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llvm-mirror/include/llvm/Analysis/CodeMetrics.h
Chandler Carruth c140bae640 [PM] Split the AssumptionTracker immutable pass into two separate APIs:
a cache of assumptions for a single function, and an immutable pass that
manages those caches.

The motivation for this change is two fold. Immutable analyses are
really hacks around the current pass manager design and don't exist in
the new design. This is usually OK, but it requires that the core logic
of an immutable pass be reasonably partitioned off from the pass logic.
This change does precisely that. As a consequence it also paves the way
for the *many* utility functions that deal in the assumptions to live in
both pass manager worlds by creating an separate non-pass object with
its own independent API that they all rely on. Now, the only bits of the
system that deal with the actual pass mechanics are those that actually
need to deal with the pass mechanics.

Once this separation is made, several simplifications become pretty
obvious in the assumption cache itself. Rather than using a set and
callback value handles, it can just be a vector of weak value handles.
The callers can easily skip the handles that are null, and eventually we
can wrap all of this up behind a filter iterator.

For now, this adds boiler plate to the various passes, but this kind of
boiler plate will end up making it possible to port these passes to the
new pass manager, and so it will end up factored away pretty reasonably.

llvm-svn: 225131
2015-01-04 12:03:27 +00:00

108 lines
3.7 KiB
C++

//===- 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/ADT/SmallPtrSet.h"
#include "llvm/IR/CallSite.h"
namespace llvm {
class AssumptionCache;
class BasicBlock;
class Loop;
class Function;
class Instruction;
class DataLayout;
class TargetTransformInfo;
class Value;
/// \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 TargetTransformInfo &TTI,
SmallPtrSetImpl<const Value*> &EphValues);
/// \brief Collect a loop's ephemeral values (those used only by an assume
/// or similar intrinsics in the loop).
static void collectEphemeralValues(const Loop *L, AssumptionCache *AC,
SmallPtrSetImpl<const Value *> &EphValues);
/// \brief Collect a functions's ephemeral values (those used only by an
/// assume or similar intrinsics in the function).
static void collectEphemeralValues(const Function *L, AssumptionCache *AC,
SmallPtrSetImpl<const Value *> &EphValues);
};
}
#endif