MC asm parser: allow ?'s in symbol names, and handle @'s in names in MS asm

This is another (final?) stab at making us able to parse our own asm output
on Windows.

Symbols on Windows often contain @'s and ?'s in their names. Our asm parser
didn't like this. ?'s were not allowed, and @'s were intepreted as trying to
reference PLT/GOT/etc.

We can't just add quotes around the bad names, since e.g. for MinGW, we use gas
to assemble, and it doesn't like quotes in some places (notably in .def
directives).

This commit makes us allow ?'s in symbol names, and @'s in symbol names for MS
assembly.

Differential Revision: http://llvm-reviews.chandlerc.com/D1978

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193000 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCAsmInfo.h

@@ -156,6 +156,10 @@ namespace llvm {
     /// symbol names.  This defaults to true.
     bool AllowPeriodsInName;
 
+    /// \brief This is true if the assembler allows @ characters in symbol
+    /// names. Defaults to false.
+    bool AllowAtInName;
+
     /// AllowUTF8 - This is true if the assembler accepts UTF-8 input.
     // FIXME: Make this a more general encoding setting?
     bool AllowUTF8;
@@ -485,6 +489,9 @@ namespace llvm {
     bool doesAllowPeriodsInName() const {
       return AllowPeriodsInName;
     }
+    bool doesAllowAtInName() const {
+      return AllowAtInName;
+    }
     bool doesAllowUTF8() const {
       return AllowUTF8;
     }

lib/MC/MCAsmInfo.cpp

@@ -53,6 +53,7 @@ MCAsmInfo::MCAsmInfo() {
   AllowQuotesInName = false;
   AllowNameToStartWithDigit = false;
   AllowPeriodsInName = true;
+  AllowAtInName = false;
   AllowUTF8 = true;
   UseDataRegionDirectives = false;
   ZeroDirective = "\t.zero\t";

lib/MC/MCParser/AsmLexer.cpp

@@ -138,9 +138,9 @@ AsmToken AsmLexer::LexHexFloatLiteral(bool NoIntDigits) {
   return AsmToken(AsmToken::Real, StringRef(TokStart, CurPtr - TokStart));
 }
 
-/// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@]*
+/// LexIdentifier: [a-zA-Z_.][a-zA-Z0-9_$.@?]*
 static bool IsIdentifierChar(char c) {
-  return isalnum(c) || c == '_' || c == '$' || c == '.' || c == '@';
+  return isalnum(c) || c == '_' || c == '$' || c == '.' || c == '@' || c == '?';
 }
 AsmToken AsmLexer::LexIdentifier() {
   // Check for floating point literals.

lib/MC/MCParser/AsmParser.cpp

@@ -769,6 +769,7 @@ bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
     Res = MCUnaryExpr::CreateLNot(Res, getContext());
     return false;
   case AsmToken::Dollar:
+  case AsmToken::At:
   case AsmToken::String:
   case AsmToken::Identifier: {
     StringRef Identifier;
@@ -792,19 +793,25 @@ bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
     EndLoc = SMLoc::getFromPointer(Identifier.end());
 
     // This is a symbol reference.
+    StringRef SymbolName = Identifier;
+    MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
     std::pair<StringRef, StringRef> Split = Identifier.split('@');
-    MCSymbol *Sym = getContext().GetOrCreateSymbol(Split.first);
 
     // Lookup the symbol variant if used.
-    MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
     if (Split.first.size() != Identifier.size()) {
       Variant = MCSymbolRefExpr::getVariantKindForName(Split.second);
-      if (Variant == MCSymbolRefExpr::VK_Invalid) {
+      if (Variant != MCSymbolRefExpr::VK_Invalid) {
+        SymbolName = Split.first;
+      } else if (MAI.doesAllowAtInName()) {
+        Variant = MCSymbolRefExpr::VK_None;
+      } else {
         Variant = MCSymbolRefExpr::VK_None;
         return TokError("invalid variant '" + Split.second + "'");
       }
     }
 
+    MCSymbol *Sym = getContext().GetOrCreateSymbol(SymbolName);
+
     // If this is an absolute variable reference, substitute it now to preserve
     // semantics in the face of reassignment.
     if (Sym->isVariable() && isa<MCConstantExpr>(Sym->getVariableValue())) {
@@ -2105,25 +2112,25 @@ bool AsmParser::parseAssignment(StringRef Name, bool allow_redef,
 ///   ::= string
 bool AsmParser::parseIdentifier(StringRef &Res) {
   // The assembler has relaxed rules for accepting identifiers, in particular we
-  // allow things like '.globl $foo', which would normally be separate
-  // tokens. At this level, we have already lexed so we cannot (currently)
+  // allow things like '.globl $foo' and '.def @feat.00', which would normally be
+  // separate tokens. At this level, we have already lexed so we cannot (currently)
   // handle this as a context dependent token, instead we detect adjacent tokens
   // and return the combined identifier.
-  if (Lexer.is(AsmToken::Dollar)) {
-    SMLoc DollarLoc = getLexer().getLoc();
+  if (Lexer.is(AsmToken::Dollar) || Lexer.is(AsmToken::At)) {
+    SMLoc PrefixLoc = getLexer().getLoc();
 
