Use the target-aware constant folder on expressions to improve the chance

they'll be simple enough to simulate, and to reduce the chance we'll encounter
equal but different simple pointer constants.

This removes the symptoms from PR11352 but is not a full fix. A proper fix would
either require a guarantee that two constant objects we simulate are folded
when equal, or a different way of handling equal pointers (ie., trying a
constantexpr icmp on them to see whether we know they're equal or non-equal or
unsure).

llvm-svn: 151093

1 files changed, 9 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index bb37bf4c26e..7c78a205448 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2388,6 +2388,8 @@ bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst,
     if (StoreInst *SI = dyn_cast<StoreInst>(CurInst)) {
       if (!SI->isSimple()) return false;  // no volatile/atomic accesses.
       Constant *Ptr = getVal(SI->getOperand(1));
+      if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+        Ptr = ConstantFoldConstantExpression(CE, TD, TLI);
       if (!isSimpleEnoughPointerToCommit(Ptr))
         // If this is too complex for us to commit, reject it.
         return false;
@@ -2423,7 +2425,9 @@ bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst,
               Constant * const IdxList[] = {IdxZero, IdxZero};
 
               Ptr = ConstantExpr::getGetElementPtr(Ptr, IdxList);
-            
+              if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+                Ptr = ConstantFoldConstantExpression(CE, TD, TLI);
+
             // If we can't improve the situation by introspecting NewTy,
             // we have to give up.
             } else {
@@ -2464,7 +2468,10 @@ bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst,
                                        cast<GEPOperator>(GEP)->isInBounds());
     } else if (LoadInst *LI = dyn_cast<LoadInst>(CurInst)) {
       if (!LI->isSimple()) return false;  // no volatile/atomic accesses.
-      InstResult = ComputeLoadResult(getVal(LI->getOperand(0)));
+      Constant *Ptr = getVal(LI->getOperand(0));
+      if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
+        Ptr = ConstantFoldConstantExpression(CE, TD, TLI);
+      InstResult = ComputeLoadResult(Ptr);
       if (InstResult == 0) return false; // Could not evaluate load.
     } else if (AllocaInst *AI = dyn_cast<AllocaInst>(CurInst)) {
       if (AI->isArrayAllocation()) return false;  // Cannot handle array allocs.