270 lines
8.0 KiB
C
270 lines
8.0 KiB
C
/* Routines required for instrumenting a program. */
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/* Compile this one with gcc. */
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/* Copyright (C) 1989-2020 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#include "libgcov.h"
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#if !defined(inhibit_libc)
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/* Detect whether target can support atomic update of profilers. */
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#if __SIZEOF_LONG_LONG__ == 4 && __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
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#define GCOV_SUPPORTS_ATOMIC 1
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#else
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#if __SIZEOF_LONG_LONG__ == 8 && __GCC_HAVE_SYNC_COMPARE_AND_SWAP_8
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#define GCOV_SUPPORTS_ATOMIC 1
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#else
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#define GCOV_SUPPORTS_ATOMIC 0
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#endif
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#endif
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#ifdef L_gcov_interval_profiler
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/* If VALUE is in interval <START, START + STEPS - 1>, then increases the
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corresponding counter in COUNTERS. If the VALUE is above or below
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the interval, COUNTERS[STEPS] or COUNTERS[STEPS + 1] is increased
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instead. */
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void
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__gcov_interval_profiler (gcov_type *counters, gcov_type value,
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int start, unsigned steps)
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{
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gcov_type delta = value - start;
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if (delta < 0)
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counters[steps + 1]++;
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else if (delta >= steps)
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counters[steps]++;
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else
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counters[delta]++;
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}
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#endif
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#if defined(L_gcov_interval_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
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/* If VALUE is in interval <START, START + STEPS - 1>, then increases the
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corresponding counter in COUNTERS. If the VALUE is above or below
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the interval, COUNTERS[STEPS] or COUNTERS[STEPS + 1] is increased
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instead. Function is thread-safe. */
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void
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__gcov_interval_profiler_atomic (gcov_type *counters, gcov_type value,
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int start, unsigned steps)
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{
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gcov_type delta = value - start;
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if (delta < 0)
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__atomic_fetch_add (&counters[steps + 1], 1, __ATOMIC_RELAXED);
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else if (delta >= steps)
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__atomic_fetch_add (&counters[steps], 1, __ATOMIC_RELAXED);
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else
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__atomic_fetch_add (&counters[delta], 1, __ATOMIC_RELAXED);
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}
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#endif
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#ifdef L_gcov_pow2_profiler
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/* If VALUE is a power of two, COUNTERS[1] is incremented. Otherwise
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COUNTERS[0] is incremented. */
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void
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__gcov_pow2_profiler (gcov_type *counters, gcov_type value)
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{
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if (value == 0 || (value & (value - 1)))
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counters[0]++;
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else
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counters[1]++;
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}
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#endif
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#if defined(L_gcov_pow2_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
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/* If VALUE is a power of two, COUNTERS[1] is incremented. Otherwise
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COUNTERS[0] is incremented. Function is thread-safe. */
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void
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__gcov_pow2_profiler_atomic (gcov_type *counters, gcov_type value)
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{
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if (value == 0 || (value & (value - 1)))
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__atomic_fetch_add (&counters[0], 1, __ATOMIC_RELAXED);
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else
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__atomic_fetch_add (&counters[1], 1, __ATOMIC_RELAXED);
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}
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#endif
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/* Tries to determine N most commons value among its inputs. */
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static inline void
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__gcov_topn_values_profiler_body (gcov_type *counters, gcov_type value,
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int use_atomic)
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{
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if (use_atomic)
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__atomic_fetch_add (&counters[0], 1, __ATOMIC_RELAXED);
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else
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counters[0]++;
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++counters;
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/* First try to find an existing value. */
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int empty_counter = -1;
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for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
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if (value == counters[2 * i])
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{
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if (use_atomic)
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__atomic_fetch_add (&counters[2 * i + 1], GCOV_TOPN_VALUES,
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__ATOMIC_RELAXED);
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else
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counters[2 * i + 1] += GCOV_TOPN_VALUES;
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return;
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}
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else if (counters[2 * i + 1] <= 0)
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empty_counter = i;
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/* Find an empty slot for a new value. */
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if (empty_counter != -1)
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{
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counters[2 * empty_counter] = value;
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counters[2 * empty_counter + 1] = GCOV_TOPN_VALUES;
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return;
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}
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/* We haven't found an empty slot, then decrement all
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counter values by one. */
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for (unsigned i = 0; i < GCOV_TOPN_VALUES; i++)
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if (use_atomic)
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__atomic_fetch_sub (&counters[2 * i + 1], 1, __ATOMIC_RELAXED);
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else
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counters[2 * i + 1]--;
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}
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#ifdef L_gcov_topn_values_profiler
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void
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__gcov_topn_values_profiler (gcov_type *counters, gcov_type value)
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{
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__gcov_topn_values_profiler_body (counters, value, 0);
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}
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#endif
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#if defined(L_gcov_topn_values_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
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/* Update one value profilers (COUNTERS) for a given VALUE.
