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).

llvm-svn: 163395

1 files changed, 8 insertions, 5 deletions

diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index 394f049ca4a..804e38ead08 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -517,13 +517,16 @@ void MCAsmStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 /// @param Size - The size of the common symbol.
 void MCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                                           unsigned ByteAlign) {
-  assert(MAI.getLCOMMDirectiveType() != LCOMM::None &&
-         "Doesn't have .lcomm, can't emit it!");
   OS << "\t.lcomm\t" << *Symbol << ',' << Size;
   if (ByteAlign > 1) {
-    assert(MAI.getLCOMMDirectiveType() == LCOMM::ByteAlignment &&
-           "Alignment not supported on .lcomm!");
-    OS << ',' << ByteAlign;
+    assert(MAI.getLCOMMDirectiveSupportsAlignment() &&
+           "alignment not supported on .lcomm!");
+    if (MAI.getCOMMDirectiveAlignmentIsInBytes()) {
+      OS << ',' << ByteAlign;
+    } else {
+      assert(isPowerOf2_32(ByteAlign) && "alignment must be a power of 2");
+      OS << ',' << Log2_32(ByteAlign);
+    }
   }
   EmitEOL();
 }