1 files changed, 30 insertions, 29 deletions

diff --git a/lib/IR/ConstantFold.cpp b/lib/IR/ConstantFold.cpp
index a915d28..d97d2c4 100644
--- a/lib/IR/ConstantFold.cpp
+++ b/lib/IR/ConstantFold.cpp
@@ -1120,27 +1120,18 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
         return ConstantInt::get(CI1->getContext(), C1V | C2V);
       case Instruction::Xor:
         return ConstantInt::get(CI1->getContext(), C1V ^ C2V);
-      case Instruction::Shl: {
-        uint32_t shiftAmt = C2V.getZExtValue();
-        if (shiftAmt < C1V.getBitWidth())
-          return ConstantInt::get(CI1->getContext(), C1V.shl(shiftAmt));
-        else
-          return UndefValue::get(C1->getType()); // too big shift is undef
-      }
-      case Instruction::LShr: {
-        uint32_t shiftAmt = C2V.getZExtValue();
-        if (shiftAmt < C1V.getBitWidth())
-          return ConstantInt::get(CI1->getContext(), C1V.lshr(shiftAmt));
-        else
-          return UndefValue::get(C1->getType()); // too big shift is undef
-      }
-      case Instruction::AShr: {
-        uint32_t shiftAmt = C2V.getZExtValue();
-        if (shiftAmt < C1V.getBitWidth())
-          return ConstantInt::get(CI1->getContext(), C1V.ashr(shiftAmt));
-        else
-          return UndefValue::get(C1->getType()); // too big shift is undef
-      }
+      case Instruction::Shl:
+        if (C2V.ult(C1V.getBitWidth()))
+          return ConstantInt::get(CI1->getContext(), C1V.shl(C2V));
+        return UndefValue::get(C1->getType()); // too big shift is undef
+      case Instruction::LShr:
+        if (C2V.ult(C1V.getBitWidth()))
+          return ConstantInt::get(CI1->getContext(), C1V.lshr(C2V));
+        return UndefValue::get(C1->getType()); // too big shift is undef
+      case Instruction::AShr:
+        if (C2V.ult(C1V.getBitWidth()))
+          return ConstantInt::get(CI1->getContext(), C1V.ashr(C2V));
+        return UndefValue::get(C1->getType()); // too big shift is undef
       }
     }
 
@@ -1327,7 +1318,7 @@ static FCmpInst::Predicate evaluateFCmpRelation(Constant *V1, Constant *V2) {
 
   if (!isa<ConstantExpr>(V1)) {
     if (!isa<ConstantExpr>(V2)) {
-      // We distilled thisUse the standard constant folder for a few cases
+      // Simple case, use the standard constant folder.
       ConstantInt *R = nullptr;
       R = dyn_cast<ConstantInt>(
                       ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, V1, V2));
@@ -1665,15 +1656,22 @@ Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
 
   // Handle some degenerate cases first
   if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
+    CmpInst::Predicate Predicate = CmpInst::Predicate(pred);
+    bool isIntegerPredicate = ICmpInst::isIntPredicate(Predicate);
     // For EQ and NE, we can always pick a value for the undef to make the
     // predicate pass or fail, so we can return undef.
-    // Also, if both operands are undef, we can return undef.
-    if (ICmpInst::isEquality(ICmpInst::Predicate(pred)) ||
-        (isa<UndefValue>(C1) && isa<UndefValue>(C2)))
+    // Also, if both operands are undef, we can return undef for int comparison.
+    if (ICmpInst::isEquality(Predicate) || (isIntegerPredicate && C1 == C2))
       return UndefValue::get(ResultTy);
-    // Otherwise, pick the same value as the non-undef operand, and fold
-    // it to true or false.
-    return ConstantInt::get(ResultTy, CmpInst::isTrueWhenEqual(pred));
+
+    // Otherwise, for integer compare, pick the same value as the non-undef
+    // operand, and fold it to true or false.
+    if (isIntegerPredicate)
+      return ConstantInt::get(ResultTy, CmpInst::isTrueWhenEqual(pred));
+
+    // Choosing NaN for the undef will always make unordered comparison succeed
+    // and ordered comparison fails.
+    return ConstantInt::get(ResultTy, CmpInst::isUnordered(Predicate));
   }
 
   // icmp eq/ne(null,GV) -> false/true
@@ -1789,7 +1787,10 @@ Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
     return ConstantVector::get(ResElts);
   }
 
-  if (C1->getType()->isFloatingPointTy()) {
+  if (C1->getType()->isFloatingPointTy() &&
+      // Only call evaluateFCmpRelation if we have a constant expr to avoid
+      // infinite recursive loop
+      (isa<ConstantExpr>(C1) || isa<ConstantExpr>(C2))) {
     int Result = -1;  // -1 = unknown, 0 = known false, 1 = known true.
     switch (evaluateFCmpRelation(C1, C2)) {
     default: llvm_unreachable("Unknown relation!");