https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77378
Bug ID: 77378
Summary: [7 Regression] tree-profile and libgcov assume long
long atomic operations are supported
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Keywords: link-failure
Severity: normal
Priority: P3
Component: gcov-profile
Assignee: unassigned at gcc dot gnu.org
Reporter: dje at gcc dot gnu.org
Target Milestone: ---
Target: powerpc*-*-*
The "Various GCOV/PGO improvements" in August 2016 implicitly assume that 64
bit atomic operations are supported in 32 bit mode.
tree-profile.c:
/* __atomic_fetch_add (&counter, 1, MEMMODEL_RELAXED); */
tree addr = tree_coverage_counter_addr (GCOV_COUNTER_ARCS, edgeno);
tree f = builtin_decl_explicit (LONG_LONG_TYPE_SIZE > 32
? BUILT_IN_ATOMIC_FETCH_ADD_8:
BUILT_IN_ATOMIC_FETCH_ADD_4);
libgcov.h:
#if LONG_LONG_TYPE_SIZE > 32
typedef signed gcov_type __attribute__ ((mode (DI)));
typedef unsigned gcov_type_unsigned __attribute__ ((mode (DI)));
#else
typedef signed gcov_type __attribute__ ((mode (SI)));
typedef unsigned gcov_type_unsigned __attribute__ ((mode (SI)));
#endif
libgcov-profiler.c:
__atomic_fetch_add (...)
LONG_LONG_TYPE_SIZE is defined as 64 on PPC32 (both PPC32 Linux and AIX), but
64 bit atomic operations are not supported. GCC emits libcalls, but no library
provides the definition, so profiled programs fail to link.
