ARM IAS: support GNU extension for ldrd, strd

The GNU assembler has an extension that allows for the elision of the paired
register (dt2) for the LDRD and STRD mnemonics.  Add support for this in the
assembly parser.  Canonicalise the usage during the instruction parsing from
the specified version.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198915 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 45 insertions, 1 deletions

diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index b80eefd398..ad134d3f99 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -2280,6 +2280,12 @@ let mayLoad = 1, neverHasSideEffects = 1, hasExtraDefRegAllocReq = 1 in {
   def LDRD : AI3ld<0b1101, 0, (outs GPR:$Rt, GPR:$Rt2), (ins addrmode3:$addr),
                    LdMiscFrm, IIC_iLoad_d_r, "ldrd", "\t$Rt, $Rt2, $addr", []>,
              Requires<[IsARM, HasV5TE]>;
+
+  // GNU Assembler extension (compatibility)
+  let isAsmParserOnly = 1 in
+    def LDRD_PAIR : AI3ld<0b1101, 0, (outs GPRPairOp:$Rt), (ins addrmode3:$addr),
+                          LdMiscFrm, IIC_iLoad_d_r, "ldrd", "\t$Rt, $addr", []>,
+                    Requires<[IsARM, HasV5TE]>;
 }
 
 def LDA : AIldracq<0b00, (outs GPR:$Rt), (ins addr_offset_none:$addr),
@@ -2545,13 +2551,22 @@ def STRH : AI3str<0b1011, (outs), (ins GPR:$Rt, addrmode3:$addr), StMiscFrm,
                [(truncstorei16 GPR:$Rt, addrmode3:$addr)]>;
 
 // Store doubleword
-let mayStore = 1, neverHasSideEffects = 1, hasExtraSrcRegAllocReq = 1 in
+let mayStore = 1, neverHasSideEffects = 1, hasExtraSrcRegAllocReq = 1 in {
   def STRD : AI3str<0b1111, (outs), (ins GPR:$Rt, GPR:$Rt2, addrmode3:$addr),
                     StMiscFrm, IIC_iStore_d_r, "strd", "\t$Rt, $Rt2, $addr", []>,
              Requires<[IsARM, HasV5TE]> {
     let Inst{21} = 0;
   }
 
+  // GNU Assembler extension (compatibility)
+  let isAsmParserOnly = 1 in
+    def STRD_PAIR : AI3str<0b1111, (outs), (ins GPRPairOp:$Rt, addrmode3:$addr),
+                           StMiscFrm, IIC_iStore_d_r, "strd", "\t$Rt, $addr", []>,
+                    Requires<[IsARM, HasV5TE]> {
+      let Inst{21} = 0;
+    }
+}
+
 // Indexed stores
 multiclass AI2_stridx<bit isByte, string opc,
                       InstrItinClass iii, InstrItinClass iir> {
diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index c4f7b01352..bebbab5327 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -5445,6 +5445,19 @@ bool ARMAsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
     }
   }
 
+  // GNU Assembler extension (compatibility)
+  if ((Mnemonic == "ldrd" || Mnemonic == "strd") && !isThumb() &&
+      Operands.size() == 4) {
+    ARMOperand *Op = static_cast<ARMOperand *>(Operands[2]);
+    assert(Op->isReg() && "expected register argument");
+    assert(MRI->getMatchingSuperReg(Op->getReg(), ARM::gsub_0,
+                                    &MRI->getRegClass(ARM::GPRPairRegClassID))
+           && "expected register pair");
+    Operands.insert(Operands.begin() + 3,
+                    ARMOperand::CreateReg(Op->getReg() + 1, Op->getStartLoc(),
+                                          Op->getEndLoc()));
+  }
+
   // FIXME: As said above, this is all a pretty gross hack.  This instruction
   // does not fit with other "subs" and tblgen.
   // Adjust operands of B9.3.19 SUBS PC, LR, #imm (Thumb2) system instruction
@@ -8793,6 +8806,11 @@ unsigned ARMAsmParser::validateTargetOperandClass(MCParsedAsmOperand *AsmOp,
              "expression value must be representiable in 32 bits");
     }
     break;
+  case MCK_GPRPair:
+    if (Op->isReg() &&
+        MRI->getRegClass(ARM::GPRRegClassID).contains(Op->getReg()))
+      return Match_Success;
+    break;
   }
   return Match_InvalidOperand;
 }
diff --git a/test/MC/ARM/arm-memory-instructions.s b/test/MC/ARM/arm-memory-instructions.s
index ad35dd26a0..f41c779b8f 100644
--- a/test/MC/ARM/arm-memory-instructions.s
+++ b/test/MC/ARM/arm-memory-instructions.s
@@ -485,3 +485,14 @@ Lbaz: .quad 0
 @ CHECK: strht	r8, [r1], #-25          @ encoding: [0xb9,0x81,0x61,0xe0]
 @ CHECK: strht	r5, [r3], r4            @ encoding: [0xb4,0x50,0xa3,0xe0]
 @ CHECK: strht	r6, [r8], -r0           @ encoding: [0xb0,0x60,0x28,0xe0]
+
+@------------------------------------------------------------------------------
+@ GNU Assembler Compatibility
+@------------------------------------------------------------------------------
+
+	ldrd r0, [sp]
+	strd r0, [sp]
+
+@ CHECK: ldrd r0, r1, [sp]              @ encoding: [0xd0,0x00,0xcd,0xe1]
+@ CHECK: strd r0, r1, [sp]              @ encoding: [0xf0,0x00,0xcd,0xe1]
+