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linker: non-recursive version of get_symbols #2894

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Sep 4, 2018
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linker: non-recursive version of get_symbols #2894

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63 changes: 31 additions & 32 deletions src/linking/remove_internal_symbols.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -19,45 +19,44 @@ Author: Daniel Kroening

#include "static_lifetime_init.h"

void get_symbols_rec(
static void get_symbols(
const namespacet &ns,
const symbolt &symbol,
find_symbols_sett &dest)
{
dest.insert(symbol.name);
std::vector<const symbolt *> working_set;
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It would have used a forward_list, but it's probably ok.

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I like the density of the vector, and the fact that it won't actually do memory allocation once the working set has reached some size.

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Quick experiment: 14.7s vs. 16.2s, for total goto-cc time on a larger .c file, in favour of the vector.


find_symbols_sett new_symbols;
working_set.push_back(&symbol);

find_type_and_expr_symbols(symbol.type, new_symbols);
find_type_and_expr_symbols(symbol.value, new_symbols);

if(symbol.type.id()==ID_code)
while(!working_set.empty())
{
const code_typet &code_type=to_code_type(symbol.type);
const code_typet::parameterst &parameters=code_type.parameters();
const symbolt *s = working_set.back();
working_set.pop_back();
const symbolt &symbol = *s;

for(code_typet::parameterst::const_iterator
it=parameters.begin();
it!=parameters.end();
it++)
{
irep_idt id=it->get_identifier();
const symbolt *s;
// identifiers for prototypes need not exist
if(!ns.lookup(id, s))
new_symbols.insert(id);
}
}
if(!dest.insert(symbol.name).second)
continue;

for(find_symbols_sett::const_iterator
it=new_symbols.begin();
it!=new_symbols.end();
it++)
{
if(dest.find(*it)==dest.end())
find_symbols_sett new_symbols;

find_type_and_expr_symbols(symbol.type, new_symbols);
find_type_and_expr_symbols(symbol.value, new_symbols);

for(const auto &s : new_symbols)
working_set.push_back(&ns.lookup(s));

if(symbol.type.id() == ID_code)
{
dest.insert(*it);
get_symbols_rec(ns, ns.lookup(*it), dest); // recursive call
const code_typet &code_type = to_code_type(symbol.type);
const code_typet::parameterst &parameters = code_type.parameters();

for(const auto &p : parameters)
{
const symbolt *s;
// identifiers for prototypes need not exist
if(!ns.lookup(p.get_identifier(), s))
working_set.push_back(s);
}
}
}
}
Expand Down Expand Up @@ -105,7 +104,7 @@ void remove_internal_symbols(

if(special.find(symbol.name)!=special.end())
{
get_symbols_rec(ns, symbol, exported);
get_symbols(ns, symbol, exported);
continue;
}

Expand Down Expand Up @@ -135,7 +134,7 @@ void remove_internal_symbols(
// body? not local (i.e., "static")?
if(has_body &&
(!is_file_local || (config.main==symbol.name.c_str())))
get_symbols_rec(ns, symbol, exported);
get_symbols(ns, symbol, exported);
}
else
{
Expand All @@ -144,7 +143,7 @@ void remove_internal_symbols(
if((has_initializer || !symbol.is_extern) &&
!is_file_local)
{
get_symbols_rec(ns, symbol, exported);
get_symbols(ns, symbol, exported);
}
}
}
Expand Down