[Sparc] Implement i64 load/store support for 32-bit sparc.

The LDD/STD instructions can load/store a 64bit quantity from/to
memory to/from a consecutive even/odd pair of (32-bit) registers. They
are part of SparcV8, and also present in SparcV9. (Although deprecated
there, as you can store 64bits in one register).

As recommended on llvmdev in the thread "How to enable use of 64bit
load/store for 32bit architecture" from Apr 2015, I've modeled the
64-bit load/store operations as working on a v2i32 type, rather than
making i64 a legal type, but with few legal operations. The latter
does not (currently) work, as there is much code in llvm which assumes
that if i64 is legal, operations like "add" will actually work on it.

The same assumption does not hold for v2i32 -- for vector types, it is
workable to support only load/store, and expand everything else.

This patch:
- Adds a new register class, IntPair, for even/odd pairs of registers.

- Modifies the list of reserved registers, the stack spilling code,
  and register copying code to support the IntPair register class.

- Adds support in AsmParser. (note that in asm text, you write the
  name of the first register of the pair only. So the parser has to
  morph the single register into the equivalent paired register).

- Adds the new instructions themselves (LDD/STD/LDDA/STDA).

- Hooks up the instructions and registers as a vector type v2i32. Adds
  custom legalizer to transform i64 load/stores into v2i32 load/stores
  and bitcasts, so that the new instructions can actually be
  generated, and marks all operations other than load/store on v2i32
  as needing to be expanded.

- Copies the unfortunate SelectInlineAsm hack from ARMISelDAGToDAG.
  This hack undoes the transformation of i64 operands into two
  arbitrarily-allocated separate i32 registers in
  SelectionDAGBuilder. and instead passes them in a single
  IntPair. (Arbitrarily allocated registers are not useful, asm code
  expects to be receiving a pair, which can be passed to ldd/std.)

Also adds a bunch of test cases covering all the bugs I've added along
the way.

Differential Revision: http://reviews.llvm.org/D8713

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244484 91177308-0d34-0410-b5e6-96231b3b80d8

Author: jyknight

lib/Target/Sparc/AsmParser/SparcAsmParser.cpp

@@ -140,13 +140,20 @@ class SparcAsmParser : public MCTargetAsmParser {
     SP::ASR24, SP::ASR25, SP::ASR26, SP::ASR27,
     SP::ASR28, SP::ASR29, SP::ASR30, SP::ASR31};
 
+  static unsigned IntPairRegs[] = {
+    Sparc::G0_G1, Sparc::G2_G3, Sparc::G4_G5, Sparc::G6_G7,
+    Sparc::O0_O1, Sparc::O2_O3, Sparc::O4_O5, Sparc::O6_O7,
+    Sparc::L0_L1, Sparc::L2_L3, Sparc::L4_L5, Sparc::L6_L7,
+    Sparc::I0_I1, Sparc::I2_I3, Sparc::I4_I5, Sparc::I6_I7};
+
 /// SparcOperand - Instances of this class represent a parsed Sparc machine
 /// instruction.
 class SparcOperand : public MCParsedAsmOperand {
 public:
   enum RegisterKind {
     rk_None,
     rk_IntReg,
+    rk_IntPairReg,
     rk_FloatReg,
     rk_DoubleReg,
     rk_QuadReg,
@@ -200,6 +207,10 @@ class SparcOperand : public MCParsedAsmOperand {
   bool isMEMrr() const { return Kind == k_MemoryReg; }
   bool isMEMri() const { return Kind == k_MemoryImm; }
 
+  bool isIntReg() const {
+    return (Kind == k_Register && Reg.Kind == rk_IntReg);
+  }
+
   bool isFloatReg() const {
     return (Kind == k_Register && Reg.Kind == rk_FloatReg);
   }
@@ -330,6 +341,25 @@ class SparcOperand : public MCParsedAsmOperand {
     return Op;
   }
 
