Change .thumb_set to have the same error checks as .set.

According to the documentation, .thumb_set is 'the equivalent of a .set directive'.

We didn't have equivalent behaviour in terms of all the errors we could throw, for
example, when a symbol is redefined.

This change refactors parseAssignment so that it can be used by .set and .thumb_set
and implements tests for .thumb_set for all the errors thrown by that method.

Reviewed by Rafael Espíndola.

llvm-svn: 240318

include/llvm/MC/MCParser/MCAsmParserUtils.h

@@ -0,0 +1,27 @@
+//===------ llvm/MC/MCAsmParserUtils.h - Asm Parser Utilities ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_MC_MCPARSER_MCASMPARSERUTILS_H
+#define LLVM_MC_MCPARSER_MCASMPARSERUTILS_H
+
+namespace llvm {
+namespace MCParserUtils {
+
+/// Parse a value expression and return whether it can be assigned to a symbol
+/// with the given name.
+///
+/// On success, returns false and sets the Symbol and Value output parameters.
+bool parseAssignmentExpression(StringRef Name, bool allow_redef,
+                               MCAsmParser &Parser, MCSymbol *&Symbol,
+                               const MCExpr *&Value);
+
+} // namespace MCParserUtils
+} // namespace llvm
+
+#endif

include/llvm/MC/MCStreamer.h

@@ -78,7 +78,7 @@ public:
   MCTargetStreamer(MCStreamer &S);
   virtual ~MCTargetStreamer();
 
-  const MCStreamer &getStreamer() { return Streamer; }
+  MCStreamer &getStreamer() { return Streamer; }
 
   // Allow a target to add behavior to the EmitLabel of MCStreamer.
   virtual void emitLabel(MCSymbol *Symbol);

lib/MC/MCParser/AsmParser.cpp

@@ -26,6 +26,7 @@
 #include "llvm/MC/MCParser/AsmCond.h"
 #include "llvm/MC/MCParser/AsmLexer.h"
 #include "llvm/MC/MCParser/MCAsmParser.h"
+#include "llvm/MC/MCParser/MCAsmParserUtils.h"
 #include "llvm/MC/MCParser/MCParsedAsmOperand.h"
 #include "llvm/MC/MCRegisterInfo.h"
 #include "llvm/MC/MCSectionMachO.h"
@@ -2178,82 +2179,20 @@ void AsmParser::handleMacroExit() {
   ActiveMacros.pop_back();
 }
 
-static bool isUsedIn(const MCSymbol *Sym, const MCExpr *Value) {
-  switch (Value->getKind()) {
-  case MCExpr::Binary: {
-    const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(Value);
-    return isUsedIn(Sym, BE->getLHS()) || isUsedIn(Sym, BE->getRHS());
-  }
-  case MCExpr::Target:
-  case MCExpr::Constant:
-    return false;
-  case MCExpr::SymbolRef: {
-    const MCSymbol &S =
-        static_cast<const MCSymbolRefExpr *>(Value)->getSymbol();
-    if (S.isVariable())
-      return isUsedIn(Sym, S.getVariableValue());
-    return &S == Sym;
-  }
-  case MCExpr::Unary:
-    return isUsedIn(Sym, static_cast<const MCUnaryExpr *>(Value)->getSubExpr());
-  }
-
-  llvm_unreachable("Unknown expr kind!");
-}
-
 bool AsmParser::parseAssignment(StringRef Name, bool allow_redef,
                                 bool NoDeadStrip) {
-  // FIXME: Use better location, we should use proper tokens.
-  SMLoc EqualLoc = Lexer.getLoc();
-
+  MCSymbol *Sym;
   const MCExpr *Value;
-  if (parseExpression(Value))
+  if (MCParserUtils::parseAssignmentExpression(Name, allow_redef, *this, Sym,
+                                               Value))
     return true;
 
