Fix alignment of unwind data.

[oota-llvm.git] / lib / MC / MCWin64EH.cpp

diff --git a/lib/MC/MCWin64EH.cpp b/lib/MC/MCWin64EH.cpp
index c3d568b454c8bb2d3486b4140694c184ba6def34..b8b07d3a180875f6bfd101c0bf576fedb353ffc2 100644 (file)
--- a/lib/MC/MCWin64EH.cpp
+++ b/lib/MC/MCWin64EH.cpp
@@ -159,11 +159,11 @@ static void EmitUnwindInfo(MCStreamer &streamer, MCWin64EHUnwindInfo *info) {
 
   MCContext &context = streamer.getContext();
   streamer.EmitValueToAlignment(4);
-  // Upper 3 bits are the version number (currently 1).
-  uint8_t flags = 0x01;
   info->Symbol = context.CreateTempSymbol();
   streamer.EmitLabel(info->Symbol);
 
+  // Upper 3 bits are the version number (currently 1).
+  uint8_t flags = 0x01;
   if (info->ChainedParent)
     flags |= Win64EH::UNW_ChainInfo << 3;
   else {
@@ -199,6 +199,14 @@ static void EmitUnwindInfo(MCStreamer &streamer, MCWin64EHUnwindInfo *info) {
     EmitUnwindCode(streamer, info->Begin, inst);
   }
 
+  // For alignment purposes, the instruction array will always have an even
+  // number of entries, with the final entry potentially unused (in which case
+  // the array will be one longer than indicated by the count of unwind codes
+  // field).
+  if (numCodes & 1) {
+    streamer.EmitIntValue(0, 2);
+  }
+
   if (flags & (Win64EH::UNW_ChainInfo << 3))
     EmitRuntimeFunction(streamer, info->ChainedParent);
   else if (flags &
@@ -206,14 +214,11 @@ static void EmitUnwindInfo(MCStreamer &streamer, MCWin64EHUnwindInfo *info) {
     streamer.EmitValue(MCSymbolRefExpr::Create(info->ExceptionHandler,
                                               MCSymbolRefExpr::VK_COFF_IMGREL32,
                                               context), 4);
-  else if (numCodes < 2) {
+  else if (numCodes == 0) {
     // The minimum size of an UNWIND_INFO struct is 8 bytes. If we're not
     // a chained unwind info, if there is no handler, and if there are fewer
     // than 2 slots used in the unwind code array, we have to pad to 8 bytes.
-    if (numCodes == 1)
-      streamer.EmitIntValue(0, 2);
-    else
-      streamer.EmitIntValue(0, 4);
+    streamer.EmitIntValue(0, 4);
   }
 }