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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12918 91177308-0d34-0410-b5e6-96231b3b80d8
111 lines
4.0 KiB
C++
111 lines
4.0 KiB
C++
//===-- Local.h - Functions to perform local transformations ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This family of functions perform various local transformations to the
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// program.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_UTILS_LOCAL_H
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#define LLVM_TRANSFORMS_UTILS_LOCAL_H
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#include "llvm/Function.h"
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namespace llvm {
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class Pass;
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class PHINode;
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class AllocaInst;
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//===----------------------------------------------------------------------===//
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// Local constant propagation...
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//
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/// doConstantPropagation - Constant prop a specific instruction. Returns true
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/// and potentially moves the iterator if constant propagation was performed.
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///
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bool doConstantPropagation(BasicBlock::iterator &I);
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/// ConstantFoldTerminator - If a terminator instruction is predicated on a
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/// constant value, convert it into an unconditional branch to the constant
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/// destination. This is a nontrivial operation because the successors of this
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/// basic block must have their PHI nodes updated.
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///
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bool ConstantFoldTerminator(BasicBlock *BB);
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/// ConstantFoldInstruction - Attempt to constant fold the specified
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/// instruction. If successful, the constant result is returned, if not, null
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/// is returned. Note that this function can only fail when attempting to fold
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/// instructions like loads and stores, which have no constant expression form.
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///
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Constant *ConstantFoldInstruction(Instruction *I);
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/// canConstantFoldCallTo - Return true if its even possible to fold a call to
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/// the specified function.
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bool canConstantFoldCallTo(Function *F);
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/// ConstantFoldCall - Attempt to constant fold a call to the specified function
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/// with the specified arguments, returning null if unsuccessful.
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Constant *ConstantFoldCall(Function *F, const std::vector<Constant*> &Operands);
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//===----------------------------------------------------------------------===//
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// Local dead code elimination...
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//
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/// isInstructionTriviallyDead - Return true if the result produced by the
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/// instruction is not used, and the instruction has no side effects.
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///
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bool isInstructionTriviallyDead(Instruction *I);
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/// dceInstruction - Inspect the instruction at *BBI and figure out if it
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/// isTriviallyDead. If so, remove the instruction and update the iterator to
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/// point to the instruction that immediately succeeded the original
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/// instruction.
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///
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bool dceInstruction(BasicBlock::iterator &BBI);
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//===----------------------------------------------------------------------===//
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// PHI Instruction Simplification
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//
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/// hasConstantValue - If the specified PHI node always merges together the same
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/// value, return the value, otherwise return null.
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///
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Value *hasConstantValue(PHINode *PN);
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//===----------------------------------------------------------------------===//
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// Control Flow Graph Restructuring...
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//
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/// SimplifyCFG - This function is used to do simplification of a CFG. For
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/// example, it adjusts branches to branches to eliminate the extra hop, it
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/// eliminates unreachable basic blocks, and does other "peephole" optimization
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/// of the CFG. It returns true if a modification was made, possibly deleting
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/// the basic block that was pointed to.
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///
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/// WARNING: The entry node of a method may not be simplified.
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///
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bool SimplifyCFG(BasicBlock *BB);
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/// DemoteRegToStack - This function takes a virtual register computed by an
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/// Instruction and replaces it with a slot in the stack frame, allocated via
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/// alloca. This allows the CFG to be changed around without fear of
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/// invalidating the SSA information for the value. It returns the pointer to
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/// the alloca inserted to create a stack slot for X.
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///
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AllocaInst *DemoteRegToStack(Instruction &X);
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} // End llvm namespace
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#endif
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