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llvm-mirror/include/llvm/Support/Allocator.h
Dan Gohman 8981962672 Add a new function, ReplaceAllUsesOfValuesWith, which handles bulk
replacement of multiple values. This is slightly more efficient
than doing multiple ReplaceAllUsesOfValueWith calls, and theoretically
could be optimized even further. However, an important property of this
new function is that it handles the case where the source value set and
destination value set overlap. This makes it feasible for isel to use
SelectNodeTo in many very common cases, which is advantageous because
SelectNodeTo avoids a temporary node and it doesn't require CSEMap
updates for users of values that don't change position.

Revamp MorphNodeTo, which is what does all the work of SelectNodeTo, to
handle operand lists more efficiently, and to correctly handle a number
of corner cases to which its new wider use exposes it.

This commit also includes a change to the encoding of post-isel opcodes
in SDNodes; now instead of being sandwiched between the target-independent
pre-isel opcodes and the target-dependent pre-isel opcodes, post-isel
opcodes are now represented as negative values. This makes it possible
to test if an opcode is pre-isel or post-isel without having to know
the size of the current target's post-isel instruction set.

These changes speed up llc overall by 3% and reduce memory usage by 10%
on the InstructionCombining.cpp testcase with -fast and -regalloc=local.

llvm-svn: 53728
2008-07-17 19:10:17 +00:00

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1.9 KiB
C++

//===--- Allocator.h - Simple memory allocation abstraction -----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the MallocAllocator and BumpPtrAllocator interfaces.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_ALLOCATOR_H
#define LLVM_SUPPORT_ALLOCATOR_H
#include "llvm/Support/AlignOf.h"
#include <cstdlib>
namespace llvm {
class MallocAllocator {
public:
MallocAllocator() {}
~MallocAllocator() {}
void Reset() {}
void *Allocate(size_t Size, size_t /*Alignment*/) { return malloc(Size); }
template <typename T>
T *Allocate() { return static_cast<T*>(malloc(sizeof(T))); }
void Deallocate(void *Ptr) { free(Ptr); }
void PrintStats() const {}
};
/// BumpPtrAllocator - This allocator is useful for containers that need very
/// simple memory allocation strategies. In particular, this just keeps
/// allocating memory, and never deletes it until the entire block is dead. This
/// makes allocation speedy, but must only be used when the trade-off is ok.
class BumpPtrAllocator {
BumpPtrAllocator(const BumpPtrAllocator &); // do not implement
void operator=(const BumpPtrAllocator &); // do not implement
void *TheMemory;
public:
BumpPtrAllocator();
~BumpPtrAllocator();
void Reset();
void *Allocate(size_t Size, size_t Alignment);
template <typename T>
T *Allocate() {
return static_cast<T*>(Allocate(sizeof(T),AlignOf<T>::Alignment));
}
template <typename T>
T *Allocate(size_t Num) {
return static_cast<T*>(Allocate(Num * sizeof(T), AlignOf<T>::Alignment));
}
void Deallocate(void * /*Ptr*/) {}
void PrintStats() const;
};
} // end namespace llvm
#endif