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llvm-mirror/include/llvm/Analysis/InstructionSimplify.h
Owen Anderson 3d4644bad9 Revert r114097, adding back in the assertion against replacing an Instruction by itself. Now that CorrelatedValuePropagation is
more careful not to call SimplifyInstructionsInBlock() on an unreachable block, the issue has been fixed at a higher level.  Add
a big warning to SimplifyInstructionsInBlock() to hopefully prevent this in the future.

llvm-svn: 114117
2010-09-16 20:51:41 +00:00

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//===-- InstructionSimplify.h - Fold instructions into simpler forms ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares routines for folding instructions into simpler forms that
// do not require creating new instructions. For example, this does constant
// folding, and can handle identities like (X&0)->0.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
#define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
namespace llvm {
class Instruction;
class Value;
class TargetData;
/// SimplifyAddInst - Given operands for an Add, see if we can
/// fold the result. If not, this returns null.
Value *SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
const TargetData *TD = 0);
/// SimplifyAndInst - Given operands for an And, see if we can
/// fold the result. If not, this returns null.
Value *SimplifyAndInst(Value *LHS, Value *RHS,
const TargetData *TD = 0);
/// SimplifyOrInst - Given operands for an Or, see if we can
/// fold the result. If not, this returns null.
Value *SimplifyOrInst(Value *LHS, Value *RHS,
const TargetData *TD = 0);
/// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
/// fold the result. If not, this returns null.
Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const TargetData *TD = 0);
/// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
/// fold the result. If not, this returns null.
Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const TargetData *TD = 0);
/// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
/// the result. If not, this returns null.
Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
const TargetData *TD = 0);
/// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
/// fold the result. If not, this returns null.
Value *SimplifyGEPInst(Value * const *Ops, unsigned NumOps,
const TargetData *TD = 0);
//=== Helper functions for higher up the class hierarchy.
/// SimplifyCmpInst - Given operands for a CmpInst, see if we can
/// fold the result. If not, this returns null.
Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const TargetData *TD = 0);
/// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
/// fold the result. If not, this returns null.
Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const TargetData *TD = 0);
/// SimplifyInstruction - See if we can compute a simplified version of this
/// instruction. If not, this returns null.
/// WARNING: If called on unreachable code, an instruction may be reported
/// to simplify to itself.
Value *SimplifyInstruction(Instruction *I, const TargetData *TD = 0);
/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
/// delete the From instruction. In addition to a basic RAUW, this does a
/// recursive simplification of the updated instructions. This catches
/// things where one simplification exposes other opportunities. This only
/// simplifies and deletes scalar operations, it does not change the CFG.
///
void ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
const TargetData *TD = 0);
} // end namespace llvm
#endif