[llvm-commits] [llvm] r129965 - /llvm/trunk/lib/CodeGen/BranchFolding.cpp

[Bill Wendling]

Author: void
Date: Thu Apr 21 20:07:09 2011
New Revision: 129965

URL: http://llvm.org/viewvc/llvm-project?rev=129965&view=rev
Log:
Branch folding is folding a landing pad into a regular BB.

An exception is thrown via a call to _cxa_throw, which we don't expect to
return. Therefore, the "true" part of the invoke goes to a BB that has
'unreachable' as its only instruction. This is lowered into an empty MachineBB.
The landing pad for this invoke, however, is directly after the "true" MBB.
When the empty MBB is removed, the landing pad is directly below the BB with the
invoke call. The unconditional branch is removed and then the two blocks are
merged together.

The testcase is too big for a regression test.
<rdar://problem/9305728>

Modified:
    llvm/trunk/lib/CodeGen/BranchFolding.cpp

Modified: llvm/trunk/lib/CodeGen/BranchFolding.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/BranchFolding.cpp?rev=129965&r1=129964&r2=129965&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/BranchFolding.cpp (original)
+++ llvm/trunk/lib/CodeGen/BranchFolding.cpp Thu Apr 21 20:07:09 2011
@@ -1048,7 +1048,7 @@
     // AnalyzeBranch.
     if (PriorCond.empty() && !PriorTBB && MBB->pred_size() == 1 &&
         PrevBB.succ_size() == 1 &&
-        !MBB->hasAddressTaken()) {
+        !MBB->hasAddressTaken() && !MBB->isLandingPad()) {
       DEBUG(dbgs() << "\nMerging into block: " << PrevBB
                    << "From MBB: " << *MBB);
       PrevBB.splice(PrevBB.end(), MBB, MBB->begin(), MBB->end());