[llvm] r297929 - [ADCE] Remove redundent code [NFC]

[Tobias Grosser via llvm-commits]

Author: grosser
Date: Wed Mar 15 22:59:23 2017
New Revision: 297929

URL: http://llvm.org/viewvc/llvm-project?rev=297929&view=rev
Log:
[ADCE] Remove redundent code [NFC]

Summary:
In commit r289548 ([ADCE] Add code to remove dead branches) a redundant loop
nest was accidentally introduced, which implements exactly the same
functionality as has already been available right after. This redundancy has
been found when inspecting the ADCE code in the context of our recent
discussions on post-dominator modeling. This redundant code was also eliminated
by r296535 (which sparked the discussion), but only as part of a larger semantic
change of the post-dominance modeling. As this redundency in [ADCE] is really
just an oversight completely independent of the post-dominance changes under
discussion, we remove this redundancy independently.

Reviewers: dberlin, david2050

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D31023

Modified:
    llvm/trunk/lib/Transforms/Scalar/ADCE.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/ADCE.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ADCE.cpp?rev=297929&r1=297928&r2=297929&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ADCE.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ADCE.cpp Wed Mar 15 22:59:23 2017
@@ -262,25 +262,6 @@ void AggressiveDeadCodeElimination::init
       continue;
     auto *BB = BBInfo.BB;
     if (!PDT.getNode(BB)) {
-      markLive(BBInfo.Terminator);
-      continue;
-    }
-    for (auto *Succ : successors(BB))
-      if (!PDT.getNode(Succ)) {
-        markLive(BBInfo.Terminator);
-        break;
-      }
-  }
-
-  // Mark blocks live if there is no path from the block to the
-  // return of the function or a successor for which this is true.
-  // This protects IDFCalculator which cannot handle such blocks.
-  for (auto &BBInfoPair : BlockInfo) {
-    auto &BBInfo = BBInfoPair.second;
-    if (BBInfo.terminatorIsLive())
-      continue;
-    auto *BB = BBInfo.BB;
-    if (!PDT.getNode(BB)) {
       DEBUG(dbgs() << "Not post-dominated by return: " << BB->getName()
                    << '\n';);
       markLive(BBInfo.Terminator);