Change ConstantArray::get to form a ConstantDataArray when possible,

kicking in the big win of ConstantDataArray.  As part of this, change
the implementation of GetConstantStringInfo in ValueTracking to work
with ConstantDataArray (and not ConstantArray) making it dramatically,
amazingly, more efficient in the process and renaming it to 
getConstantStringInfo.

This keeps around a GetConstantStringInfo entrypoint that (grossly)
forwards to getConstantStringInfo and constructs the std::string 
required, but existing clients should move over to 
getConstantStringInfo instead.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149351 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 93 insertions, 38 deletions

diff --git a/lib/VMCore/Constants.cpp b/lib/VMCore/Constants.cpp
index f7884c6..624dc2e 100644
--- a/lib/VMCore/Constants.cpp
+++ b/lib/VMCore/Constants.cpp
@@ -666,6 +666,13 @@ UndefValue *UndefValue::getElementValue(unsigned Idx) const {
 //                            ConstantXXX Classes
 //===----------------------------------------------------------------------===//
 
+template <typename ItTy, typename EltTy>
+static bool rangeOnlyContains(ItTy Start, ItTy End, EltTy Elt) {
+  for (; Start != End; ++Start)
+    if (*Start != Elt)
+      return false;
+  return true;
+}
 
 ConstantArray::ConstantArray(ArrayType *T, ArrayRef<Constant *> V)
   : Constant(T, ConstantArrayVal,
@@ -680,54 +687,103 @@ ConstantArray::ConstantArray(ArrayType *T, ArrayRef<Constant *> V)
 }
 
 Constant *ConstantArray::get(ArrayType *Ty, ArrayRef<Constant*> V) {
+  // Empty arrays are canonicalized to ConstantAggregateZero.
+  if (V.empty())
+    return ConstantAggregateZero::get(Ty);
+
   for (unsigned i = 0, e = V.size(); i != e; ++i) {
     assert(V[i]->getType() == Ty->getElementType() &&
            "Wrong type in array element initializer");
   }
   LLVMContextImpl *pImpl = Ty->getContext().pImpl;
-  // If this is an all-zero array, return a ConstantAggregateZero object
-  bool isAllZero = true;
-  bool isUndef = false;
-  if (!V.empty()) {
-    Constant *C = V[0];
-    isAllZero = C->isNullValue();
-    isUndef = isa<UndefValue>(C);
-
-    if (isAllZero || isUndef)
-      for (unsigned i = 1, e = V.size(); i != e; ++i)
-        if (V[i] != C) {
-          isAllZero = false;
-          isUndef = false;
-          break;
-        }
-  }
+  
+  // If this is an all-zero array, return a ConstantAggregateZero object.  If
+  // all undef, return an UndefValue, if "all simple", then return a
+  // ConstantDataArray.
+  Constant *C = V[0];
+  if (isa<UndefValue>(C) && rangeOnlyContains(V.begin(), V.end(), C))
+    return UndefValue::get(Ty);
 
