Minor cleanup related to my latest scheduler changes.

[oota-llvm.git] / lib / Transforms / InstCombine / InstCombineCasts.cpp

diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 0434d6ba0fdc6926b8c6550e3c9ad3285c423c5e..88ee1453faf0c81eb6e4a725a047107d9635782f 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1019,8 +1019,25 @@ Instruction *InstCombiner::visitSExt(SExtInst &CI) {
     }
   }
   }
-  
-  
+
+  // vector (x <s 0) ? -1 : 0 -> ashr x, 31   -> all ones if signed.
+  if (const VectorType *VTy = dyn_cast<VectorType>(DestTy)) {
+    ICmpInst::Predicate Pred; Value *CmpLHS;
+    if (match(Src, m_ICmp(Pred, m_Value(CmpLHS), m_Zero()))) {
+      if (Pred == ICmpInst::ICMP_SLT && CmpLHS->getType() == DestTy) {
+        const Type *EltTy = VTy->getElementType();
+
+        // splat the shift constant to a cosntant vector
+        Constant *Sh = ConstantInt::get(EltTy, EltTy->getScalarSizeInBits()-1);
+        std::vector<Constant *> Elts(VTy->getNumElements(), Sh);
+        Constant *VSh = ConstantVector::get(Elts);
+
+        Value *In = Builder->CreateAShr(CmpLHS, VSh,CmpLHS->getName()+".lobit");
+        return ReplaceInstUsesWith(CI, In);
+      }
+    }
+  }
+
   // If the input is a shl/ashr pair of a same constant, then this is a sign
   // extension from a smaller value.  If we could trust arbitrary bitwidth
   // integers, we could turn this into a truncate to the smaller bit and then
@@ -1139,7 +1156,7 @@ Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
         Arg->getOperand(0)->getType()->isFloatTy()) {
       Function *Callee = Call->getCalledFunction();
       Module *M = CI.getParent()->getParent()->getParent();
-      Constant* SqrtfFunc = M->getOrInsertFunction("sqrtf", 
+      Constant *SqrtfFunc = M->getOrInsertFunction("sqrtf", 
                                                    Callee->getAttributes(),
                                                    Builder->getFloatTy(),
                                                    Builder->getFloatTy(),
@@ -1147,6 +1164,11 @@ Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
       CallInst *ret = CallInst::Create(SqrtfFunc, Arg->getOperand(0),
                                        "sqrtfcall");
       ret->setAttributes(Callee->getAttributes());
+      
+      
+      // Remove the old Call.  With -fmath-errno, it won't get marked readnone.
+      Call->replaceAllUsesWith(UndefValue::get(Call->getType()));
+      EraseInstFromFunction(*Call);
       return ret;
     }
   }
@@ -1381,6 +1403,9 @@ static unsigned getTypeSizeIndex(unsigned Value, const Type *Ty) {
 static bool CollectInsertionElements(Value *V, unsigned ElementIndex,
                                      SmallVectorImpl<Value*> &Elements,
                                      const Type *VecEltTy) {
+  // Undef values never contribute useful bits to the result.
+  if (isa<UndefValue>(V)) return true;
+  
   // If we got down to a value of the right type, we win, try inserting into the
   // right element.
   if (V->getType() == VecEltTy) {