1 //
2 // Copyright 2012-2016 Francisco Jerez
3 // Copyright 2012-2016 Advanced Micro Devices, Inc.
4 //
5 // Permission is hereby granted, free of charge, to any person obtaining a
6 // copy of this software and associated documentation files (the "Software"),
7 // to deal in the Software without restriction, including without limitation
8 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
9 // and/or sell copies of the Software, and to permit persons to whom the
10 // Software is furnished to do so, subject to the following conditions:
11 //
12 // The above copyright notice and this permission notice shall be included in
13 // all copies or substantial portions of the Software.
14 //
15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 // THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
19 // OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
20 // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
21 // OTHER DEALINGS IN THE SOFTWARE.
22 //
23
24 ///
25 /// \file
26 /// Generate code using an arbitrary LLVM back-end capable of emitting
27 /// executable code as an ELF object file.
28 ///
29
30 #include <llvm/Target/TargetMachine.h>
31 #include <llvm/Transforms/Utils/Cloning.h>
32
33 #include "llvm/codegen.hpp"
34 #include "llvm/compat.hpp"
35 #include "llvm/util.hpp"
36 #include "core/error.hpp"
37
38 using clover::binary;
39 using clover::build_error;
40 using namespace clover::llvm;
41 using ::llvm::TargetMachine;
42
43 #if defined(USE_LIBELF)
44
45 #include <libelf.h>
46 #include <gelf.h>
47
48 namespace {
49 namespace elf {
50 std::unique_ptr<Elf, int (*)(Elf *)>
get(const std::vector<char> & code)51 get(const std::vector<char> &code) {
52 // One of the libelf implementations
53 // (http://www.mr511.de/software/english.htm) requires calling
54 // elf_version() before elf_memory().
55 elf_version(EV_CURRENT);
56 return { elf_memory(const_cast<char *>(code.data()), code.size()),
57 elf_end };
58 }
59
60 Elf_Scn *
get_symbol_table(Elf * elf)61 get_symbol_table(Elf *elf) {
62 size_t section_str_index;
63 elf_getshdrstrndx(elf, §ion_str_index);
64
65 for (Elf_Scn *s = elf_nextscn(elf, NULL); s; s = elf_nextscn(elf, s)) {
66 GElf_Shdr header;
67 if (gelf_getshdr(s, &header) != &header)
68 return nullptr;
69
70 if (!std::strcmp(elf_strptr(elf, section_str_index, header.sh_name),
71 ".symtab"))
72 return s;
73 }
74
75 return nullptr;
76 }
77
78 std::map<std::string, unsigned>
get_symbol_offsets(Elf * elf,Elf_Scn * symtab)79 get_symbol_offsets(Elf *elf, Elf_Scn *symtab) {
80 Elf_Data *const symtab_data = elf_getdata(symtab, NULL);
81 GElf_Shdr header;
82 if (gelf_getshdr(symtab, &header) != &header)
83 return {};
84
85 std::map<std::string, unsigned> symbol_offsets;
86 GElf_Sym symbol;
87 unsigned i = 0;
88
89 while (GElf_Sym *s = gelf_getsym(symtab_data, i++, &symbol)) {
90 const char *name = elf_strptr(elf, header.sh_link, s->st_name);
91 symbol_offsets[name] = s->st_value;
92 }
93
94 return symbol_offsets;
95 }
96 }
97
98 std::map<std::string, unsigned>
get_symbol_offsets(const std::vector<char> & code,std::string & r_log)99 get_symbol_offsets(const std::vector<char> &code, std::string &r_log) {
100 const auto elf = elf::get(code);
101 const auto symtab = elf::get_symbol_table(elf.get());
102 if (!symtab)
103 fail(r_log, build_error(), "Unable to find symbol table.");
104
105 return elf::get_symbol_offsets(elf.get(), symtab);
106 }
107
108 std::vector<char>
emit_code(::llvm::Module & mod,const target & target,compat::CodeGenFileType ft,std::string & r_log)109 emit_code(::llvm::Module &mod, const target &target,
110 compat::CodeGenFileType ft,
111 std::string &r_log) {
112 std::string err;
113 auto t = ::llvm::TargetRegistry::lookupTarget(target.triple, err);
114 if (!t)
115 fail(r_log, build_error(), err);
116
117 std::unique_ptr<TargetMachine> tm {
118 t->createTargetMachine(target.triple, target.cpu, "", {},
119 #if LLVM_VERSION_MAJOR >= 16
120 std::nullopt, std::nullopt,
121 #else
122 ::llvm::None, ::llvm::None,
123 #endif
124 #if LLVM_VERSION_MAJOR >= 18
125 ::llvm::CodeGenOptLevel::Default) };
126 #else
127 ::llvm::CodeGenOpt::Default) };
128 #endif
129 if (!tm)
130 fail(r_log, build_error(),
131 "Could not create TargetMachine: " + target.triple);
132
133 ::llvm::SmallVector<char, 1024> data;
134
135 {
136 ::llvm::legacy::PassManager pm;
137 ::llvm::raw_svector_ostream os { data };
138
139 mod.setDataLayout(tm->createDataLayout());
140 tm->Options.MCOptions.AsmVerbose =
141 (ft == compat::CGFT_AssemblyFile);
142
143 if (tm->addPassesToEmitFile(pm, os, nullptr, ft))
144 fail(r_log, build_error(), "TargetMachine can't emit this file");
145
146 pm.run(mod);
147 }
148
149 return { data.begin(), data.end() };
150 }
151 }
152
153 binary
build_module_native(::llvm::Module & mod,const target & target,const clang::CompilerInstance & c,std::string & r_log)154 clover::llvm::build_module_native(::llvm::Module &mod, const target &target,
155 const clang::CompilerInstance &c,
156 std::string &r_log) {
157 const auto code = emit_code(mod, target,
158 compat::CGFT_ObjectFile, r_log);
159 return build_module_common(mod, code, get_symbol_offsets(code, r_log), c);
160 }
161
162 std::string
print_module_native(const::llvm::Module & mod,const target & target)163 clover::llvm::print_module_native(const ::llvm::Module &mod,
164 const target &target) {
165 std::string log;
166 try {
167 std::unique_ptr< ::llvm::Module> cmod { ::llvm::CloneModule(mod) };
168 return as_string(emit_code(*cmod, target,
169 compat::CGFT_AssemblyFile, log));
170 } catch (...) {
171 return "Couldn't output native disassembly: " + log;
172 }
173 }
174
175 #else
176
177 binary
build_module_native(::llvm::Module & mod,const target & target,const clang::CompilerInstance & c,std::string & r_log)178 clover::llvm::build_module_native(::llvm::Module &mod, const target &target,
179 const clang::CompilerInstance &c,
180 std::string &r_log) {
181 unreachable("Native codegen support disabled at build time");
182 }
183
184 std::string
print_module_native(const::llvm::Module & mod,const target & target)185 clover::llvm::print_module_native(const ::llvm::Module &mod,
186 const target &target) {
187 unreachable("Native codegen support disabled at build time");
188 }
189
190 #endif
191