diff --git a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
--- a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
+++ b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
@@ -127,6 +127,7 @@
   OperandMatchResultTy parseRegister(OperandVector &Operands,
                                      bool AllowParens = false);
   OperandMatchResultTy parseMemOpBaseReg(OperandVector &Operands);
+  OperandMatchResultTy parseAtomicMemOp(OperandVector &Operands);
   OperandMatchResultTy parseOperandWithModifier(OperandVector &Operands);
   OperandMatchResultTy parseBareSymbol(OperandVector &Operands);
   OperandMatchResultTy parseCallSymbol(OperandVector &Operands);
@@ -1282,6 +1283,66 @@
   return MatchOperand_Success;
 }
 
+OperandMatchResultTy RISCVAsmParser::parseAtomicMemOp(OperandVector &Operands) {
+  // Atomic operations such as lr.w, sc.w, and amo*.w accept a "memory operand"
+  // as one of their register operands, such as `(a0)`. This just denotes that
+  // the register (in this case `a0`) contains a memory address.
+  //
+  // Normally, we would be able to parse these by putting the parens into the
+  // instruction string. However, GCC also accepts a zero-offset memory operand
+  // (such as `0(a0)`), and ignores the 0. Normally this would be parsed with
+  // parseImmediate followed by parseMemOpBaseReg, but these instructions do not
+  // accept an immediate operand, and we do not want to add a "dummy" operand
+  // that is silently dropped.
+  //
+  // Instead, we use this custom parser. This will: allow (and discard) an
+  // offset if it zero; expects (and discards) parentheses; and will only add
+  // the parsed register operand to `Operands`.
+  //
+  // These operands are printed with RISCVInstPrinter::printAtomicMemOp, which
+  // will only print the register surrounded by parentheses (which GCC also uses
+  // as its canonical representation for these operands).
+  bool FoundInteger = false;
+  int64_t IntegerVal;
+  SMLoc PotentialIntegerLoc = getLoc();
+
+  if (getLexer().isNot(AsmToken::LParen)) {
+    if (getParser().parseIntToken(IntegerVal,
+                                  "expected '(' or optional integer offset"))
+      return MatchOperand_ParseFail;
+
+    FoundInteger = true;
+  }
+
+  if (getLexer().isNot(AsmToken::LParen)) {
+    Error(getLoc(), FoundInteger ? "expected '(' after optional integer offset"
+                                 : "expected '(' or optional integer offset");
+    return MatchOperand_ParseFail;
+  }
+  getParser().Lex(); // Eat '('
+
+  if (parseRegister(Operands) != MatchOperand_Success) {
+    Error(getLoc(), "expected register");
+    return MatchOperand_ParseFail;
+  }
+
+  if (getLexer().isNot(AsmToken::RParen)) {
+    Error(getLoc(), "expected ')'");
+    return MatchOperand_ParseFail;
+  }
+  getParser().Lex(); // Eat ')'
+
+  // Deferred Handling of non-zero offsets
+  if (FoundInteger) {
+    if (IntegerVal != 0) {
+      Error(PotentialIntegerLoc, "optional integer offset must be 0");
+      return MatchOperand_ParseFail;
+    }
+  }
+
+  return MatchOperand_Success;
+}
+
 /// Looks at a token type and creates the relevant operand from this
 /// information, adding to Operands. If operand was parsed, returns false, else
 /// true.
diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVInstPrinter.h b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVInstPrinter.h
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVInstPrinter.h
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVInstPrinter.h
@@ -37,6 +37,8 @@
                      const MCSubtargetInfo &STI, raw_ostream &O);
   void printFRMArg(const MCInst *MI, unsigned OpNo, const MCSubtargetInfo &STI,
                    raw_ostream &O);
+  void printAtomicMemOp(const MCInst *MI, unsigned OpNo,
+                        const MCSubtargetInfo &STI, raw_ostream &O);
 
   // Autogenerated by tblgen.
   void printInstruction(const MCInst *MI, const MCSubtargetInfo &STI,
diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVInstPrinter.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVInstPrinter.cpp
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVInstPrinter.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVInstPrinter.cpp
@@ -112,3 +112,15 @@
       static_cast<RISCVFPRndMode::RoundingMode>(MI->getOperand(OpNo).getImm());
   O << RISCVFPRndMode::roundingModeToString(FRMArg);
 }
+
+void RISCVInstPrinter::printAtomicMemOp(const MCInst *MI, unsigned OpNo,
+                                        const MCSubtargetInfo &STI,
+                                        raw_ostream &O) {
+  const MCOperand &MO = MI->getOperand(OpNo);
+
+  assert(MO.isReg() && "printAtomicMemOp can only print register operands");
+  O << "(";
+  printRegName(O, MO.getReg());
+  O << ")";
+  return;
+}
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoA.td b/llvm/lib/Target/RISCV/RISCVInstrInfoA.td
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoA.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoA.td
@@ -11,6 +11,24 @@
 //
 //===----------------------------------------------------------------------===//
 
+//===----------------------------------------------------------------------===//
+// Operand and SDNode transformation definitions.
+//===----------------------------------------------------------------------===//
+
+// A parse method for (${gpr}) or 0(${gpr}), where the 0 is be silently ignored.
+// Used for GCC Compatibility.