+  static bool MorphToIntPairReg(SparcOperand &Op) {
+    unsigned Reg = Op.getReg();
+    assert(Op.Reg.Kind == rk_IntReg);
+    unsigned regIdx = 32;
+    if (Reg >= Sparc::G0 && Reg <= Sparc::G7)
+      regIdx = Reg - Sparc::G0;
+    else if (Reg >= Sparc::O0 && Reg <= Sparc::O7)
+      regIdx = Reg - Sparc::O0 + 8;
+    else if (Reg >= Sparc::L0 && Reg <= Sparc::L7)
+      regIdx = Reg - Sparc::L0 + 16;
+    else if (Reg >= Sparc::I0 && Reg <= Sparc::I7)
+      regIdx = Reg - Sparc::I0 + 24;
+    if (regIdx % 2 || regIdx > 31)
+      return false;
+    Op.Reg.RegNum = IntPairRegs[regIdx / 2];
+    Op.Reg.Kind = rk_IntPairReg;
+    return true;
+  }
+
   static bool MorphToDoubleReg(SparcOperand &Op) {
     unsigned Reg = Op.getReg();
     assert(Op.Reg.Kind == rk_FloatReg);
@@ -1051,5 +1081,9 @@ unsigned SparcAsmParser::validateTargetOperandClass(MCParsedAsmOperand &GOp,
       break;
     }
   }
+  if (Op.isIntReg() && Kind == MCK_IntPair) {
+    if (SparcOperand::MorphToIntPairReg(Op))
+      return MCTargetAsmParser::Match_Success;
+  }
   return Match_InvalidOperand;
 }

lib/Target/Sparc/Disassembler/SparcDisassembler.cpp

@@ -117,6 +117,13 @@ static const unsigned ASRRegDecoderTable[] = {
   SP::ASR24, SP::ASR25, SP::ASR26, SP::ASR27,
   SP::ASR28, SP::ASR29, SP::ASR30, SP::ASR31};
 
+static const uint16_t IntPairDecoderTable[] = {
+  SP::G0_G1, SP::G2_G3, SP::G4_G5, SP::G6_G7,
+  SP::O0_O1, SP::O2_O3, SP::O4_O5, SP::O6_O7,
+  SP::L0_L1, SP::L2_L3, SP::L4_L5, SP::L6_L7,
+  SP::I0_I1, SP::I2_I3, SP::I4_I5, SP::I6_I7,
+};
+
 static DecodeStatus DecodeIntRegsRegisterClass(MCInst &Inst,
                                                unsigned RegNo,
                                                uint64_t Address,
@@ -196,9 +203,25 @@ static DecodeStatus DecodeASRRegsRegisterClass(MCInst &Inst, unsigned RegNo,
   return MCDisassembler::Success;
 }
 
+static DecodeStatus DecodeIntPairRegisterClass(MCInst &Inst, unsigned RegNo,
+                                   uint64_t Address, const void *Decoder) {
+  DecodeStatus S = MCDisassembler::Success;
+
+  if (RegNo > 31)
+    return MCDisassembler::Fail;
+
+  if ((RegNo & 1))
+    S = MCDisassembler::SoftFail;
+
+  unsigned RegisterPair = IntPairDecoderTable[RegNo/2];
+  Inst.addOperand(MCOperand::createReg(RegisterPair));
+  return S;
+}
 
 static DecodeStatus DecodeLoadInt(MCInst &Inst, unsigned insn, uint64_t Address,
                                   const void *Decoder);
+static DecodeStatus DecodeLoadIntPair(MCInst &Inst, unsigned insn, uint64_t Address,
+                                  const void *Decoder);
 static DecodeStatus DecodeLoadFP(MCInst &Inst, unsigned insn, uint64_t Address,
                                  const void *Decoder);
 static DecodeStatus DecodeLoadDFP(MCInst &Inst, unsigned insn, uint64_t Address,
@@ -207,6 +230,8 @@ static DecodeStatus DecodeLoadQFP(MCInst &Inst, unsigned insn, uint64_t Address,
                                   const void *Decoder);
 static DecodeStatus DecodeStoreInt(MCInst &Inst, unsigned insn,
                                    uint64_t Address, const void *Decoder);
+static DecodeStatus DecodeStoreIntPair(MCInst &Inst, unsigned insn,
+                                   uint64_t Address, const void *Decoder);
 static DecodeStatus DecodeStoreFP(MCInst &Inst, unsigned insn,
                                   uint64_t Address, const void *Decoder);
 static DecodeStatus DecodeStoreDFP(MCInst &Inst, unsigned insn,
@@ -326,6 +351,12 @@ static DecodeStatus DecodeLoadInt(MCInst &Inst, unsigned insn, uint64_t Address,
                    DecodeIntRegsRegisterClass);
 }
 