-  if (isAllZero)
+  if (C->isNullValue() && rangeOnlyContains(V.begin(), V.end(), C))
     return ConstantAggregateZero::get(Ty);
-  if (isUndef)
-    return UndefValue::get(Ty);
+
+  // Check to see if all of the elements are ConstantFP or ConstantInt and if
+  // the element type is compatible with ConstantDataVector.  If so, use it.
+  if (ConstantDataSequential::isElementTypeCompatible(C->getType())) {
+    // We speculatively build the elements here even if it turns out that there
+    // is a constantexpr or something else weird in the array, since it is so
+    // uncommon for that to happen.
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
+      if (CI->getType()->isIntegerTy(8)) {
+        SmallVector<uint8_t, 16> Elts;
+        for (unsigned i = 0, e = V.size(); i != e; ++i)
+          if (ConstantInt *CI = dyn_cast<ConstantInt>(V[i]))
+            Elts.push_back(CI->getZExtValue());
+          else
+            break;
+        if (Elts.size() == V.size())
+          return ConstantDataArray::get(C->getContext(), Elts);
+      } else if (CI->getType()->isIntegerTy(16)) {
+        SmallVector<uint16_t, 16> Elts;
+        for (unsigned i = 0, e = V.size(); i != e; ++i)
+          if (ConstantInt *CI = dyn_cast<ConstantInt>(V[i]))
+            Elts.push_back(CI->getZExtValue());
+          else
+            break;
+        if (Elts.size() == V.size())
+          return ConstantDataArray::get(C->getContext(), Elts);
+      } else if (CI->getType()->isIntegerTy(32)) {
+        SmallVector<uint32_t, 16> Elts;
+        for (unsigned i = 0, e = V.size(); i != e; ++i)
+          if (ConstantInt *CI = dyn_cast<ConstantInt>(V[i]))
+            Elts.push_back(CI->getZExtValue());
+          else
+            break;
+        if (Elts.size() == V.size())
+          return ConstantDataArray::get(C->getContext(), Elts);
+      } else if (CI->getType()->isIntegerTy(64)) {
+        SmallVector<uint64_t, 16> Elts;
+        for (unsigned i = 0, e = V.size(); i != e; ++i)
+          if (ConstantInt *CI = dyn_cast<ConstantInt>(V[i]))
+            Elts.push_back(CI->getZExtValue());
+          else
+            break;
+        if (Elts.size() == V.size())
+          return ConstantDataArray::get(C->getContext(), Elts);
+      }
+    }
+    
+    if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
+      if (CFP->getType()->isFloatTy()) {
+        SmallVector<float, 16> Elts;
+        for (unsigned i = 0, e = V.size(); i != e; ++i)
+          if (ConstantFP *CFP = dyn_cast<ConstantFP>(V[i]))
+            Elts.push_back(CFP->getValueAPF().convertToFloat());
+          else
+            break;
+        if (Elts.size() == V.size())
+          return ConstantDataArray::get(C->getContext(), Elts);
+      } else if (CFP->getType()->isDoubleTy()) {
+        SmallVector<double, 16> Elts;
+        for (unsigned i = 0, e = V.size(); i != e; ++i)
+          if (ConstantFP *CFP = dyn_cast<ConstantFP>(V[i]))
+            Elts.push_back(CFP->getValueAPF().convertToDouble());
+          else
+            break;
+        if (Elts.size() == V.size())
+          return ConstantDataArray::get(C->getContext(), Elts);
+      }
+    }
+  }
+
+  // Otherwise, we really do want to create a ConstantArray.
   return pImpl->ArrayConstants.getOrCreate(Ty, V);
 }
 
-/// ConstantArray::get(const string&) - Return an array that is initialized to
-/// contain the specified string.  If length is zero then a null terminator is 
-/// added to the specified string so that it may be used in a natural way. 
-/// Otherwise, the length parameter specifies how much of the string to use 
-/// and it won't be null terminated.
-///
+// FIXME: Remove this method.
 Constant *ConstantArray::get(LLVMContext &Context, StringRef Str,
                              bool AddNull) {
-  SmallVector<Constant*, 8> ElementVals;
-  ElementVals.reserve(Str.size() + size_t(AddNull));
-  for (unsigned i = 0; i < Str.size(); ++i)
-    ElementVals.push_back(ConstantInt::get(Type::getInt8Ty(Context), Str[i]));
-
-  // Add a null terminator to the string...
-  if (AddNull)
-    ElementVals.push_back(ConstantInt::get(Type::getInt8Ty(Context), 0));
-
-  ArrayType *ATy = ArrayType::get(Type::getInt8Ty(Context), ElementVals.size());
-  return get(ATy, ElementVals);
+  return ConstantDataArray::getString(Context, Str, AddNull);
 }
 
 /// getTypeForElements - Return an anonymous struct type to use for a constant
@@ -839,8 +895,7 @@ Constant *ConstantVector::get(ArrayRef<Constant*> V) {
    
   // Check to see if all of the elements are ConstantFP or ConstantInt and if
   // the element type is compatible with ConstantDataVector.  If so, use it.
-  if (ConstantDataSequential::isElementTypeCompatible(C->getType()) &&
-      (isa<ConstantFP>(C) || isa<ConstantInt>(C))) {
+  if (ConstantDataSequential::isElementTypeCompatible(C->getType())) {
     // We speculatively build the elements here even if it turns out that there
     // is a constantexpr or something else weird in the array, since it is so
     // uncommon for that to happen.