5 files changed, 17 insertions, 10 deletions
diff --git a/lib/MC/MCAsmInfo.cpp b/lib/MC/MCAsmInfo.cpp
index 11e368c..7ea0f3b 100644
--- a/lib/MC/MCAsmInfo.cpp
+++ b/lib/MC/MCAsmInfo.cpp
@@ -69,7 +69,7 @@ MCAsmInfo::MCAsmInfo() {
   HasSetDirective = true;
   HasAggressiveSymbolFolding = true;
   COMMDirectiveAlignmentIsInBytes = true;
-  LCOMMDirectiveSupportsAlignment = false;
+  LCOMMDirectiveAlignmentType = LCOMM::NoAlignment;
   HasDotTypeDotSizeDirective = true;
   HasSingleParameterDotFile = true;
   HasNoDeadStrip = false;
diff --git a/lib/MC/MCAsmInfoCOFF.cpp b/lib/MC/MCAsmInfoCOFF.cpp
index 4b426f8..fd79193 100644
--- a/lib/MC/MCAsmInfoCOFF.cpp
+++ b/lib/MC/MCAsmInfoCOFF.cpp
@@ -19,8 +19,10 @@ void MCAsmInfoCOFF::anchor() { }
 
 MCAsmInfoCOFF::MCAsmInfoCOFF() {
   GlobalPrefix = "_";
-  COMMDirectiveAlignmentIsInBytes = true;
-  LCOMMDirectiveSupportsAlignment = true;
+  // MingW 4.5 and later support .comm with log2 alignment, but .lcomm uses byte
+  // alignment.
+  COMMDirectiveAlignmentIsInBytes = false;
+  LCOMMDirectiveAlignmentType = LCOMM::ByteAlignment;
   HasDotTypeDotSizeDirective = false;
   HasSingleParameterDotFile = false;
   PrivateGlobalPrefix = "L";  // Prefix for private global symbols
diff --git a/lib/MC/MCAsmInfoDarwin.cpp b/lib/MC/MCAsmInfoDarwin.cpp
index 99520d4..a0e3eba 100644
--- a/lib/MC/MCAsmInfoDarwin.cpp
+++ b/lib/MC/MCAsmInfoDarwin.cpp
@@ -32,7 +32,7 @@ MCAsmInfoDarwin::MCAsmInfoDarwin() {
 
   AlignmentIsInBytes = false;
   COMMDirectiveAlignmentIsInBytes = false;
-  LCOMMDirectiveSupportsAlignment = true;
+  LCOMMDirectiveAlignmentType = LCOMM::Log2Alignment;
   InlineAsmStart = " InlineAsm Start";
   InlineAsmEnd = " InlineAsm End";
 
diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 804e38e..b0bc290 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -519,13 +519,16 @@ void MCAsmStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                                           unsigned ByteAlign) {
   OS << "\t.lcomm\t" << *Symbol << ',' << Size;
   if (ByteAlign > 1) {
-    assert(MAI.getLCOMMDirectiveSupportsAlignment() &&
-           "alignment not supported on .lcomm!");
-    if (MAI.getCOMMDirectiveAlignmentIsInBytes()) {
+    switch (MAI.getLCOMMDirectiveAlignmentType()) {
+    case LCOMM::NoAlignment:
+      llvm_unreachable("alignment not supported on .lcomm!");
+    case LCOMM::ByteAlignment:
       OS << ',' << ByteAlign;
-    } else {
+      break;
+    case LCOMM::Log2Alignment:
       assert(isPowerOf2_32(ByteAlign) && "alignment must be a power of 2");
       OS << ',' << Log2_32(ByteAlign);
+      break;
     }
   }
   EmitEOL();
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 271fee0..55ef01c 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -2280,11 +2280,13 @@ bool AsmParser::ParseDirectiveComm(bool IsLocal) {
     if (ParseAbsoluteExpression(Pow2Alignment))
       return true;
 
-    if (IsLocal && !Lexer.getMAI().getLCOMMDirectiveSupportsAlignment())
+    LCOMM::LCOMMType LCOMM = Lexer.getMAI().getLCOMMDirectiveAlignmentType();
+    if (IsLocal && LCOMM == LCOMM::NoAlignment)
       return Error(Pow2AlignmentLoc, "alignment not supported on this target");
 
     // If this target takes alignments in bytes (not log) validate and convert.
-    if (Lexer.getMAI().getCOMMDirectiveAlignmentIsInBytes()) {
+    if ((!IsLocal && Lexer.getMAI().getCOMMDirectiveAlignmentIsInBytes()) ||
+        (IsLocal && LCOMM == LCOMM::ByteAlignment)) {
       if (!isPowerOf2_64(Pow2Alignment))
         return Error(Pow2AlignmentLoc, "alignment must be a power of 2");
       Pow2Alignment = Log2_64(Pow2Alignment);