reactos/sdk/tools/gcc_plugin_seh/main.cpp

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/*
* PROJECT: ReactOS SDK
* LICENSE: BSD Zero Clause License (https://spdx.org/licenses/0BSD)
* PURPOSE: Helper pragma implementation for pseh library (amd64)
* COPYRIGHT: Copyright 2021 Jérôme Gardou
* Copyright 2024 Timo Kreuzer <timo.kreuzer@reactos.org>
*/
#include <gcc-plugin.h>
#include <plugin-version.h>
#include <function.h>
#include <tree.h>
#include <c-family/c-pragma.h>
#include <c-family/c-common.h>
#include <iostream>
#include <sstream>
#include <unordered_map>
#include <vector>
#include <cstdio>
#if 0 // To enable tracing
#define trace(...) fprintf(stderr, __VA_ARGS__)
#else
#define trace(...)
#endif
#define is_alpha(c) (((c)>64 && (c)<91) || ((c)>96 && (c)<123))
#if defined(_WIN32) || defined(WIN32)
#define VISIBLE __declspec(dllexport)
#else
#define VISIBLE __attribute__((__visibility__("default")))
#endif
#define UNUSED __attribute__((__unused__))
int
VISIBLE
plugin_is_GPL_compatible = 1;
constexpr size_t k_header_statement_max_size = 20000;
struct seh_handler
{
bool is_except;
unsigned int line;
};
struct seh_function
{
bool unwind;
bool except;
tree asm_header_text;
tree asm_header;
size_t count;
std::vector<seh_handler> handlers;
seh_function(struct function* fun)
: unwind(false)
, except(false)
, count(0)
{
/* Reserve space for our header statement */
#if 0 // FIXME: crashes on older GCC
asm_header_text = build_string(k_header_statement_max_size, "");
#else
char buf[k_header_statement_max_size];
memset(buf, 0, sizeof(buf));
asm_header_text = build_string(sizeof(buf), buf);
#endif
asm_header = build_stmt(fun->function_start_locus, ASM_EXPR, asm_header_text, NULL_TREE, NULL_TREE, NULL_TREE, NULL_TREE);
ASM_VOLATILE_P(asm_header) = 1;
add_stmt(asm_header);
}
};
static std::unordered_map<struct function*, struct seh_function*> func_seh_map = {};
static
struct seh_function*
get_seh_function()
{
auto search = func_seh_map.find(cfun);
if (search != func_seh_map.end())
return search->second;
auto seh_fun = new seh_function(cfun);
func_seh_map.insert({cfun, seh_fun});
return seh_fun;
}
static
void
handle_seh_pragma(cpp_reader* UNUSED parser)
{
tree x, arg, line;
std::stringstream label_decl;
bool is_except;
if (!cfun)
{
error("%<#pragma REACTOS seh%> is not allowed outside functions");
return;
}
if ((pragma_lex(&x) != CPP_OPEN_PAREN) ||
(pragma_lex(&arg) != CPP_NAME) || // except or finally
(pragma_lex(&x) != CPP_COMMA) ||
(pragma_lex(&line) != CPP_NUMBER) || // Line number
(pragma_lex(&x) != CPP_CLOSE_PAREN) ||
(pragma_lex(&x) != CPP_EOF)
)
{
error("%<#pragma REACTOS seh%> needs two parameters%>");
return;
}
trace(stderr, "Pragma: %s, %u\n", IDENTIFIER_POINTER(arg), TREE_INT_CST_LOW(line));
const char* op = IDENTIFIER_POINTER(arg);
seh_function* seh_fun = get_seh_function();
if (strcmp(op, "__seh$$except") == 0)
{
is_except = true;
seh_fun->except = true;
}
else if (strcmp(op, "__seh$$finally") == 0)
{
is_except = false;
seh_fun->unwind = true;
}
else
{
error("Wrong argument for %<#pragma REACTOS seh%>. Expected \"except\" or \"finally\"");
return;
}
seh_fun->count++;
seh_fun->handlers.push_back({is_except, (unsigned int)TREE_INT_CST_LOW(line)});
/* Make sure we use a frame pointer. REACTOS' PSEH depends on this */
cfun->machine->accesses_prev_frame = 1;
}
static
void
finish_seh_function(void* event_data, void* UNUSED user_data)
{
tree fndef = (tree)event_data;
struct function* fun = DECL_STRUCT_FUNCTION(fndef);
auto search = func_seh_map.find(fun);
if (search == func_seh_map.end())
return;
/* Get our SEH details and remove us from the map */
seh_function* seh_fun = search->second;
func_seh_map.erase(search);
if (DECL_FUNCTION_PERSONALITY(fndef) != nullptr)
{
error("Function %s has a personality. Are you mixing SEH with C++ exceptions ?",
IDENTIFIER_POINTER(fndef));
return;
}
/* Update asm statement */
std::stringstream asm_str;
asm_str << ".seh_handler __C_specific_handler";
if (seh_fun->unwind)
asm_str << ", @unwind";
if (seh_fun->except)
asm_str << ", @except";
asm_str << "\n";
asm_str << "\t.seh_handlerdata\n";
asm_str << "\t.long " << seh_fun->count << "\n";
for (auto& handler : seh_fun->handlers)
{
asm_str << "\n\t.rva " << "__seh2$$begin_try__" << handler.line; /* Begin of tried code */
asm_str << "\n\t.rva " << "__seh2$$end_try__" << handler.line; /* End of tried code */
asm_str << "\n\t.rva " << "__seh2$$filter__" << handler.line; /* Filter function */
if (handler.is_except)
asm_str << "\n\t.rva " << "__seh2$$begin_except__" << handler.line; /* Called on except */
else
asm_str << "\n\t.long 0"; /* No unwind handler */
}
asm_str << "\n\t.seh_code\n";
strncpy(const_cast<char*>(TREE_STRING_POINTER(seh_fun->asm_header_text)),
asm_str.str().c_str(),
TREE_STRING_LENGTH(seh_fun->asm_header_text));
trace(stderr, "ASM: %s\n", asm_str.str().c_str());
delete seh_fun;
}
static
void
register_seh_pragmas(void* UNUSED event_data, void* UNUSED user_data)
{
c_register_pragma("REACTOS", "seh", handle_seh_pragma);
}
/* Return 0 on success or error code on failure */
extern "C"
VISIBLE
int plugin_init(struct plugin_name_args *info, /* Argument infor */
struct plugin_gcc_version *version) /* Version of GCC */
{
if (!plugin_default_version_check (version, &gcc_version))
{
std::cerr << "This GCC plugin is for version " << GCCPLUGIN_VERSION_MAJOR << "." << GCCPLUGIN_VERSION_MINOR << "\n";
return 1;
}
register_callback(info->base_name, PLUGIN_PRAGMAS, register_seh_pragmas, NULL);
register_callback(info->base_name, PLUGIN_FINISH_PARSE_FUNCTION, finish_seh_function, NULL);
return 0;
}