[Pipeline] Add preliminary stall lowering #5467
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| size_t nStageInputArgs = parent.pipeline.getNumStageArguments(block); | ||
| inputs = mod.getArguments().take_front(nStageInputArgs); | ||
| llvm::SmallVector<Value> stageExtInputs; | ||
| parent.getStageExtInputs(block, stageExtInputs); | ||
| extInputs = | ||
| mod.getArguments().slice(nStageInputArgs, stageExtInputs.size()); | ||
| valid = mod.getArgument(mod.getNumArguments() - 3); | ||
| valid = mod.getArgument(mod.getNumArguments() - (withStall ? 4 : 3)); |
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Please either break these magic numbers into well named constants or include inline comments.
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Or computing them dynamically by adding the variable length args together. Or by tracking them.
I've had trouble with assuming / recomputing offsets in the past (in the ESI port mapping code), so I refactored it to explicitly track them. Made the code much nicer.
| valid = mod.getArgument(mod.getNumArguments() - 3); | ||
| valid = mod.getArgument(mod.getNumArguments() - (withStall ? 4 : 3)); | ||
| if (withStall) | ||
| stall = mod.getArgument(mod.getNumArguments() - 3); | ||
| clock = mod.getArgument(mod.getNumArguments() - 2); | ||
| reset = mod.getArgument(mod.getNumArguments() - 1); |
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These assumed offsets make this lowering code brittle. Could you please break them out into well-named constants which are used everywhere in the lower in a subsequent "cleanup" PR?
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like 'resetOffsetFromEnd'?
And maybe add an assert that it's the expected value or type in places where you assemble an array?
Whenever I see magic numbers, I get concerned that future modifications will break this in a way not caught by a test.
I hate them just as much as you. Hoping to get #5473 in tree and then go back and fix these. |
mortbopet
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This commit adds preliminary stall lowering. Given the presence of a stall signal, every stage registers' clock enable value is now &'ed with the (pipeline) global stall signal.
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This commit adds preliminary stall lowering.
Given the presence of a stall signal, every stage registers' clock enable value is now &'ed with the (pipeline) global stall signal.