[MC][X86] Enhance X86 Register expression handling to more closely match GCC.

Allow the comparison of x86 registers in the evaluation of assembler
directives. This generalizes and simplifies the extension from r334022
to catch another case found in the Linux kernel.

Reviewers: rnk, void

Reviewed By: rnk

Subscribers: hiraditya, nickdesaulniers, llvm-commits

Differential Revision: https://reviews.llvm.org/D50795

llvm-svn: 339895

diff --git a/llvm/include/llvm/MC/MCExpr.h b/llvm/include/llvm/MC/MCExpr.h
index 0d8f3ca9c40a28244290df6cb5adde87ceb3d134..23dde10e785bb69e9a96ecd1f3726a558140b6f2 100644 (file)
--- a/llvm/include/llvm/MC/MCExpr.h
+++ b/llvm/include/llvm/MC/MCExpr.h
@@ -589,6 +589,8 @@ public:
   virtual bool evaluateAsRelocatableImpl(MCValue &Res,
                                          const MCAsmLayout *Layout,
                                          const MCFixup *Fixup) const = 0;
+  // allow Target Expressions to be checked for equality
+  virtual bool isEqualTo(const MCExpr *x) const { return false; }
   // This should be set when assigned expressions are not valid ".set"
   // expressions, e.g. registers, and must be inlined.
   virtual bool inlineAssignedExpr() const { return false; }

diff --git a/llvm/include/llvm/MC/MCParser/MCAsmParserUtils.h b/llvm/include/llvm/MC/MCParser/MCAsmParserUtils.h
index 259113bc38609ec88fcc605eea14e0a8cdbe06ab..84173bb9cb8ebe97a1af130b374c67ad3d8dc1ed 100644 (file)
--- a/llvm/include/llvm/MC/MCParser/MCAsmParserUtils.h
+++ b/llvm/include/llvm/MC/MCParser/MCAsmParserUtils.h
@@ -25,7 +25,7 @@ namespace MCParserUtils {
 /// 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, bool AllowExtendedExpr = false);
+                               const MCExpr *&Value);
 
 } // namespace MCParserUtils
 

diff --git a/llvm/include/llvm/MC/MCParser/MCTargetAsmParser.h b/llvm/include/llvm/MC/MCParser/MCTargetAsmParser.h
index 2d188a6755e17c831842f2b7b1e240eb549739be..135b5fab07cebec565558201a27f493e7f539bd4 100644 (file)
--- a/llvm/include/llvm/MC/MCParser/MCTargetAsmParser.h
+++ b/llvm/include/llvm/MC/MCParser/MCTargetAsmParser.h
@@ -372,9 +372,9 @@ public:
     SemaCallback = Callback;
   }
 
-  // Target-specific parsing of assembler-level variable assignment.
-  virtual bool parseAssignmentExpression(const MCExpr *&Res, SMLoc &EndLoc) {
-    return getParser().parseExpression(Res, EndLoc);
+  // Target-specific parsing of expression.
+  virtual bool parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
+    return getParser().parsePrimaryExpr(Res, EndLoc);
   }
 
   virtual bool ParseRegister(unsigned &RegNo, SMLoc &StartLoc,

diff --git a/llvm/lib/MC/MCExpr.cpp b/llvm/lib/MC/MCExpr.cpp
index e3a6f8e7bffad9dbb02ee9029fa49959f71d57d0..638cb35da740d91268ee137ff2a3394e5db2fc81 100644 (file)
--- a/llvm/lib/MC/MCExpr.cpp
+++ b/llvm/lib/MC/MCExpr.cpp
@@ -751,8 +751,22 @@ bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
     if (!ABE->getLHS()->evaluateAsRelocatableImpl(LHSValue, Asm, Layout, Fixup,
                                                   Addrs, InSet) ||
         !ABE->getRHS()->evaluateAsRelocatableImpl(RHSValue, Asm, Layout, Fixup,
-                                                  Addrs, InSet))
+                                                  Addrs, InSet)) {
+      // Check if both are Target Expressions, see if we can compare them.
+      if (const MCTargetExpr *L = dyn_cast<MCTargetExpr>(ABE->getLHS()))
+        if (const MCTargetExpr *R = cast<MCTargetExpr>(ABE->getRHS())) {
+          switch (ABE->getOpcode()) {
+          case MCBinaryExpr::EQ:
+            Res = MCValue::get((L->isEqualTo(R)) ? -1 : 0);
+            return true;
+          case MCBinaryExpr::NE:
+            Res = MCValue::get((R->isEqualTo(R)) ? 0 : -1);
+            return true;
+          default: {}
+          }
+        }
       return false;
+    }
 
