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https://github.com/vtil-project/VTIL-Core
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71 lines
2.7 KiB
C++
71 lines
2.7 KiB
C++
// Copyright (c) 2020 Can Boluk and contributors of the VTIL Project
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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// 3. Neither the name of VTIL Project nor the names of its contributors
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// may be used to endorse or promote products derived from this software
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// without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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#include "istack_ref_substitution_pass.hpp"
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namespace vtil::optimizer
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{
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// Implement the pass.
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//
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size_t istack_ref_substitution_pass::pass( basic_block* blk, bool xblock )
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{
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size_t counter = 0;
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cached_tracer ctrace = {};
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// For each instruction:
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//
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for ( auto it = blk->begin(); !it.is_end(); it++ )
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{
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// Skip volatile instructions.
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//
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if ( it->is_volatile() ) continue;
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// Filter to instructions that operate with non-sp based pointers.
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//
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if ( it->base->accesses_memory() && !it->memory_location().first.is_stack_pointer() )
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{
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// Try to simplify pointer to SP + C.
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//
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auto delta = ctrace( { it, it->memory_location().first } ) - ctrace( { it, REG_SP } );
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// If successful, replace the operands.
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//
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if ( auto stack_offset = delta.get<int64_t>() )
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{
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( +it )->operands[ it->base->memory_operand_index ] = { REG_SP };
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( +it )->operands[ it->base->memory_operand_index + 1 ].imm().i64 += *stack_offset;
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// Validate modification and increment counter.
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//
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it->is_valid( true );
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counter++;
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}
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}
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}
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return counter;
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}
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}
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