llvm-6502/include/llvm/Transforms/Utils/Local.h
Chris Lattner 6cc8a93c48 Generalize instcombine's isSafeToLoadUnconditionally() function
to ignore readonly calls, and factor it out of instcombine so
that it can be used by other passes.  Patch by Frits van Bommel!



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73506 91177308-0d34-0410-b5e6-96231b3b80d8
2009-06-16 17:23:12 +00:00

127 lines
4.9 KiB
C++

//===-- Local.h - Functions to perform local transformations ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This family of functions perform various local transformations to the
// program.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TRANSFORMS_UTILS_LOCAL_H
#define LLVM_TRANSFORMS_UTILS_LOCAL_H
namespace llvm {
class User;
class BasicBlock;
class Instruction;
class Value;
class Pass;
class PHINode;
class AllocaInst;
class ConstantExpr;
class TargetData;
struct DbgInfoIntrinsic;
template<typename T> class SmallVectorImpl;
//===----------------------------------------------------------------------===//
// Local analysis.
//
/// isSafeToLoadUnconditionally - Return true if we know that executing a load
/// from this value cannot trap. If it is not obviously safe to load from the
/// specified pointer, we do a quick local scan of the basic block containing
/// ScanFrom, to determine if the address is already accessed.
bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom);
//===----------------------------------------------------------------------===//
// Local constant propagation.
//
/// ConstantFoldTerminator - If a terminator instruction is predicated on a
/// constant value, convert it into an unconditional branch to the constant
/// destination. This is a nontrivial operation because the successors of this
/// basic block must have their PHI nodes updated.
///
bool ConstantFoldTerminator(BasicBlock *BB);
//===----------------------------------------------------------------------===//
// Local dead code elimination.
//
/// isInstructionTriviallyDead - Return true if the result produced by the
/// instruction is not used, and the instruction has no side effects.
///
bool isInstructionTriviallyDead(Instruction *I);
/// RecursivelyDeleteTriviallyDeadInstructions - If the specified value is a
/// trivially dead instruction, delete it. If that makes any of its operands
/// trivially dead, delete them too, recursively.
void RecursivelyDeleteTriviallyDeadInstructions(Value *V);
/// RecursivelyDeleteDeadPHINode - If the specified value is an effectively
/// dead PHI node, due to being a def-use chain of single-use nodes that
/// either forms a cycle or is terminated by a trivially dead instruction,
/// delete it. If that makes any of its operands trivially dead, delete them
/// too, recursively.
void RecursivelyDeleteDeadPHINode(PHINode *PN);
//===----------------------------------------------------------------------===//
// Control Flow Graph Restructuring.
//
/// MergeBasicBlockIntoOnlyPred - BB is a block with one predecessor and its
/// predecessor is known to have one successor (BB!). Eliminate the edge
/// between them, moving the instructions in the predecessor into BB. This
/// deletes the predecessor block.
///
void MergeBasicBlockIntoOnlyPred(BasicBlock *BB);
/// SimplifyCFG - This function is used to do simplification of a CFG. For
/// example, it adjusts branches to branches to eliminate the extra hop, it
/// eliminates unreachable basic blocks, and does other "peephole" optimization
/// of the CFG. It returns true if a modification was made, possibly deleting
/// the basic block that was pointed to.
///
/// WARNING: The entry node of a method may not be simplified.
///
bool SimplifyCFG(BasicBlock *BB);
/// DemoteRegToStack - This function takes a virtual register computed by an
/// Instruction and replaces it with a slot in the stack frame, allocated via
/// alloca. This allows the CFG to be changed around without fear of
/// invalidating the SSA information for the value. It returns the pointer to
/// the alloca inserted to create a stack slot for X.
///
AllocaInst *DemoteRegToStack(Instruction &X, bool VolatileLoads = false,
Instruction *AllocaPoint = 0);
/// DemotePHIToStack - This function takes a virtual register computed by a phi
/// node and replaces it with a slot in the stack frame, allocated via alloca.
/// The phi node is deleted and it returns the pointer to the alloca inserted.
AllocaInst *DemotePHIToStack(PHINode *P, Instruction *AllocaPoint = 0);
/// OnlyUsedByDbgIntrinsics - Return true if the instruction I is only used
/// by DbgIntrinsics. If DbgInUses is specified then the vector is filled
/// with DbgInfoIntrinsic that use the instruction I.
bool OnlyUsedByDbgInfoIntrinsics(Instruction *I,
SmallVectorImpl<DbgInfoIntrinsic *> *DbgInUses = 0);
/// UserIsDebugInfo - Return true if U is a constant expr used by
/// llvm.dbg.variable or llvm.dbg.global_variable
bool UserIsDebugInfo(User *U);
/// RemoveDbgInfoUser - Remove an User which is representing debug info.
void RemoveDbgInfoUser(User *U);
} // End llvm namespace
#endif