This PR fixes https://github.com/llvm/llvm-project/issues/124703:
* added a new API call `SPIRVTranslate` that is to replace entirely old
`SPIRVTranslateModule` after existing clients switch into the new
function;
* the new `SPIRVTranslate` doesn't require option parsing, replacing the
`Opts` argument with explicit `CodeGenOptLevel` and `Triple` arguments;
* the old `SPIRVTranslateModule` call is a wrapper for `SPIRVTranslate`,
it doesn't require option parsing either and doesn't hold any logic
inside except for converting string options into `CodeGenOptLevel` and
`Triple` arguments;
* usage of the extensions list is reworked to avoid writes to the global
cl::opt variable `lib/Target/SPIRV/SPIRVSubtarget.cpp::Extensions` --
instead a new class member in SPIRVSubtarget.cpp is implemented that
allows to replace supported extensions after SPIRVSubtarget.cpp is
created;
* both API calls don't require option parsing and don't write to global
cl::opt variables.
Other related/required changes:
* SPIRV::Capability::Shader is marked as an capability of lesser
priority for OpenCL environment (to remediate absence of the
"avoid-spirv-capabilities" command line option in API calls);
* unit tests are updated and extended to cover testing of a newer API
call;
* old API call is marked with TODO to remove it after existing clients
switch into the new function.
Adding SPIRV to LLVM_ALL_TARGETS
(https://github.com/llvm/llvm-project/pull/119653) revealed a series of
minor compilation problems and sanitizer complaints. This PR is to move
unit tests resources (a Module ptr) from the class-scope to a local
scope of the class member function to be sure that before the test env
is teared down the ptr is released.
Following discussions in #110443, and the following earlier discussions
in https://lists.llvm.org/pipermail/llvm-dev/2017-October/117907.html,
https://reviews.llvm.org/D38482, https://reviews.llvm.org/D38489, this
PR attempts to overhaul the `TargetMachine` and `LLVMTargetMachine`
interface classes. More specifically:
1. Makes `TargetMachine` the only class implemented under
`TargetMachine.h` in the `Target` library.
2. `TargetMachine` contains target-specific interface functions that
relate to IR/CodeGen/MC constructs, whereas before (at least on paper)
it was supposed to have only IR/MC constructs. Any Target that doesn't
want to use the independent code generator simply does not implement
them, and returns either `false` or `nullptr`.
3. Renames `LLVMTargetMachine` to `CodeGenCommonTMImpl`. This renaming
aims to make the purpose of `LLVMTargetMachine` clearer. Its interface
was moved under the CodeGen library, to further emphasis its usage in
Targets that use CodeGen directly.
4. Makes `TargetMachine` the only interface used across LLVM and its
projects. With these changes, `CodeGenCommonTMImpl` is simply a set of
shared function implementations of `TargetMachine`, and CodeGen users
don't need to static cast to `LLVMTargetMachine` every time they need a
CodeGen-specific feature of the `TargetMachine`.
5. More importantly, does not change any requirements regarding library
linking.
cc @arsenm @aeubanks
The goal of this PR is to facilitate integration of SPIRV Backend into
misc 3rd party tools and libraries by means of exposing an API call that
translate LLVM module to SPIR-V and write results into a string as
binary SPIR-V output, providing diagnostics on fail and means of
configuring translation in a style of command line options.
An example of a use case may be Khronos Translator that provides
bidirectional translation LLVM IR <=> SPIR-V, where LLVM IR => SPIR-V
step may be substituted by the call to SPIR-V Backend API, implemented
by this PR.
