llvm-6502/include/llvm/Analysis/CodeMetrics.h
James Molloy 67ae135759 Add a new attribute, 'noduplicate'. If a function contains a noduplicate call, the call cannot be duplicated - Jump threading, loop unrolling, loop unswitching, and loop rotation are inhibited if they would duplicate the call.
Similarly inlining of the function is inhibited, if that would duplicate the call (in particular inlining is still allowed when there is only one callsite and the function has internal linkage).



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170704 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-20 16:04:27 +00:00

99 lines
3.4 KiB
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//===- CodeMetrics.h - Code cost measurements -------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements various weight measurements for code, helping
// the Inliner and other passes decide whether to duplicate its contents.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_CODEMETRICS_H
#define LLVM_ANALYSIS_CODEMETRICS_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/CallSite.h"
namespace llvm {
class BasicBlock;
class Function;
class Instruction;
class DataLayout;
class Value;
/// \brief Check whether an instruction is likely to be "free" when lowered.
bool isInstructionFree(const Instruction *I, const DataLayout *TD = 0);
/// \brief Check whether a call will lower to something small.
///
/// This tests checks whether this callsite will lower to something
/// significantly cheaper than a traditional call, often a single
/// instruction. Note that if isInstructionFree(CS.getInstruction()) would
/// return true, so will this function.
bool callIsSmall(ImmutableCallSite CS);
/// \brief Utility to calculate the size and a few similar metrics for a set
/// of basic blocks.
struct CodeMetrics {
/// \brief True if this function contains a call to setjmp or other functions
/// with attribute "returns twice" without having the attribute itself.
bool exposesReturnsTwice;
/// \brief True if this function calls itself.
bool isRecursive;
/// \brief True if this function cannot be duplicated.
///
/// True if this function contains one or more indirect branches, or it contains
/// one or more 'noduplicate' instructions.
bool notDuplicatable;
/// \brief True if this function calls alloca (in the C sense).
bool usesDynamicAlloca;
/// \brief Number of instructions in the analyzed blocks.
unsigned NumInsts;
/// \brief Number of analyzed blocks.
unsigned NumBlocks;
/// \brief Keeps track of basic block code size estimates.
DenseMap<const BasicBlock *, unsigned> NumBBInsts;
/// \brief Keep track of the number of calls to 'big' functions.
unsigned NumCalls;
/// \brief The number of calls to internal functions with a single caller.
///
/// These are likely targets for future inlining, likely exposed by
/// interleaved devirtualization.
unsigned NumInlineCandidates;
/// \brief How many instructions produce vector values.
///
/// The inliner is more aggressive with inlining vector kernels.
unsigned NumVectorInsts;
/// \brief How many 'ret' instructions the blocks contain.
unsigned NumRets;
CodeMetrics() : exposesReturnsTwice(false), isRecursive(false),
notDuplicatable(false), usesDynamicAlloca(false),
NumInsts(0), NumBlocks(0), NumCalls(0),
NumInlineCandidates(0), NumVectorInsts(0),
NumRets(0) {}
/// \brief Add information about a block to the current state.
void analyzeBasicBlock(const BasicBlock *BB, const DataLayout *TD = 0);
/// \brief Add information about a function to the current state.
void analyzeFunction(Function *F, const DataLayout *TD = 0);
};
}
#endif