Rn),
   let Inst{7-0}   = 0;
 }
 
+// However, the MSR (banked register) system instruction (ARMv7VE) *does* have a
+// separate encoding (distinguished by bit 5.
+def t2MSRbanked : T2I<(outs), (ins banked_reg:$banked, rGPR:$Rn),
+                      NoItinerary, "msr", "\t$banked, $Rn", []>,
+                  Requires<[IsThumb, HasVirtualization]> {
+  bits<6> banked;
+  bits<4> Rn;
+
+  let Inst{31-21} = 0b11110011100;
+  let Inst{20} = banked{5}; // R bit
+  let Inst{19-16} = Rn;
+  let Inst{15-12} = 0b1000;
+  let Inst{11-8} = banked{3-0};
+  let Inst{7-5} = 0b001;
+  let Inst{4} = banked{4};
+  let Inst{3-0} = 0b0000;
+}
+
+
 // M class MSR.
 //
 // Move from ARM core register to Special Register
diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index da6b700e607..ba46c937d80 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -290,6 +290,7 @@ class ARMAsmParser : public MCTargetAsmParser {
   OperandMatchResultTy parseInstSyncBarrierOptOperand(OperandVector &);
   OperandMatchResultTy parseProcIFlagsOperand(OperandVector &);
   OperandMatchResultTy parseMSRMaskOperand(OperandVector &);
+  OperandMatchResultTy parseBankedRegOperand(OperandVector &);
   OperandMatchResultTy parsePKHImm(OperandVector &O, StringRef Op, int Low,
                                    int High);
   OperandMatchResultTy parsePKHLSLImm(OperandVector &O) {
@@ -383,6 +384,7 @@ class ARMOperand : public MCParsedAsmOperand {
     k_Memory,
     k_PostIndexRegister,
     k_MSRMask,
+    k_BankedReg,
     k_ProcIFlags,
     k_VectorIndex,
     k_Register,
@@ -435,6 +437,10 @@ class ARMOperand : public MCParsedAsmOperand {
     unsigned Val;
   };
 
+  struct BankedRegOp {
+    unsigned Val;
+  };
+
   struct TokOp {
     const char *Data;
     unsigned Length;
@@ -517,6 +523,7 @@ class ARMOperand : public MCParsedAsmOperand {
     struct ITMaskOp ITMask;
     struct IFlagsOp IFlags;
     struct MMaskOp MMask;
+    struct BankedRegOp BankedReg;
     struct TokOp Tok;
     struct RegOp Reg;
     struct VectorListOp VectorList;
@@ -585,6 +592,9 @@ public:
     case k_MSRMask:
       MMask = o.MMask;
       break;
+    case k_BankedReg:
+      BankedReg = o.BankedReg;
+      break;
     case k_ProcIFlags:
       IFlags = o.IFlags;
       break;
@@ -679,6 +689,11 @@ public:
     return MMask.Val;
   }
 
+  unsigned getBankedReg() const {
+    assert(Kind == k_BankedReg && "Invalid access!");
+    return BankedReg.Val;
+  }
+
   bool isCoprocNum() const { return Kind == k_CoprocNum; }
   bool isCoprocReg() const { return Kind == k_CoprocReg; }
   bool isCoprocOption() const { return Kind == k_CoprocOption; }
@@ -1384,6 +1399,7 @@ public:
   }
 
   bool isMSRMask() const { return Kind == k_MSRMask; }
+  bool isBankedReg() const { return Kind == k_BankedReg; }
   bool isProcIFlags() const { return Kind == k_ProcIFlags; }
 
   // NEON operands.
@@ -2334,6 +2350,11 @@ public:
     Inst.addOperand(MCOperand::CreateImm(unsigned(getMSRMask())));
   }
 
+  void addBankedRegOperands(MCInst &Inst, unsigned N) const {
+    assert(N == 1 && "Invalid number of operands!");
+    Inst.addOperand(MCOperand::CreateImm(unsigned(getBankedReg())));
+  }
+
   void addProcIFlagsOperands(MCInst &Inst, unsigned N) const {
     assert(N == 1 && "Invalid number of operands!");
     Inst.addOperand(MCOperand::CreateImm(unsigned(getProcIFlags())));
@@ -2736,6 +2757,14 @@ public:
     Op->EndLoc = S;
     return Op;
   }
+
+  static std::unique_ptr<ARMOperand> CreateBankedReg(unsigned Reg, SMLoc S) {
+    auto Op = make_unique<ARMOperand>(k_BankedReg);
+    Op->BankedReg.Val = Reg;
+    Op->StartLoc = S;
+    Op->EndLoc = S;
+    return Op;
+  }
 };
 
