libstdc++ "freestanding" ('--disable-hosted-libstdcxx') with '-fno-rtti', '-fno-exceptions': 'libstdc++-v3/libsupc++/eh_alloc.cc' global constructors

[Thomas Schwinge <thomas@codesourcery.com>]

Hi!

In context of <https://gcc.gnu.org/PR101544> '[OpenMP][AMDGCN][nvptx]
C++ offloading: unresolved _Znwm = "operator new(unsigned long)"'
I'm looking into building GCN, nvptx offloading libstdc++ "freestanding"
('--disable-hosted-libstdcxx') with '-fno-rtti', '-fno-exceptions'.
(I've basically got these things wired up; details to be shared later.)

For nvptx, I'm running into:

    In function ‘(static initializers for [...]/libstdc++-v3/libsupc++/eh_alloc.cc)’:
    cc1plus: sorry, unimplemented: global constructors not supported on this target
    make[4]: *** [Makefile:777: eh_alloc.lo] Error 1

... because, indeed, "global constructors not supported" for nvptx at
this time.  This may change, but I'd first like to get clarified
conceptually to which extent 'libstdc++-v3/libsupc++/eh_alloc.cc' is
actually relevant for such a libstdc++ configuration, and/or whether this
should be expected to compile fine already?  Do certain things simply
need to be '#if'-conditionalized, or similar, for example?  I've not yet
looked into the details; hoping that's maybe easy for you to answer?


Grüße
 Thomas
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