PPCSubtarget.cpp revision 239462
1//===-- PowerPCSubtarget.cpp - PPC Subtarget Information ------------------===// 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 implements the PPC specific subclass of TargetSubtargetInfo. 11// 12//===----------------------------------------------------------------------===// 13 14#include "PPCSubtarget.h" 15#include "PPCRegisterInfo.h" 16#include "PPC.h" 17#include "llvm/GlobalValue.h" 18#include "llvm/Target/TargetMachine.h" 19#include "llvm/Support/Host.h" 20#include "llvm/Support/TargetRegistry.h" 21#include <cstdlib> 22 23#define GET_SUBTARGETINFO_TARGET_DESC 24#define GET_SUBTARGETINFO_CTOR 25#include "PPCGenSubtargetInfo.inc" 26 27using namespace llvm; 28 29PPCSubtarget::PPCSubtarget(const std::string &TT, const std::string &CPU, 30 const std::string &FS, bool is64Bit) 31 : PPCGenSubtargetInfo(TT, CPU, FS) 32 , StackAlignment(16) 33 , DarwinDirective(PPC::DIR_NONE) 34 , HasMFOCRF(false) 35 , Has64BitSupport(false) 36 , Use64BitRegs(false) 37 , IsPPC64(is64Bit) 38 , HasAltivec(false) 39 , HasFSQRT(false) 40 , HasSTFIWX(false) 41 , HasISEL(false) 42 , IsBookE(false) 43 , HasLazyResolverStubs(false) 44 , IsJITCodeModel(false) 45 , TargetTriple(TT) { 46 47 // Determine default and user specified characteristics 48 std::string CPUName = CPU; 49 if (CPUName.empty()) 50 CPUName = "generic"; 51#if (defined(__APPLE__) || defined(__linux__)) && \ 52 (defined(__ppc__) || defined(__powerpc__)) 53 if (CPUName == "generic") 54 CPUName = sys::getHostCPUName(); 55#endif 56 57 // Parse features string. 58 ParseSubtargetFeatures(CPUName, FS); 59 60 // Initialize scheduling itinerary for the specified CPU. 61 InstrItins = getInstrItineraryForCPU(CPUName); 62 63 // If we are generating code for ppc64, verify that options make sense. 64 if (is64Bit) { 65 Has64BitSupport = true; 66 // Silently force 64-bit register use on ppc64. 67 Use64BitRegs = true; 68 } 69 70 // If the user requested use of 64-bit regs, but the cpu selected doesn't 71 // support it, ignore. 72 if (use64BitRegs() && !has64BitSupport()) 73 Use64BitRegs = false; 74 75 // Set up darwin-specific properties. 76 if (isDarwin()) 77 HasLazyResolverStubs = true; 78} 79 80/// SetJITMode - This is called to inform the subtarget info that we are 81/// producing code for the JIT. 82void PPCSubtarget::SetJITMode() { 83 // JIT mode doesn't want lazy resolver stubs, it knows exactly where 84 // everything is. This matters for PPC64, which codegens in PIC mode without 85 // stubs. 86 HasLazyResolverStubs = false; 87 88 // Calls to external functions need to use indirect calls 89 IsJITCodeModel = true; 90} 91 92 93/// hasLazyResolverStub - Return true if accesses to the specified global have 94/// to go through a dyld lazy resolution stub. This means that an extra load 95/// is required to get the address of the global. 96bool PPCSubtarget::hasLazyResolverStub(const GlobalValue *GV, 97 const TargetMachine &TM) const { 98 // We never have stubs if HasLazyResolverStubs=false or if in static mode. 99 if (!HasLazyResolverStubs || TM.getRelocationModel() == Reloc::Static) 100 return false; 101 // If symbol visibility is hidden, the extra load is not needed if 102 // the symbol is definitely defined in the current translation unit. 103 bool isDecl = GV->isDeclaration() && !GV->isMaterializable(); 104 if (GV->hasHiddenVisibility() && !isDecl && !GV->hasCommonLinkage()) 105 return false; 106 return GV->hasWeakLinkage() || GV->hasLinkOnceLinkage() || 107 GV->hasCommonLinkage() || isDecl; 108} 109 110bool PPCSubtarget::enablePostRAScheduler( 111 CodeGenOpt::Level OptLevel, 112 TargetSubtargetInfo::AntiDepBreakMode& Mode, 113 RegClassVector& CriticalPathRCs) const { 114 // FIXME: It would be best to use TargetSubtargetInfo::ANTIDEP_ALL here, 115 // but we can't because we can't reassign the cr registers. There is a 116 // dependence between the cr register and the RLWINM instruction used 117 // to extract its value which the anti-dependency breaker can't currently 118 // see. Maybe we should make a late-expanded pseudo to encode this dependency. 119 // (the relevant code is in PPCDAGToDAGISel::SelectSETCC) 120 121 Mode = TargetSubtargetInfo::ANTIDEP_CRITICAL; 122 123 CriticalPathRCs.clear(); 124 125 if (isPPC64()) 126 CriticalPathRCs.push_back(&PPC::G8RCRegClass); 127 else 128 CriticalPathRCs.push_back(&PPC::GPRCRegClass); 129 130 CriticalPathRCs.push_back(&PPC::F8RCRegClass); 131 CriticalPathRCs.push_back(&PPC::VRRCRegClass); 132 133 return OptLevel >= CodeGenOpt::Default; 134} 135 136