[PATCH] D57358: [BranchFolding] Remove what appears to be dead code

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: rnk, void, efriedma.

This code tries to handle the case where IBB is an EHPad, but there's an earlier check that uses PBB->hasEHPadSuccessor(). Where PBB is a predecessor of IBB. The hasEHPadSuccessor function would have visited IBB and seen that it was an EHPad and returned false. This would prevent us from reaching this code with IBB as an EHPad.


https://reviews.llvm.org/D57358

Files:
  lib/CodeGen/BranchFolding.cpp


Index: lib/CodeGen/BranchFolding.cpp
===================================================================
--- lib/CodeGen/BranchFolding.cpp
+++ lib/CodeGen/BranchFolding.cpp
@@ -1182,29 +1182,6 @@
           }
         }
 
-        // Failing case: the only way IBB can be reached from PBB is via
-        // exception handling.  Happens for landing pads.  Would be nice to have
-        // a bit in the edge so we didn't have to do all this.
-        if (IBB->isEHPad()) {
-          MachineFunction::iterator IP = ++PBB->getIterator();
-          MachineBasicBlock *PredNextBB = nullptr;
-          if (IP != MF.end())
-            PredNextBB = &*IP;
-          if (!TBB) {
-            if (IBB != PredNextBB)      // fallthrough
-              continue;
-          } else if (FBB) {
-            if (TBB != IBB && FBB != IBB)   // cbr then ubr
-              continue;
-          } else if (Cond.empty()) {
-            if (TBB != IBB)               // ubr
-              continue;
-          } else {
-            if (TBB != IBB && IBB != PredNextBB)  // cbr
-              continue;
-          }
-        }
-
         // Remove the unconditional branch at the end, if any.
         if (TBB && (Cond.empty() || FBB)) {
           DebugLoc dl = PBB->findBranchDebugLoc();


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