[FIRRTL] Actually copy the leading part of the path in LowerClasses. #7130
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This turns the multiple-instantiation error into a warning in ResolvePaths and LowerClasses. In real designs coming from Chisel today, we are not yet able to enforce single instantiation. This was never a requirement of the original way that we handled hierarchical paths in EmitOMIR, so this removes the requirement for now. Adding it back is tracked in #7128. With this change, the ResolvePaths logic was simplified to stop trying to disambiguate paths in some cases, and instead allow the annotations to simply convey the user's requested local or hierarchical path. In LowerClasses, if there are multiple instances, this means we have ambiguity. In practice, this logic will produce the same outputs as EmitOMIR, once we fix #7125.
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This is orthogonal to, but stacked on #7129. |
mikeurbach
commented
Jun 4, 2024
| InstanceRecord *inst = *node->usesBegin(); | ||
| path.push_back( | ||
| OpAnnoTarget(inst->getInstance<InstanceOp>()) | ||
| .getNLAReference(namespaces[inst->getParent()->getModule()])); |
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We need to use the inner symbol namespace here from the current instances parent, so we can't use moduleNamespace, since that's not the right namespace. This is why I added the full inner symbol namespace collection as an instance variable. I think this should be safe, but wanted to call it out.
mikeurbach
commented
Jun 4, 2024
| // Copy the leading part of the hierarchical path from the owning module | ||
| // to the start of the annotation's NLA. | ||
| InstanceGraphNode *node = instanceGraph.lookup(moduleName); | ||
| while (true) { |
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In this patch, I have just added a fresh instance graph walk up for each hierpath op. We could coordinate this with the walk in getOrComputeAltBasePath, but then we'd need to update the state to cache the array of paths as well. In large designs, I didn't observe any noticeable performance regression from this.
We stated in a comment that we copy the leading part of the hierarchical path from the owning module to the start of the annotation's NLA. But we never actually did that, so this adds (back) that logic. Fixes #7125.
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We stated in a comment that we copy the leading part of the hierarchical path from the owning module to the start of the annotation's NLA. But we never actually did that, so this adds (back) that logic.
Fixes #7125.