+def AtomicMemOpOperand : AsmOperandClass {
+  let Name = "AtomicMemOpOperand";
+  let RenderMethod = "addRegOperands";
+  let PredicateMethod = "isReg";
+  let ParserMethod = "parseAtomicMemOp";
+}
+
+def GPRMemAtomic : RegisterOperand<GPR> {
+  let ParserMatchClass = AtomicMemOpOperand;
+  let PrintMethod = "printAtomicMemOp";
+}
+
 //===----------------------------------------------------------------------===//
 // Instruction class templates
 //===----------------------------------------------------------------------===//
@@ -18,8 +36,8 @@
 let hasSideEffects = 0, mayLoad = 1, mayStore = 0 in
 class LR_r<bit aq, bit rl, bits<3> funct3, string opcodestr>
     : RVInstRAtomic<0b00010, aq, rl, funct3, OPC_AMO,
-                    (outs GPR:$rd), (ins GPR:$rs1),
-                    opcodestr, "$rd, (${rs1})"> {
+                    (outs GPR:$rd), (ins GPRMemAtomic:$rs1),
+                    opcodestr, "$rd, $rs1"> {
   let rs2 = 0;
 }
 
@@ -33,8 +51,8 @@
 let hasSideEffects = 0, mayLoad = 1, mayStore = 1 in
 class AMO_rr<bits<5> funct5, bit aq, bit rl, bits<3> funct3, string opcodestr>
     : RVInstRAtomic<funct5, aq, rl, funct3, OPC_AMO,
-                    (outs GPR:$rd), (ins GPR:$rs1, GPR:$rs2),
-                    opcodestr, "$rd, $rs2, (${rs1})">;
+                    (outs GPR:$rd), (ins GPRMemAtomic:$rs1, GPR:$rs2),
+                    opcodestr, "$rd, $rs2, $rs1">;
 
 multiclass AMO_rr_aq_rl<bits<5> funct5, bits<3> funct3, string opcodestr> {
   def ""     : AMO_rr<funct5, 0, 0, funct3, opcodestr>;
diff --git a/llvm/test/MC/RISCV/rv32a-invalid.s b/llvm/test/MC/RISCV/rv32a-invalid.s
--- a/llvm/test/MC/RISCV/rv32a-invalid.s
+++ b/llvm/test/MC/RISCV/rv32a-invalid.s
@@ -1,9 +1,10 @@
 # RUN: not llvm-mc -triple riscv32 -mattr=+a < %s 2>&1 | FileCheck %s
 
 # Final operand must have parentheses
-amoswap.w a1, a2, a3 # CHECK: :[[@LINE]]:19: error: invalid operand for instruction
-amomin.w a1, a2, 1 # CHECK: :[[@LINE]]:18: error: invalid operand for instruction
-lr.w a4, a5 # CHECK: :[[@LINE]]:10: error: invalid operand for instruction
+amoswap.w a1, a2, a3 # CHECK: :[[@LINE]]:19: error: expected '(' or optional integer offset
+amomin.w a1, a2, 1 # CHECK: :[[@LINE]]:20: error: expected '(' after optional integer offset
+amomin.w a1, a2, 1(a3) # CHECK: :[[@LINE]]:18: error: optional integer offset must be 0
+lr.w a4, a5 # CHECK: :[[@LINE]]:10: error: expected '(' or optional integer offset
 
 # Only .aq, .rl, and .aqrl suffixes are valid
 amoxor.w.rlqa a2, a3, (a4) # CHECK: :[[@LINE]]:1: error: unrecognized instruction mnemonic
diff --git a/llvm/test/MC/RISCV/rv64a-aliases-valid.s b/llvm/test/MC/RISCV/rv64a-aliases-valid.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/RISCV/rv64a-aliases-valid.s
@@ -0,0 +1,189 @@
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+a -riscv-no-aliases \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+a \
+# RUN:     | FileCheck -check-prefix=CHECK-ALIAS %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 -mattr=+a < %s \
+# RUN:     | llvm-objdump -d -mattr=+a -riscv-no-aliases - \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 -mattr=+a < %s \
+# RUN:     | llvm-objdump -d -mattr=+a - \
+# RUN:     | FileCheck -check-prefix=CHECK-ALIAS %s
+
+# The below tests for lr.d, sc.d and amo*.d, using `0(reg)` are actually
+# implemented using a custom parser, but we test them as if they're aliases.
+
+# CHECK-INST: lr.d a1, (a0)
+# CHECK-ALIAS: lr.d a1, (a0)
+lr.d a1, 0(a0)
+
+# CHECK-INST: lr.d.aq a1, (a0)
+# CHECK-ALIAS: lr.d.aq a1, (a0)
+lr.d.aq a1, 0(a0)
+
+# CHECK-INST: lr.d.rl a1, (a0)
+# CHECK-ALIAS: lr.d.rl a1, (a0)
+lr.d.rl a1, 0(a0)
+
+# CHECK-INST: lr.d.aqrl a1, (a0)
+# CHECK-ALIAS: lr.d.aqrl a1, (a0)
+lr.d.aqrl a1, 0(a0)
+
+# CHECK-INST: sc.d a2, a1, (a0)
+# CHECK-ALIAS: sc.d a2, a1, (a0)
+sc.d a2, a1, 0(a0)
+
+# CHECK-INST: sc.d.aq a2, a1, (a0)
