Refactor code to share stuff

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1127 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 89 insertions, 0 deletions

diff --git a/lib/Transforms/TransformInternals.cpp b/lib/Transforms/TransformInternals.cpp
new file mode 100644
index 0000000..e7eef2d
--- /dev/null
+++ b/lib/Transforms/TransformInternals.cpp
@@ -0,0 +1,89 @@
+//===-- TransformInternals.cpp - Implement shared functions for transforms --=//
+//
+//  This file defines shared functions used by the different components of the
+//  Transforms library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "TransformInternals.h"
+#include "llvm/Method.h"
+#include "llvm/Type.h"
+
+// TargetData Hack: Eventually we will have annotations given to us by the
+// backend so that we know stuff about type size and alignments.  For now
+// though, just use this, because it happens to match the model that GCC uses.
+//
+const TargetData TD("LevelRaise: Should be GCC though!");
+
+// losslessCastableTypes - Return true if the types are bitwise equivalent.
+// This predicate returns true if it is possible to cast from one type to
+// another without gaining or losing precision, or altering the bits in any way.
+//
+bool losslessCastableTypes(const Type *T1, const Type *T2) {
+  if (!T1->isPrimitiveType() && !T1->isPointerType()) return false;
+  if (!T2->isPrimitiveType() && !T2->isPointerType()) return false;
+
+  if (T1->getPrimitiveID() == T2->getPrimitiveID())
+    return true;  // Handles identity cast, and cast of differing pointer types
+
+  // Now we know that they are two differing primitive or pointer types
+  switch (T1->getPrimitiveID()) {
+  case Type::UByteTyID:   return T2 == Type::SByteTy;
+  case Type::SByteTyID:   return T2 == Type::UByteTy;
+  case Type::UShortTyID:  return T2 == Type::ShortTy;
+  case Type::ShortTyID:   return T2 == Type::UShortTy;
+  case Type::UIntTyID:    return T2 == Type::IntTy;
+  case Type::IntTyID:     return T2 == Type::UIntTy;
+  case Type::ULongTyID:
+  case Type::LongTyID:
+  case Type::PointerTyID:
+    return T2 == Type::ULongTy || T2 == Type::LongTy ||
+           T2->getPrimitiveID() == Type::PointerTyID;
+  default:
+    return false;  // Other types have no identity values
+  }
+}
+
+
+// ReplaceInstWithValue - Replace all uses of an instruction (specified by BI)
+// with a value, then remove and delete the original instruction.
+//
+void ReplaceInstWithValue(BasicBlock::InstListType &BIL,
+                          BasicBlock::iterator &BI, Value *V) {
+  Instruction *I = *BI;
+  // Replaces all of the uses of the instruction with uses of the value
+  I->replaceAllUsesWith(V);
+
+  // Remove the unneccesary instruction now...
+  BIL.remove(BI);
+
+  // Make sure to propogate a name if there is one already...
+  if (I->hasName() && !V->hasName())
+    V->setName(I->getName(), BIL.getParent()->getSymbolTable());
+
+  // Remove the dead instruction now...
+  delete I;
+}
+
+
+// ReplaceInstWithInst - Replace the instruction specified by BI with the
+// instruction specified by I.  The original instruction is deleted and BI is
+// updated to point to the new instruction.
+//
+void ReplaceInstWithInst(BasicBlock::InstListType &BIL,
+                         BasicBlock::iterator &BI, Instruction *I) {
+  assert(I->getParent() == 0 &&
+         "ReplaceInstWithInst: Instruction already inserted into basic block!");
+
+  // Insert the new instruction into the basic block...
+  BI = BIL.insert(BI, I)+1;
+
+  // Replace all uses of the old instruction, and delete it.
+  ReplaceInstWithValue(BIL, BI, I);
+
+  // Reexamine the instruction just inserted next time around the cleanup pass
+  // loop.
+  --BI;
+}
+
+