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This patch adds an experimental stage named MicroOpQueueStage. MicroOpQueueStage can be used to simulate a hardware micro-op queue (basically, a decoupling queue between 'decode' and 'dispatch'). Users can specify a queue size, as well as a optional MaxIPC (which - in the absence of a "Decoders" stage - can be used to simulate a different throughput from the decoders). This stage is added to the default pipeline between the EntryStage and the DispatchStage only if PipelineOption::MicroOpQueue is different than zero. By default, llvm-mca sets PipelineOption::MicroOpQueue to the value of hidden flag -micro-op-queue-size. Throughput from the decoder can be simulated via another hidden flag named -decoder-throughput. That flag allows us to quickly experiment with different frontend throughputs. For targets that declare a loop buffer, flag -decoder-throughput allows users to do multiple runs, each time simulating a different throughput from the decoders. This stage can/will be extended in future. For example, we could add a "buffer full" event to notify bottlenecks caused by backpressure. flag -decoder-throughput would probably go away if in future we delegate to another stage (DecoderStage?) the simulation of a (potentially variable) throughput from the decoders. For now, flag -decoder-throughput is "good enough" to run some simple experiments. Differential Revision: https://reviews.llvm.org/D59928 llvm-svn: 357248 |
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| .. | ||
| HardwareUnits | ||
| Stages | ||
| CMakeLists.txt | ||
| Context.cpp | ||
| HWEventListener.cpp | ||
| InstrBuilder.cpp | ||
| Instruction.cpp | ||
| LLVMBuild.txt | ||
| Pipeline.cpp | ||
| Support.cpp | ||