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llvm-mirror/include/llvm/LLVMContext.h
Chris Lattner 9ab48420db Fix a major source of compile-time slowness at -O0 -g by optimizing
the storage of !dbg metadata kinds in the instruction themselves.
The on-the-side hash table works great for metadata that not-all
instructions get, or for metadata that only exists when optimizing.
But when compile-time is everything, it isn't great.

I'm not super thrilled with the fact that this plops a TrackingVH in
Instruction, because it grows it by 3 words.  I'm investigating 
alternatives, but this should be a step in the right direction in any
case.

llvm-svn: 99957
2010-03-30 23:03:27 +00:00

62 lines
2.0 KiB
C++

//===-- llvm/LLVMContext.h - Class for managing "global" state --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares LLVMContext, a container of "global" state in LLVM, such
// as the global type and constant uniquing tables.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LLVMCONTEXT_H
#define LLVM_LLVMCONTEXT_H
namespace llvm {
class LLVMContextImpl;
class StringRef;
template <typename T> class SmallVectorImpl;
/// This is an important class for using LLVM in a threaded context. It
/// (opaquely) owns and manages the core "global" data of LLVM's core
/// infrastructure, including the type and constant uniquing tables.
/// LLVMContext itself provides no locking guarantees, so you should be careful
/// to have one context per thread.
class LLVMContext {
// DO NOT IMPLEMENT
LLVMContext(LLVMContext&);
void operator=(LLVMContext&);
public:
LLVMContextImpl *const pImpl;
LLVMContext();
~LLVMContext();
// Pinned metadata names, which always have the same value. This is a
// compile-time performance optimization, not a correctness optimization.
enum {
MD_dbg = 1 // "dbg" -> 1.
};
/// getMDKindID - Return a unique non-zero ID for the specified metadata kind.
/// This ID is uniqued across modules in the current LLVMContext.
unsigned getMDKindID(StringRef Name) const;
/// getMDKindNames - Populate client supplied SmallVector with the name for
/// custom metadata IDs registered in this LLVMContext. ID #0 is not used,
/// so it is filled in as an empty string.
void getMDKindNames(SmallVectorImpl<StringRef> &Result) const;
};
/// getGlobalContext - Returns a global context. This is for LLVM clients that
/// only care about operating on a single thread.
extern LLVMContext &getGlobalContext();
}
#endif