MC: Overhaul handling of .lcomm

- Darwin lied about not supporting .lcomm and turned it into zerofill in the
  asm parser. Push the zerofill-conversion down into macho-specific code.
- This makes the tri-state LCOMMType enum superfluous, there are no targets
  without .lcomm.
- Do proper error reporting when trying to use .lcomm with alignment on a target
  that doesn't support it.
- .comm and .lcomm alignment was parsed in bytes on COFF, should be power of 2.
- Fixes PR13755 (.lcomm crashes on ELF).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163395 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 6 deletions

diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index d60a270190..271fee02ad 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -2280,8 +2280,11 @@ bool AsmParser::ParseDirectiveComm(bool IsLocal) {
     if (ParseAbsoluteExpression(Pow2Alignment))
       return true;
 
+    if (IsLocal && !Lexer.getMAI().getLCOMMDirectiveSupportsAlignment())
+      return Error(Pow2AlignmentLoc, "alignment not supported on this target");
+
     // If this target takes alignments in bytes (not log) validate and convert.
-    if (Lexer.getMAI().getAlignmentIsInBytes()) {
+    if (Lexer.getMAI().getCOMMDirectiveAlignmentIsInBytes()) {
       if (!isPowerOf2_64(Pow2Alignment))
         return Error(Pow2AlignmentLoc, "alignment must be a power of 2");
       Pow2Alignment = Log2_64(Pow2Alignment);
@@ -2309,13 +2312,9 @@ bool AsmParser::ParseDirectiveComm(bool IsLocal) {
   if (!Sym->isUndefined())
     return Error(IDLoc, "invalid symbol redefinition");
 
-  // '.lcomm' is equivalent to '.zerofill'.
   // Create the Symbol as a common or local common with Size and Pow2Alignment
   if (IsLocal) {
-    getStreamer().EmitZerofill(Ctx.getMachOSection(
-                                 "__DATA", "__bss", MCSectionMachO::S_ZEROFILL,
-                                 0, SectionKind::getBSS()),
-                               Sym, Size, 1 << Pow2Alignment);
+    getStreamer().EmitLocalCommonSymbol(Sym, Size, 1 << Pow2Alignment);
     return false;
   }