+# CHECK-ALIAS: sc.d.aq a2, a1, (a0)
+sc.d.aq a2, a1, 0(a0)
+
+# CHECK-INST: sc.d.rl a2, a1, (a0)
+# CHECK-ALIAS: sc.d.rl a2, a1, (a0)
+sc.d.rl a2, a1, 0(a0)
+
+# CHECK-INST: sc.d.aqrl a2, a1, (a0)
+# CHECK-ALIAS: sc.d.aqrl a2, a1, (a0)
+sc.d.aqrl a2, a1, 0(a0)
+
+# CHECK-INST: amoswap.d a2, a1, (a0)
+# CHECK-ALIAS: amoswap.d a2, a1, (a0)
+amoswap.d a2, a1, 0(a0)
+
+# CHECK-INST: amoswap.d.aq a2, a1, (a0)
+# CHECK-ALIAS: amoswap.d.aq a2, a1, (a0)
+amoswap.d.aq a2, a1, 0(a0)
+
+# CHECK-INST: amoswap.d.rl a2, a1, (a0)
+# CHECK-ALIAS: amoswap.d.rl a2, a1, (a0)
+amoswap.d.rl a2, a1, 0(a0)
+
+# CHECK-INST: amoswap.d.aqrl a2, a1, (a0)
+# CHECK-ALIAS: amoswap.d.aqrl a2, a1, (a0)
+amoswap.d.aqrl a2, a1, 0(a0)
+
+# CHECK-INST: amoadd.d a2, a1, (a0)
+# CHECK-ALIAS: amoadd.d a2, a1, (a0)
+amoadd.d a2, a1, 0(a0)
+
+# CHECK-INST: amoadd.d.aq a2, a1, (a0)
+# CHECK-ALIAS: amoadd.d.aq a2, a1, (a0)
+amoadd.d.aq a2, a1, 0(a0)
+
+# CHECK-INST: amoadd.d.rl a2, a1, (a0)
+# CHECK-ALIAS: amoadd.d.rl a2, a1, (a0)
+amoadd.d.rl a2, a1, 0(a0)
+
+# CHECK-INST: amoadd.d.aqrl a2, a1, (a0)
+# CHECK-ALIAS: amoadd.d.aqrl a2, a1, (a0)
+amoadd.d.aqrl a2, a1, 0(a0)
+
+# CHECK-INST: amoxor.d a2, a1, (a0)
+# CHECK-ALIAS: amoxor.d a2, a1, (a0)
+amoxor.d a2, a1, 0(a0)
+
+# CHECK-INST: amoxor.d.aq a2, a1, (a0)
+# CHECK-ALIAS: amoxor.d.aq a2, a1, (a0)
+amoxor.d.aq a2, a1, 0(a0)
+
+# CHECK-INST: amoxor.d.rl a2, a1, (a0)
+# CHECK-ALIAS: amoxor.d.rl a2, a1, (a0)
+amoxor.d.rl a2, a1, 0(a0)
+
+# CHECK-INST: amoxor.d.aqrl a2, a1, (a0)
+# CHECK-ALIAS: amoxor.d.aqrl a2, a1, (a0)
+amoxor.d.aqrl a2, a1, 0(a0)
+
+# CHECK-INST: amoand.d a2, a1, (a0)
+# CHECK-ALIAS: amoand.d a2, a1, (a0)
+amoand.d a2, a1, 0(a0)
+
+# CHECK-INST: amoand.d.aq a2, a1, (a0)
+# CHECK-ALIAS: amoand.d.aq a2, a1, (a0)
+amoand.d.aq a2, a1, 0(a0)
+
+# CHECK-INST: amoand.d.rl a2, a1, (a0)
+# CHECK-ALIAS: amoand.d.rl a2, a1, (a0)
+amoand.d.rl a2, a1, 0(a0)
+
+# CHECK-INST: amoand.d.aqrl a2, a1, (a0)
+# CHECK-ALIAS: amoand.d.aqrl a2, a1, (a0)
+amoand.d.aqrl a2, a1, 0(a0)
+
+# CHECK-INST: amoor.d a2, a1, (a0)
+# CHECK-ALIAS: amoor.d a2, a1, (a0)
+amoor.d a2, a1, 0(a0)
+
+# CHECK-INST: amoor.d.aq a2, a1, (a0)
+# CHECK-ALIAS: amoor.d.aq a2, a1, (a0)
+amoor.d.aq a2, a1, 0(a0)
+
+# CHECK-INST: amoor.d.rl a2, a1, (a0)
+# CHECK-ALIAS: amoor.d.rl a2, a1, (a0)
+amoor.d.rl a2, a1, 0(a0)
+
+# CHECK-INST: amoor.d.aqrl a2, a1, (a0)
+# CHECK-ALIAS: amoor.d.aqrl a2, a1, (a0)
+amoor.d.aqrl a2, a1, 0(a0)
+
+# CHECK-INST: amomin.d a2, a1, (a0)
+# CHECK-ALIAS: amomin.d a2, a1, (a0)
+amomin.d a2, a1, 0(a0)
+
+# CHECK-INST: amomin.d.aq a2, a1, (a0)
+# CHECK-ALIAS: amomin.d.aq a2, a1, (a0)
+amomin.d.aq a2, a1, 0(a0)
+
+# CHECK-INST: amomin.d.rl a2, a1, (a0)
+# CHECK-ALIAS: amomin.d.rl a2, a1, (a0)
+amomin.d.rl a2, a1, 0(a0)
+
+# CHECK-INST: amomin.d.aqrl a2, a1, (a0)
+# CHECK-ALIAS: amomin.d.aqrl a2, a1, (a0)
+amomin.d.aqrl a2, a1, 0(a0)
+
+# CHECK-INST: amomax.d a2, a1, (a0)
+# CHECK-ALIAS: amomax.d a2, a1, (a0)
+amomax.d a2, a1, 0(a0)
+
+# CHECK-INST: amomax.d.aq a2, a1, (a0)
+# CHECK-ALIAS: amomax.d.aq a2, a1, (a0)
+amomax.d.aq a2, a1, 0(a0)
+
+# CHECK-INST: amomax.d.rl a2, a1, (a0)
+# CHECK-ALIAS: amomax.d.rl a2, a1, (a0)
+amomax.d.rl a2, a1, 0(a0)
+
+# CHECK-INST: amomax.d.aqrl a2, a1, (a0)
+# CHECK-ALIAS: amomax.d.aqrl a2, a1, (a0)
+amomax.d.aqrl a2, a1, 0(a0)
+
+# CHECK-INST: amominu.d a2, a1, (a0)
+# CHECK-ALIAS: amominu.d a2, a1, (a0)
+amominu.d a2, a1, 0(a0)
+
+# CHECK-INST: amominu.d.aq a2, a1, (a0)
+# CHECK-ALIAS: amominu.d.aq a2, a1, (a0)
+amominu.d.aq a2, a1, 0(a0)
+
+# CHECK-INST: amominu.d.rl a2, a1, (a0)
+# CHECK-ALIAS: amominu.d.rl a2, a1, (a0)
+amominu.d.rl a2, a1, 0(a0)
+
+# CHECK-INST: amominu.d.aqrl a2, a1, (a0)
+# CHECK-ALIAS: amominu.d.aqrl a2, a1, (a0)
+amominu.d.aqrl a2, a1, 0(a0)
+
+# CHECK-INST: amomaxu.d a2, a1, (a0)
+# CHECK-ALIAS: amomaxu.d a2, a1, (a0)
+amomaxu.d a2, a1, 0(a0)
+
