1 files changed, 33 insertions, 13 deletions

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 052ad85..6d12f7a 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -281,7 +281,7 @@ static Value *GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue,
   return BI->getCondition();
 }
 
-/// ComputeSpeculuationCost - Compute an abstract "cost" of speculating the
+/// ComputeSpeculationCost - Compute an abstract "cost" of speculating the
 /// given instruction, which is assumed to be safe to speculate. 1 means
 /// cheap, 2 means less cheap, and UINT_MAX means prohibitively expensive.
 static unsigned ComputeSpeculationCost(const User *I) {
@@ -533,9 +533,7 @@ Value *SimplifyCFGOpt::isValueEqualityComparison(TerminatorInst *TI) {
   } else if (BranchInst *BI = dyn_cast<BranchInst>(TI))
     if (BI->isConditional() && BI->getCondition()->hasOneUse())
       if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition()))
-        if ((ICI->getPredicate() == ICmpInst::ICMP_EQ ||
-             ICI->getPredicate() == ICmpInst::ICMP_NE) &&
-            GetConstantInt(ICI->getOperand(1), TD))
+        if (ICI->isEquality() && GetConstantInt(ICI->getOperand(1), TD))
           CV = ICI->getOperand(0);
 
   // Unwrap any lossless ptrtoint cast.
@@ -1083,9 +1081,9 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
       (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2)))
     return false;
 
-  // If we get here, we can hoist at least one instruction.
   BasicBlock *BIParent = BI->getParent();
 
+  bool Changed = false;
   do {
     // If we are hoisting the terminator instruction, don't move one (making a
     // broken BB), instead clone it, and remove BI.
@@ -1100,6 +1098,7 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
       I2->replaceAllUsesWith(I1);
     I1->intersectOptionalDataWith(I2);
     I2->eraseFromParent();
+    Changed = true;
 
     I1 = BB1_Itr++;
     I2 = BB2_Itr++;
@@ -1119,7 +1118,23 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
 HoistTerminator:
   // It may not be possible to hoist an invoke.
   if (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2))
-    return true;
+    return Changed;
+
+  for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) {
+    PHINode *PN;
+    for (BasicBlock::iterator BBI = SI->begin();
+         (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
+      Value *BB1V = PN->getIncomingValueForBlock(BB1);
+      Value *BB2V = PN->getIncomingValueForBlock(BB2);
+      if (BB1V == BB2V)
+        continue;
+
+      if (isa<ConstantExpr>(BB1V) && !isSafeToSpeculativelyExecute(BB1V))
+        return Changed;
+      if (isa<ConstantExpr>(BB2V) && !isSafeToSpeculativelyExecute(BB2V))
+        return Changed;
+    }
+  }
 
   // Okay, it is safe to hoist the terminator.
   Instruction *NT = I1->clone();
@@ -1362,8 +1377,8 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) {
 ///
 /// \return The pointer to the value of the previous store if the store can be
 ///         hoisted into the predecessor block. 0 otherwise.
-Value *isSafeToSpeculateStore(Instruction *I, BasicBlock *BrBB,
-                              BasicBlock *StoreBB, BasicBlock *EndBB) {
+static Value *isSafeToSpeculateStore(Instruction *I, BasicBlock *BrBB,
+                                     BasicBlock *StoreBB, BasicBlock *EndBB) {
   StoreInst *StoreToHoist = dyn_cast<StoreInst>(I);
   if (!StoreToHoist)
     return 0;
@@ -1522,18 +1537,23 @@ static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *ThenBB) {
     Value *OrigV = PN->getIncomingValueForBlock(BB);
     Value *ThenV = PN->getIncomingValueForBlock(ThenBB);
 
+    // FIXME: Try to remove some of the duplication with HoistThenElseCodeToIf.
     // Skip PHIs which are trivial.
     if (ThenV == OrigV)
       continue;
 
     HaveRewritablePHIs = true;
-    ConstantExpr *CE = dyn_cast<ConstantExpr>(ThenV);
-    if (!CE)
+    ConstantExpr *OrigCE = dyn_cast<ConstantExpr>(OrigV);
+    ConstantExpr *ThenCE = dyn_cast<ConstantExpr>(ThenV);
+    if (!OrigCE && !ThenCE)
       continue; // Known safe and cheap.
 
-    if (!isSafeToSpeculativelyExecute(CE))
+    if ((ThenCE && !isSafeToSpeculativelyExecute(ThenCE)) ||
+        (OrigCE && !isSafeToSpeculativelyExecute(OrigCE)))
       return false;
-    if (ComputeSpeculationCost(CE) > PHINodeFoldingThreshold)
+    unsigned OrigCost = OrigCE ? ComputeSpeculationCost(OrigCE) : 0;
+    unsigned ThenCost = ThenCE ? ComputeSpeculationCost(ThenCE) : 0;
+    if (OrigCost + ThenCost > 2 * PHINodeFoldingThreshold)
       return false;
 
     // Account for the cost of an unfolded ConstantExpr which could end up
@@ -3643,7 +3663,7 @@ bool SwitchLookupTable::WouldFitInRegister(const DataLayout *TD,
 }
 
 /// ShouldBuildLookupTable - Determine whether a lookup table should be built
-/// for this switch, based on the number of caes, size of the table and the
+/// for this switch, based on the number of cases, size of the table and the
 /// types of the results.
 static bool ShouldBuildLookupTable(SwitchInst *SI,
                                    uint64_t TableSize,