[all-commits] [llvm/llvm-project] 910696: [Assignment Tracking][SROA] Don't un-poison dbg.as...

[Orlando Cazalet-Hyams via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9106960724b5c8b0e3ba333238571cbbd3c10130
      https://github.com/llvm/llvm-project/commit/9106960724b5c8b0e3ba333238571cbbd3c10130
  Author: OCHyams <orlando.hyams at sony.com>
  Date:   2023-04-11 (Tue, 11 Apr 2023)

  Changed paths:
    M llvm/lib/Transforms/Scalar/SROA.cpp
    M llvm/test/DebugInfo/Generic/assignment-tracking/sroa/fail-fragment.ll

  Log Message:
  -----------
  [Assignment Tracking][SROA] Don't un-poison dbg.assigns using multiple loc ops

Some dbg.assigns using poison become un-poisoned in SROA. The reason this
happens at all is because dbg.assigns linked to memory intrinsics use poison to
indicate they can't describe the stored value, but the value becomes available
after some optimisations. This needs reworking eventually, but for now we need
to ensure that when it does occur we don't create invalid expressions.

D147312 prevented this occuring when the dbg.assign uses DIArgLists, but that
wasn't a complete fix. We also need to ensure we avoid un-poisoning when the
existing expression uses more than one location operand (DW_OP_arg, n).

Reviewed By: jmorse

Differential Revision: https://reviews.llvm.org/D148020


  Commit: d05b5709881f15973aab6b1d463d919cd152f770
      https://github.com/llvm/llvm-project/commit/d05b5709881f15973aab6b1d463d919cd152f770
  Author: OCHyams <orlando.hyams at sony.com>
  Date:   2023-04-11 (Tue, 11 Apr 2023)

  Changed paths:
    M llvm/lib/IR/DebugInfo.cpp
    A llvm/test/DebugInfo/Generic/assignment-tracking/declare-to-assign/structured-bindings.ll
    A llvm/test/DebugInfo/Generic/assignment-tracking/declare-to-assign/var-not-alloca-sized.ll

  Log Message:
  -----------
  [Assignment Tracking] Trunc fragments for stores to vars smaller than the alloca

In D147777 emitDbgAssign was fixed to discard assignments which touched any
bits outside the bounds of a variable. This patch changes emitDbgAssign to
discard assignments which touch bits only outside the variable bounds, and
creates a truncated fragment expression for stores partially overlapping the
variable. This is necessary because the alloca is interpreted as a store (of
undef), meaning without this patch emitDbgAssign would discard the inital
dbg.assign for a variable that is smaller than the alloca.

Reviewed By: jmorse

Differential Revision: https://reviews.llvm.org/D148018


Compare: https://github.com/llvm/llvm-project/compare/20b929b29732...d05b5709881f