indvars -disable-iv-rewrite: handle an edge case involving identity phis.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134124 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 2a3e472..00f8831 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -1015,9 +1015,9 @@
(SE->getSCEV(UseInst) != SE->getSCEV(IVOperand)))
return false;
- UseInst->replaceAllUsesWith(IVOperand);
-
DEBUG(dbgs() << "INDVARS: Eliminated identity: " << *UseInst << '\n');
+
+ UseInst->replaceAllUsesWith(IVOperand);
++NumElimIdentity;
Changed = true;
DeadInsts.push_back(UseInst);
@@ -1037,7 +1037,9 @@
// Avoid infinite or exponential worklist processing.
// Also ensure unique worklist users.
- if (Simplified.insert(User))
+ // If Def is a LoopPhi, it may not be in the Simplified set, so check for
+ // self edges first.
+ if (User != Def && Simplified.insert(User))
SimpleIVUsers.push_back(std::make_pair(User, Def));
}
}
@@ -1111,6 +1113,9 @@
// Use-def pairs if IVUsers waiting to be processed for CurrIV.
SmallVector<std::pair<Instruction*, Instruction*>, 8> SimpleIVUsers;
+ // Push users of the current LoopPhi. In rare cases, pushIVUsers may be
+ // called multiple times for the same LoopPhi. This is the proper thing to
+ // do for loop header phis that use each other.
pushIVUsers(CurrIV, Simplified, SimpleIVUsers);
while (!SimpleIVUsers.empty()) {