     // We only support a few operations on non-constant expressions, handle
     // those first.

diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index 39a760826d96df9ed42376eda8653c5dc3ca722b..b43babba78ea1e49cb926d1b32896800546eb457 100644 (file)
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -337,7 +337,7 @@ private:
   StringRef parseStringToComma();
 
   bool parseAssignment(StringRef Name, bool allow_redef,
-                       bool NoDeadStrip = false, bool AllowExtendedExpr = false);
+                       bool NoDeadStrip = false);
 
   unsigned getBinOpPrecedence(AsmToken::TokenKind K,
                               MCBinaryExpr::Opcode &Kind);
@@ -1363,7 +1363,8 @@ void AsmParser::altMacroString(StringRef AltMacroStr,std::string &Res) {
 bool AsmParser::parseExpression(const MCExpr *&Res, SMLoc &EndLoc) {
   // Parse the expression.
   Res = nullptr;
-  if (parsePrimaryExpr(Res, EndLoc) || parseBinOpRHS(1, Res, EndLoc))
+  if (getTargetParser().parsePrimaryExpr(Res, EndLoc) ||
+      parseBinOpRHS(1, Res, EndLoc))
     return true;
 
   // As a special case, we support 'a op b @ modifier' by rewriting the
@@ -1617,7 +1618,7 @@ bool AsmParser::parseBinOpRHS(unsigned Precedence, const MCExpr *&Res,
 
     // Eat the next primary expression.
     const MCExpr *RHS;
-    if (parsePrimaryExpr(RHS, EndLoc))
+    if (getTargetParser().parsePrimaryExpr(RHS, EndLoc))
       return true;
 
     // If BinOp binds less tightly with RHS than the operator after RHS, let
@@ -1826,7 +1827,7 @@ bool AsmParser::parseStatement(ParseStatementInfo &Info,
     // identifier '=' ... -> assignment statement
     Lex();
 
-    return parseAssignment(IDVal, true, /*NoDeadStrip*/ false, /*AllowExtendedExpr*/true);
+    return parseAssignment(IDVal, true);
 
   default: // Normal instruction or directive.
     break;
@@ -2766,11 +2767,11 @@ void AsmParser::handleMacroExit() {
 }
 
 bool AsmParser::parseAssignment(StringRef Name, bool allow_redef,
-                                bool NoDeadStrip, bool AllowExtendedExpr) {
+                                bool NoDeadStrip) {
   MCSymbol *Sym;
   const MCExpr *Value;
   if (MCParserUtils::parseAssignmentExpression(Name, allow_redef, *this, Sym,
-                                               Value, AllowExtendedExpr))
+                                               Value))
     return true;
 
   if (!Sym) {
@@ -5839,17 +5840,13 @@ static bool isSymbolUsedInExpression(const MCSymbol *Sym, const MCExpr *Value) {
 
 bool parseAssignmentExpression(StringRef Name, bool allow_redef,
                                MCAsmParser &Parser, MCSymbol *&Sym,
-                               const MCExpr *&Value, bool AllowExtendedExpr) {
+                               const MCExpr *&Value) {
 
   // FIXME: Use better location, we should use proper tokens.
   SMLoc EqualLoc = Parser.getTok().getLoc();
   SMLoc EndLoc;
-  if (AllowExtendedExpr) {
-    if (Parser.getTargetParser().parseAssignmentExpression(Value, EndLoc)) {
-      return Parser.TokError("missing expression");
-    }
-  } else if (Parser.parseExpression(Value, EndLoc))
-      return Parser.TokError("missing expression");
+  if (Parser.parseExpression(Value))
+    return Parser.TokError("missing expression");
 
   // Note: we don't count b as used in "a = b". This is to allow
   // a = b

diff --git a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
index fafbed0bd935128ecd18ffb681f4d7432d0bc9cd..b02e4d80fbba24ecfb64302e237d8711ce3372d6 100644 (file)
--- a/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -955,7 +955,7 @@ public:
 
   void SetFrameRegister(unsigned RegNo) override;
 