+# CHECK-INST: amomaxu.d.aq a2, a1, (a0)
+# CHECK-ALIAS: amomaxu.d.aq a2, a1, (a0)
+amomaxu.d.aq a2, a1, 0(a0)
+
+# CHECK-INST: amomaxu.d.rl a2, a1, (a0)
+# CHECK-ALIAS: amomaxu.d.rl a2, a1, (a0)
+amomaxu.d.rl a2, a1, 0(a0)
+
+# CHECK-INST: amomaxu.d.aqrl a2, a1, (a0)
+# CHECK-ALIAS: amomaxu.d.aqrl a2, a1, (a0)
+amomaxu.d.aqrl a2, a1, 0(a0)
diff --git a/llvm/test/MC/RISCV/rv64a-invalid.s b/llvm/test/MC/RISCV/rv64a-invalid.s
--- a/llvm/test/MC/RISCV/rv64a-invalid.s
+++ b/llvm/test/MC/RISCV/rv64a-invalid.s
@@ -1,9 +1,10 @@
 # RUN: not llvm-mc -triple riscv64 -mattr=+a < %s 2>&1 | FileCheck %s
 
 # Final operand must have parentheses
-amoswap.d a1, a2, a3 # CHECK: :[[@LINE]]:19: error: invalid operand for instruction
-amomin.d a1, a2, 1 # CHECK: :[[@LINE]]:18: error: invalid operand for instruction
-lr.d a4, a5 # CHECK: :[[@LINE]]:10: error: invalid operand for instruction
+amoswap.d a1, a2, a3 # CHECK: :[[@LINE]]:19: error: expected '(' or optional integer offset
+amomin.d a1, a2, 1 # CHECK: :[[@LINE]]:20: error: expected '(' after optional integer offset
+amomin.d a1, a2, 1(a3) # CHECK: :[[@LINE]]:18: error: optional integer offset must be 0
+lr.d a4, a5 # CHECK: :[[@LINE]]:10: error: expected '(' or optional integer offset
 
 # Only .aq, .rl, and .aqrl suffixes are valid
 amoxor.d.rlqa a2, a3, (a4) # CHECK: :[[@LINE]]:1: error: unrecognized instruction mnemonic
diff --git a/llvm/test/MC/RISCV/rva-aliases-invalid.s b/llvm/test/MC/RISCV/rva-aliases-invalid.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/RISCV/rva-aliases-invalid.s
@@ -0,0 +1,94 @@
+# RUN: not llvm-mc %s -triple=riscv32 2>&1 | FileCheck %s
+# RUN: not llvm-mc %s -triple=riscv64 2>&1 | FileCheck %s
+
+# The below tests for lr(.w), sc(.w) and amo*(.w), using `0(reg)` are actually
+# implemented using a custom parser. These tests ensure the custom parser gives
+# good error messages.
+
+lr.w a1, a0     # CHECK: :[[@LINE]]:10: error: expected '(' or optional integer offset
+lr.w a1, foo    # CHECK: :[[@LINE]]:10: error: expected '(' or optional integer offset
+lr.w a1, 1(a0)  # CHECK: :[[@LINE]]:10: error: optional integer offset must be 0
+lr.w a1, (foo)  # CHECK: :[[@LINE]]:11: error: expected register
+lr.w a1, 0(foo) # CHECK: :[[@LINE]]:12: error: expected register
+lr.w a1, 0(a0   # CHECK: :[[@LINE]]:17: error: expected ')'
+lr.w a1, (a0    # CHECK: :[[@LINE]]:17: error: expected ')'
+
+sc.w a2, a1, a0     # CHECK: :[[@LINE]]:14: error: expected '(' or optional integer offset
+sc.w a2, a1, foo    # CHECK: :[[@LINE]]:14: error: expected '(' or optional integer offset
+sc.w a2, a1, 1(a0)  # CHECK: :[[@LINE]]:14: error: optional integer offset must be 0
+sc.w a2, a1, (foo)  # CHECK: :[[@LINE]]:15: error: expected register
+sc.w a2, a1, 0(foo) # CHECK: :[[@LINE]]:16: error: expected register
+sc.w a2, a1, 0(a0   # CHECK: :[[@LINE]]:21: error: expected ')'
+sc.w a2, a1, (a0    # CHECK: :[[@LINE]]:21: error: expected ')'
+
+amoswap.w a2, a1, a0     # CHECK: :[[@LINE]]:19: error: expected '(' or optional integer offset
+amoswap.w a2, a1, foo    # CHECK: :[[@LINE]]:19: error: expected '(' or optional integer offset
+amoswap.w a2, a1, 1(a0)  # CHECK: :[[@LINE]]:19: error: optional integer offset must be 0
+amoswap.w a2, a1, (foo)  # CHECK: :[[@LINE]]:20: error: expected register
+amoswap.w a2, a1, 0(foo) # CHECK: :[[@LINE]]:21: error: expected register
+amoswap.w a2, a1, 0(a0   # CHECK: :[[@LINE]]:26: error: expected ')'
+amoswap.w a2, a1, (a0    # CHECK: :[[@LINE]]:26: error: expected ')'
+
+amoadd.w a2, a1, a0     # CHECK: :[[@LINE]]:18: error: expected '(' or optional integer offset
+amoadd.w a2, a1, foo    # CHECK: :[[@LINE]]:18: error: expected '(' or optional integer offset
+amoadd.w a2, a1, 1(a0)  # CHECK: :[[@LINE]]:18: error: optional integer offset must be 0
+amoadd.w a2, a1, (foo)  # CHECK: :[[@LINE]]:19: error: expected register
