Add support for parsing ARM symbol variants on ELF targets

ARM symbol variants are written with parens instead of @ like this:

  .word __GLOBAL_I_a(target1)

This commit adds support for parsing these symbol variants in
expressions. We introduce a new flag to MCAsmInfo that indicates the
parser should use parens to parse the symbol variant. The expression
parser is modified to look for symbol variants using parens instead
of @ when the corresponding MCAsmInfo flag is true.

The MCAsmInfo parens flag is enabled only for ARM on ELF.

By adding this flag to MCAsmInfo, we are able to get rid of
redundant ARM-specific symbol variants and use the generic variants
instead (e.g. VK_GOT instead of VK_ARM_GOT). We use the new
UseParensForSymbolVariant attribute in MCAsmInfo to correctly print
the symbol variants for arm.

To achive this we need to keep a handle to the MCAsmInfo in the
MCSymbolRefExpr class that we can check when printing the symbol
variant.

Updated Tests:
  Changed case of symbol variant to match the generic kind.
  test/CodeGen/ARM/tls-models.ll
  test/CodeGen/ARM/tls1.ll
  test/CodeGen/ARM/tls2.ll
  test/CodeGen/Thumb2/tls1.ll
  test/CodeGen/Thumb2/tls2.ll

PR18080

llvm-svn: 196424

1 files changed, 17 insertions, 3 deletions

diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index a91bd93105b..01fe87e0d66 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -789,20 +789,34 @@ bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
         return true;
       }
     }
+    // Parse symbol variant
+    std::pair<StringRef, StringRef> Split;
+    if (!MAI.useParensForSymbolVariant()) {
+      Split = Identifier.split('@');
+    } else if (Lexer.is(AsmToken::LParen)) {
+      Lexer.Lex(); // eat (
+      StringRef VName;
+      parseIdentifier(VName);
+      if (Lexer.isNot(AsmToken::RParen)) {
+          return Error(Lexer.getTok().getLoc(),
+                       "unexpected token in variant, expected ')'");
+      }
+      Lexer.Lex(); // eat )
+      Split = std::make_pair(Identifier, VName);
+    }
 
     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('@');
 
     // Lookup the symbol variant if used.
-    if (Split.first.size() != Identifier.size()) {
+    if (Split.second.size()) {
       Variant = MCSymbolRefExpr::getVariantKindForName(Split.second);
       if (Variant != MCSymbolRefExpr::VK_Invalid) {
         SymbolName = Split.first;
-      } else if (MAI.doesAllowAtInName()) {
+      } else if (MAI.doesAllowAtInName() && !MAI.useParensForSymbolVariant()) {
         Variant = MCSymbolRefExpr::VK_None;
       } else {
         Variant = MCSymbolRefExpr::VK_None;