[mips] Fix crash on recursive using of .set

[atanasyan]

Summary

Switch to the MCParserUtils::parseAssignmentExpression for parsing assignment expressions in the .set directive reduces code and allows to print an error message instead of crashing in case of incorrect recursive using of the .set.

Fix for the bug https://bugs.llvm.org/show_bug.cgi?id=41053.

[Petar.Avramovic]

LGTM.

llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp

 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCInstrDesc.h"
 #include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/MC/MCParser/MCAsmLexer.h"
 #include "llvm/MC/MCParser/MCAsmParser.h"
 #include "llvm/MC/MCParser/MCAsmParserExtension.h"
+#include "llvm/MC/MCParser/MCAsmParserUtils.h"
 #include "llvm/MC/MCParser/MCParsedAsmOperand.h"
 #include "llvm/MC/MCParser/MCTargetAsmParser.h"
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCSymbolELF.h"
 #include "llvm/MC/MCValue.h"
bool MipsAsmParser::parseSetHardFloatDirective() {
 
   clearFeatureBits(Mips::FeatureSoftFloat, "soft-float");
   getTargetStreamer().emitDirectiveSetHardFloat();
   return false;
 }
 
 bool MipsAsmParser::parseSetAssignment() {
   StringRef Name;
-  const MCExpr *Value;
   MCAsmParser &Parser = getParser();
 
   if (Parser.parseIdentifier(Name))
     return reportParseError("expected identifier after .set");
 
   if (getLexer().isNot(AsmToken::Comma))
     return reportParseError("unexpected token, expected comma");
   Lex(); // Eat comma
 
   if (getLexer().is(AsmToken::Dollar) &&
       getLexer().peekTok().is(AsmToken::Integer)) {
     // Parse assignment of a numeric register:
     //   .set r1,$1
     Parser.Lex(); // Eat $.
     RegisterSets[Name] = Parser.getTok();
     Parser.Lex(); // Eat identifier.
     getContext().getOrCreateSymbol(Name);
-  } else if (!Parser.parseExpression(Value)) {
-    // Parse assignment of an expression including
-    // symbolic registers:
-    //   .set  $tmp, $BB0-$BB1
-    //   .set  r2, $f2
-    MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
-    Sym->setVariableValue(Value);
-  } else {
-    return reportParseError("expected valid expression after comma");
+    return false;
   }
 
+  MCSymbol *Sym;
+  const MCExpr *Value;
+  if (MCParserUtils::parseAssignmentExpression(Name, /* allow_redef */ true,
+                                               Parser, Sym, Value))
+    return true;
+  Sym->setVariableValue(Value);
+
   return false;
 }
 
 bool MipsAsmParser::parseSetMips0Directive() {
   MCAsmParser &Parser = getParser();
   Parser.Lex();
   if (getLexer().isNot(AsmToken::EndOfStatement))
     return reportParseError("unexpected token, expected end of statement");

llvm/test/MC/Mips/set-sym-recursive.s

+# RUN: not llvm-mc -triple mips-unknown-linux %s 2>&1 | FileCheck %s
+
+.set A, A + 1
+# CHECK: :[[@LINE-1]]:9: error: Recursive use of 'A'
+.word A