+amoadd.w a2, a1, 0(foo) # CHECK: :[[@LINE]]:20: error: expected register
+amoadd.w a2, a1, 0(a0   # CHECK: :[[@LINE]]:25: error: expected ')'
+amoadd.w a2, a1, (a0    # CHECK: :[[@LINE]]:25: error: expected ')'
+
+amoxor.w a2, a1, a0     # CHECK: :[[@LINE]]:18: error: expected '(' or optional integer offset
+amoxor.w a2, a1, foo    # CHECK: :[[@LINE]]:18: error: expected '(' or optional integer offset
+amoxor.w a2, a1, 1(a0)  # CHECK: :[[@LINE]]:18: error: optional integer offset must be 0
+amoxor.w a2, a1, (foo)  # CHECK: :[[@LINE]]:19: error: expected register
+amoxor.w a2, a1, 0(foo) # CHECK: :[[@LINE]]:20: error: expected register
+amoxor.w a2, a1, 0(a0   # CHECK: :[[@LINE]]:25: error: expected ')'
+amoxor.w a2, a1, (a0    # CHECK: :[[@LINE]]:25: error: expected ')'
+
+amoand.w a2, a1, a0     # CHECK: :[[@LINE]]:18: error: expected '(' or optional integer offset
+amoand.w a2, a1, foo    # CHECK: :[[@LINE]]:18: error: expected '(' or optional integer offset
+amoand.w a2, a1, 1(a0)  # CHECK: :[[@LINE]]:18: error: optional integer offset must be 0
+amoand.w a2, a1, (foo)  # CHECK: :[[@LINE]]:19: error: expected register
+amoand.w a2, a1, 0(foo) # CHECK: :[[@LINE]]:20: error: expected register
+amoand.w a2, a1, 0(a0   # CHECK: :[[@LINE]]:25: error: expected ')'
+amoand.w a2, a1, (a0    # CHECK: :[[@LINE]]:25: error: expected ')'
+
+amoor.w a2, a1, a0     # CHECK: :[[@LINE]]:17: error: expected '(' or optional integer offset
+amoor.w a2, a1, foo    # CHECK: :[[@LINE]]:17: error: expected '(' or optional integer offset
+amoor.w a2, a1, 1(a0)  # CHECK: :[[@LINE]]:17: error: optional integer offset must be 0
+amoor.w a2, a1, (foo)  # CHECK: :[[@LINE]]:18: error: expected register
+amoor.w a2, a1, 0(foo) # CHECK: :[[@LINE]]:19: error: expected register
+amoor.w a2, a1, 0(a0   # CHECK: :[[@LINE]]:24: error: expected ')'
+amoor.w a2, a1, (a0    # CHECK: :[[@LINE]]:24: error: expected ')'
+
+amomin.w a2, a1, a0     # CHECK: :[[@LINE]]:18: error: expected '(' or optional integer offset
+amomin.w a2, a1, foo    # CHECK: :[[@LINE]]:18: error: expected '(' or optional integer offset
+amomin.w a2, a1, 1(a0)  # CHECK: :[[@LINE]]:18: error: optional integer offset must be 0
+amomin.w a2, a1, (foo)  # CHECK: :[[@LINE]]:19: error: expected register
+amomin.w a2, a1, 0(foo) # CHECK: :[[@LINE]]:20: error: expected register
+amomin.w a2, a1, 0(a0   # CHECK: :[[@LINE]]:25: error: expected ')'
+amomin.w a2, a1, (a0    # CHECK: :[[@LINE]]:25: error: expected ')'
+
+amomax.w a2, a1, a0     # CHECK: :[[@LINE]]:18: error: expected '(' or optional integer offset
+amomax.w a2, a1, foo    # CHECK: :[[@LINE]]:18: error: expected '(' or optional integer offset
+amomax.w a2, a1, 1(a0)  # CHECK: :[[@LINE]]:18: error: optional integer offset must be 0
+amomax.w a2, a1, (foo)  # CHECK: :[[@LINE]]:19: error: expected register
+amomax.w a2, a1, 0(foo) # CHECK: :[[@LINE]]:20: error: expected register
+amomax.w a2, a1, 0(a0   # CHECK: :[[@LINE]]:25: error: expected ')'
+amomax.w a2, a1, (a0    # CHECK: :[[@LINE]]:25: error: expected ')'
+
+amominu.w a2, a1, a0     # CHECK: :[[@LINE]]:19: error: expected '(' or optional integer offset
+amominu.w a2, a1, foo    # CHECK: :[[@LINE]]:19: error: expected '(' or optional integer offset
+amominu.w a2, a1, 1(a0)  # CHECK: :[[@LINE]]:19: error: optional integer offset must be 0
+amominu.w a2, a1, (foo)  # CHECK: :[[@LINE]]:20: error: expected register
+amominu.w a2, a1, 0(foo) # CHECK: :[[@LINE]]:21: error: expected register
+amominu.w a2, a1, 0(a0   # CHECK: :[[@LINE]]:26: error: expected ')'
+amominu.w a2, a1, (a0    # CHECK: :[[@LINE]]:26: error: expected ')'
+
+amomaxu.w a2, a1, a0     # CHECK: :[[@LINE]]:19: error: expected '(' or optional integer offset
+amomaxu.w a2, a1, foo    # CHECK: :[[@LINE]]:19: error: expected '(' or optional integer offset
+amomaxu.w a2, a1, 1(a0)  # CHECK: :[[@LINE]]:19: error: optional integer offset must be 0
