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Use DWARF unwinding with Clang to avoid overproduction of linking warnings with clang + gfortran #18

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Use DWARF unwinding with Clang to avoid overproduction of linking warnings with clang + gfortran #18

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fef6cae
Use DWARF unwinding with Clang to avoid overproduction of linking
GiudGiud Jan 13, 2025
ac33154
Add a linking test before adding linking flags to disable compact unw…
GiudGiud Jan 30, 2025
a5196d0
Fix linking test
GiudGiud Jan 31, 2025
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30 changes: 27 additions & 3 deletions acsm_compiler_flags.m4
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Original file line number Diff line number Diff line change
Expand Up @@ -594,6 +594,30 @@ AC_DEFUN([ACSM_SET_CXX_FLAGS],
ACSM_CXXFLAGS_DBG="$ACSM_CXXFLAGS_DBG -Wunused-parameter -Wunused -Wpointer-arith -Wformat -Wparentheses -Qunused-arguments -Woverloaded-virtual -fno-limit-debug-info"
ACSM_NODEPRECATEDFLAG="-Wno-deprecated"

dnl On Darwin with clang + gfortran, we get very many warnings for compact unwinding issues
dnl We deliberately keep relying on the less performant dwarf unwinding until the over-production of warnings is solved.
old_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="${CXXFLAGS} -femit-dwarf-unwind=always -Wl,-keep_dwarf_unwind -Wl,-no_compact_unwind "

AC_LINK_IFELSE([
AC_LANG_SOURCE(
[[int main() { return 0; }]]
)],[
AC_MSG_RESULT(<<< Disabling compact unwinding and retaining dwarf unwinding for gfortran compatibility >>>)
dnl Ideally we would be passing this as a fortran flag.
ACSM_CXXFLAGS_OPT+=" -femit-dwarf-unwind=always -Wl,-keep_dwarf_unwind -Wl,-no_compact_unwind "
ACSM_CXXFLAGS_DEVEL+=" -femit-dwarf-unwind=always -Wl,-keep_dwarf_unwind -Wl,-no_compact_unwind "
ACSM_CXXFLAGS_DBG+=" -femit-dwarf-unwind=always -Wl,-keep_dwarf_unwind -Wl,-no_compact_unwind "
ACSM_CFLAGS_OPT+=" -femit-dwarf-unwind=always -Wl,-keep_dwarf_unwind -Wl,-no_compact_unwind "
dnl CFLAGS_OPT are copied into _DEVEL and _DBG
],[
AC_MSG_RESULT(<<< Compact unwinding enabled >>>)
dnl Failed to link with new flags, do not add them
])
dnl Reset to old flags in case for any potential other test
CXXFLAGS="$old_CXXFLAGS"
AC_OUTPUT

dnl -ftrapping-math is only supported with
dnl clang 10 and newer.
dnl
Expand All @@ -617,9 +641,9 @@ AC_DEFUN([ACSM_SET_CXX_FLAGS],
ACSM_PARANOID_FLAGS="$ACSM_PARANOID_FLAGS -Wunused-parameter -Wunused-value -Wvariadic-macros"
ACSM_PARANOID_FLAGS="$ACSM_PARANOID_FLAGS -Wvolatile-register-var -Wwrite-strings"

ACSM_CFLAGS_OPT="-O2 -Qunused-arguments -Wunused"
ACSM_CFLAGS_DEVEL="$ACSM_CFLAGS_OPT -g -Wimplicit -fno-limit-debug-info -Wunused"
ACSM_CFLAGS_DBG="-g -Wimplicit -Qunused-arguments -fno-limit-debug-info -Wunused"
ACSM_CFLAGS_OPT+="-O2 -Qunused-arguments -Wunused"
ACSM_CFLAGS_DEVEL+="$ACSM_CFLAGS_OPT -g -Wimplicit -fno-limit-debug-info -Wunused"
ACSM_CFLAGS_DBG+="-g -Wimplicit -Qunused-arguments -fno-limit-debug-info -Wunused"
],

dnl default case
Expand Down