[RISCV][MC] Add support for evaluating constant symbols as immediates

This further improves compatibility with GNU as, allowing input such as the
following to be assembled:

.equ CONST, 0x123456
li a0, CONST
addi a0, a0, %lo(CONST)

.equ CONST, 1
slli a0, a0, CONST

Note that we don't have perfect compatibility with gas, as it will avoid
emitting a relocation in this case:

addi a0, a0, %lo(CONST2)
.equ CONST2, 0x123456

Thanks to Shiva Chen for suggesting a better way to approach this during review.

Differential Revision: https://reviews.llvm.org/D52298

llvm-svn: 350831

1 files changed, 1 insertions, 8 deletions

diff --git a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
index d7fc2b2fbdb..1d1112cc512 100644
--- a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
+++ b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
@@ -1033,17 +1033,10 @@ OperandMatchResultTy RISCVAsmParser::parseImmediate(OperandVector &Operands) {
   case AsmToken::Plus:
   case AsmToken::Integer:
   case AsmToken::String:
+  case AsmToken::Identifier:
     if (getParser().parseExpression(Res))
       return MatchOperand_ParseFail;
     break;
-  case AsmToken::Identifier: {
-    StringRef Identifier;
-    if (getParser().parseIdentifier(Identifier))
-      return MatchOperand_ParseFail;
-    MCSymbol *Sym = getContext().getOrCreateSymbol(Identifier);
-    Res = MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_None, getContext());
-    break;
-  }
   case AsmToken::Percent:
     return parseOperandWithModifier(Operands);
   }