Re-commit r192758 - MC: quote tricky symbol names in asm output

The reason this got reverted was that the @feat.00 symbol which was emitted
for every TU became quoted, and on cygwin/mingw we use the gas assembler which
couldn't handle the quotes.

This commit fixes the problem by only emitting @feat.00 for win32, where we use
clang -cc1as to assemble. gas would just drop this symbol anyway, so there is no
loss there.

With @feat.00 gone, there shouldn't be quoted symbols showing up on cygwin since
it uses the Itanium ABI, which doesn't put these funny characters in symbols.

> Because of win32 mangling, we produce symbol and section names with
> funny characters in them, most notably @ characters.
>
> MC would choke on trying to parse its own assembly output. This patch addresses
> that by:
>
> - Making @ trigger quoting of symbol names
> - Also quote section names in the same way
> - Just parse section names like other identifiers (to allow for quotes)
> - Don't assume @ signifies a symbol variant if it is in a string.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192859 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 1 deletions

diff --git a/lib/MC/MCSectionCOFF.cpp b/lib/MC/MCSectionCOFF.cpp
index 64aa2c5c49..a8f5db095b 100644
--- a/lib/MC/MCSectionCOFF.cpp
+++ b/lib/MC/MCSectionCOFF.cpp
@@ -39,6 +39,22 @@ void MCSectionCOFF::setSelection(int Selection,
   Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
 }
 
+static bool isAcceptableSectionNameChar(char C) {
+  return (C >= 'a' && C <= 'z') ||
+         (C >= 'A' && C <= 'Z') ||
+         (C >= '0' && C <= '9') ||
+         C == '_' || C == '$' || C == '.';
+}
+
+/// NameNeedsQuoting - Return true if the identifier \p Str needs quotes to be
+/// syntactically correct.
+static bool sectionNameNeedsQuoting(StringRef Name) {
+  for (unsigned i = 0, e = Name.size(); i != e; ++i)
+    if (!isAcceptableSectionNameChar(Name[i]))
+      return true;
+  return false;
+}
+
 void MCSectionCOFF::PrintSwitchToSection(const MCAsmInfo &MAI,
                                          raw_ostream &OS,
                                          const MCExpr *Subsection) const {
@@ -49,7 +65,10 @@ void MCSectionCOFF::PrintSwitchToSection(const MCAsmInfo &MAI,
     return;
   }
 
-  OS << "\t.section\t" << getSectionName() << ",\"";
+  if (sectionNameNeedsQuoting(getSectionName()))
+    OS << "\t.section\t" << '"' << getSectionName() << '"' << ",\"";
+  else
+    OS << "\t.section\t" << getSectionName() << ",\"";
   if (getKind().isText())
     OS << 'x';
   if (getKind().isWriteable())