Passes.cpp revision 5aa3211e2d9c618f1f2ae590792067dbcb572741 
1//===-- Passes.cpp - Target independent code generation passes ------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines interfaces to access the target independent code
11// generation passes provided by the LLVM backend.
12//
13//===---------------------------------------------------------------------===//
14
15#include "llvm/CodeGen/RegAllocRegistry.h"
16#include "llvm/CodeGen/Passes.h"
17
18using namespace llvm;
19
20//===---------------------------------------------------------------------===//
21///
22/// RegisterRegAlloc class - Track the registration of register allocators.
23///
24//===---------------------------------------------------------------------===//
25MachinePassRegistry RegisterRegAlloc::Registry;
26
27static FunctionPass *createDefaultRegisterAllocator() { return 0; }
28static RegisterRegAlloc
29defaultRegAlloc("default",
30                "pick register allocator based on -O option",
31                createDefaultRegisterAllocator);
32
33//===---------------------------------------------------------------------===//
34///
35/// RegAlloc command line options.
36///
37//===---------------------------------------------------------------------===//
38static cl::opt<RegisterRegAlloc::FunctionPassCtor, false,
39               RegisterPassParser<RegisterRegAlloc> >
40RegAlloc("regalloc",
41         cl::init(&createDefaultRegisterAllocator),
42         cl::desc("Register allocator to use"));
43
44
45//===---------------------------------------------------------------------===//
46///
47/// createRegisterAllocator - choose the appropriate register allocator.
48///
49//===---------------------------------------------------------------------===//
50FunctionPass *llvm::createRegisterAllocator(CodeGenOpt::Level OptLevel) {
51  RegisterRegAlloc::FunctionPassCtor Ctor = RegisterRegAlloc::getDefault();
52
53  if (!Ctor) {
54    Ctor = RegAlloc;
55    RegisterRegAlloc::setDefault(RegAlloc);
56  }
57
58  // This forces linking of the greedy register allocator, so -regalloc=greedy
59  // works in clang.
60  if (Ctor == createLinearScanRegisterAllocator)
61    return createLinearScanRegisterAllocator();
62
63  if (Ctor != createDefaultRegisterAllocator)
64    return Ctor();
65
66  // When the 'default' allocator is requested, pick one based on OptLevel.
67  switch (OptLevel) {
68  case CodeGenOpt::None:
69    return createFastRegisterAllocator();
70  default:
71    return createGreedyRegisterAllocator();
72  }
73}
74