[all-commits] [llvm/llvm-project] 171f70: [Assignment Tracking][5/*] Add core infrastructure...

[Orlando Cazalet-Hyams via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 171f7024cc82e8702abebdedb699d37b50574be7
      https://github.com/llvm/llvm-project/commit/171f7024cc82e8702abebdedb699d37b50574be7
  Author: OCHyams <orlando.hyams at sony.com>
  Date:   2022-11-07 (Mon, 07 Nov 2022)

  Changed paths:
    M llvm/include/llvm/AsmParser/LLParser.h
    M llvm/include/llvm/IR/DebugInfo.h
    M llvm/include/llvm/IR/Instruction.h
    M llvm/lib/AsmParser/LLParser.cpp
    M llvm/lib/IR/DebugInfo.cpp
    M llvm/lib/IR/Instruction.cpp
    M llvm/lib/IR/LLVMContextImpl.h
    M llvm/lib/IR/Metadata.cpp
    M llvm/lib/IR/Verifier.cpp
    M llvm/test/DebugInfo/Generic/assignment-tracking/parse-and-verify/verify.ll
    M llvm/unittests/IR/DebugInfoTest.cpp

  Log Message:
  -----------
  [Assignment Tracking][5/*] Add core infrastructure for instruction reference

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)

These core utils are tested in llvm/unittests/IR/DebugInfoTest.cpp.

Reviewed By: jmorse

Differential Revision: https://reviews.llvm.org/D132224