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https://github.com/c64scene-ar/llvm-6502.git
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eb5a93b86b
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6052 91177308-0d34-0410-b5e6-96231b3b80d8
54 lines
1.7 KiB
C++
54 lines
1.7 KiB
C++
//===-- Callback.cpp - Trap handler for function resolution ---------------===//
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//
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// This file defines the SIGSEGV handler which is invoked when a reference to a
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// non-codegen'd function is found.
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//
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//===----------------------------------------------------------------------===//
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#include "VM.h"
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#include "Support/Statistic.h"
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#include <iostream>
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static VM *TheVM = 0;
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// CompilationCallback - Invoked the first time that a call site is found,
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// which causes lazy compilation of the target function.
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//
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void VM::CompilationCallback() {
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#if defined(i386) || defined(__i386__) || defined(__x86__)
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unsigned *StackPtr = (unsigned*)__builtin_frame_address(0);
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unsigned RetAddr = (unsigned)__builtin_return_address(0);
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assert(StackPtr[1] == RetAddr &&
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"Could not find return address on the stack!");
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// The call instruction should have pushed the return value onto the stack...
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RetAddr -= 4; // Backtrack to the reference itself...
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DEBUG(std::cerr << "In callback! Addr=0x" << std::hex << RetAddr
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<< " ESP=0x" << (unsigned)StackPtr << std::dec
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<< ": Resolving call to function: "
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<< TheVM->getFunctionReferencedName((void*)RetAddr) << "\n");
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// Sanity check to make sure this really is a call instruction...
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assert(((unsigned char*)RetAddr)[-1] == 0xE8 && "Not a call instr!");
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unsigned NewVal = (unsigned)TheVM->resolveFunctionReference((void*)RetAddr);
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// Rewrite the call target... so that we don't fault every time we execute
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// the call.
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*(unsigned*)RetAddr = NewVal-RetAddr-4;
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// Change the return address to reexecute the call instruction...
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StackPtr[1] -= 5;
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#else
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abort();
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#endif
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}
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void VM::registerCallback() {
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TheVM = this;
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}
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