ARMSubtarget.cpp revision 42a83f2d15cbbc08f5be19856198e3c885221e9c 
1//===-- ARMSubtarget.cpp - ARM Subtarget Information ------------*- C++ -*-===//
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 ARM specific subclass of TargetSubtarget.
11//
12//===----------------------------------------------------------------------===//
13
14#include "ARMSubtarget.h"
15#include "ARMGenSubtarget.inc"
16#include "llvm/Target/TargetOptions.h"
17#include "llvm/Support/CommandLine.h"
18using namespace llvm;
19
20static cl::opt<bool>
21ReserveR9("arm-reserve-r9", cl::Hidden,
22          cl::desc("Reserve R9, making it unavailable as GPR"));
23
24ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
25                           bool isThumb)
26  : ARMArchVersion(V4T)
27  , ARMFPUType(None)
28  , UseNEONForSinglePrecisionFP(false)
29  , IsThumb(isThumb)
30  , ThumbMode(Thumb1)
31  , IsR9Reserved(ReserveR9)
32  , stackAlignment(4)
33  , CPUString("generic")
34  , TargetType(isELF) // Default to ELF unless otherwise specified.
35  , TargetABI(ARM_ABI_APCS) {
36  // default to soft float ABI
37  if (FloatABIType == FloatABI::Default)
38    FloatABIType = FloatABI::Soft;
39
40  // Determine default and user specified characteristics
41
42  // Parse features string.
43  CPUString = ParseSubtargetFeatures(FS, CPUString);
44
45  // Set the boolean corresponding to the current target triple, or the default
46  // if one cannot be determined, to true.
47  unsigned Len = TT.length();
48  unsigned Idx = 0;
49
50  if (Len >= 5 && TT.substr(0, 4) == "armv")
51    Idx = 4;
52  else if (Len >= 6 && TT.substr(0, 5) == "thumb") {
53    IsThumb = true;
54    if (Len >= 7 && TT[5] == 'v')
55      Idx = 6;
56  }
57  if (Idx) {
58    unsigned SubVer = TT[Idx];
59    if (SubVer > '4' && SubVer <= '9') {
60      if (SubVer >= '7') {
61        ARMArchVersion = V7A;
62      } else if (SubVer == '6') {
63        ARMArchVersion = V6;
64        if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == '2')
65          ARMArchVersion = V6T2;
66      } else if (SubVer == '5') {
67        ARMArchVersion = V5T;
68        if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == 'e')
69          ARMArchVersion = V5TE;
70      }
71      if (ARMArchVersion >= V6T2)
72        ThumbMode = Thumb2;
73    }
74  }
75
76  // Thumb2 implies at least V6T2.
77  if (ARMArchVersion < V6T2 && ThumbMode >= Thumb2)
78    ARMArchVersion = V6T2;
79
80  if (Len >= 10) {
81    if (TT.find("-darwin") != std::string::npos)
82      // arm-darwin
83      TargetType = isDarwin;
84  } else if (TT.empty()) {
85#if defined(__APPLE__)
86    TargetType = isDarwin;
87#endif
88  }
89
90  if (TT.find("eabi") != std::string::npos)
91    TargetABI = ARM_ABI_AAPCS;
92
93  if (isAAPCS_ABI())
94    stackAlignment = 8;
95
96  if (isTargetDarwin())
97    IsR9Reserved = ReserveR9 | (ARMArchVersion < V6);
98}
99