1 //===-- Local.h - Functions to perform local transformations ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This family of functions perform various local transformations to the
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_TRANSFORMS_UTILS_LOCAL_H
16 #define LLVM_TRANSFORMS_UTILS_LOCAL_H
18 #include "llvm/Function.h"
24 //===----------------------------------------------------------------------===//
25 // Local constant propagation...
28 /// doConstantPropagation - Constant prop a specific instruction. Returns true
29 /// and potentially moves the iterator if constant propagation was performed.
31 bool doConstantPropagation(BasicBlock::iterator &I);
33 /// ConstantFoldTerminator - If a terminator instruction is predicated on a
34 /// constant value, convert it into an unconditional branch to the constant
35 /// destination. This is a nontrivial operation because the successors of this
36 /// basic block must have their PHI nodes updated.
38 bool ConstantFoldTerminator(BasicBlock *BB);
41 //===----------------------------------------------------------------------===//
42 // Local dead code elimination...
45 /// isInstructionTriviallyDead - Return true if the result produced by the
46 /// instruction is not used, and the instruction has no side effects.
48 bool isInstructionTriviallyDead(Instruction *I);
51 /// dceInstruction - Inspect the instruction at *BBI and figure out if it
52 /// isTriviallyDead. If so, remove the instruction and update the iterator to
53 /// point to the instruction that immediately succeeded the original
56 bool dceInstruction(BasicBlock::iterator &BBI);
59 //===----------------------------------------------------------------------===//
60 // Control Flow Graph Restructuring...
63 /// SimplifyCFG - This function is used to do simplification of a CFG. For
64 /// example, it adjusts branches to branches to eliminate the extra hop, it
65 /// eliminates unreachable basic blocks, and does other "peephole" optimization
66 /// of the CFG. It returns true if a modification was made, possibly deleting
67 /// the basic block that was pointed to.
69 /// WARNING: The entry node of a method may not be simplified.
71 bool SimplifyCFG(BasicBlock *BB);
73 } // End llvm namespace