[PATCH] Merge empty landing pads in SimplifyCFG

[Philip Reames]

================
Comment at: lib/Transforms/Utils/SimplifyCFG.cpp:4462
@@ +4461,3 @@
+  if (LandingPadInst *LPad = dyn_cast<LandingPadInst>(I)) {
+    for (++I; isa<DbgInfoIntrinsic>(I); ++I) {}
+    if (I->isTerminator() &&
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andrew.w.kaylor wrote:
> If I'm reading this right these debug intrinsics just get thrown away if a merge is performed.  Do they not contain anything that might be different from the corresponding debug intrinsics in the potential merge block?
This is correct.  dbg intriniscs are not allowed to modify optimization or code gen.  You're right that we could contain them if they were the same though.  

Actually, there's a bug here.  I need to remove *both* sets of debug intrinsics if I they're not the same.

http://reviews.llvm.org/D8297

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