[PowerPC] Add accumulator register class and instructions

This patch adds the xxmfacc, xxmtacc and xxsetaccz instructions to manipulate
accumulator registers. It also adds the ACC register class definition for the
accumulator registers.

Differential Revision: https://reviews.llvm.org/D84847

Author: Baptiste Saleil

llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp

@@ -290,6 +290,11 @@ struct PPCOperand : public MCParsedAsmOperand {
     return (unsigned) Imm.Val;
   }
 
+  unsigned getACCReg() const {
+    assert(isACCRegNumber() && "Invalid access!");
+    return (unsigned) Imm.Val;
+  }
+
   unsigned getVSRpEvenReg() const {
     assert(isVSRpEvenRegNumber() && "Invalid access!");
     return (unsigned) Imm.Val >> 1;
@@ -407,6 +412,9 @@ struct PPCOperand : public MCParsedAsmOperand {
                                   (getImm() & 3) == 0); }
   bool isImmZero() const { return Kind == Immediate && getImm() == 0; }
   bool isRegNumber() const { return Kind == Immediate && isUInt<5>(getImm()); }
+  bool isACCRegNumber() const {
+    return Kind == Immediate && isUInt<3>(getImm());
+  }
   bool isVSRpEvenRegNumber() const {
     return Kind == Immediate && isUInt<6>(getImm()) && ((getImm() & 1) == 0);
   }
@@ -510,6 +518,11 @@ struct PPCOperand : public MCParsedAsmOperand {
     Inst.addOperand(MCOperand::createReg(SPERegs[getReg()]));
   }
 
+  void addRegACCRCOperands(MCInst &Inst, unsigned N) const {
+    assert(N == 1 && "Invalid number of operands!");
+    Inst.addOperand(MCOperand::createReg(ACCRegs[getACCReg()]));
+  }
+
   void addRegVSRpRCOperands(MCInst &Inst, unsigned N) const {
     assert(N == 1 && "Invalid number of operands!");
     Inst.addOperand(MCOperand::createReg(VSRpRegs[getVSRpEvenReg()]));

llvm/lib/Target/PowerPC/Disassembler/PPCDisassembler.cpp

@@ -173,6 +173,12 @@ static DecodeStatus DecodeSPERCRegisterClass(MCInst &Inst, uint64_t RegNo,
   return decodeRegisterClass(Inst, RegNo, SPERegs);
 }
 
+static DecodeStatus DecodeACCRCRegisterClass(MCInst &Inst, uint64_t RegNo,
+                                             uint64_t Address,
+                                             const void *Decoder) {
+  return decodeRegisterClass(Inst, RegNo, ACCRegs);
+}
+
 static DecodeStatus DecodeVSRpRCRegisterClass(MCInst &Inst, uint64_t RegNo,
                                               uint64_t Address,
                                               const void *Decoder) {

llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.h

@@ -124,6 +124,11 @@ static inline bool isRunOfOnes64(uint64_t Val, unsigned &MB, unsigned &ME) {
 #define GET_SUBTARGETINFO_ENUM
 #include "PPCGenSubtargetInfo.inc"
 
+#define PPC_REGS0_7(X)                                                         \
+  {                                                                            \
+    X##0, X##1, X##2, X##3, X##4, X##5, X##6, X##7                             \
+  }
+
 #define PPC_REGS0_31(X)                                                        \
   {                                                                            \
     X##0, X##1, X##2, X##3, X##4, X##5, X##6, X##7, X##8, X##9, X##10, X##11,  \
@@ -179,8 +184,6 @@ using llvm::MCPhysReg;
     PPC::CR5LT, PPC::CR5GT, PPC::CR5EQ, PPC::CR5UN, \
     PPC::CR6LT, PPC::CR6GT, PPC::CR6EQ, PPC::CR6UN, \
     PPC::CR7LT, PPC::CR7GT, PPC::CR7EQ, PPC::CR7UN}; \
-  static const MCPhysReg CRRegs[8] = { \
-    PPC::CR0, PPC::CR1, PPC::CR2, PPC::CR3, \
-    PPC::CR4, PPC::CR5, PPC::CR6, PPC::CR7}
-
+  static const MCPhysReg CRRegs[8] = PPC_REGS0_7(PPC::CR); \
+  static const MCPhysReg ACCRegs[8] = PPC_REGS0_7(PPC::ACC)
 #endif // LLVM_LIB_TARGET_POWERPC_MCTARGETDESC_PPCMCTARGETDESC_H

llvm/lib/Target/PowerPC/PPCInstrPrefix.td

@@ -586,6 +586,30 @@ multiclass 8LS_DForm_R_XTp5_SI34_MEM_p<bits<6> pref, bits<6> opcode, dag OOL,
                                      isPCRel;
 }
 
