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