Reapply r113875 with additional cleanups.

"The register specified for a dregpair is the corresponding Q register, so to
get the pair, we need to look up the sub-regs based on the qreg. Create a
lookup function since we don't have access to TargetRegisterInfo here to
be able to use getSubReg(ARM::dsub_[01])."

Additionaly, fix the NEON VLD1* and VST1* instruction patterns not to use
the dregpair modifier for the 2xdreg versions. Explicitly specifying the two
registers as operands is more correct and more consistent with the other
instruction patterns. This enables further cleanup of special case code in the
disassembler as a nice side-effect.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113903 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 35 deletions

diff --git a/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp b/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp
index 9f493b9aee..edfb20766c 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassemblerCore.cpp
@@ -79,22 +79,9 @@ const char *ARMUtils::OpcodeName(unsigned Opcode) {
 }
 
 // Return the register enum Based on RegClass and the raw register number.
-// For DRegPair, see comments below.
 // FIXME: Auto-gened?
-static unsigned getRegisterEnum(BO B, unsigned RegClassID, unsigned RawRegister,
-                                bool DRegPair = false) {
-
-  if (DRegPair && RegClassID == ARM::QPRRegClassID) {
-    // LLVM expects { Dd, Dd+1 } to form a super register; this is not specified
-    // in the ARM Architecture Manual as far as I understand it (A8.6.307).
-    // Therefore, we morph the RegClassID to be the sub register class and don't
-    // subsequently transform the RawRegister encoding when calculating RegNum.
-    //
-    // See also ARMinstPrinter::printOperand() wrt "dregpair" modifier part
-    // where this workaround is meant for.
-    RegClassID = ARM::DPRRegClassID;
-  }
-
+static unsigned
+getRegisterEnum(BO B, unsigned RegClassID, unsigned RawRegister) {
   // For this purpose, we can treat rGPR as if it were GPR.
   if (RegClassID == ARM::rGPRRegClassID) RegClassID = ARM::GPRRegClassID;
 
@@ -2201,22 +2188,6 @@ static unsigned decodeN3VImm(uint32_t insn) {
   return (insn >> 8) & 0xF;
 }
 
-static bool UseDRegPair(unsigned Opcode) {
-  switch (Opcode) {
-  default:
-    return false;
-  case ARM::VLD1q8_UPD:
-  case ARM::VLD1q16_UPD:
-  case ARM::VLD1q32_UPD:
-  case ARM::VLD1q64_UPD:
-  case ARM::VST1q8_UPD:
-  case ARM::VST1q16_UPD:
-  case ARM::VST1q32_UPD:
-  case ARM::VST1q64_UPD:
-    return true;
-  }
-}
-
 // VLD*
 //   D[d] D[d2] ... Rn [TIED_TO Rn] align [Rm]
 // VLD*LN*
@@ -2243,10 +2214,9 @@ static bool DisassembleNLdSt0(MCInst &MI, unsigned Opcode, uint32_t insn,
 
   // We have homogeneous NEON registers for Load/Store.
   unsigned RegClass = 0;
-  bool DRegPair = UseDRegPair(Opcode);
 
   // Double-spaced registers have increments of 2.
-  unsigned Inc = (DblSpaced || DRegPair) ? 2 : 1;
+  unsigned Inc = DblSpaced ? 2 : 1;
 
   unsigned Rn = decodeRn(insn);
   unsigned Rm = decodeRm(insn);
@@ -2292,7 +2262,7 @@ static bool DisassembleNLdSt0(MCInst &MI, unsigned Opcode, uint32_t insn,
     RegClass = OpInfo[OpIdx].RegClass;
     while (OpIdx < NumOps && (unsigned)OpInfo[OpIdx].RegClass == RegClass) {
       MI.addOperand(MCOperand::CreateReg(
-                      getRegisterEnum(B, RegClass, Rd, DRegPair)));
+                      getRegisterEnum(B, RegClass, Rd)));
       Rd += Inc;
       ++OpIdx;
     }
@@ -2311,7 +2281,7 @@ static bool DisassembleNLdSt0(MCInst &MI, unsigned Opcode, uint32_t insn,
 
     while (OpIdx < NumOps && (unsigned)OpInfo[OpIdx].RegClass == RegClass) {
       MI.addOperand(MCOperand::CreateReg(
-                      getRegisterEnum(B, RegClass, Rd, DRegPair)));
+                      getRegisterEnum(B, RegClass, Rd)));
       Rd += Inc;
       ++OpIdx;
     }