+static DecodeStatus DecodeLoadIntPair(MCInst &Inst, unsigned insn, uint64_t Address,
+                                  const void *Decoder) {
+  return DecodeMem(Inst, insn, Address, Decoder, true,
+                   DecodeIntPairRegisterClass);
+}
+
 static DecodeStatus DecodeLoadFP(MCInst &Inst, unsigned insn, uint64_t Address,
                                  const void *Decoder) {
   return DecodeMem(Inst, insn, Address, Decoder, true,
@@ -350,6 +381,12 @@ static DecodeStatus DecodeStoreInt(MCInst &Inst, unsigned insn,
                    DecodeIntRegsRegisterClass);
 }
 
+static DecodeStatus DecodeStoreIntPair(MCInst &Inst, unsigned insn,
+                                   uint64_t Address, const void *Decoder) {
+  return DecodeMem(Inst, insn, Address, Decoder, false,
+                   DecodeIntPairRegisterClass);
+}
+
 static DecodeStatus DecodeStoreFP(MCInst &Inst, unsigned insn, uint64_t Address,
                                   const void *Decoder) {
   return DecodeMem(Inst, insn, Address, Decoder, false,

lib/Target/Sparc/SparcCallingConv.td

@@ -21,7 +21,11 @@ def CC_Sparc32 : CallingConv<[
   // i32 f32 arguments get passed in integer registers if there is space.
   CCIfType<[i32, f32], CCAssignToReg<[I0, I1, I2, I3, I4, I5]>>,
   // f64 arguments are split and passed through registers or through stack.
-  CCIfType<[f64], CCCustom<"CC_Sparc_Assign_f64">>,
+  CCIfType<[f64], CCCustom<"CC_Sparc_Assign_Split_64">>,
+  // As are v2i32 arguments (this would be the default behavior for
+  // v2i32 if it wasn't allocated to the IntPair register-class)
+  CCIfType<[v2i32], CCCustom<"CC_Sparc_Assign_Split_64">>,
+
 
   // Alternatively, they are assigned to the stack in 4-byte aligned units.
   CCAssignToStack<4, 4>
@@ -30,7 +34,8 @@ def CC_Sparc32 : CallingConv<[
 def RetCC_Sparc32 : CallingConv<[
   CCIfType<[i32], CCAssignToReg<[I0, I1, I2, I3, I4, I5]>>,
   CCIfType<[f32], CCAssignToReg<[F0, F1, F2, F3]>>,
-  CCIfType<[f64], CCAssignToReg<[D0, D1]>>
+  CCIfType<[f64], CCAssignToReg<[D0, D1]>>,
+  CCIfType<[v2i32], CCCustom<"CC_Sparc_Assign_Ret_Split_64">>
 ]>;
 
 

lib/Target/Sparc/SparcFrameLowering.cpp

@@ -213,23 +213,35 @@ bool SparcFrameLowering::isLeafProc(MachineFunction &MF) const
 }
 
 void SparcFrameLowering::remapRegsForLeafProc(MachineFunction &MF) const {
-
   MachineRegisterInfo &MRI = MF.getRegInfo();
-
   // Remap %i[0-7] to %o[0-7].
   for (unsigned reg = SP::I0; reg <= SP::I7; ++reg) {
     if (MRI.reg_nodbg_empty(reg))
       continue;
-    unsigned mapped_reg = (reg - SP::I0 + SP::O0);
+
+    unsigned mapped_reg = reg - SP::I0 + SP::O0;
     assert(MRI.reg_nodbg_empty(mapped_reg));
 
     // Replace I register with O register.
     MRI.replaceRegWith(reg, mapped_reg);
+
+    // Also replace register pair super-registers.
+    if ((reg - SP::I0) % 2 == 0) {
+      unsigned preg = (reg - SP::I0) / 2 + SP::I0_I1;
+      unsigned mapped_preg = preg - SP::I0_I1 + SP::O0_O1;
+      MRI.replaceRegWith(preg, mapped_preg);
+    }
   }
 
   // Rewrite MBB's Live-ins.
   for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
        MBB != E; ++MBB) {
+    for (unsigned reg = SP::I0_I1; reg <= SP::I6_I7; ++reg) {
+      if (!MBB->isLiveIn(reg))
+        continue;
+      MBB->removeLiveIn(reg);
+      MBB->addLiveIn(reg - SP::I0_I1 + SP::O0_O1);
+    }
     for (unsigned reg = SP::I0; reg <= SP::I7; ++reg) {
       if (!MBB->isLiveIn(reg))
         continue;