+amomaxu.w a2, a1, (foo)  # CHECK: :[[@LINE]]:20: error: expected register
+amomaxu.w a2, a1, 0(foo) # CHECK: :[[@LINE]]:21: error: expected register
+amomaxu.w a2, a1, 0(a0   # CHECK: :[[@LINE]]:26: error: expected ')'
+amomaxu.w a2, a1, (a0    # CHECK: :[[@LINE]]:26: error: expected ')'
\ No newline at end of file
diff --git a/llvm/test/MC/RISCV/rva-aliases-valid.s b/llvm/test/MC/RISCV/rva-aliases-valid.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/RISCV/rva-aliases-valid.s
@@ -0,0 +1,297 @@
+# RUN: llvm-mc %s -triple=riscv32 -mattr=+a -riscv-no-aliases \
+# RUN:     | FileCheck -check-prefixes=CHECK-S-NOALIAS,CHECK-S-OBJ-NOALIAS %s
+# RUN: llvm-mc %s -triple=riscv32 -mattr=+a \
+# RUN:     | FileCheck -check-prefixes=CHECK-S,CHECK-S-OBJ %s
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+a -riscv-no-aliases\
+# RUN:     | FileCheck -check-prefixes=CHECK-S-NOALIAS,CHECK-S-OBJ-NOALIAS %s
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+a \
+# RUN:     | FileCheck -check-prefixes=CHECK-S,CHECK-S-OBJ %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+a < %s \
+# RUN:     | llvm-objdump -d -mattr=+a -riscv-no-aliases - \
+# RUN:     | FileCheck -check-prefixes=CHECK-OBJ-NOALIAS,CHECK-S-OBJ-NOALIAS %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+a < %s \
+# RUN:     | llvm-objdump -d -mattr=+a - \
+# RUN:     | FileCheck -check-prefixes=CHECK-OBJ,CHECK-S-OBJ %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 -mattr=+a < %s \
+# RUN:     | llvm-objdump -d -mattr=+a -riscv-no-aliases - \
+# RUN:     | FileCheck -check-prefixes=CHECK-OBJ-NOALIAS,CHECK-S-OBJ-NOALIAS %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 -mattr=+a < %s \
+# RUN:     | llvm-objdump -d -mattr=+a - \
+# RUN:     | FileCheck -check-prefixes=CHECK-OBJ,CHECK-S-OBJ %s
+
+# The following check prefixes are used in this test:
+# CHECK-S                 Match the .s output with aliases enabled
+# CHECK-S-NOALIAS         Match the .s output with aliases disabled
+# CHECK-OBJ               Match the objdumped object output with aliases enabled
+# CHECK-OBJ-NOALIAS       Match the objdumped object output with aliases enabled
+# CHECK-S-OBJ             Match both the .s and objdumped object output with
+#                         aliases enabled
+# CHECK-S-OBJ-NOALIAS     Match both the .s and objdumped object output with
+#                         aliases disabled
+
+# The below tests for lr.w, sc.w and amo*.w, using `0(reg)` are actually
+# implemented using a custom parser, but we test them as if they're aliases.
+
+# CHECK-S: lr.w a1, (a0)
+# CHECK-S-NOALIAS: lr.w a1, (a0)
+# CHECK-OBJ: lr.w a1, (a0)
+# CHECK-OBJ-NOALIAS: lr.w a1, (a0)
+lr.w a1, 0(a0)
+
+# CHECK-S: lr.w.aq a1, (a0)
+# CHECK-S-NOALIAS: lr.w.aq a1, (a0)
+# CHECK-OBJ: lr.w.aq a1, (a0)
+# CHECK-OBJ-NOALIAS: lr.w.aq a1, (a0)
+lr.w.aq a1, 0(a0)
+
+# CHECK-S: lr.w.rl a1, (a0)
+# CHECK-S-NOALIAS: lr.w.rl a1, (a0)
+# CHECK-OBJ: lr.w.rl a1, (a0)
+# CHECK-OBJ-NOALIAS: lr.w.rl a1, (a0)
+lr.w.rl a1, 0(a0)
+
+# CHECK-S: lr.w.aqrl a1, (a0)
+# CHECK-S-NOALIAS: lr.w.aqrl a1, (a0)
+# CHECK-OBJ: lr.w.aqrl a1, (a0)
+# CHECK-OBJ-NOALIAS: lr.w.aqrl a1, (a0)
+lr.w.aqrl a1, 0(a0)
+
+# CHECK-S: sc.w a2, a1, (a0)
+# CHECK-S-NOALIAS: sc.w a2, a1, (a0)
+# CHECK-OBJ: sc.w a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: sc.w a2, a1, (a0)
+sc.w a2, a1, 0(a0)
+
+# CHECK-S: sc.w.aq a2, a1, (a0)
+# CHECK-S-NOALIAS: sc.w.aq a2, a1, (a0)
+# CHECK-OBJ: sc.w.aq a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: sc.w.aq a2, a1, (a0)
+sc.w.aq a2, a1, 0(a0)
+
+# CHECK-S: sc.w.rl a2, a1, (a0)
+# CHECK-S-NOALIAS: sc.w.rl a2, a1, (a0)
+# CHECK-OBJ: sc.w.rl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: sc.w.rl a2, a1, (a0)
+sc.w.rl a2, a1, 0(a0)
+
+# CHECK-S: sc.w.aqrl a2, a1, (a0)
+# CHECK-S-NOALIAS: sc.w.aqrl a2, a1, (a0)
