Add -fexcess-precision=standard so gcc inserts ISO C99 conformant
rounding at assignments, casts, and returns — without it, double values
on x87 happily stay at 80-bit extended precision across operations and
diverge from the SSE/x86_64 behavior, making strict equality comparisons
architecture-dependent.
The flag doesn't fully cover x87: per gcc PR#323
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=323), a function return
value carried in ST(0) can arrive at the caller still at 80-bit, so a
double that ought to compare equal to a same-magnitude literal picks up
extra mantissa bits and doesn't. Wrap fp_equal in volatile-double
temporaries to force a memory roundtrip — the only operation that
reliably truncates on x87 — so its callers get consistent results
regardless of how the operands were produced.
Add a TEST(fp_equal) case that exercises the previously-broken pattern:
a runtime 1.0/10.0 computed inside a noinline helper, returned across
the function ABI boundary, then compared against the literal 0.1.
Without the volatile truncation this assertion fails on 32-bit gcc.
exp10() has a symbol version > 2.34 on latest glibc. To allow
dropping our baseline required glibc runtime version to <= 2.34,
let's add our own version to prevent pulling in the newer symbol
from glibc.
Let's not leak details from src/shared and src/libsystemd into
src/basic, even though you can't actually do anything useful with
just forward declarations from src/shared.
The sd-forward.h header is put in src/libsystemd/sd-common as we
don't have a directory for shared internal headers for libsystemd
yet.
Let's also rename forward.h to basic-forward.h to keep things
self-explanatory.
Daan De Meyer
Daan De Meyer
Yu Watanabe