https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88698
Bug ID: 88698
Summary: Relax generic vector conversions
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: husseydevin at gmail dot com
Target Milestone: ---
GCC is far too strict about vector conversions.
Currently, mixing generic vector extensions and platform-specific intrinsics
almost always requires either a cast or -flax-vector-extensions, which is
annoying and breaks a lot of things Clang happily accepts.
Here is my proposal:
* x86's __mNi should implicitly convert between any N-bit vector. This matches
the void pointer-like behavior of SSE's vectors.
* Any vector with equivalent lane types and number of lanes should convert
without an issue. For example, uint32_t vector_size(16) and NEON's uint32x4_t
have no reason not to be compatible.
* Signed <-> unsigned should act like other implicit signed <-> unsigned
conversions, -Wextra in C and warning in C++.
* Implicit conversions between different vectors of the same size should emit
an error.
