X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FConstantFolding.cpp;h=f2e89a773e7dc945f180a9e4aa90ad22f5214ea4;hb=c0362d5c6e0066c741bce056a65d8b4c026de19f;hp=96656a3c73f7175bfe3d8e7d994ab4467b20878d;hpb=38cb1cdfb7308e82ed00985427f78d11d817d88a;p=oota-llvm.git

diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 96656a3c73f..f2e89a773e7 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -695,20 +695,26 @@ static Constant *SymbolicallyEvaluateGEP(Constant *const *Ops, unsigned NumOps,
 /// instructions like loads and stores, which have no constant expression form.
 ///
 Constant *llvm::ConstantFoldInstruction(Instruction *I, const TargetData *TD) {
+  // Handle PHI nodes specially here...
   if (PHINode *PN = dyn_cast<PHINode>(I)) {
-    if (PN->getNumIncomingValues() == 0)
-      return UndefValue::get(PN->getType());
-
-    Constant *Result = dyn_cast<Constant>(PN->getIncomingValue(0));
-    if (Result == 0) return 0;
-
-    // Handle PHI nodes specially here...
-    for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i)
-      if (PN->getIncomingValue(i) != Result && PN->getIncomingValue(i) != PN)
-        return 0;   // Not all the same incoming constants...
+    Constant *CommonValue = 0;
+
+    for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+      Value *Incoming = PN->getIncomingValue(i);
+      // If the incoming value is equal to the phi node itself or is undef then
+      // skip it.
+      if (Incoming == PN || isa<UndefValue>(Incoming))
+        continue;
+      // If the incoming value is not a constant, or is a different constant to
+      // the one we saw previously, then give up.
+      Constant *C = dyn_cast<Constant>(Incoming);
+      if (!C || (CommonValue && C != CommonValue))
+        return 0;
+      CommonValue = C;
+    }
 
-    // If we reach here, all incoming values are the same constant.
-    return Result;
+    // If we reach here, all incoming values are the same constant or undef.
+    return CommonValue ? CommonValue : UndefValue::get(PN->getType());
   }
 
   // Scan the operand list, checking to see if they are all constants, if so,
@@ -1001,6 +1007,7 @@ llvm::canConstantFoldCallTo(const Function *F) {
   case Intrinsic::usub_with_overflow:
   case Intrinsic::sadd_with_overflow:
   case Intrinsic::ssub_with_overflow:
+  case Intrinsic::smul_with_overflow:
   case Intrinsic::convert_from_fp16:
   case Intrinsic::convert_to_fp16:
     return true;
@@ -1094,6 +1101,13 @@ llvm::ConstantFoldCall(Function *F,
 
       if (!Ty->isFloatTy() && !Ty->isDoubleTy())
         return 0;
+
+      /// We only fold functions with finite arguments. Folding NaN and inf is
+      /// likely to be aborted with an exception anyway, and some host libms
+      /// have known errors raising exceptions.
+      if (Op->getValueAPF().isNaN() || Op->getValueAPF().isInfinity())
+        return 0;
+
       /// Currently APFloat versions of these functions do not exist, so we use
       /// the host native double versions.  Float versions are not called
       /// directly but for all these it is true (float)(f((double)arg)) ==
@@ -1241,42 +1255,37 @@ llvm::ConstantFoldCall(Function *F,
       if (ConstantInt *Op2 = dyn_cast<ConstantInt>(Operands[1])) {
         switch (F->getIntrinsicID()) {
         default: break;
-        case Intrinsic::uadd_with_overflow: {
-          Constant *Res = ConstantExpr::getAdd(Op1, Op2);           // result.
+        case Intrinsic::sadd_with_overflow:
+        case Intrinsic::uadd_with_overflow:
+        case Intrinsic::ssub_with_overflow:
+        case Intrinsic::usub_with_overflow:
+        case Intrinsic::smul_with_overflow: {
+          APInt Res;
+          bool Overflow;
+          switch (F->getIntrinsicID()) {
+          default: assert(0 && "Invalid case");
+          case Intrinsic::sadd_with_overflow:
+            Res = Op1->getValue().sadd_ov(Op2->getValue(), Overflow);
+            break;
+          case Intrinsic::uadd_with_overflow:
+            Res = Op1->getValue().uadd_ov(Op2->getValue(), Overflow);
+            break;
+          case Intrinsic::ssub_with_overflow:
+            Res = Op1->getValue().ssub_ov(Op2->getValue(), Overflow);
+            break;
+          case Intrinsic::usub_with_overflow:
+            Res = Op1->getValue().usub_ov(Op2->getValue(), Overflow);
+            break;
+          case Intrinsic::smul_with_overflow:
+            Res = Op1->getValue().smul_ov(Op2->getValue(), Overflow);
+            break;
+          }
           Constant *Ops[] = {
-            Res, ConstantExpr::getICmp(CmpInst::ICMP_ULT, Res, Op1) // overflow.
+            ConstantInt::get(F->getContext(), Res),
+            ConstantInt::get(Type::getInt1Ty(F->getContext()), Overflow)
           };
           return ConstantStruct::get(F->getContext(), Ops, 2, false);
         }
-        case Intrinsic::usub_with_overflow: {
-          Constant *Res = ConstantExpr::getSub(Op1, Op2);           // result.
-          Constant *Ops[] = {
-            Res, ConstantExpr::getICmp(CmpInst::ICMP_UGT, Res, Op1) // overflow.
-          };
-          return ConstantStruct::get(F->getContext(), Ops, 2, false);
-        }
-        case Intrinsic::sadd_with_overflow: {
-          Constant *Res = ConstantExpr::getAdd(Op1, Op2);           // result.
-          Constant *Overflow = ConstantExpr::getSelect(
-              ConstantExpr::getICmp(CmpInst::ICMP_SGT,
-                ConstantInt::get(Op1->getType(), 0), Op1),
-              ConstantExpr::getICmp(CmpInst::ICMP_SGT, Res, Op2), 
-              ConstantExpr::getICmp(CmpInst::ICMP_SLT, Res, Op2)); // overflow.
-
-          Constant *Ops[] = { Res, Overflow };
-          return ConstantStruct::get(F->getContext(), Ops, 2, false);
-        }
-        case Intrinsic::ssub_with_overflow: {
-          Constant *Res = ConstantExpr::getSub(Op1, Op2);           // result.
-          Constant *Overflow = ConstantExpr::getSelect(
-              ConstantExpr::getICmp(CmpInst::ICMP_SGT,
-                ConstantInt::get(Op2->getType(), 0), Op2),
-              ConstantExpr::getICmp(CmpInst::ICMP_SLT, Res, Op1), 
-              ConstantExpr::getICmp(CmpInst::ICMP_SGT, Res, Op1)); // overflow.
-
-          Constant *Ops[] = { Res, Overflow };
-          return ConstantStruct::get(F->getContext(), Ops, 2, false);
-        }
         }
       }