The structure layout for MCFragment had gaps because of unions, bitfields, etc.,

and 64-bit values (uint64_t and pointers). I have permuted the fields so that
the struct is now 8 bytes (out of 64) smaller than before.

I have also incorporated Jan's suggestions and keyed inserting into the previous
fragment on the MCSectionData flags.

BUG= http://code.google.com/p/nativeclient/issues/detail?id=2545
TEST=none
Review URL: https://chromiumcodereview.appspot.com/10828204/

1 files changed, 9 insertions, 6 deletions

diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp
index c569a4b3f4..26b171ed21 100644
--- a/lib/MC/MCELFStreamer.cpp
+++ b/lib/MC/MCELFStreamer.cpp
@@ -487,13 +487,16 @@ void MCELFStreamer::EmitInstToData(const MCInst &Inst) {
     }
     DF->getContents().append(Code.begin(), Code.end());
   } else {
+    // Only create a new fragment if:
+    // 1) there is no current fragment,
+    // 2) we are not currently emitting a bundle locked sequence, or
+    // 3) we are emitting the first instruction of a bundle locked sequence.
+    // Otherwise, append to the current fragment to reduce the number of
+    // fragments.
     MCTinyFragment *TF = dyn_cast_or_null<MCTinyFragment>(getCurrentFragment());
-    // A bundle group is a contiguous group of bytes aligned as a unit.  We
-    // always try to append to the current bundle group, if there is one, to
-    // reduce the number of fragments created.
-    if (!TF || !TF->isBundleGroupStart() || TF->isBundleGroupEnd()) {
-      // We need to start a new bundle group.
-      TF = new MCTinyFragment(getCurrentSectionData());
+    MCSectionData *SD = getCurrentSectionData();
+    if (!TF || !SD->isBundleLocked() || SD->isBundleGroupFirstFrag()) {
+      TF = new MCTinyFragment(SD);
     }
     TF->getContents().append(Code.begin(), Code.end());
   }