[SYCL] Fix static_assert with -funsigned-char #17133
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hvdijk
changed the title
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ping, we are working on non-x86 target support, this is a blocker for AArch64 where |
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ping again, it's been two weeks now, could someone review this please? |
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ping again @intel/llvm-reviewers-runtime |
Sorry about the delay. Could you also rebase your PR over the latest SYCL branch? The CI results are quite old, rebasing would re-trigger the CI. |
The type of (ext_vector<int8_t, 2>{1, 0} == 0)[1] has type char, not
int8_t, and therefore depending on whether -funsigned-char is in effect
may either have the value -1 or have the value 255. Cast to int8_t to
ensure it always gets taken as signed. This is only needed for the
static_assert: the rest of the code already works for signed and
unsigned plain char alike.
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Sure, changed to |
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@intel/llvm-gatekeepers This is ready to be merged, thanks (Edit: ha, already merged just as I was posting this. thanks!) |
| static_assert( | ||
| static_cast<int8_t>((ext_vector<int8_t, 2>{1, 0} == 0)[1]) == -1); |
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I think a better fix would be to use the same expression here and in line 272 (whatever it would be). @hvdijk any thoughts on that?
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Ideally yes, but the below needs to construct a vector which cannot be done with static_cast (and also, ext_vector is not available on GCC, but that might not matter here), and the below reinterpret_cast makes the expression non-constant so it cannot be used in static_assert.
The type of (ext_vector<int8_t, 2>{1, 0} == 0)[1] has type char, not int8_t, and therefore depending on whether -funsigned-char is in effect may either have the value -1 or have the value 255. Cast to int8_t to ensure it always gets taken as signed. This is only needed for the static_assert: the rest of the code already works for signed and unsigned plain char alike.