-  // Note: we don't count b as used in "a = b". This is to allow
-  // a = b
-  // b = c
-
-  if (Lexer.isNot(AsmToken::EndOfStatement))
-    return TokError("unexpected token in assignment");
-
-  // Eat the end of statement marker.
-  Lex();
-
-  // Validate that the LHS is allowed to be a variable (either it has not been
-  // used as a symbol, or it is an absolute symbol).
-  MCSymbol *Sym = getContext().lookupSymbol(Name);
-  if (Sym) {
-    // Diagnose assignment to a label.
-    //
-    // FIXME: Diagnostics. Note the location of the definition as a label.
-    // FIXME: Diagnose assignment to protected identifier (e.g., register name).
-    if (isUsedIn(Sym, Value))
-      return Error(EqualLoc, "Recursive use of '" + Name + "'");
-    else if (Sym->isUndefined() && !Sym->isUsed() && !Sym->isVariable())
-      ; // Allow redefinitions of undefined symbols only used in directives.
-    else if (Sym->isVariable() && !Sym->isUsed() && allow_redef)
-      ; // Allow redefinitions of variables that haven't yet been used.
-    else if (!Sym->isUndefined() && (!Sym->isVariable() || !allow_redef))
-      return Error(EqualLoc, "redefinition of '" + Name + "'");
-    else if (!Sym->isVariable())
-      return Error(EqualLoc, "invalid assignment to '" + Name + "'");
-    else if (!isa<MCConstantExpr>(Sym->getVariableValue()))
-      return Error(EqualLoc, "invalid reassignment of non-absolute variable '" +
-                                 Name + "'");
-
-    // Don't count these checks as uses.
-    Sym->setUsed(false);
-  } else if (Name == ".") {
-    if (Out.EmitValueToOffset(Value, 0)) {
-      Error(EqualLoc, "expected absolute expression");
-      eatToEndOfStatement();
-    }
+  if (!Sym) {
+    // In the case where we parse an expression starting with a '.', we will
+    // not generate an error, nor will we create a symbol.  In this case we
+    // should just return out.
     return false;
-  } else
-    Sym = getContext().getOrCreateSymbol(Name);
-
-  Sym->setRedefinable(allow_redef);
+  }
 
   // Do the assignment.
   Out.EmitAssignment(Sym, Value);
@@ -4777,6 +4716,103 @@ bool AsmParser::parseMSInlineAsm(
   return false;
 }
 
+namespace llvm {
+namespace MCParserUtils {
+
+/// Returns whether the given symbol is used anywhere in the given expression,
+/// or subexpressions.
+static bool isSymbolUsedInExpression(const MCSymbol *Sym, const MCExpr *Value) {
+  switch (Value->getKind()) {
+  case MCExpr::Binary: {
+    const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(Value);
+    return isSymbolUsedInExpression(Sym, BE->getLHS()) ||
+           isSymbolUsedInExpression(Sym, BE->getRHS());
+  }
+  case MCExpr::Target:
+  case MCExpr::Constant:
+    return false;
+  case MCExpr::SymbolRef: {
+    const MCSymbol &S =
+        static_cast<const MCSymbolRefExpr *>(Value)->getSymbol();
+    if (S.isVariable())
+      return isSymbolUsedInExpression(Sym, S.getVariableValue());
+    return &S == Sym;
+  }
+  case MCExpr::Unary:
+    return isSymbolUsedInExpression(
+        Sym, static_cast<const MCUnaryExpr *>(Value)->getSubExpr());
+  }
+
+  llvm_unreachable("Unknown expr kind!");
+}
+
+bool parseAssignmentExpression(StringRef Name, bool allow_redef,
+                               MCAsmParser &Parser, MCSymbol *&Sym,
+                               const MCExpr *&Value) {
+  MCAsmLexer &Lexer = Parser.getLexer();
+
+  // FIXME: Use better location, we should use proper tokens.
+  SMLoc EqualLoc = Lexer.getLoc();
+
+  if (Parser.parseExpression(Value)) {
+    Parser.TokError("missing expression");
+    Parser.eatToEndOfStatement();
+    return true;
+  }
+
+  // Note: we don't count b as used in "a = b". This is to allow
+  // a = b
+  // b = c
+
+  if (Lexer.isNot(AsmToken::EndOfStatement))
+    return Parser.TokError("unexpected token in assignment");
+
+  // Eat the end of statement marker.
+  Parser.Lex();
+
+  // Validate that the LHS is allowed to be a variable (either it has not been
+  // used as a symbol, or it is an absolute symbol).
+  Sym = Parser.getContext().lookupSymbol(Name);
+  if (Sym) {
+    // Diagnose assignment to a label.
+    //
+    // FIXME: Diagnostics. Note the location of the definition as a label.
+    // FIXME: Diagnose assignment to protected identifier (e.g., register name).
+    if (isSymbolUsedInExpression(Sym, Value))
+      return Parser.Error(EqualLoc, "Recursive use of '" + Name + "'");
+    else if (Sym->isUndefined() && !Sym->isUsed() && !Sym->isVariable())
+      ; // Allow redefinitions of undefined symbols only used in directives.
+    else if (Sym->isVariable() && !Sym->isUsed() && allow_redef)
+      ; // Allow redefinitions of variables that haven't yet been used.
+    else if (!Sym->isUndefined() && (!Sym->isVariable() || !allow_redef))
+      return Parser.Error(EqualLoc, "redefinition of '" + Name + "'");
+    else if (!Sym->isVariable())
+      return Parser.Error(EqualLoc, "invalid assignment to '" + Name + "'");
+    else if (!isa<MCConstantExpr>(Sym->getVariableValue()))
+      return Parser.Error(EqualLoc,
+                          "invalid reassignment of non-absolute variable '" +
+                              Name + "'");
+
+    // Don't count these checks as uses.
+    Sym->setUsed(false);
+  } else if (Name == ".") {
+    if (Parser.getStreamer().EmitValueToOffset(Value, 0)) {
+      Parser.Error(EqualLoc, "expected absolute expression");
+      Parser.eatToEndOfStatement();
+      return true;
+    }
+    return false;
+  } else
+    Sym = Parser.getContext().getOrCreateSymbol(Name);
+
+  Sym->setRedefinable(allow_redef);
+
+  return false;
+}
+
+} // namespace MCParserUtils
+} // namespace llvm
+
 /// \brief Create an MCAsmParser instance.
 MCAsmParser *llvm::createMCAsmParser(SourceMgr &SM, MCContext &C,
                                      MCStreamer &Out, const MCAsmInfo &MAI) {

