Repair bundles that were broken by removing and reinserting the first

instruction.

This isn't strictly necessary at the moment because Thumb2SizeReduction
also copies all MI flags from the old instruction to the new. However, a
future patch will make that kind of direct flag tampering illegal.

llvm-svn: 170395

diff --git a/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp b/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp
index 7e3b552..efc9bc3 100644 (file)
--- a/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp
+++ b/llvm/lib/Target/ARM/Thumb2SizeReduction.cpp
@@ -896,13 +896,20 @@ bool Thumb2SizeReduce::ReduceMBB(MachineBasicBlock &MBB) {
 
     LiveCPSR = UpdateCPSRUse(*MI, LiveCPSR);
 
+    // Does NextMII belong to the same bundle as MI?
+    bool NextInSameBundle = NextMII != E && NextMII->isBundledWithPred();
+
     if (ReduceMI(MBB, MI, LiveCPSR, CPSRDef, IsSelfLoop)) {
       Modified = true;
       MachineBasicBlock::instr_iterator I = prior(NextMII);
       MI = &*I;
+      // Removing and reinserting the first instruction in a bundle will break
+      // up the bundle. Fix the bundling if it was broken.
+      if (NextInSameBundle && !NextMII->isBundledWithPred())
+        NextMII->bundleWithPred();
     }
 
-    if (NextMII != E && MI->isInsideBundle() && !NextMII->isInsideBundle()) {
+    if (!NextInSameBundle && MI->isInsideBundle()) {
       // FIXME: Since post-ra scheduler operates on bundles, the CPSR kill
       // marker is only on the BUNDLE instruction. Process the BUNDLE
       // instruction as we finish with the bundled instruction to work around