[RFC] spirv-link: allow linking functions with different pointer arguments #5534
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Since llvm-17 there are no typed pointers and hte SPIRV-LLVM-Translator doesn't know the function signature of imported functions. I'm investigating different ways of solving this problem and adding an option to work around it inside `spirv-link` is one of those. The code is almost complete, just I'm having troubles constructing the bitcast to cast the pointer parameters to the final type.
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A few modifications to be made, commented in line.
New unit tests would also be needed:
- testing that a mismatch in pointers is not rejected when the flag is set,
- and is still rejected when it is not.
- Setting the flag still rejects a mismatch between a pointer and a non-pointer.
Otherwise, the change looks reasonable to me.
| @@ -815,21 +882,27 @@ spv_result_t Link(const Context& context, const uint32_t* const* binaries, | |||
| &linked_context); | |||
| if (res != SPV_SUCCESS) return res; | |||
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| // Phase 10: Compact the IDs used in the module | |||
| // Phase 10: Optionall fix function call types | |||
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| // Phase 10: Optionall fix function call types | |
| // Phase 10: Optional fix function call types |
| const auto& exported_param = exported_params[i]; | ||
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| if (!imported_param->IsSame(exported_param) && | ||
| imported_param->kind() != Type::kPointer && |
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| imported_param->kind() != Type::kPointer && | |
| !(imported_param->kind() == Type::kPointer && |
The previous code would result in correct == false for imported_param being a pointer, and exported_param being a structure (for example)
Maybe even change to !(imported_param->isSame(exported_param) || (imported_param->kind() == Type::kPointer && exported_param->kind() == Type::kPointer))
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| if (!imported_param->IsSame(exported_param) && | ||
| imported_param->kind() != Type::kPointer && | ||
| exported_param->kind() != Type::kPointer) { |
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| exported_param->kind() != Type::kPointer) { | |
| exported_param->kind() == Type::kPointer)) { |
| // - get target type id | ||
| // - insert instruction | ||
| // - replace operand | ||
| new Instruction(&context, spv::Op::OpBitcast, ..., 0u, {{SPV_OPERAND_TYPE_ID, arg.AsId()}}); |
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I do not think this will compile as-is, and a res_id of 0 seems wrong.
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yeah, that's why I put the comments on top because I was kinda stuck there
Since llvm-17 there are no typed pointers and hte SPIRV-LLVM-Translator doesn't know the function signature of imported functions.
I'm investigating different ways of solving this problem and adding an option to work around it inside
spirv-linkis one of those.The code is almost complete, just I'm having troubles constructing the bitcast to cast the pointer parameters to the final type.
If anybody here has any better ideas on how to fix this, please tell.
Some background:
Supporting this is useful for OpenCL implementations using SPIR-V binaries as the internal program representation and not using LLVM for backend compilation.
spirv-linkis used to link program objects together before handing it off into the backend compiler. It's just that llvm-17 dropping typed pointers broke several OpenCL C tests as constructing the extern function signature became impossible to do.