1 //===--- X86.cpp - X86 Helpers for Tools ------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "X86.h"
10 #include "ToolChains/CommonArgs.h"
11 #include "clang/Driver/Driver.h"
12 #include "clang/Driver/DriverDiagnostic.h"
13 #include "clang/Driver/Options.h"
14 #include "llvm/ADT/StringExtras.h"
15 #include "llvm/ADT/StringMap.h"
16 #include "llvm/Option/ArgList.h"
17 #include "llvm/Support/Host.h"
18 
19 using namespace clang::driver;
20 using namespace clang::driver::tools;
21 using namespace clang;
22 using namespace llvm::opt;
23 
getX86TargetCPU(const Driver & D,const ArgList & Args,const llvm::Triple & Triple)24 std::string x86::getX86TargetCPU(const Driver &D, const ArgList &Args,
25                                  const llvm::Triple &Triple) {
26   if (const Arg *A = Args.getLastArg(clang::driver::options::OPT_march_EQ)) {
27     StringRef CPU = A->getValue();
28     if (CPU != "native")
29       return std::string(CPU);
30 
31     // FIXME: Reject attempts to use -march=native unless the target matches
32     // the host.
33     CPU = llvm::sys::getHostCPUName();
34     if (!CPU.empty() && CPU != "generic")
35       return std::string(CPU);
36   }
37 
38   if (const Arg *A = Args.getLastArg(options::OPT__SLASH_arch)) {
39     // Mapping built by looking at lib/Basic's X86TargetInfo::initFeatureMap().
40     // The keys are case-sensitive; this matches link.exe.
41     // 32-bit and 64-bit /arch: flags.
42     llvm::StringMap<StringRef> ArchMap({
43         {"AVX", "sandybridge"},
44         {"AVX2", "haswell"},
45         {"AVX512F", "knl"},
46         {"AVX512", "skylake-avx512"},
47     });
48     if (Triple.getArch() == llvm::Triple::x86) {
49       // 32-bit-only /arch: flags.
50       ArchMap.insert({
51           {"IA32", "i386"},
52           {"SSE", "pentium3"},
53           {"SSE2", "pentium4"},
54       });
55     }
56     StringRef CPU = ArchMap.lookup(A->getValue());
57     if (CPU.empty()) {
58       std::vector<StringRef> ValidArchs{ArchMap.keys().begin(),
59                                         ArchMap.keys().end()};
60       sort(ValidArchs);
61       D.Diag(diag::warn_drv_invalid_arch_name_with_suggestion)
62           << A->getValue() << (Triple.getArch() == llvm::Triple::x86)
63           << join(ValidArchs, ", ");
64     }
65     return std::string(CPU);
66   }
67 
68   // Select the default CPU if none was given (or detection failed).
69 
70   if (!Triple.isX86())
71     return ""; // This routine is only handling x86 targets.
72 
73   bool Is64Bit = Triple.getArch() == llvm::Triple::x86_64;
74 
75   // FIXME: Need target hooks.
76   if (Triple.isOSDarwin()) {
77     if (Triple.getArchName() == "x86_64h")
78       return "core-avx2";
79     // macosx10.12 drops support for all pre-Penryn Macs.
80     // Simulators can still run on 10.11 though, like Xcode.
81     if (Triple.isMacOSX() && !Triple.isOSVersionLT(10, 12))
82       return "penryn";
83 
84     if (Triple.isDriverKit())
85       return "nehalem";
86 
87     // The oldest x86_64 Macs have core2/Merom; the oldest x86 Macs have Yonah.
88     return Is64Bit ? "core2" : "yonah";
89   }
90 
91   // Set up default CPU name for PS4/PS5 compilers.
92   if (Triple.isPS4())
93     return "btver2";
94   if (Triple.isPS5())
95     return "znver2";
96 
97   // On Android use targets compatible with gcc
98   if (Triple.isAndroid())
99     return Is64Bit ? "x86-64" : "i686";
100 
101   // Everything else goes to x86-64 in 64-bit mode.
102   if (Is64Bit)
103     return "x86-64";
104 
105   switch (Triple.getOS()) {
106   case llvm::Triple::NetBSD:
107     return "i486";
108   case llvm::Triple::Haiku:
109   case llvm::Triple::OpenBSD:
110     return "i586";
111   case llvm::Triple::FreeBSD:
112     return "i686";
113   default:
114     // Fallback to p4.
115     return "pentium4";
116   }
117 }
118 
getX86TargetFeatures(const Driver & D,const llvm::Triple & Triple,const ArgList & Args,std::vector<StringRef> & Features)119 void x86::getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
120                                const ArgList &Args,
121                                std::vector<StringRef> &Features) {
122   // If -march=native, autodetect the feature list.
123   if (const Arg *A = Args.getLastArg(clang::driver::options::OPT_march_EQ)) {
124     if (StringRef(A->getValue()) == "native") {
125       llvm::StringMap<bool> HostFeatures;
126       if (llvm::sys::getHostCPUFeatures(HostFeatures))
127         for (auto &F : HostFeatures)
128           Features.push_back(
129               Args.MakeArgString((F.second ? "+" : "-") + F.first()));
130     }
131   }
132 
133   if (Triple.getArchName() == "x86_64h") {
134     // x86_64h implies quite a few of the more modern subtarget features
135     // for Haswell class CPUs, but not all of them. Opt-out of a few.
136     Features.push_back("-rdrnd");
137     Features.push_back("-aes");
138     Features.push_back("-pclmul");
139     Features.push_back("-rtm");
140     Features.push_back("-fsgsbase");
141   }
142 
143   const llvm::Triple::ArchType ArchType = Triple.getArch();
144   // Add features to be compatible with gcc for Android.
