[PATCH] D150133: [RISCV] Support constant immediate for la pseudo instruction

[garvit gupta via Phabricator via llvm-commits]

garvitgupta08 added inline comments.


================
Comment at: llvm/lib/Target/RISCV/RISCVInstrInfo.td:1619
+    isCodeGenOnly = 0, isAsmParserOnly = 1 in
+def PseudoLAImm : Pseudo<(outs GPR:$rd), (ins ixlenimm_la:$imm), [],
+                         "la", "$rd, $imm">;
----------------
jrtc27 wrote:
> I don't understand why you need a new pseudo rather than teaching the existing one to also accept an integer
I did this in the revision https://reviews.llvm.org/D150133?id=521304. Below is the diff for the same but I believe that having a separate defintion for supporting constant operand in la will be much cleaner and readable than modifying the existing defintion to accept bare symbol and constant as argument.


+++ llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp

+  OperandMatchResultTy parseBareSymbolOrConstant(OperandVector &Operands);

+  // Allow Constant Immediate as well as BareSymbols
+  bool isBareSymbolOrConstant() const {
+    if (isBareSymbol())
+      return true;
+    int64_t Imm;
+    RISCVMCExpr::VariantKind VK = RISCVMCExpr::VK_RISCV_None;
+    if (!isImm())
+      return false;
+    bool IsConstantImm = evaluateConstantImm(getImm(), Imm, VK);
+    bool IsInRange = isInt<32>(Imm) || isUInt<32>(Imm) || isRV64Imm();
+    return IsConstantImm && IsInRange && VK == RISCVMCExpr::VK_RISCV_None;
+  }
+

+  case Match_InvalidBareSymbolOrConstant: {
+    return generateImmOutOfRangeError(
+        Operands, ErrorInfo, std::numeric_limits<int32_t>::min(),
+        std::numeric_limits<uint32_t>::max(),
+        "operand either must be a Bare Symbol or an integer in the range");
+  }

+OperandMatchResultTy RISCVAsmParser::parseBareSymbolOrConstant(OperandVector &Operands) {
+  if (getLexer().getKind() == AsmToken::Identifier) {
+    OperandMatchResultTy Result = parseImmediate(Operands);
+    if (Result == MatchOperand_Success)
+      return MatchOperand_Success;
+  }
+  return parseBareSymbol(Operands);
+}
+


+++ llvm/lib/Target/RISCV/RISCVInstrInfo.td
 
+def BareSymbolOrConstant : AsmOperandClass {
+  let Name = "BareSymbolOrConstant";
+  let RenderMethod = "addImmOperands";
+  let DiagnosticType = "InvalidBareSymbolOrConstant";
+  let ParserMethod = "parseBareSymbolOrConstant";
+}
+
 
+// support constant operand for la pseudoinstruction.
+def bare_symbol_or_constant : Operand<XLenVT> {
+  let ParserMatchClass = BareSymbolOrConstant;
+}
+

-def PseudoLA : Pseudo<(outs GPR:$dst), (ins bare_symbol:$src), [],
+def PseudoLA : Pseudo<(outs GPR:$dst), (ins bare_symbol_or_constant:$src), [],



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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D150133/new/

https://reviews.llvm.org/D150133