lib/Target/ARM/AsmParser/ARMAsmParser.cpp

@@ -28,6 +28,7 @@
 #include "llvm/MC/MCObjectFileInfo.h"
 #include "llvm/MC/MCParser/MCAsmLexer.h"
 #include "llvm/MC/MCParser/MCAsmParser.h"
+#include "llvm/MC/MCParser/MCAsmParserUtils.h"
 #include "llvm/MC/MCParser/MCParsedAsmOperand.h"
 #include "llvm/MC/MCRegisterInfo.h"
 #include "llvm/MC/MCSection.h"
@@ -9887,22 +9888,13 @@ bool ARMAsmParser::parseDirectiveThumbSet(SMLoc L) {
   }
   Lex();
 
+  MCSymbol *Sym;
   const MCExpr *Value;
-  if (Parser.parseExpression(Value)) {
-    TokError("missing expression");
-    Parser.eatToEndOfStatement();
-    return false;
-  }
+  if (MCParserUtils::parseAssignmentExpression(Name, /* allow_redef */ true,
+                                               Parser, Sym, Value))
+    return true;
 
-  if (getLexer().isNot(AsmToken::EndOfStatement)) {
-    TokError("unexpected token");
-    Parser.eatToEndOfStatement();
-    return false;
-  }
-  Lex();
-
-  MCSymbol *Alias = getContext().getOrCreateSymbol(Name);
-  getTargetStreamer().emitThumbSet(Alias, Value);
+  getTargetStreamer().emitThumbSet(Sym, Value);
   return false;
 }
 

test/MC/ARM/thumb_set-diagnostics.s

@@ -41,3 +41,31 @@
 @ CHECK: 	.thumb_set trailer_trash, 0x11fe1e55,
 @ CHECK:                                            ^
 
+	.type alpha,%function
+alpha:
+	nop
+
+        .type beta,%function
+beta:
+	bkpt
+
+	.thumb_set beta, alpha
+
+@ CHECK: error: redefinition of 'beta'
+@ CHECK: 	.thumb_set beta, alpha
+@ CHECK:                                            ^
+
+	.type recursive_use,%function
+	.thumb_set recursive_use, recursive_use + 1
+
+@ CHECK: error: Recursive use of 'recursive_use'
+@ CHECK: 	.thumb_set recursive_use, recursive_use + 1
+@ CHECK:                                            ^
+
+  variable_result = alpha + 1
+  .long variable_result
+	.thumb_set variable_result, 1
+
+@ CHECK: error: invalid reassignment of non-absolute variable 'variable_result'
+@ CHECK: 	.thumb_set variable_result, 1
+@ CHECK:                                            ^

test/MC/ARM/thumb_set.s

@@ -54,8 +54,6 @@ alpha:
 	nop
 
         .type beta,%function
-beta:
-	bkpt
 
 	.thumb_set beta, alpha