From 006c77df8cc7f6a9dac575600b797b8ba32b29eb Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Thu, 23 Jul 2009 23:25:33 +0000
Subject: Privatize the ConstantStruct table.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76912 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/VMCore/LLVMContextImpl.cpp | 104 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)

(limited to 'lib/VMCore/LLVMContextImpl.cpp')

diff --git a/lib/VMCore/LLVMContextImpl.cpp b/lib/VMCore/LLVMContextImpl.cpp
index 1c5af77..156d4ca 100644
--- a/lib/VMCore/LLVMContextImpl.cpp
+++ b/lib/VMCore/LLVMContextImpl.cpp
@@ -29,6 +29,14 @@ static std::vector<Constant*> getValType(ConstantArray *CA) {
   return Elements;
 }
 
+static std::vector<Constant*> getValType(ConstantStruct *CS) {
+  std::vector<Constant*> Elements;
+  Elements.reserve(CS->getNumOperands());
+  for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i)
+    Elements.push_back(cast<Constant>(CS->getOperand(i)));
+  return Elements;
+}
+
 namespace llvm {
 template<typename T, typename Alloc>
 struct VISIBILITY_HIDDEN ConstantTraits< std::vector<T, Alloc> > {
@@ -83,6 +91,21 @@ struct ConvertConstantType<ConstantArray, ArrayType> {
     OldC->destroyConstant();    // This constant is now dead, destroy it.
   }
 };
+
+template<>
+struct ConvertConstantType<ConstantStruct, StructType> {
+  static void convert(ConstantStruct *OldC, const StructType *NewTy) {
+    // Make everyone now use a constant of the new type...
+    std::vector<Constant*> C;
+    for (unsigned i = 0, e = OldC->getNumOperands(); i != e; ++i)
+      C.push_back(cast<Constant>(OldC->getOperand(i)));
+    Constant *New = NewTy->getContext().getConstantStruct(NewTy, C);
+    assert(New != OldC && "Didn't replace constant??");
+
+    OldC->uncheckedReplaceAllUsesWith(New);
+    OldC->destroyConstant();    // This constant is now dead, destroy it.
+  }
+};
 }
   
 template<class ValType, class TypeClass, class ConstantClass,
@@ -324,11 +347,13 @@ LLVMContextImpl::LLVMContextImpl(LLVMContext &C) :
     Context(C), TheTrueVal(0), TheFalseVal(0) {
   AggZeroConstants = new ValueMap<char, Type, ConstantAggregateZero>();
   ArrayConstants = new ArrayConstantsTy();
+  StructConstants = new StructConstantsTy();
 }
 
 LLVMContextImpl::~LLVMContextImpl() {
   delete AggZeroConstants;
   delete ArrayConstants;
+  delete StructConstants;
 }
 
 // Get a ConstantInt from an APInt. Note that the value stored in the DenseMap 
@@ -456,6 +481,17 @@ Constant *LLVMContextImpl::getConstantArray(const ArrayType *Ty,
   return Context.getConstantAggregateZero(Ty);
 }
 
+Constant *LLVMContextImpl::getConstantStruct(const StructType *Ty,
+                              const std::vector<Constant*> &V) {
+  // Create a ConstantAggregateZero value if all elements are zeros...
+  for (unsigned i = 0, e = V.size(); i != e; ++i)
+    if (!V[i]->isNullValue())
+      // Implicitly locked.
+      return StructConstants->getOrCreate(Ty, V);
+
+  return Context.getConstantAggregateZero(Ty);
+}
+
 // *** erase methods ***
 
 void LLVMContextImpl::erase(MDString *M) {
@@ -477,7 +513,12 @@ void LLVMContextImpl::erase(ConstantArray *C) {
   ArrayConstants->remove(C);
 }
 
+void LLVMContextImpl::erase(ConstantStruct *S) {
+  StructConstants->remove(S);
+}
+
 // *** RAUW helpers ***
+
 Constant *LLVMContextImpl::replaceUsesOfWithOnConstant(ConstantArray *CA,
                                                Value *From, Value *To, Use *U) {
   assert(isa<Constant>(To) && "Cannot make Constant refer to non-constant!");
@@ -556,3 +597,66 @@ Constant *LLVMContextImpl::replaceUsesOfWithOnConstant(ConstantArray *CA,
   return Replacement;
 }
 
+Constant *LLVMContextImpl::replaceUsesOfWithOnConstant(ConstantStruct *CS,
+                                               Value *From, Value *To, Use *U) {
+  assert(isa<Constant>(To) && "Cannot make Constant refer to non-constant!");
+  Constant *ToC = cast<Constant>(To);
+
+  unsigned OperandToUpdate = U - CS->OperandList;
+  assert(CS->getOperand(OperandToUpdate) == From &&
+         "ReplaceAllUsesWith broken!");
+
+  std::pair<StructConstantsTy::MapKey, Constant*> Lookup;
+  Lookup.first.first = CS->getType();
+  Lookup.second = CS;
+  std::vector<Constant*> &Values = Lookup.first.second;
+  Values.reserve(CS->getNumOperands());  // Build replacement struct.
+  
+  
+  // Fill values with the modified operands of the constant struct.  Also, 
+  // compute whether this turns into an all-zeros struct.
+  bool isAllZeros = false;
+  if (!ToC->isNullValue()) {
+    for (Use *O = CS->OperandList, *E = CS->OperandList + CS->getNumOperands(); 
+         O != E; ++O)
+      Values.push_back(cast<Constant>(O->get()));
+  } else {
+    isAllZeros = true;
+    for (Use *O = CS->OperandList, *E = CS->OperandList + CS->getNumOperands(); 
+         O != E; ++O) {
+      Constant *Val = cast<Constant>(O->get());
+      Values.push_back(Val);
+      if (isAllZeros) isAllZeros = Val->isNullValue();
+    }
+  }
+  Values[OperandToUpdate] = ToC;
+  
+  Constant *Replacement = 0;
+  if (isAllZeros) {
+    Replacement = Context.getConstantAggregateZero(CS->getType());
+  } else {
+    // Check to see if we have this array type already.
+    sys::SmartScopedWriter<true> Writer(ConstantsLock);
+    bool Exists;
+    StructConstantsTy::MapTy::iterator I =
+      StructConstants->InsertOrGetItem(Lookup, Exists);
+    
+    if (Exists) {
+      Replacement = I->second;
+    } else {
+      // Okay, the new shape doesn't exist in the system yet.  Instead of
+      // creating a new constant struct, inserting it, replaceallusesof'ing the
+      // old with the new, then deleting the old... just update the current one
+      // in place!
+      StructConstants->MoveConstantToNewSlot(CS, I);
+      
+      // Update to the new value.
+      CS->setOperand(OperandToUpdate, ToC);
+      return 0;
+    }
+  }
+  
+  assert(Replacement != CS && "I didn't contain From!");
+  
+  return Replacement;
+}
\ No newline at end of file
-- 
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