Use instruction itinerary to determine what instructions are 'cheap'.

[oota-llvm.git] / include / llvm / Analysis / ConstantFolding.h

diff --git a/include/llvm/Analysis/ConstantFolding.h b/include/llvm/Analysis/ConstantFolding.h
index ef1c052d9eee62124948264c2e09ec1cf7520cc0..e2675eb2d4f0eeef163fbfa8197eff76be447b70 100644 (file)
--- a/include/llvm/Analysis/ConstantFolding.h
+++ b/include/llvm/Analysis/ConstantFolding.h
@@ -1,30 +1,81 @@
-//===-- ConstantFolding.h - Analyze constant folding possibilities --------===//
+//===-- ConstantFolding.h - Fold instructions into constants --------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
-// This family of functions determines the possibility of performing constant
-// folding.
+// This file declares routines for folding instructions into constants.
+//
+// Also, to supplement the basic VMCore ConstantExpr simplifications,
+// this file declares some additional folding routines that can make use of
+// TargetData information. These functions cannot go in VMCore due to library
+// dependency issues.
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Constants.h"
-#include "llvm/Function.h"
-using namespace llvm;
+#ifndef LLVM_ANALYSIS_CONSTANTFOLDING_H
+#define LLVM_ANALYSIS_CONSTANTFOLDING_H
 
 namespace llvm {
+  class Constant;
+  class ConstantExpr;
+  class Instruction;
+  class TargetData;
+  class Function;
+  class Type;
+
+/// ConstantFoldInstruction - Attempt to constant fold the specified
+/// instruction.  If successful, the constant result is returned, if not, null
+/// is returned.  Note that this function can only fail when attempting to fold
+/// instructions like loads and stores, which have no constant expression form.
+///
+Constant *ConstantFoldInstruction(Instruction *I, const TargetData *TD = 0);
+
+/// ConstantFoldConstantExpression - Attempt to fold the constant expression
+/// using the specified TargetData.  If successful, the constant result is
+/// result is returned, if not, null is returned.
+Constant *ConstantFoldConstantExpression(const ConstantExpr *CE,
+                                         const TargetData *TD = 0);
+
+/// ConstantFoldInstOperands - Attempt to constant fold an instruction with the
+/// specified operands.  If successful, the constant result is returned, if not,
+/// null is returned.  Note that this function can fail when attempting to 
+/// fold instructions like loads and stores, which have no constant expression 
+/// form.
+///
+Constant *ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
+                                   Constant *const *Ops, unsigned NumOps,
+                                   const TargetData *TD = 0);
+
+/// ConstantFoldCompareInstOperands - Attempt to constant fold a compare
+/// instruction (icmp/fcmp) with the specified operands.  If it fails, it
+/// returns a constant expression of the specified operands.
+///
+Constant *ConstantFoldCompareInstOperands(unsigned Predicate,
+                                          Constant *LHS, Constant *RHS,
+                                          const TargetData *TD = 0);
+
+/// ConstantFoldLoadFromConstPtr - Return the value that a load from C would
+/// produce if it is constant and determinable.  If this is not determinable,
+/// return null.
+Constant *ConstantFoldLoadFromConstPtr(Constant *C, const TargetData *TD = 0);
 
+/// ConstantFoldLoadThroughGEPConstantExpr - Given a constant and a
+/// getelementptr constantexpr, return the constant value being addressed by the
+/// constant expression, or null if something is funny and we can't decide.
+Constant *ConstantFoldLoadThroughGEPConstantExpr(Constant *C, ConstantExpr *CE);
+  
 /// canConstantFoldCallTo - Return true if its even possible to fold a call to
 /// the specified function.
-bool canConstantFoldCallTo(Function *F);
+bool canConstantFoldCallTo(const Function *F);
 
 /// ConstantFoldCall - Attempt to constant fold a call to the specified function
 /// with the specified arguments, returning null if unsuccessful.
 Constant *
-ConstantFoldCall(Function *F, Constant** Operands, unsigned NumOperands);
+ConstantFoldCall(Function *F, Constant *const *Operands, unsigned NumOperands);
 }
 
+#endif