//===-- Local.h - Functions to perform local transformations ----*- C++ -*-===//
-//
+//
// 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 perform various local transformations to the
#ifndef LLVM_TRANSFORMS_UTILS_LOCAL_H
#define LLVM_TRANSFORMS_UTILS_LOCAL_H
-#include "llvm/Function.h"
-
namespace llvm {
+class User;
+class BasicBlock;
+class BranchInst;
+class Instruction;
+class Value;
class Pass;
class PHINode;
class AllocaInst;
+class ConstantExpr;
+class TargetData;
+struct DbgInfoIntrinsic;
+template<typename T> class SmallVectorImpl;
+
//===----------------------------------------------------------------------===//
-// Local constant propagation...
+// Local analysis.
//
-/// doConstantPropagation - Constant prop a specific instruction. Returns true
-/// and potentially moves the iterator if constant propagation was performed.
-///
-bool doConstantPropagation(BasicBlock::iterator &I);
+/// 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
///
bool ConstantFoldTerminator(BasicBlock *BB);
-/// 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);
-
-
//===----------------------------------------------------------------------===//
-// Local dead code elimination...
+// Local dead code elimination.
//
/// isInstructionTriviallyDead - Return true if the result produced by the
///
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);
-/// dceInstruction - Inspect the instruction at *BBI and figure out if it
-/// isTriviallyDead. If so, remove the instruction and update the iterator to
-/// point to the instruction that immediately succeeded the original
-/// instruction.
-///
-bool dceInstruction(BasicBlock::iterator &BBI);
+/// 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);
//===----------------------------------------------------------------------===//
-// PHI Instruction Simplification
+// Control Flow Graph Restructuring.
//
-/// hasConstantValue - If the specified PHI node always merges together the same
-/// value, return the value, otherwise return null.
+/// RemovePredecessorAndSimplify - Like BasicBlock::removePredecessor, this
+/// method is called when we're about to delete Pred as a predecessor of BB. If
+/// BB contains any PHI nodes, this drops the entries in the PHI nodes for Pred.
///
-Value *hasConstantValue(PHINode *PN);
-
-
-//===----------------------------------------------------------------------===//
-// Control Flow Graph Restructuring...
-//
+/// Unlike the removePredecessor method, this attempts to simplify uses of PHI
+/// nodes that collapse into identity values. For example, if we have:
+/// x = phi(1, 0, 0, 0)
+/// y = and x, z
+///
+/// .. and delete the predecessor corresponding to the '1', this will attempt to
+/// recursively fold the 'and' to 0.
+void RemovePredecessorAndSimplify(BasicBlock *BB, BasicBlock *Pred,
+ TargetData *TD = 0);
+
+
+/// 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, Pass *P = 0);
+
+
+/// TryToSimplifyUncondBranchFromEmptyBlock - BB is known to contain an
+/// unconditional branch, and contains no instructions other than PHI nodes,
+/// potential debug intrinsics and the branch. If possible, eliminate BB by
+/// rewriting all the predecessors to branch to the successor block and return
+/// true. If we can't transform, return false.
+bool TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB);
+
+/// EliminateDuplicatePHINodes - Check for and eliminate duplicate PHI
+/// nodes in this block. This doesn't try to be clever about PHI nodes
+/// which differ only in the order of the incoming values, but instcombine
+/// orders them so it usually won't matter.
+///
+bool EliminateDuplicatePHINodes(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
///
bool SimplifyCFG(BasicBlock *BB);
+/// FoldBranchToCommonDest - If this basic block is ONLY a setcc and a branch,
+/// and if a predecessor branches to us and one of our successors, fold the
+/// setcc into the predecessor and use logical operations to pick the right
+/// destination.
+bool FoldBranchToCommonDest(BranchInst *BI);
+
/// 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);
+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);
} // End llvm namespace
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