mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-25 14:32:53 +00:00
328a4fbfbb
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188844 91177308-0d34-0410-b5e6-96231b3b80d8
84 lines
3.3 KiB
C++
84 lines
3.3 KiB
C++
//===-- Analysis/CFG.h - BasicBlock Analyses --------------------*- 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 performs analyses on basic blocks, and instructions
|
|
// contained within basic blocks.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_ANALYSIS_CFG_H
|
|
#define LLVM_ANALYSIS_CFG_H
|
|
|
|
#include "llvm/IR/BasicBlock.h"
|
|
#include "llvm/Support/CFG.h"
|
|
|
|
namespace llvm {
|
|
|
|
class BasicBlock;
|
|
class DominatorTree;
|
|
class Function;
|
|
class Instruction;
|
|
class LoopInfo;
|
|
class TerminatorInst;
|
|
|
|
/// Analyze the specified function to find all of the loop backedges in the
|
|
/// function and return them. This is a relatively cheap (compared to
|
|
/// computing dominators and loop info) analysis.
|
|
///
|
|
/// The output is added to Result, as pairs of <from,to> edge info.
|
|
void FindFunctionBackedges(
|
|
const Function &F,
|
|
SmallVectorImpl<std::pair<const BasicBlock *, const BasicBlock *> > &
|
|
Result);
|
|
|
|
/// Search for the specified successor of basic block BB and return its position
|
|
/// in the terminator instruction's list of successors. It is an error to call
|
|
/// this with a block that is not a successor.
|
|
unsigned GetSuccessorNumber(BasicBlock *BB, BasicBlock *Succ);
|
|
|
|
/// Return true if the specified edge is a critical edge. Critical edges are
|
|
/// edges from a block with multiple successors to a block with multiple
|
|
/// predecessors.
|
|
///
|
|
bool isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum,
|
|
bool AllowIdenticalEdges = false);
|
|
|
|
/// \brief Determine whether instruction 'To' is reachable from 'From',
|
|
/// returning true if uncertain.
|
|
///
|
|
/// Determine whether there is a path from From to To within a single function.
|
|
/// Returns false only if we can prove that once 'From' has been executed then
|
|
/// 'To' can not be executed. Conservatively returns true.
|
|
///
|
|
/// This function is linear with respect to the number of blocks in the CFG,
|
|
/// walking down successors from From to reach To, with a fixed threshold.
|
|
/// Using DT or LI allows us to answer more quickly. LI reduces the cost of
|
|
/// an entire loop of any number of blocsk to be the same as the cost of a
|
|
/// single block. DT reduces the cost by allowing the search to terminate when
|
|
/// we find a block that dominates the block containing 'To'. DT is most useful
|
|
/// on branchy code but not loops, and LI is most useful on code with loops but
|
|
/// does not help on branchy code outside loops.
|
|
bool isPotentiallyReachable(const Instruction *From, const Instruction *To,
|
|
const DominatorTree *DT = 0,
|
|
const LoopInfo *LI = 0);
|
|
|
|
/// \brief Determine whether block 'To' is reachable from 'From', returning
|
|
/// true if uncertain.
|
|
///
|
|
/// Determine whether there is a path from From to To within a single function.
|
|
/// Returns false only if we can prove that once 'From' has been reached then
|
|
/// 'To' can not be executed. Conservatively returns true.
|
|
bool isPotentiallyReachable(const BasicBlock *From, const BasicBlock *To,
|
|
const DominatorTree *DT = 0,
|
|
const LoopInfo *LI = 0);
|
|
|
|
} // End llvm namespace
|
|
|
|
#endif
|