145   if (Triple.isAndroid()) {
146     if (ArchType == llvm::Triple::x86_64) {
147       Features.push_back("+sse4.2");
148       Features.push_back("+popcnt");
149       Features.push_back("+cx16");
150     } else
151       Features.push_back("+ssse3");
152   }
153 
154   // Translate the high level `-mretpoline` flag to the specific target feature
155   // flags. We also detect if the user asked for retpoline external thunks but
156   // failed to ask for retpolines themselves (through any of the different
157   // flags). This is a bit hacky but keeps existing usages working. We should
158   // consider deprecating this and instead warn if the user requests external
159   // retpoline thunks and *doesn't* request some form of retpolines.
160   auto SpectreOpt = clang::driver::options::ID::OPT_INVALID;
161   if (Args.hasArgNoClaim(options::OPT_mretpoline, options::OPT_mno_retpoline,
162                          options::OPT_mspeculative_load_hardening,
163                          options::OPT_mno_speculative_load_hardening)) {
164     if (Args.hasFlag(options::OPT_mretpoline, options::OPT_mno_retpoline,
165                      false)) {
166       Features.push_back("+retpoline-indirect-calls");
167       Features.push_back("+retpoline-indirect-branches");
168       SpectreOpt = options::OPT_mretpoline;
169     } else if (Args.hasFlag(options::OPT_mspeculative_load_hardening,
170                             options::OPT_mno_speculative_load_hardening,
171                             false)) {
172       // On x86, speculative load hardening relies on at least using retpolines
173       // for indirect calls.
174       Features.push_back("+retpoline-indirect-calls");
175       SpectreOpt = options::OPT_mspeculative_load_hardening;
176     }
177   } else if (Args.hasFlag(options::OPT_mretpoline_external_thunk,
178                           options::OPT_mno_retpoline_external_thunk, false)) {
179     // FIXME: Add a warning about failing to specify `-mretpoline` and
180     // eventually switch to an error here.
181     Features.push_back("+retpoline-indirect-calls");
182     Features.push_back("+retpoline-indirect-branches");
183     SpectreOpt = options::OPT_mretpoline_external_thunk;
184   }
185 
186   auto LVIOpt = clang::driver::options::ID::OPT_INVALID;
187   if (Args.hasFlag(options::OPT_mlvi_hardening, options::OPT_mno_lvi_hardening,
188                    false)) {
189     Features.push_back("+lvi-load-hardening");
190     Features.push_back("+lvi-cfi"); // load hardening implies CFI protection
191     LVIOpt = options::OPT_mlvi_hardening;
192   } else if (Args.hasFlag(options::OPT_mlvi_cfi, options::OPT_mno_lvi_cfi,
193                           false)) {
194     Features.push_back("+lvi-cfi");
195     LVIOpt = options::OPT_mlvi_cfi;
196   }
197 
198   if (Args.hasFlag(options::OPT_m_seses, options::OPT_mno_seses, false)) {
199     if (LVIOpt == options::OPT_mlvi_hardening)
200       D.Diag(diag::err_drv_argument_not_allowed_with)
201           << D.getOpts().getOptionName(options::OPT_mlvi_hardening)
202           << D.getOpts().getOptionName(options::OPT_m_seses);
203 
204     if (SpectreOpt != clang::driver::options::ID::OPT_INVALID)
205       D.Diag(diag::err_drv_argument_not_allowed_with)
206           << D.getOpts().getOptionName(SpectreOpt)
207           << D.getOpts().getOptionName(options::OPT_m_seses);
208 
209     Features.push_back("+seses");
210     if (!Args.hasArg(options::OPT_mno_lvi_cfi)) {
211       Features.push_back("+lvi-cfi");
212       LVIOpt = options::OPT_mlvi_cfi;
213     }
214   }
215 
216   if (SpectreOpt != clang::driver::options::ID::OPT_INVALID &&
217       LVIOpt != clang::driver::options::ID::OPT_INVALID) {
218     D.Diag(diag::err_drv_argument_not_allowed_with)
219         << D.getOpts().getOptionName(SpectreOpt)
220         << D.getOpts().getOptionName(LVIOpt);
221   }
222 
223   // Now add any that the user explicitly requested on the command line,
224   // which may override the defaults.
225   for (const Arg *A : Args.filtered(options::OPT_m_x86_Features_Group,
226                                     options::OPT_mgeneral_regs_only)) {
227     StringRef Name = A->getOption().getName();
228     A->claim();
229 
230     // Skip over "-m".
231     assert(Name.startswith("m") && "Invalid feature name.");
232     Name = Name.substr(1);
233 
234     // Replace -mgeneral-regs-only with -x87, -mmx, -sse
235     if (A->getOption().getID() == options::OPT_mgeneral_regs_only) {
236       Features.insert(Features.end(), {"-x87", "-mmx", "-sse"});
237       continue;
238     }
239 
240     bool IsNegative = Name.startswith("no-");
241     if (IsNegative)
242       Name = Name.substr(3);
243     Features.push_back(Args.MakeArgString((IsNegative ? "-" : "+") + Name));
244   }
245 
246   // Enable/disable straight line speculation hardening.
247   if (Arg *A = Args.getLastArg(options::OPT_mharden_sls_EQ)) {
248     StringRef Scope = A->getValue();
249     if (Scope == "all") {
250       Features.push_back("+harden-sls-ijmp");
251       Features.push_back("+harden-sls-ret");
252     } else if (Scope == "return") {
253       Features.push_back("+harden-sls-ret");
254     } else if (Scope == "indirect-jmp") {
255       Features.push_back("+harden-sls-ijmp");
256     } else if (Scope != "none") {
257       D.Diag(diag::err_drv_unsupported_option_argument)
258           << A->getSpelling() << Scope;
259     }
260   }
261 }
262