WebSVN – QNX 8.QNX8 LLVM/Clang compiler suite – Blame – //llvm-build/x86_64/include/llvm/Transforms/Utils/GlobalStatus.h

Rev	Author	Line No.	Line
14	pmbaty	1	//===- GlobalStatus.h - Compute status info for globals ---------- C++ --===//
		2	//
		3	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
		4	// See https://llvm.org/LICENSE.txt for license information.
		5	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
		6	//
		7	//===----------------------------------------------------------------------===//
		8
		9	#ifndef LLVM_TRANSFORMS_UTILS_GLOBALSTATUS_H
		10	#define LLVM_TRANSFORMS_UTILS_GLOBALSTATUS_H
		11
		12	#include "llvm/IR/Instructions.h"
		13	#include "llvm/Support/AtomicOrdering.h"
		14
		15	namespace llvm {
		16
		17	class Constant;
		18	class Function;
		19	class Value;
		20
		21	/// It is safe to destroy a constant iff it is only used by constants itself.
		22	/// Note that constants cannot be cyclic, so this test is pretty easy to
		23	/// implement recursively.
		24	///
		25	bool isSafeToDestroyConstant(const Constant *C);
		26
		27	/// As we analyze each global, keep track of some information about it. If we
		28	/// find out that the address of the global is taken, none of this info will be
		29	/// accurate.
		30	struct GlobalStatus {
		31	/// True if the global's address is used in a comparison.
		32	bool IsCompared = false;
		33
		34	/// True if the global is ever loaded. If the global isn't ever loaded it
		35	/// can be deleted.
		36	bool IsLoaded = false;
		37
		38	/// Number of stores to the global.
		39	unsigned NumStores = 0;
		40
		41	/// Keep track of what stores to the global look like.
		42	enum StoredType {
		43	/// There is no store to this global. It can thus be marked constant.
		44	NotStored,
		45
		46	/// This global is stored to, but the only thing stored is the constant it
		47	/// was initialized with. This is only tracked for scalar globals.
		48	InitializerStored,
		49
		50	/// This global is stored to, but only its initializer and one other value
		51	/// is ever stored to it. If this global isStoredOnce, we track the value
		52	/// stored to it via StoredOnceStore below. This is only tracked for scalar
		53	/// globals.
		54	StoredOnce,
		55
		56	/// This global is stored to by multiple values or something else that we
		57	/// cannot track.
		58	Stored
		59	} StoredType = NotStored;
		60
		61	/// If only one value (besides the initializer constant) is ever stored to
		62	/// this global, keep track of what value it is via the store instruction.
		63	const StoreInst *StoredOnceStore = nullptr;
		64
		65	/// If only one value (besides the initializer constant) is ever stored to
		66	/// this global return the stored value.
		67	Value *getStoredOnceValue() const {
		68	return (StoredType == StoredOnce && StoredOnceStore)
		69	? StoredOnceStore->getOperand(0)
		70	: nullptr;
		71	}
		72
		73	/// These start out null/false. When the first accessing function is noticed,
		74	/// it is recorded. When a second different accessing function is noticed,
		75	/// HasMultipleAccessingFunctions is set to true.
		76	const Function *AccessingFunction = nullptr;
		77	bool HasMultipleAccessingFunctions = false;
		78
		79	/// Set to the strongest atomic ordering requirement.
		80	AtomicOrdering Ordering = AtomicOrdering::NotAtomic;
		81
		82	GlobalStatus();
		83
		84	/// Look at all uses of the global and fill in the GlobalStatus structure. If
		85	/// the global has its address taken, return true to indicate we can't do
		86	/// anything with it.
		87	static bool analyzeGlobal(const Value *V, GlobalStatus &GS);
		88	};
		89
		90	} // end namespace llvm
		91
		92	#endif // LLVM_TRANSFORMS_UTILS_GLOBALSTATUS_H

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QNX 8.QNX8 LLVM/Clang compiler suite//llvm-build/x86_64/include/llvm/Transforms/Utils/GlobalStatus.h – Rev 14