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CAVEAT: Following function is not thread-safe, only total number
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of executions (COUNTERS[2]) is update with an atomic instruction.
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Problem is that one cannot atomically update two counters
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(COUNTERS[0] and COUNTERS[1]), for more information please read
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following email thread:
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https://gcc.gnu.org/ml/gcc-patches/2016-08/msg00024.html. */
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void
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__gcov_topn_values_profiler_atomic (gcov_type *counters, gcov_type value)
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{
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__gcov_topn_values_profiler_body (counters, value, 1);
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}
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#endif
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#ifdef L_gcov_indirect_call_profiler_v4
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/* These two variables are used to actually track caller and callee. Keep
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them in TLS memory so races are not common (they are written to often).
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The variables are set directly by GCC instrumented code, so declaration
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here must match one in tree-profile.c */
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#if defined(HAVE_CC_TLS) && !defined (USE_EMUTLS)
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__thread
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#endif
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struct indirect_call_tuple __gcov_indirect_call;
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/* By default, the C++ compiler will use function addresses in the
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vtable entries. Setting TARGET_VTABLE_USES_DESCRIPTORS to nonzero
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tells the compiler to use function descriptors instead. The value
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of this macro says how many words wide the descriptor is (normally 2).
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It is assumed that the address of a function descriptor may be treated
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as a pointer to a function. */
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/* Tries to determine the most common value among its inputs. */
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void
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__gcov_indirect_call_profiler_v4 (gcov_type value, void* cur_func)
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{
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/* If the C++ virtual tables contain function descriptors then one
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function may have multiple descriptors and we need to dereference
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the descriptors to see if they point to the same function. */
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if (cur_func == __gcov_indirect_call.callee
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|| (__LIBGCC_VTABLE_USES_DESCRIPTORS__
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&& *(void **) cur_func == *(void **) __gcov_indirect_call.callee))
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__gcov_topn_values_profiler_body (__gcov_indirect_call.counters, value, 0);
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__gcov_indirect_call.callee = NULL;
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}
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#endif
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#ifdef L_gcov_time_profiler
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/* Counter for first visit of each function. */
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gcov_type __gcov_time_profiler_counter ATTRIBUTE_HIDDEN;
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#endif
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#ifdef L_gcov_average_profiler
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/* Increase corresponding COUNTER by VALUE. FIXME: Perhaps we want
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to saturate up. */
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void
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__gcov_average_profiler (gcov_type *counters, gcov_type value)
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{
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counters[0] += value;
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counters[1] ++;
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}
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#endif
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#if defined(L_gcov_average_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
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/* Increase corresponding COUNTER by VALUE. FIXME: Perhaps we want
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to saturate up. Function is thread-safe. */
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void
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__gcov_average_profiler_atomic (gcov_type *counters, gcov_type value)
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{
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__atomic_fetch_add (&counters[0], value, __ATOMIC_RELAXED);
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__atomic_fetch_add (&counters[1], 1, __ATOMIC_RELAXED);
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}
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#endif
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#ifdef L_gcov_ior_profiler
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/* Bitwise-OR VALUE into COUNTER. */
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void
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__gcov_ior_profiler (gcov_type *counters, gcov_type value)
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{
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*counters |= value;
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}
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#endif
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#if defined(L_gcov_ior_profiler_atomic) && GCOV_SUPPORTS_ATOMIC
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/* Bitwise-OR VALUE into COUNTER. Function is thread-safe. */
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void
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__gcov_ior_profiler_atomic (gcov_type *counters, gcov_type value)
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{
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__atomic_fetch_or (&counters[0], value, __ATOMIC_RELAXED);
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}
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#endif
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#endif /* inhibit_libc */
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