PPCSubtarget.cpp revision 203954 
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 TargetSubtarget.
11//
12//===----------------------------------------------------------------------===//
13
14#include "PPCSubtarget.h"
15#include "PPC.h"
16#include "llvm/GlobalValue.h"
17#include "llvm/Target/TargetMachine.h"
18#include "PPCGenSubtarget.inc"
19#include <cstdlib>
20using namespace llvm;
21
22#if defined(__APPLE__)
23#include <mach/mach.h>
24#include <mach/mach_host.h>
25#include <mach/host_info.h>
26#include <mach/machine.h>
27
28/// GetCurrentPowerPCFeatures - Returns the current CPUs features.
29static const char *GetCurrentPowerPCCPU() {
30  host_basic_info_data_t hostInfo;
31  mach_msg_type_number_t infoCount;
32
33  infoCount = HOST_BASIC_INFO_COUNT;
34  host_info(mach_host_self(), HOST_BASIC_INFO, (host_info_t)&hostInfo,
35            &infoCount);
36
37  if (hostInfo.cpu_type != CPU_TYPE_POWERPC) return "generic";
38
39  switch(hostInfo.cpu_subtype) {
40  case CPU_SUBTYPE_POWERPC_601:   return "601";
41  case CPU_SUBTYPE_POWERPC_602:   return "602";
42  case CPU_SUBTYPE_POWERPC_603:   return "603";
43  case CPU_SUBTYPE_POWERPC_603e:  return "603e";
44  case CPU_SUBTYPE_POWERPC_603ev: return "603ev";
45  case CPU_SUBTYPE_POWERPC_604:   return "604";
46  case CPU_SUBTYPE_POWERPC_604e:  return "604e";
47  case CPU_SUBTYPE_POWERPC_620:   return "620";
48  case CPU_SUBTYPE_POWERPC_750:   return "750";
49  case CPU_SUBTYPE_POWERPC_7400:  return "7400";
50  case CPU_SUBTYPE_POWERPC_7450:  return "7450";
51  case CPU_SUBTYPE_POWERPC_970:   return "970";
52  default: ;
53  }
54
55  return "generic";
56}
57#endif
58
59
60PPCSubtarget::PPCSubtarget(const std::string &TT, const std::string &FS,
61                           bool is64Bit)
62  : StackAlignment(16)
63  , DarwinDirective(PPC::DIR_NONE)
64  , IsGigaProcessor(false)
65  , Has64BitSupport(false)
66  , Use64BitRegs(false)
67  , IsPPC64(is64Bit)
68  , HasAltivec(false)
69  , HasFSQRT(false)
70  , HasSTFIWX(false)
71  , HasLazyResolverStubs(false)
72  , DarwinVers(0) {
73
74  // Determine default and user specified characteristics
75  std::string CPU = "generic";
76#if defined(__APPLE__)
77  CPU = GetCurrentPowerPCCPU();
78#endif
79
80  // Parse features string.
81  ParseSubtargetFeatures(FS, CPU);
82
83  // If we are generating code for ppc64, verify that options make sense.
84  if (is64Bit) {
85    Has64BitSupport = true;
86    // Silently force 64-bit register use on ppc64.
87    Use64BitRegs = true;
88  }
89
90  // If the user requested use of 64-bit regs, but the cpu selected doesn't
91  // support it, ignore.
92  if (use64BitRegs() && !has64BitSupport())
93    Use64BitRegs = false;
94
95  // Set the boolean corresponding to the current target triple, or the default
96  // if one cannot be determined, to true.
97  if (TT.length() > 7) {
98    // Determine which version of darwin this is.
99    size_t DarwinPos = TT.find("-darwin");
100    if (DarwinPos != std::string::npos) {
101      if (isdigit(TT[DarwinPos+7]))
102        DarwinVers = atoi(&TT[DarwinPos+7]);
103      else
104        DarwinVers = 8;  // Minimum supported darwin is Tiger.
105    }
106  }
107
108  // Set up darwin-specific properties.
109  if (isDarwin())
110    HasLazyResolverStubs = true;
111}
112
113/// SetJITMode - This is called to inform the subtarget info that we are
114/// producing code for the JIT.
115void PPCSubtarget::SetJITMode() {
116  // JIT mode doesn't want lazy resolver stubs, it knows exactly where
117  // everything is.  This matters for PPC64, which codegens in PIC mode without
118  // stubs.
119  HasLazyResolverStubs = false;
120}
121
122
123/// hasLazyResolverStub - Return true if accesses to the specified global have
124/// to go through a dyld lazy resolution stub.  This means that an extra load
125/// is required to get the address of the global.
126bool PPCSubtarget::hasLazyResolverStub(const GlobalValue *GV,
127                                       const TargetMachine &TM) const {
128  // We never hae stubs if HasLazyResolverStubs=false or if in static mode.
129  if (!HasLazyResolverStubs || TM.getRelocationModel() == Reloc::Static)
130    return false;
131  // If symbol visibility is hidden, the extra load is not needed if
132  // the symbol is definitely defined in the current translation unit.
133  bool isDecl = GV->isDeclaration() && !GV->isMaterializable();
134  if (GV->hasHiddenVisibility() && !isDecl && !GV->hasCommonLinkage())
135    return false;
136  return GV->hasWeakLinkage() || GV->hasLinkOnceLinkage() ||
137         GV->hasCommonLinkage() || isDecl;
138}
139