Rename ConstantHandling.* -> ConstantFolding.*

Move a bunch of (now) private stuff from ConstantFolding.h into
ConstantFolding.cpp.

This _finally_ gets us to a place where we have a sane constant folder.  The
rules are:

1. LLVM clients now use ConstantExpr::get* methods to fold constants.  If they
   cannot be folded, a constantexpr is created, so these methods always return
   valid Constant*'s.
2. The implementation of ConstantExpr::get* uses the functions exposed by
   ConstantFolding.h to try to fold constants.  If they cannot be folded,
   they should return a null pointer.
3. The implementation of ConstantFolding can do whatever it wants, and only
   has one client (Constants.cpp)

This cuts down on the wierd dependencies, and eliminates the two interfaces.
The old constanthandling interface was especially bad for clients to use
because almost none of them took the failure condition into consideration,
thus leading to obscure problems.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10807 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 49 insertions, 3 deletions

diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp
index ddec284..ee74280 100644
--- a/lib/VMCore/ConstantFold.cpp
+++ b/lib/VMCore/ConstantFold.cpp
@@ -1,4 +1,4 @@
-//===- ConstantHandling.cpp - Implement ConstantHandling.h ----------------===//
+//===- ConstantFolding.cpp - LLVM constant folder -------------------------===//
 // 
 //                     The LLVM Compiler Infrastructure
 //
@@ -7,11 +7,13 @@
 // 
 //===----------------------------------------------------------------------===//
 //
-// This file implements the various intrinsic operations, on constant values.
+// This file implements folding of constants for LLVM.  This implements the
+// (internal) ConstantFolding.h interface, which is used by the
+// ConstantExpr::get* methods to automatically fold constants when possible.
 //
 //===----------------------------------------------------------------------===//
 
-#include "ConstantHandling.h"
+#include "ConstantFolding.h"
 #include "llvm/Constants.h"
 #include "llvm/iPHINode.h"
 #include "llvm/InstrTypes.h"
@@ -25,6 +27,50 @@ static unsigned getSize(const Type *Ty) {
   return S ? S : 8;  // Treat pointers at 8 bytes
 }
 
+namespace {
+  struct ConstRules {
+    ConstRules() {}
+    
+    // Binary Operators...
+    virtual Constant *add(const Constant *V1, const Constant *V2) const = 0;
+    virtual Constant *sub(const Constant *V1, const Constant *V2) const = 0;
+    virtual Constant *mul(const Constant *V1, const Constant *V2) const = 0;
+    virtual Constant *div(const Constant *V1, const Constant *V2) const = 0;
+    virtual Constant *rem(const Constant *V1, const Constant *V2) const = 0;
+    virtual Constant *op_and(const Constant *V1, const Constant *V2) const = 0;
+    virtual Constant *op_or (const Constant *V1, const Constant *V2) const = 0;
+    virtual Constant *op_xor(const Constant *V1, const Constant *V2) const = 0;
+    virtual Constant *shl(const Constant *V1, const Constant *V2) const = 0;
+    virtual Constant *shr(const Constant *V1, const Constant *V2) const = 0;
+    virtual Constant *lessthan(const Constant *V1, const Constant *V2) const =0;
+    virtual Constant *equalto(const Constant *V1, const Constant *V2) const = 0;
+
+    // Casting operators.
+    virtual Constant *castToBool  (const Constant *V) const = 0;
+    virtual Constant *castToSByte (const Constant *V) const = 0;
+    virtual Constant *castToUByte (const Constant *V) const = 0;
+    virtual Constant *castToShort (const Constant *V) const = 0;
+    virtual Constant *castToUShort(const Constant *V) const = 0;
+    virtual Constant *castToInt   (const Constant *V) const = 0;
+    virtual Constant *castToUInt  (const Constant *V) const = 0;
+    virtual Constant *castToLong  (const Constant *V) const = 0;
+    virtual Constant *castToULong (const Constant *V) const = 0;
+    virtual Constant *castToFloat (const Constant *V) const = 0;
+    virtual Constant *castToDouble(const Constant *V) const = 0;
+    virtual Constant *castToPointer(const Constant *V,
+                                    const PointerType *Ty) const = 0;
+    
+    // ConstRules::get - Return an instance of ConstRules for the specified
+    // constant operands.
+    //
+    static ConstRules &get(const Constant *V1, const Constant *V2);
+  private:
+    ConstRules(const ConstRules &);             // Do not implement
+    ConstRules &operator=(const ConstRules &);  // Do not implement
+  };
+}
+
+
 Constant *llvm::ConstantFoldCastInstruction(const Constant *V,
                                             const Type *DestTy) {
   if (V->getType() == DestTy) return (Constant*)V;