 } // end anonymous namespace.
@@ -2769,6 +2798,9 @@ void ARMOperand::print(raw_ostream &OS) const {
   case k_MSRMask:
     OS << "<mask: " << getMSRMask() << ">";
     break;
+  case k_BankedReg:
+    OS << "<banked reg: " << getBankedReg() << ">";
+    break;
   case k_Immediate:
     getImm()->print(OS);
     break;
@@ -4002,6 +4034,62 @@ ARMAsmParser::parseMSRMaskOperand(OperandVector &Operands) {
   return MatchOperand_Success;
 }
 
+/// parseBankedRegOperand - Try to parse a banked register (e.g. "lr_irq") for
+/// use in the MRS/MSR instructions added to support virtualization.
+ARMAsmParser::OperandMatchResultTy
+ARMAsmParser::parseBankedRegOperand(OperandVector &Operands) {
+  SMLoc S = Parser.getTok().getLoc();
+  const AsmToken &Tok = Parser.getTok();
+  if (!Tok.is(AsmToken::Identifier))
+    return MatchOperand_NoMatch;
+  StringRef RegName = Tok.getString();
+
+  // The values here come from B9.2.3 of the ARM ARM, where bits 4-0 are SysM
+  // and bit 5 is R.
+  unsigned Encoding = StringSwitch<unsigned>(RegName.lower())
+                          .Case("r8_usr", 0x00)
+                          .Case("r9_usr", 0x01)
+                          .Case("r10_usr", 0x02)
+                          .Case("r11_usr", 0x03)
+                          .Case("r12_usr", 0x04)
+                          .Case("sp_usr", 0x05)
+                          .Case("lr_usr", 0x06)
+                          .Case("r8_fiq", 0x08)
+                          .Case("r9_fiq", 0x09)
+                          .Case("r10_fiq", 0x0a)
+                          .Case("r11_fiq", 0x0b)
+                          .Case("r12_fiq", 0x0c)
+                          .Case("sp_fiq", 0x0d)
+                          .Case("lr_fiq", 0x0e)
+                          .Case("lr_irq", 0x10)
+                          .Case("sp_irq", 0x11)
+                          .Case("lr_svc", 0x12)
+                          .Case("sp_svc", 0x13)
+                          .Case("lr_abt", 0x14)
+                          .Case("sp_abt", 0x15)
+                          .Case("lr_und", 0x16)
+                          .Case("sp_und", 0x17)
+                          .Case("lr_mon", 0x1c)
+                          .Case("sp_mon", 0x1d)
+                          .Case("elr_hyp", 0x1e)
+                          .Case("sp_hyp", 0x1f)
+                          .Case("spsr_fiq", 0x2e)
+                          .Case("spsr_irq", 0x30)
+                          .Case("spsr_svc", 0x32)
+                          .Case("spsr_abt", 0x34)
+                          .Case("spsr_und", 0x36)
+                          .Case("spsr_mon", 0x3c)
+                          .Case("spsr_hyp", 0x3e)
+                          .Default(~0U);
+
+  if (Encoding == ~0U)
+    return MatchOperand_NoMatch;
+
+  Parser.Lex(); // Eat identifier token.
+  Operands.push_back(ARMOperand::CreateBankedReg(Encoding, S));
+  return MatchOperand_Success;
+}
+
 ARMAsmParser::OperandMatchResultTy
 ARMAsmParser::parsePKHImm(OperandVector &Operands, StringRef Op, int Low,
                           int High) {
diff --git a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index 48bcc9b2dcd..0940e2a2407 100644
--- a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -281,6 +281,8 @@ static DecodeStatus DecodeInstSyncBarrierOption(MCInst &Inst, unsigned Insn,
                                uint64_t Address, const void *Decoder);
 static DecodeStatus DecodeMSRMask(MCInst &Inst, unsigned Insn,
                                uint64_t Address, const void *Decoder);
+static DecodeStatus DecodeBankedReg(MCInst &Inst, unsigned Insn,
+                               uint64_t Address, const void *Decoder);
 static DecodeStatus DecodeDoubleRegLoad(MCInst &Inst, unsigned Insn,
                                uint64_t Address, const void *Decoder);
 static DecodeStatus DecodeDoubleRegStore(MCInst &Inst, unsigned Insn,
@@ -4025,6 +4027,29 @@ static DecodeStatus DecodeMSRMask(MCInst &Inst, unsigned Val,
   return MCDisassembler::Success;
 }
 