+# CHECK-OBJ: sc.w.aqrl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: sc.w.aqrl a2, a1, (a0)
+sc.w.aqrl a2, a1, 0(a0)
+
+# CHECK-S: amoswap.w a2, a1, (a0)
+# CHECK-S-NOALIAS: amoswap.w a2, a1, (a0)
+# CHECK-OBJ: amoswap.w a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoswap.w a2, a1, (a0)
+amoswap.w a2, a1, 0(a0)
+
+# CHECK-S: amoswap.w.aq a2, a1, (a0)
+# CHECK-S-NOALIAS: amoswap.w.aq a2, a1, (a0)
+# CHECK-OBJ: amoswap.w.aq a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoswap.w.aq a2, a1, (a0)
+amoswap.w.aq a2, a1, 0(a0)
+
+# CHECK-S: amoswap.w.rl a2, a1, (a0)
+# CHECK-S-NOALIAS: amoswap.w.rl a2, a1, (a0)
+# CHECK-OBJ: amoswap.w.rl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoswap.w.rl a2, a1, (a0)
+amoswap.w.rl a2, a1, 0(a0)
+
+# CHECK-S: amoswap.w.aqrl a2, a1, (a0)
+# CHECK-S-NOALIAS: amoswap.w.aqrl a2, a1, (a0)
+# CHECK-OBJ: amoswap.w.aqrl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoswap.w.aqrl a2, a1, (a0)
+amoswap.w.aqrl a2, a1, 0(a0)
+
+# CHECK-S: amoadd.w a2, a1, (a0)
+# CHECK-S-NOALIAS: amoadd.w a2, a1, (a0)
+# CHECK-OBJ: amoadd.w a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoadd.w a2, a1, (a0)
+amoadd.w a2, a1, 0(a0)
+
+# CHECK-S: amoadd.w.aq a2, a1, (a0)
+# CHECK-S-NOALIAS: amoadd.w.aq a2, a1, (a0)
+# CHECK-OBJ: amoadd.w.aq a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoadd.w.aq a2, a1, (a0)
+amoadd.w.aq a2, a1, 0(a0)
+
+# CHECK-S: amoadd.w.rl a2, a1, (a0)
+# CHECK-S-NOALIAS: amoadd.w.rl a2, a1, (a0)
+# CHECK-OBJ: amoadd.w.rl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoadd.w.rl a2, a1, (a0)
+amoadd.w.rl a2, a1, 0(a0)
+
+# CHECK-S: amoadd.w.aqrl a2, a1, (a0)
+# CHECK-S-NOALIAS: amoadd.w.aqrl a2, a1, (a0)
+# CHECK-OBJ: amoadd.w.aqrl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoadd.w.aqrl a2, a1, (a0)
+amoadd.w.aqrl a2, a1, 0(a0)
+
+# CHECK-S: amoxor.w a2, a1, (a0)
+# CHECK-S-NOALIAS: amoxor.w a2, a1, (a0)
+# CHECK-OBJ: amoxor.w a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoxor.w a2, a1, (a0)
+amoxor.w a2, a1, 0(a0)
+
+# CHECK-S: amoxor.w.aq a2, a1, (a0)
+# CHECK-S-NOALIAS: amoxor.w.aq a2, a1, (a0)
+# CHECK-OBJ: amoxor.w.aq a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoxor.w.aq a2, a1, (a0)
+amoxor.w.aq a2, a1, 0(a0)
+
+# CHECK-S: amoxor.w.rl a2, a1, (a0)
+# CHECK-S-NOALIAS: amoxor.w.rl a2, a1, (a0)
+# CHECK-OBJ: amoxor.w.rl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoxor.w.rl a2, a1, (a0)
+amoxor.w.rl a2, a1, 0(a0)
+
+# CHECK-S: amoxor.w.aqrl a2, a1, (a0)
+# CHECK-S-NOALIAS: amoxor.w.aqrl a2, a1, (a0)
+# CHECK-OBJ: amoxor.w.aqrl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoxor.w.aqrl a2, a1, (a0)
+amoxor.w.aqrl a2, a1, 0(a0)
+
+# CHECK-S: amoand.w a2, a1, (a0)
+# CHECK-S-NOALIAS: amoand.w a2, a1, (a0)
+# CHECK-OBJ: amoand.w a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoand.w a2, a1, (a0)
+amoand.w a2, a1, 0(a0)
+
+# CHECK-S: amoand.w.aq a2, a1, (a0)
+# CHECK-S-NOALIAS: amoand.w.aq a2, a1, (a0)
+# CHECK-OBJ: amoand.w.aq a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoand.w.aq a2, a1, (a0)
+amoand.w.aq a2, a1, 0(a0)
+
+# CHECK-S: amoand.w.rl a2, a1, (a0)
+# CHECK-S-NOALIAS: amoand.w.rl a2, a1, (a0)
+# CHECK-OBJ: amoand.w.rl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoand.w.rl a2, a1, (a0)
+amoand.w.rl a2, a1, 0(a0)
+
+# CHECK-S: amoand.w.aqrl a2, a1, (a0)
+# CHECK-S-NOALIAS: amoand.w.aqrl a2, a1, (a0)
+# CHECK-OBJ: amoand.w.aqrl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoand.w.aqrl a2, a1, (a0)
+amoand.w.aqrl a2, a1, 0(a0)
+
+# CHECK-S: amoor.w a2, a1, (a0)
+# CHECK-S-NOALIAS: amoor.w a2, a1, (a0)
+# CHECK-OBJ: amoor.w a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoor.w a2, a1, (a0)
+amoor.w a2, a1, 0(a0)
+
+# CHECK-S: amoor.w.aq a2, a1, (a0)
+# CHECK-S-NOALIAS: amoor.w.aq a2, a1, (a0)
+# CHECK-OBJ: amoor.w.aq a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoor.w.aq a2, a1, (a0)