-    // Consume the dollar sign, and check for a following identifier.
+    // Consume the prefix character, and check for a following identifier.
     Lex();
     if (Lexer.isNot(AsmToken::Identifier))
       return true;
 
-    // We have a '$' followed by an identifier, make sure they are adjacent.
-    if (DollarLoc.getPointer() + 1 != getTok().getLoc().getPointer())
+    // We have a '$' or '@' followed by an identifier, make sure they are adjacent.
+    if (PrefixLoc.getPointer() + 1 != getTok().getLoc().getPointer())
       return true;
 
     // Construct the joined identifier and consume the token.
     Res =
-        StringRef(DollarLoc.getPointer(), getTok().getIdentifier().size() + 1);
+        StringRef(PrefixLoc.getPointer(), getTok().getIdentifier().size() + 1);
     Lex();
     return false;
   }

lib/Target/X86/MCTargetDesc/X86MCAsmInfo.cpp

@@ -135,6 +135,8 @@ X86MCAsmInfoMicrosoft::X86MCAsmInfoMicrosoft(const Triple &Triple) {
   AssemblerDialect = AsmWriterFlavor;
 
   TextAlignFillValue = 0x90;
+
+  AllowAtInName = true;
 }
 
 void X86MCAsmInfoGNUCOFF::anchor() { }

test/MC/COFF/tricky-names.ll

@@ -0,0 +1,38 @@
+; Check how tricky symbols are printed in the asm output.
+; RUN: llc -mtriple=i686-pc-win32 %s -o - | FileCheck %s --check-prefix=ASM
+
+; Check that we can roundtrip these names through our assembler.
+; RUN: llc -mtriple=i686-pc-win32 %s -o - | llvm-mc -triple i686-pc-win32 -filetype=obj | llvm-readobj -t | FileCheck %s --check-prefix=READOBJ
+
+
+@"\01??__E_Generic_object@?$_Error_objects@H@std@@YAXXZ" = global i32 0
+@"\01__ZL16ExceptionHandlerP19_EXCEPTION_POINTERS@4" = global i32 0
+@"\01@foo.bar" = global i32 0
+
+define weak i32 @"\01??_B?$num_put@_WV?$back_insert_iterator@V?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@std@@@std@@@std@@51"() section ".text" {
+  %a = load i32* @"\01??__E_Generic_object@?$_Error_objects@H@std@@YAXXZ"
+  %b = load i32* @"\01__ZL16ExceptionHandlerP19_EXCEPTION_POINTERS@4"
+  %c = load i32* @"\01@foo.bar"
+  %x = add i32 %a, %b
+  %y = add i32 %x, %c
+  ret i32 %y
+}
+
+; Check that these symbols are not quoted. They occur in output that gets passed to GAS.
+; ASM: .globl __ZL16ExceptionHandlerP19_EXCEPTION_POINTERS@4
+; ASM-NOT: .globl "__ZL16ExceptionHandlerP19_EXCEPTION_POINTERS@4"
+; ASM: .globl @foo.bar
+; ASM-NOT: .globl "@foo.bar"
+
+; READOBJ: Symbol
+; READOBJ: Name: .text$??_B?$num_put@_WV?$back_insert_iterator@V?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@std@@@std@@@std@@51
+; READOBJ: Section: .text$??_B?$num_put@_WV?$back_insert_iterator@V?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@std@@@std@@@std@@51
+; READOBJ: Symbol
+; READOBJ: Name: ??_B?$num_put@_WV?$back_insert_iterator@V?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@std@@@std@@@std@@51
+; READOBJ: Section: .text$??_B?$num_put@_WV?$back_insert_iterator@V?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@std@@@std@@@std@@51
+; READOBJ: Symbol
+; READOBJ: Name: ??__E_Generic_object@?$_Error_objects@H@std@@YAXXZ
+; READOBJ: Symbol
+; READOBJ: Name: __ZL16ExceptionHandlerP19_EXCEPTION_POINTERS@4
+; READOBJ: Symbol
+; READOBJ: Name: @foo.bar

test/MC/ELF/bad-relocation.s

@@ -0,0 +1,7 @@
+// RUN: not llvm-mc -filetype=obj -triple i386-pc-linux-gnu %s -o /dev/null 2>&1 | FileCheck  %s
+
+// CHECK: error: invalid variant 'BADRELOC'
+
+        .text
+foo:
+	leal	.Lfoo@BADRELOC(%ebx), %eax

test/MC/ELF/symbol-names.s

@@ -0,0 +1,12 @@
+// RUN: llvm-mc -triple i686-pc-linux -filetype=obj %s -o - | llvm-readobj -t | FileCheck %s
+
+// MC allows ?'s in symbol names as an extension.
+
+.text
+.globl foo?bar
+.type foo?bar, @function
+foo?bar:
+ret
+
+// CHECK: Symbol
+// CHECK: Name: foo?bar