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

6 files changed, 26 insertions, 16 deletions

diff --git a/lib/MC/MCAsmInfo.cpp b/lib/MC/MCAsmInfo.cpp
index 8da2e0e583..11e368c81a 100644
--- a/lib/MC/MCAsmInfo.cpp
+++ b/lib/MC/MCAsmInfo.cpp
@@ -68,8 +68,8 @@ MCAsmInfo::MCAsmInfo() {
   GlobalDirective = "\t.globl\t";
   HasSetDirective = true;
   HasAggressiveSymbolFolding = true;
-  LCOMMDirectiveType = LCOMM::None;
   COMMDirectiveAlignmentIsInBytes = true;
+  LCOMMDirectiveSupportsAlignment = false;
   HasDotTypeDotSizeDirective = true;
   HasSingleParameterDotFile = true;
   HasNoDeadStrip = false;
diff --git a/lib/MC/MCAsmInfoCOFF.cpp b/lib/MC/MCAsmInfoCOFF.cpp
index 678e75af5d..2637be7978 100644
--- a/lib/MC/MCAsmInfoCOFF.cpp
+++ b/lib/MC/MCAsmInfoCOFF.cpp
@@ -20,7 +20,7 @@ void MCAsmInfoCOFF::anchor() { }
 MCAsmInfoCOFF::MCAsmInfoCOFF() {
   GlobalPrefix = "_";
   COMMDirectiveAlignmentIsInBytes = false;
-  LCOMMDirectiveType = LCOMM::ByteAlignment;
+  LCOMMDirectiveSupportsAlignment = true;
   HasDotTypeDotSizeDirective = false;
   HasSingleParameterDotFile = false;
   PrivateGlobalPrefix = "L";  // Prefix for private global symbols
diff --git a/lib/MC/MCAsmInfoDarwin.cpp b/lib/MC/MCAsmInfoDarwin.cpp
index 8e0ac23efc..99520d4bf9 100644
--- a/lib/MC/MCAsmInfoDarwin.cpp
+++ b/lib/MC/MCAsmInfoDarwin.cpp
@@ -32,6 +32,7 @@ MCAsmInfoDarwin::MCAsmInfoDarwin() {
 
   AlignmentIsInBytes = false;
   COMMDirectiveAlignmentIsInBytes = false;
+  LCOMMDirectiveSupportsAlignment = true;
   InlineAsmStart = " InlineAsm Start";
   InlineAsmEnd = " InlineAsm End";
 
diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 394f049ca4..804e38ead0 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/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();
 }
diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index b75fe2c3a7..74f6dc62e1 100644
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -70,9 +70,7 @@ public:
     llvm_unreachable("macho doesn't support this directive");
   }
   virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
-                                     unsigned ByteAlignment) {
-    llvm_unreachable("macho doesn't support this directive");
-  }
+                                     unsigned ByteAlignment);
   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
                             uint64_t Size = 0, unsigned ByteAlignment = 0);
   virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
@@ -325,6 +323,15 @@ void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
   SD.setCommon(Size, ByteAlignment);
 }
 
+void MCMachOStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                            unsigned ByteAlignment) {
+  // '.lcomm' is equivalent to '.zerofill'.
+  return EmitZerofill(getContext().getMachOSection("__DATA", "__bss",
+                                                   MCSectionMachO::S_ZEROFILL,
+                                                   0, SectionKind::getBSS()),
+                      Symbol, Size, ByteAlignment);
+}
+
 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
                                    uint64_t Size, unsigned ByteAlignment) {
   MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
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;
   }