[PHITransAddr] Don't translate unreachable values

[oota-llvm.git] / lib / Analysis / PHITransAddr.cpp

diff --git a/lib/Analysis/PHITransAddr.cpp b/lib/Analysis/PHITransAddr.cpp
index 71e2cdcbb42d1bc4264190cec91b571c9fb2119b..633d6aaad35e919cb17a13ec74367ffe4f6bc45c 100644 (file)
--- a/lib/Analysis/PHITransAddr.cpp
+++ b/lib/Analysis/PHITransAddr.cpp
@@ -315,21 +315,26 @@ Value *PHITransAddr::PHITranslateSubExpr(Value *V, BasicBlock *CurBB,
 
 
 /// PHITranslateValue - PHI translate the current address up the CFG from
-/// CurBB to Pred, updating our state to reflect any needed changes.  If the
-/// dominator tree DT is non-null, the translated value must dominate
+/// CurBB to Pred, updating our state to reflect any needed changes.  If
+/// 'MustDominate' is true, the translated value must dominate
 /// PredBB.  This returns true on failure and sets Addr to null.
 bool PHITransAddr::PHITranslateValue(BasicBlock *CurBB, BasicBlock *PredBB,
-                                     const DominatorTree *DT) {
+                                     const DominatorTree *DT,
+                                     bool MustDominate) {
+  assert(DT || !MustDominate);
   assert(Verify() && "Invalid PHITransAddr!");
-  Addr = PHITranslateSubExpr(Addr, CurBB, PredBB, DT);
+  if (DT && DT->isReachableFromEntry(PredBB))
+    Addr =
+        PHITranslateSubExpr(Addr, CurBB, PredBB, MustDominate ? DT : nullptr);
+  else
+    Addr = nullptr;
   assert(Verify() && "Invalid PHITransAddr!");
 
-  if (DT) {
+  if (MustDominate)
     // Make sure the value is live in the predecessor.
     if (Instruction *Inst = dyn_cast_or_null<Instruction>(Addr))
       if (!DT->dominates(Inst->getParent(), PredBB))
         Addr = nullptr;
-  }
 
   return Addr == nullptr;
 }
@@ -372,7 +377,7 @@ InsertPHITranslatedSubExpr(Value *InVal, BasicBlock *CurBB,
   // See if we have a version of this value already available and dominating
   // PredBB.  If so, there is no need to insert a new instance of it.
   PHITransAddr Tmp(InVal, DL, AC);
-  if (!Tmp.PHITranslateValue(CurBB, PredBB, &DT))
+  if (!Tmp.PHITranslateValue(CurBB, PredBB, &DT, /*MustDominate=*/true))
     return Tmp.getAddr();
 
   // If we don't have an available version of this value, it must be an