Prior to this change spv_ptrcast (and OpBitcast) was never emitted for
GEP resulting pointers. While such SPIR-V was (mostly) accepted by the
NEO GPU driver, the generated SPIR-V was incorrect.
The newly added test (pointers/getelementptr-bitcast-load.ll) verifies
that a correct bitcast is added for more complex cases and passes
spirv-val. The test is based on an OpenCL CTS test (basic/prefetch).
This commit adds 2 new instructions in the selector:
- OpAccessChain
- OpInBoundsAccessChain.
The choice between the two relies on the `inbounds` marker.
Those instruction are not used for OpenCL, to maintain the same
behavior as previously. They are only added when building for logical
SPIR-V, as it doesn't support the pointer equivalent.
Because logical SPIR-V doesn't support pointer cast either, the
assign_ptr_type intrinsic need to be generated so OpAccessChain gets
lowered with the correct pointer type, instead of i8*.
Fixes#66107
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Signed-off-by: Nathan Gauër <brioche@google.com>