+def PPCRegACCRCAsmOperand : AsmOperandClass {
+  let Name = "RegACCRC"; let PredicateMethod = "isACCRegNumber";
+}
+
+def acc : RegisterOperand<ACCRC> {
+  let ParserMatchClass = PPCRegACCRCAsmOperand;
+}
+
+// [PO AS XO2 XO]
+class XForm_AT3<bits<6> opcode, bits<5> xo2, bits<10> xo, dag OOL, dag IOL,
+                    string asmstr, InstrItinClass itin, list<dag> pattern>
+  : I<opcode, OOL, IOL, asmstr, itin> {
+  bits<3> AT;
+
+  let Pattern = pattern;
+
+  let Inst{6-8}  = AT;
+  let Inst{9-10}  = 0;
+  let Inst{11-15} = xo2;
+  let Inst{16-20} = 0;
+  let Inst{21-30} = xo;
+  let Inst{31} = 0;
+}
+
 def PrefixInstrs : Predicate<"Subtarget->hasPrefixInstrs()">;
 def IsISA3_1 : Predicate<"Subtarget->isISA3_1()">;
 def PairedVectorMemops : Predicate<"Subtarget->pairedVectorMemops()">;
@@ -741,6 +765,25 @@ let Predicates = [PrefixInstrs] in {
   }
 }
 
+let Predicates = [MMA] in {
+  def XXMFACC :
+    XForm_AT3<31, 0, 177, (outs acc:$ASo), (ins acc:$AS), "xxmfacc $AS",
+              IIC_VecGeneral, []>, RegConstraint<"$ASo = $AS">,
+              NoEncode<"$ASo">;
+  def XXMTACC :
+    XForm_AT3<31, 1, 177, (outs acc:$AT), (ins acc:$ATi), "xxmtacc $AT",
+              IIC_VecGeneral, []>, RegConstraint<"$ATi = $AT">,
+              NoEncode<"$ATi">;
+  // We define XXSETACCZ as rematerializable to undo CSE of that intrinsic in
+  // the backend. We avoid CSE here because it generates a copy of the acc
+  // register and this copy is more expensive than calling the intrinsic again.
+  let isAsCheapAsAMove = 1, isReMaterializable = 1 in {
+    def XXSETACCZ :
+      XForm_AT3<31, 3, 177, (outs acc:$AT), (ins), "xxsetaccz $AT",
+                IIC_VecGeneral, []>;
+  }
+}
+
 let mayLoad = 1, mayStore = 0, Predicates = [PairedVectorMemops] in {
   def LXVP : DQForm_XTp5_RA17_MEM<6, 0, (outs vsrprc:$XTp),
                                   (ins memrix16:$DQ_RA), "lxvp $XTp, $DQ_RA",

llvm/lib/Target/PowerPC/PPCRegisterInfo.h

@@ -151,6 +151,10 @@ class PPCRegisterInfo : public PPCGenRegisterInfo {
   /// register name so that only the number is left.  Used by for linux asm.
   static const char *stripRegisterPrefix(const char *RegName) {
     switch (RegName[0]) {
+      case 'a':
+        if (RegName[1] == 'c' && RegName[2] == 'c')
+          return RegName + 3;
+      break;
       case 'r':
       case 'f':
       case 'v':

llvm/lib/Target/PowerPC/PPCRegisterInfo.td

@@ -18,6 +18,8 @@ def sub_32 : SubRegIndex<32>;
 def sub_64 : SubRegIndex<64>;
 def sub_vsx0 : SubRegIndex<128>;
 def sub_vsx1 : SubRegIndex<128>;
+def sub_pair0 : SubRegIndex<256>;
+def sub_pair1 : SubRegIndex<256>;
 }
 
 
@@ -96,6 +98,12 @@ class CRBIT<bits<5> num, string n> : PPCReg<n> {
   let HWEncoding{4-0} = num;
 }
 
