lib/CodeGen/Passes.cpp

   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
  18 using namespace llvm;
  19
  20 //===---------------------------------------------------------------------===//
  21 ///
  22 /// RegisterRegAlloc class - Track the registration of register allocators.
  23 ///
  24 //===---------------------------------------------------------------------===//
  25 MachinePassRegistry RegisterRegAlloc::Registry;
  26
  27 static FunctionPass *createDefaultRegisterAllocator() { return 0; }
  28 static RegisterRegAlloc
  29 defaultRegAlloc("default",
  30                 "pick register allocator based on -O option",
  31                 createDefaultRegisterAllocator);
  32
  33 //===---------------------------------------------------------------------===//
  34 ///
  35 /// RegAlloc command line options.
  36 ///
  37 //===---------------------------------------------------------------------===//
  38 static cl::opt<RegisterRegAlloc::FunctionPassCtor, false,
  39                RegisterPassParser<RegisterRegAlloc> >
  40 RegAlloc("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 //===---------------------------------------------------------------------===//
  50 FunctionPass *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 == createGreedyRegisterAllocator)
  61     return createGreedyRegisterAllocator();
  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 createLinearScanRegisterAllocator();
  72   }
  73 }