+static DecodeStatus DecodeBankedReg(MCInst &Inst, unsigned Val,
+                                    uint64_t Address, const void *Decoder) {
+
+  unsigned R = fieldFromInstruction(Val, 5, 1);
+  unsigned SysM = fieldFromInstruction(Val, 0, 5);
+
+  // The table of encodings for these banked registers comes from B9.2.3 of the
+  // ARM ARM. There are patterns, but nothing regular enough to make this logic
+  // neater. So by fiat, these values are UNPREDICTABLE:
+  if (!R) {
+    if (SysM == 0x7 || SysM == 0xf || SysM == 0x18 || SysM == 0x19 ||
+        SysM == 0x1a || SysM == 0x1b)
+      return MCDisassembler::SoftFail;
+  } else {
+    if (SysM != 0xe && SysM != 0x10 && SysM != 0x12 && SysM != 0x14 &&
+        SysM != 0x16 && SysM != 0x1c && SysM != 0x1e)
+      return MCDisassembler::SoftFail;
+  }
+
+  Inst.addOperand(MCOperand::CreateImm(Val));
+  return MCDisassembler::Success;
+}
+
 static DecodeStatus DecodeDoubleRegLoad(MCInst &Inst, unsigned Insn,
                                         uint64_t Address, const void *Decoder) {
   DecodeStatus S = MCDisassembler::Success;
diff --git a/llvm/lib/Target/ARM/InstPrinter/ARMInstPrinter.cpp b/llvm/lib/Target/ARM/InstPrinter/ARMInstPrinter.cpp
index 228fb5756ca..5782ae39cf0 100644
--- a/llvm/lib/Target/ARM/InstPrinter/ARMInstPrinter.cpp
+++ b/llvm/lib/Target/ARM/InstPrinter/ARMInstPrinter.cpp
@@ -882,6 +882,42 @@ void ARMInstPrinter::printMSRMaskOperand(const MCInst *MI, unsigned OpNum,
   }
 }
 
+void ARMInstPrinter::printBankedRegOperand(const MCInst *MI, unsigned OpNum,
+                                           raw_ostream &O) {
+  uint32_t Banked = MI->getOperand(OpNum).getImm();
+  uint32_t R = (Banked & 0x20) >> 5;
+  uint32_t SysM = Banked & 0x1f;
+
+  // Nothing much we can do about this, the encodings are specified in B9.2.3 of
+  // the ARM ARM v7C, and are all over the shop.
+  if (R) {
+    O << "SPSR_";
+
+    switch(SysM) {
+    case 0x0e: O << "fiq"; return;
+    case 0x10: O << "irq"; return;
+    case 0x12: O << "svc"; return;
+    case 0x14: O << "abt"; return;
+    case 0x16: O << "und"; return;
+    case 0x1c: O << "mon"; return;
+    case 0x1e: O << "hyp"; return;
+    default: llvm_unreachable("Invalid banked SPSR register");
+    }
+  }
+
+  assert(!R && "should have dealt with SPSR regs");
+  const char *RegNames[] = {
+    "r8_usr", "r9_usr", "r10_usr", "r11_usr", "r12_usr", "sp_usr", "lr_usr", "",
+    "r8_fiq", "r9_fiq", "r10_fiq", "r11_fiq", "r12_fiq", "sp_fiq", "lr_fiq", "",
+    "lr_irq", "sp_irq", "lr_svc",  "sp_svc",  "lr_abt",  "sp_abt", "lr_und", "sp_und",
+    "",       "",       "",        "",        "lr_mon",  "sp_mon", "elr_hyp", "sp_hyp"
+  };
+  const char *Name = RegNames[SysM];
+  assert(Name[0] && "invalid banked register operand");
+
+  O << Name;
+}
+
 void ARMInstPrinter::printPredicateOperand(const MCInst *MI, unsigned OpNum,
                                            raw_ostream &O) {
   ARMCC::CondCodes CC = (ARMCC::CondCodes)MI->getOperand(OpNum).getImm();
diff --git a/llvm/lib/Target/ARM/InstPrinter/ARMInstPrinter.h b/llvm/lib/Target/ARM/InstPrinter/ARMInstPrinter.h
index 45b92adae92..451eaa51ef2 100644
--- a/llvm/lib/Target/ARM/InstPrinter/ARMInstPrinter.h
+++ b/llvm/lib/Target/ARM/InstPrinter/ARMInstPrinter.h
@@ -117,6 +117,7 @@ public:
   void printCPSIMod(const MCInst *MI, unsigned OpNum, raw_ostream &O);
   void printCPSIFlag(const MCInst *MI, unsigned OpNum, raw_ostream &O);
   void printMSRMaskOperand(const MCInst *MI, unsigned OpNum, raw_ostream &O);
+  void printBankedRegOperand(const MCInst *MI, unsigned OpNum, raw_ostream &O);
   void printPredicateOperand(const MCInst *MI, unsigned OpNum, raw_ostream &O);
   void printMandatoryPredicateOperand(const MCInst *MI, unsigned OpNum,
                                       raw_ostream &O);