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4ee89e903d
This patch addresses slowness when setting breakpoints, especially in
heavily templatized code. Profiling showed that find_pc_sect_line in
symtab.c was the performance bottleneck. The original logic performed a
linear search over ordered data. This patch uses a binary search, as
suggested by comments around the function. There are no behavioural
changes, but gdb is now faster at setting breakpoints in template code.
Tested using on make check on an x86 target. The optimisation speeds up
the included template-breakpoints.py performance test by a factor of 7
on my machine.
ChangeLog:
2018-03-20 Stephen Roberts <stephen.roberts@arm.com>
* gdb/symtab.c (find_pc_sect_line): now uses binary search.
gdb/testsuite/
* gdb.perf/template-breakpoints.cc: New file.
* gdb.perf/template-breakpoints.exp: New file.
* gdb.perf/template-breakpoints.py: New file.
98 lines
2.2 KiB
C++
98 lines
2.2 KiB
C++
/* This testcase is part of GDB, the GNU debugger.
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Copyright (C) 2018 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <iostream>
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template <int I, int J, int K, int VAL>
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struct ThirdDimension
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{
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int
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value () const
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{
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ThirdDimension<I, J, K - 1, VAL> d3;
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return d3.value();
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}
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};
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template <int I, int J, int VAL>
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struct ThirdDimension<I, J, 0, VAL>
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{
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int
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value () const
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{
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// Please note - this testcase sets a breakpoint on the following line.
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// It is therefore sensitive to line numbers. If any changes are made to
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// this file, please ensure that the testcase is updated to reflect this.
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std::cout << "Value: " << VAL << std::endl;
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return VAL;
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}
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};
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template <int I, int J, int K, int VAL>
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struct SecondDimension
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{
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int
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value () const
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{
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SecondDimension<I, J - 1, K, VAL> d1;
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ThirdDimension<I, J, K, VAL> d2;
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return d1.value() + d2.value();
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}
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};
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template <int I, int K, int VAL>
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struct SecondDimension<I, 0, K, VAL>
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{
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int
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value () const
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{
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ThirdDimension<I, 0, K, VAL> d2;
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return d2.value();
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}
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};
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template <int I, int J, int K, int VAL>
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struct FirstDimension
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{
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int
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value () const
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{
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FirstDimension<I - 1, J, K, VAL> d1;
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SecondDimension<I, J, K, VAL> d2;
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return d1.value() + d2.value();
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}
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};
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template <int J, int K, int VAL>
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struct FirstDimension<0, J, K, VAL>
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{
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int
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value () const
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{
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SecondDimension<0, J, K, VAL> d2;
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return d2.value();
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}
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};
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int
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main (int argc, char *argv[])
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{
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FirstDimension<EXPANSION_DEPTH, EXPANSION_DEPTH, EXPANSION_DEPTH, 1> product;
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std::cout << product.value() << std::endl;
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return 0;
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}
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