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FortranCInterface: Fix compatibility with GCC gfortran 12 LTO

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Since version 12.0 the GCC Fortran compiler has implemented "WG5/N1942",
which causes, if link-time opmization is enabled, obfuscation of hard-coded
string values in the compiler objects and its resulting ELF-binaries.

This causes the CMake-internal detection of the mangling scheme for the
naming of subroutines to fail.  Thus we must ensure to have any link-time
optimization features to be disabled on the executable file we perform the
detection on.

The static libraries, however, must be build with LTO and non-LTO objects,
as that will ensure the verify step will operate on IPO objects, if building
those is requested by the system compiler flags.

Fixes: #23123

Signed-off-by: Björn Esser <besser82@fedoraproject.org>
This commit is contained in:
Björn Esser
2022-01-19 17:26:14 +01:00
parent d79c40b1d5
commit 6a0ce19ce1
1 changed files with 13 additions and 0 deletions
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13
Modules/FortranCInterface/CMakeLists.txt
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@@ -102,6 +102,19 @@ set_property(TARGET symbols PROPERTY POSITION_INDEPENDENT_CODE 1)
add_executable(FortranCInterface main.F call_sub.f ${call_mod})
target_link_libraries(FortranCInterface PUBLIC symbols)
# If IPO is enabled here, GCC gfortran >= 12.0 will obfuscate
# the strings of the return values in the compiled executable,
# which we use to regex match against later.
# The static libraries must be build with IPO and non-IPO objects,
# as that will ensure the verify step will operate on IPO objects,
# if requested by the system compiler flags.
if(CMAKE_Fortran_COMPILER_ID STREQUAL "GNU" AND
CMAKE_Fortran_COMPILER_VERSION VERSION_GREATER_EQUAL 12)
target_compile_options(FortranCInterface PRIVATE "-fno-lto")
target_compile_options(myfort PRIVATE "-flto=auto" "-ffat-lto-objects")
target_compile_options(symbols PRIVATE "-flto=auto" "-ffat-lto-objects")
endif()
file(GENERATE OUTPUT exe-$<CONFIG>.cmake CONTENT [[
set(FortranCInterface_EXE "$<TARGET_FILE:FortranCInterface>")
]])