+// ACC - One of the 8 512-bit VSX accumulators.
+class ACC<bits<3> num, string n, list<Register> subregs> : PPCReg<n> {
+  let HWEncoding{2-0} = num;
+  let SubRegs = subregs;
+}
+
 // VSR Pairs - One of the 32 paired even-odd consecutive VSRs.
 class VSRPair<bits<5> num, string n, list<Register> subregs> : PPCReg<n> {
   let HWEncoding{4-0} = num;
@@ -397,6 +405,21 @@ def CARRYRC : RegisterClass<"PPC", [i32], 32, (add CARRY, XER)> {
   let CopyCost = -1;
 }
 
+let SubRegIndices = [sub_pair0, sub_pair1] in {
+  def ACC0 : ACC<0, "acc0", [VSRp0, VSRp1]>, DwarfRegNum<[0, 0]>;
+  def ACC1 : ACC<1, "acc1", [VSRp2, VSRp3]>, DwarfRegNum<[0, 0]>;
+  def ACC2 : ACC<2, "acc2", [VSRp4, VSRp5]>, DwarfRegNum<[0, 0]>;
+  def ACC3 : ACC<3, "acc3", [VSRp6, VSRp7]>, DwarfRegNum<[0, 0]>;
+  def ACC4 : ACC<4, "acc4", [VSRp8, VSRp9]>, DwarfRegNum<[0, 0]>;
+  def ACC5 : ACC<5, "acc5", [VSRp10, VSRp11]>, DwarfRegNum<[0, 0]>;
+  def ACC6 : ACC<6, "acc6", [VSRp12, VSRp13]>, DwarfRegNum<[0, 0]>;
+  def ACC7 : ACC<7, "acc7", [VSRp14, VSRp15]>, DwarfRegNum<[0, 0]>;
+}
+def ACCRC : RegisterClass<"PPC", [v512i1], 128, (add ACC0, ACC1, ACC2, ACC3,
+                                                      ACC4, ACC5, ACC6, ACC7)> {
+  let Size = 512;
+}
+
 // Allocate in the same order as the underlying VSX registers.
 def VSRpRC :
   RegisterClass<"PPC", [v256i1], 128,

llvm/test/MC/Disassembler/PowerPC/ppc64-encoding-ISA31.txt

@@ -25,6 +25,15 @@
 # CHECK: pstxv 33, 8589934591(0), 1
 0x04 0x11 0xff 0xff 0xdc 0x20 0xff 0xff
 
+# CHECK: xxmfacc 0
+0x7c 0x00 0x01 0x62
+
+# CHECK: xxmtacc 0
+0x7c 0x01 0x01 0x62
+
+# CHECK: xxsetaccz 0
+0x7c 0x03 0x01 0x62
+
 # CHECK: lxvp 2, 32(4)
 0x18 0x44 0x00 0x20
 

llvm/test/MC/PowerPC/ppc64-encoding-ISA31.s

@@ -23,6 +23,15 @@
 # CHECK-LE: pstxv 33, -8589934592(31), 0    # encoding: [0x00,0x00,0x02,0x04
 # CHECK-LE-SAME:                                         0x00,0x00,0x3f,0xdc]
             pstxv 33, -8589934592(31), 0
+# CHECK-BE: xxmfacc 2                          # encoding: [0x7d,0x00,0x01,0x62]
+# CHECK-LE: xxmfacc 2                          # encoding: [0x62,0x01,0x00,0x7d]
+            xxmfacc 2
+# CHECK-BE: xxmtacc 2                          # encoding: [0x7d,0x01,0x01,0x62]
+# CHECK-LE: xxmtacc 2                          # encoding: [0x62,0x01,0x01,0x7d]
+            xxmtacc 2
+# CHECK-BE: xxsetaccz 1                        # encoding: [0x7c,0x83,0x01,0x62]
+# CHECK-LE: xxsetaccz 1                        # encoding: [0x62,0x01,0x83,0x7c]
+            xxsetaccz 1
 # CHECK-BE: lxvp 2, 32(4)                      # encoding: [0x18,0x44,0x00,0x20]
 # CHECK-LE: lxvp 2, 32(4)                      # encoding: [0x20,0x00,0x44,0x18]
             lxvp 2, 32(4)