Reapply [Assignment Tracking][5/*] Add core infrastructure for instruction reference
Previously reverted in
41f5a0004e442ae71c8e754fdadb4bd1e172fb2d. Fold in
D133576 previously reverted in
d29d5ffb6332569e85d5eda5130603bbd8664635.
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The Assignment Tracking debug-info feature is outlined in this RFC:
https://discourse.llvm.org/t/
rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir
Overview
It's possible to find intrinsics linked to an instruction by looking at the
MetadataAsValue uses of the attached DIAssignID. That covers instruction ->
intrinsic(s) lookup. Add a global DIAssignID -> instruction(s) map which gives
us the ability to perform intrinsic -> instruction(s) lookup. Add plumbing to
keep the map up to date through optimisations and add utility functions
including two that perform those lookups. Finally, add a unittest.
Details
In llvm/lib/IR/LLVMContextImpl.h add AssignmentIDToInstrs which maps DIAssignID
* attachments to Instruction *s. Because the DIAssignID * is the key we can't
use a TrackingMDNodeRef for it, and therefore cannot easily update the mapping
when a temporary DIAssignID is replaced.
Temporary DIAssignID's are only used in IR parsing to deal with metadata
forward references. Update llvm/lib/AsmParser/LLParser.cpp to avoid using
temporary DIAssignID's for attachments.
In llvm/lib/IR/Metadata.cpp add Instruction::updateDIAssignIDMapping which is
called to remove or add an entry (or both) to AssignmentIDToInstrs. Call this
from Instruction::setMetadata and add a call to setMetadata in Intruction's
dtor that explicitly unsets the DIAssignID so that the mappging gets updated.
In llvm/lib/IR/DebugInfo.cpp and DebugInfo.h add utility functions:
getAssignmentInsts(const DbgAssignIntrinsic *DAI)
getAssignmentMarkers(const Instruction *Inst)
RAUW(DIAssignID *Old, DIAssignID *New)
deleteAll(Function *F)
deleteAssignmentMarkers(const Instruction *Inst)
These core utils are tested in llvm/unittests/IR/DebugInfoTest.cpp.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D132224