+amoor.w.aq a2, a1, 0(a0)
+
+# CHECK-S: amoor.w.rl a2, a1, (a0)
+# CHECK-S-NOALIAS: amoor.w.rl a2, a1, (a0)
+# CHECK-OBJ: amoor.w.rl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoor.w.rl a2, a1, (a0)
+amoor.w.rl a2, a1, 0(a0)
+
+# CHECK-S: amoor.w.aqrl a2, a1, (a0)
+# CHECK-S-NOALIAS: amoor.w.aqrl a2, a1, (a0)
+# CHECK-OBJ: amoor.w.aqrl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amoor.w.aqrl a2, a1, (a0)
+amoor.w.aqrl a2, a1, 0(a0)
+
+# CHECK-S: amomin.w a2, a1, (a0)
+# CHECK-S-NOALIAS: amomin.w a2, a1, (a0)
+# CHECK-OBJ: amomin.w a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomin.w a2, a1, (a0)
+amomin.w a2, a1, 0(a0)
+
+# CHECK-S: amomin.w.aq a2, a1, (a0)
+# CHECK-S-NOALIAS: amomin.w.aq a2, a1, (a0)
+# CHECK-OBJ: amomin.w.aq a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomin.w.aq a2, a1, (a0)
+amomin.w.aq a2, a1, 0(a0)
+
+# CHECK-S: amomin.w.rl a2, a1, (a0)
+# CHECK-S-NOALIAS: amomin.w.rl a2, a1, (a0)
+# CHECK-OBJ: amomin.w.rl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomin.w.rl a2, a1, (a0)
+amomin.w.rl a2, a1, 0(a0)
+
+# CHECK-S: amomin.w.aqrl a2, a1, (a0)
+# CHECK-S-NOALIAS: amomin.w.aqrl a2, a1, (a0)
+# CHECK-OBJ: amomin.w.aqrl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomin.w.aqrl a2, a1, (a0)
+amomin.w.aqrl a2, a1, 0(a0)
+
+# CHECK-S: amomax.w a2, a1, (a0)
+# CHECK-S-NOALIAS: amomax.w a2, a1, (a0)
+# CHECK-OBJ: amomax.w a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomax.w a2, a1, (a0)
+amomax.w a2, a1, 0(a0)
+
+# CHECK-S: amomax.w.aq a2, a1, (a0)
+# CHECK-S-NOALIAS: amomax.w.aq a2, a1, (a0)
+# CHECK-OBJ: amomax.w.aq a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomax.w.aq a2, a1, (a0)
+amomax.w.aq a2, a1, 0(a0)
+
+# CHECK-S: amomax.w.rl a2, a1, (a0)
+# CHECK-S-NOALIAS: amomax.w.rl a2, a1, (a0)
+# CHECK-OBJ: amomax.w.rl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomax.w.rl a2, a1, (a0)
+amomax.w.rl a2, a1, 0(a0)
+
+# CHECK-S: amomax.w.aqrl a2, a1, (a0)
+# CHECK-S-NOALIAS: amomax.w.aqrl a2, a1, (a0)
+# CHECK-OBJ: amomax.w.aqrl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomax.w.aqrl a2, a1, (a0)
+amomax.w.aqrl a2, a1, 0(a0)
+
+# CHECK-S: amominu.w a2, a1, (a0)
+# CHECK-S-NOALIAS: amominu.w a2, a1, (a0)
+# CHECK-OBJ: amominu.w a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amominu.w a2, a1, (a0)
+amominu.w a2, a1, 0(a0)
+
+# CHECK-S: amominu.w.aq a2, a1, (a0)
+# CHECK-S-NOALIAS: amominu.w.aq a2, a1, (a0)
+# CHECK-OBJ: amominu.w.aq a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amominu.w.aq a2, a1, (a0)
+amominu.w.aq a2, a1, 0(a0)
+
+# CHECK-S: amominu.w.rl a2, a1, (a0)
+# CHECK-S-NOALIAS: amominu.w.rl a2, a1, (a0)
+# CHECK-OBJ: amominu.w.rl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amominu.w.rl a2, a1, (a0)
+amominu.w.rl a2, a1, 0(a0)
+
+# CHECK-S: amominu.w.aqrl a2, a1, (a0)
+# CHECK-S-NOALIAS: amominu.w.aqrl a2, a1, (a0)
+# CHECK-OBJ: amominu.w.aqrl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amominu.w.aqrl a2, a1, (a0)
+amominu.w.aqrl a2, a1, 0(a0)
+
+# CHECK-S: amomaxu.w a2, a1, (a0)
+# CHECK-S-NOALIAS: amomaxu.w a2, a1, (a0)
+# CHECK-OBJ: amomaxu.w a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomaxu.w a2, a1, (a0)
+amomaxu.w a2, a1, 0(a0)
+
+# CHECK-S: amomaxu.w.aq a2, a1, (a0)
+# CHECK-S-NOALIAS: amomaxu.w.aq a2, a1, (a0)
+# CHECK-OBJ: amomaxu.w.aq a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomaxu.w.aq a2, a1, (a0)
+amomaxu.w.aq a2, a1, 0(a0)
+
+# CHECK-S: amomaxu.w.rl a2, a1, (a0)
+# CHECK-S-NOALIAS: amomaxu.w.rl a2, a1, (a0)
+# CHECK-OBJ: amomaxu.w.rl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomaxu.w.rl a2, a1, (a0)
+amomaxu.w.rl a2, a1, 0(a0)
+
+# CHECK-S: amomaxu.w.aqrl a2, a1, (a0)
+# CHECK-S-NOALIAS: amomaxu.w.aqrl a2, a1, (a0)
+# CHECK-OBJ: amomaxu.w.aqrl a2, a1, (a0)
+# CHECK-OBJ-NOALIAS: amomaxu.w.aqrl a2, a1, (a0)
+amomaxu.w.aqrl a2, a1, 0(a0)