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https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9012 91177308-0d34-0410-b5e6-96231b3b80d8
71 lines
2.6 KiB
C++
71 lines
2.6 KiB
C++
//===-- Intercept.cpp - System function interception routines -------------===//
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//
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// If a function call occurs to an external function, the JIT is designed to use
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// the dynamic loader interface to find a function to call. This is useful for
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// calling system calls and library functions that are not available in LLVM.
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// Some system calls, however, need to be handled specially. For this reason,
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// we intercept some of them here and use our own stubs to handle them.
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//
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//===----------------------------------------------------------------------===//
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#include "VM.h"
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#include "Support/DynamicLinker.h"
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#include <iostream>
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// AtExitHandlers - List of functions to call when the program exits,
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// registered with the atexit() library function.
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static std::vector<void (*)()> AtExitHandlers;
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/// runAtExitHandlers - Run any functions registered by the program's
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/// calls to atexit(3), which we intercept and store in
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/// AtExitHandlers.
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///
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void VM::runAtExitHandlers() {
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while (!AtExitHandlers.empty()) {
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void (*Fn)() = AtExitHandlers.back();
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AtExitHandlers.pop_back();
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Fn();
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}
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}
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//===----------------------------------------------------------------------===//
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// Function stubs that are invoked instead of certain library calls
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//===----------------------------------------------------------------------===//
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// NoopFn - Used if we have nothing else to call...
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static void NoopFn() {}
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// jit_exit - Used to intercept the "exit" library call.
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static void jit_exit(int Status) {
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VM::runAtExitHandlers(); // Run atexit handlers...
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exit(Status);
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}
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// jit_atexit - Used to intercept the "atexit" library call.
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static int jit_atexit(void (*Fn)(void)) {
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AtExitHandlers.push_back(Fn); // Take note of atexit handler...
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return 0; // Always successful
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}
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//===----------------------------------------------------------------------===//
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//
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/// getPointerToNamedFunction - This method returns the address of the specified
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/// function by using the dynamic loader interface. As such it is only useful
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/// for resolving library symbols, not code generated symbols.
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///
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void *VM::getPointerToNamedFunction(const std::string &Name) {
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// Check to see if this is one of the functions we want to intercept...
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if (Name == "exit") return (void*)&jit_exit;
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if (Name == "atexit") return (void*)&jit_atexit;
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// If it's an external function, look it up in the process image...
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void *Ptr = GetAddressOfSymbol(Name);
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if (Ptr == 0) {
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std::cerr << "WARNING: Cannot resolve fn '" << Name
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<< "' using a dummy noop function instead!\n";
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Ptr = (void*)NoopFn;
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}
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return Ptr;
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}
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