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Performance improvement and cleanup of local bitvector analysis #6528

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Merged
merged 3 commits into from
Dec 15, 2021
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Performance improvement and cleanup of local bitvector analysis #6528

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38604cf
Local bitvector analysis: reduce number of node visits
tautschnig Dec 15, 2021
472a393
local_bitvector_analysist::merge: use bitwise or
tautschnig Dec 15, 2021
8834dc5
Local bitvector analysis: cleanup improver use of unsigned
tautschnig Dec 15, 2021
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21 changes: 9 additions & 12 deletions src/analyses/local_bitvector_analysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -45,10 +45,7 @@ bool local_bitvector_analysist::merge(points_tot &a, points_tot &b)
std::max(a.size(), b.size());

for(std::size_t i=0; i<max_index; i++)
{
if(a[i].merge(b[i]))
result=true;
}
result |= a[i].merge(b[i]);
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I would add a comment that the bitwise or is used instead of the logical or to prevent the short-circuit semantics.


return result;
}
Expand All @@ -73,7 +70,7 @@ void local_bitvector_analysist::assign_lhs(

if(is_tracked(identifier))
{
unsigned dest_pointer=pointers.number(identifier);
const auto dest_pointer = pointers.number(identifier);
flagst rhs_flags=get_rec(rhs, loc_info_src);
loc_info_dest[dest_pointer]=rhs_flags;
}
Expand Down Expand Up @@ -128,7 +125,7 @@ local_bitvector_analysist::flagst local_bitvector_analysist::get_rec(
const irep_idt &identifier=to_symbol_expr(rhs).get_identifier();
if(is_tracked(identifier))
{
unsigned src_pointer=pointers.number(identifier);
const auto src_pointer = pointers.number(identifier);
return loc_info_src[src_pointer];
}
else
Expand Down Expand Up @@ -242,8 +239,8 @@ void local_bitvector_analysist::build()
if(cfg.nodes.empty())
return;

work_queuet work_queue;
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This one has a friend who would also like to become a set:

cbmc/src/analyses/local_may_alias.h

Line 61 in eeddb3f

typedef std::stack<local_cfgt::node_nrt> work_queuet;

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Good call, I'll do so in a follow-up PR.

work_queue.push(0);
std::set<local_cfgt::node_nrt> work_queue;
work_queue.insert(0);

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Queues are usually ordered (especially in the UK). Is the set really helping performance, and if so, I'd rename it to "work_set".

loc_infos.resize(cfg.nodes.size());

Expand All @@ -258,10 +255,10 @@ void local_bitvector_analysist::build()

while(!work_queue.empty())
{
unsigned loc_nr=work_queue.top();
const auto loc_nr = *work_queue.begin();
const local_cfgt::nodet &node=cfg.nodes[loc_nr];
const goto_programt::instructiont &instruction=*node.t;
work_queue.pop();
work_queue.erase(work_queue.begin());

auto &loc_info_src=loc_infos[loc_nr];
auto loc_info_dest=loc_infos[loc_nr];
Expand Down Expand Up @@ -338,7 +335,7 @@ void local_bitvector_analysist::build()
{
assert(succ<loc_infos.size());
if(merge(loc_infos[succ], (loc_info_dest)))
work_queue.push(succ);
work_queue.insert(succ);
}
}
}
Expand All @@ -348,7 +345,7 @@ void local_bitvector_analysist::output(
const goto_functiont &goto_function,
const namespacet &ns) const
{
unsigned l=0;
std::size_t l = 0;

for(const auto &instruction : goto_function.body.instructions)
{
Expand Down
4 changes: 0 additions & 4 deletions src/analyses/local_bitvector_analysis.h
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Expand Up @@ -12,8 +12,6 @@ Author: Daniel Kroening, [email protected]
#ifndef CPROVER_ANALYSES_LOCAL_BITVECTOR_ANALYSIS_H
#define CPROVER_ANALYSES_LOCAL_BITVECTOR_ANALYSIS_H

#include <stack>

#include <util/expanding_vector.h>
#include <util/numbering.h>

Expand Down Expand Up @@ -182,8 +180,6 @@ class local_bitvector_analysist
const namespacet &ns;
void build();

typedef std::stack<unsigned> work_queuet;

numberingt<irep_idt> pointers;

// pointers -> flagst
Expand Down