Remove old processor detection code on Power #5547
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Signed-off-by: Harry Yu <harryyu1994@gmail.com>
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@fjeremic This is similar to what I had done to Z. I figured you can easily review and merge this one. |
aviansie-ben
approved these changes
Sep 15, 2020
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@genie-omr build plinux,aix |
harryyu1994
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Sep 23, 2020
Summary of changes:
- Retire old version cpu detection code on Power
- Move `CPU::getProcessorDescription()` to base J9CPU class as the 3 platforms (X, Z, Power) share the same code. There is no need to have 3 copies
- Reasons for the removal:
- We kept the old version because we wanted to make sure new version and old version give us the same behaviour
- Now it's been a few month and we don't see any bugs with the new version there's no reason to keep the old version
- Also we want to prevent developers from using the old version.
Old design
- Initializes the `TR_Processor` struct via j9port library
- Initialization occurs in `TR_J9VM::initializeProcessorType()`
- obtain cpu information using `CPU::TO_PORTLIB_getJ9ProcessorDesc()`
- `TR::Compiler->target.cpu.setProcessor` to set processor
- Fields and methods associated with the old design live in `Class CPU`
- Common APIs:
- `CPU::TO_PORTLIB_getJ9ProcessorDesc()`
- `j9sysinfo_processor_has_feature(processorDesc, feature)` (j9port library API)
- `CPU::id()`
- `CPU::setProcessor(TR_Processor)`
New design
- Initializes the `OMRProcessorDesc` struct via omrport library
- `CPU::detect()` to initialize `OMRProcessorDesc processorDescription`
- `CPU::applyUserOptions()` to apply any debug options after initialization
- `TR::Compiler->target.cpu` singleton variable that holds the CPU instance
- `comp()->target().cpu` per compilation variable which is used for cross-cpu compilation support
- For JIT we initialize `comp()->target().cpu` with `TR::Compiler->target.cpu` (Host CPU)
- For AOT we initialize `comp()->target().cpu` with `TR::Compiler->relocatableTarget.cpu` (Portable CPU)
- Fields and methods associated with the new design live in `Class CPU`
- Common APIs:
- `CPU::supportsFeature(feature)`
- `CPU::isAtLeast(OMRProcessorArchitecture)`
- Benefits:
- Common to all 3 platforms
- Simpler interface
- Cross-CPU compilation support (Use one cpu for AOT and another for JIT)
- The implementation for the new design is first introduced here eclipse-omr/omr#5197 and eclipse-openj9#9571
issue: eclipse-omr/omr#4339
depends on: eclipse-omr/omr#5547
Signed-off-by: Harry Yu <harryyu1994@gmail.com>
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Signed-off-by: Harry Yu harryyu1994@gmail.com