-  bool parseAssignmentExpression(const MCExpr *&Res, SMLoc &EndLoc) override;
+  bool parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) override;
 
   bool ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
                         SMLoc NameLoc, OperandVector &Operands) override;
@@ -2260,15 +2260,17 @@ std::unique_ptr<X86Operand> X86AsmParser::ParseMemOperand(unsigned SegReg,
   return X86Operand::CreateMem(getPointerWidth(), Disp, MemStart, MemEnd);
 }
 
-// Parse either a standard expression or a register.
-bool X86AsmParser::parseAssignmentExpression(const MCExpr *&Res,
-                                             SMLoc &EndLoc) {
+// Parse either a standard primary expression or a register.
+bool X86AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
   MCAsmParser &Parser = getParser();
-  if (Parser.parseExpression(Res, EndLoc)) {
+  if (Parser.parsePrimaryExpr(Res, EndLoc)) {
     SMLoc StartLoc = Parser.getTok().getLoc();
     // Normal Expression parse fails, check if it could be a register.
     unsigned RegNo;
-    if (Parser.getTargetParser().ParseRegister(RegNo, StartLoc, EndLoc))
+    bool TryRegParse =
+        getTok().is(AsmToken::Percent) ||
+        (isParsingIntelSyntax() && getTok().is(AsmToken::Identifier));
+    if (!TryRegParse || ParseRegister(RegNo, StartLoc, EndLoc))
       return true;
     // Clear previous parse error and return correct expression.
     Parser.clearPendingErrors();

diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCExpr.h b/llvm/lib/Target/X86/MCTargetDesc/X86MCExpr.h
index f1438cd24960267884f40edd2ccd8a68913f7eec..1070f70468fa2870c426913625ab5591f1a589eb 100644 (file)
--- a/llvm/lib/Target/X86/MCTargetDesc/X86MCExpr.h
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86MCExpr.h
@@ -48,7 +48,7 @@ public:
   /// @}
 
   void printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const override {
-    if (MAI->getAssemblerDialect() == 0)
+    if (!MAI || MAI->getAssemblerDialect() == 0)
       OS << '%';
     OS << X86ATTInstPrinter::getRegisterName(RegNo);
   }
@@ -59,6 +59,11 @@ public:
   }
   // Register values should be inlined as they are not valid .set expressions.
   bool inlineAssignedExpr() const override { return true; }
+  bool isEqualTo(const MCExpr *X) const override {
+    if (auto *E = dyn_cast<X86MCExpr>(X))
+      return getRegNo() == E->getRegNo();
+    return false;
+  }
   void visitUsedExpr(MCStreamer &Streamer) const override{};
   MCFragment *findAssociatedFragment() const override { return nullptr; }
 

diff --git a/llvm/test/MC/X86/pr37425.s b/llvm/test/MC/X86/pr37425.s
index 965d56ea1c5f4266492975cb59c3be7bdd9808f2..2cfa5e98a392c5541d10fbfbad2ea11c3f2be42e 100644 (file)
--- a/llvm/test/MC/X86/pr37425.s
+++ b/llvm/test/MC/X86/pr37425.s
@@ -1,5 +1,4 @@
-// RUN: llvm-mc -triple x86_64-unknown-unknown -defsym=ERR=0 %s -o -      | FileCheck %s
-// RUN: not llvm-mc -triple x86_64-unknown-unknown -defsym=ERR=1 %s -o - 2>&1 | FileCheck --check-prefix=ERR %s
+// RUN: llvm-mc -triple x86_64-unknown-unknown %s -o -      | FileCheck %s
        
 // CHECK-NOT: .set var_xdata
 var_xdata = %rcx
@@ -7,10 +6,15 @@ var_xdata = %rcx
 // CHECK: xorq %rcx, %rcx
 xorq var_xdata, var_xdata
 
-.if (ERR==1)
-// ERR: [[@LINE+2]]:15: error: unknown token in expression in '.set' directive
-// ERR: [[@LINE+1]]:15: error: missing expression in '.set' directive
-.set err_var, %rcx
-.endif 
+// CHECK: .data
+// CHECK-NEXT: .byte 1 
+.data 
+.if var_xdata == %rax
+  .byte 0
+.elseif var_xdata == %rcx
+  .byte 1
+.else
+  .byte 2      
+.endif