* test/linker: Code factorisation and small tweaks
* linker: Do not fail when going over limits
The limits are minima and implementations or APIs might support higher
limits, so just warn the user about it. And only check for the limits
right before emitting the binary, as limits might change earlier when
removing duplicate instructions, function prototypes, etc.
The only check performed right before merging, is making sure the ID
bound will not overflow the 32 bits following the merge.
Also, use the defines for the limits instead of hard-coding them.
* linker: Require a memory model in each input module
The existing code could run into weird situation. For example, if the
first module had no memory model, it would not emit any memory model
(sort of reasonable) and would accept without complains all possible mix
from later modules as it would not verify them.
* linker: Replace hex version with SPV_SPIRV_VERSION_WORD
* linker: Error out when linking together different versions
Fixes https://github.com/KhronosGroup/SPIRV-Tools/issues/4135
* tools/linker: Do not write to disk if linking failed
Also, do not consider warnings as errors.
* tools/linker: Fix formatting in help message
* tools/linker: Further clarify the use of --target-env
Also update the text for the default version to reflect the change made
in 7d768812 ("Basic support for SPIR-V 1.6 (#4663)").
CPPreference.com has this description of digits10:
“The value of std::numeric_limits<T>::digits10 is the number of
base-10 digits that can be represented by the type T without change,
that is, any number with this many significant decimal digits can be
converted to a value of type T and back to decimal form, without
change due to rounding or overflow.”
This means that any number with this many digits can be represented
accurately in the corresponding type. A change in any digit in a
number after that may or may not cause it a different bitwise
representation. Therefore this isn’t necessarily enough precision to
accurately represent the value in text. Instead we need max_digits10
which has the following description:
“The value of std::numeric_limits<T>::max_digits10 is the number of
base-10 digits that are necessary to uniquely represent all distinct
values of the type T, such as necessary for
serialization/deserialization to text.”
The patch includes a test case in hex_float_test which tries to do a
round-robin conversion of a number that requires more than 6 decimal
places to be accurately represented. This would fail without the
patch.
Sadly this also breaks a bunch of other tests. Some of the tests in
hex_float_test use ldexp and then compare it with a value which is not
the same as the one returned by ldexp but instead is the value rounded
to 6 decimals. Others use values that are not evenly representable as
a binary floating fraction but then happened to generate the same
value when rounded to 6 decimals. Where the actual value didn’t seem
to matter these have been changed with different values that can be
represented as a binary fraction.
