[all-commits] [llvm/llvm-project] b60afe: [SimplifyCFG] Keep a debug location on calls clone...

[Akash Manna via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b60afea0d31f4da34b9d867a00817a0e53dbdb05
      https://github.com/llvm/llvm-project/commit/b60afea0d31f4da34b9d867a00817a0e53dbdb05
  Author: Akash Manna <akash.manna.mymail at gmail.com>
  Date:   2026-09-25 (Fri, 25 Sep 2026)

  Changed paths:
    M llvm/lib/Transforms/Utils/SimplifyCFG.cpp
    A llvm/test/Transforms/SimplifyCFG/fold-branch-to-common-dest-call-debugloc.ll

  Log Message:
  -----------
  [SimplifyCFG] Keep a debug location on calls cloned by `FoldBranchToCommonDest` (#224247)

Fixes #220848

When folding a branch to a common destination, SimplifyCFG clones the
bonus instructions into the predecessor and resets their debug
locations, so the debugger doesn't step onto code from a branch that
wasn't taken. It did that with `setDebugLoc(DebugLoc::getDropped())` for
every instruction. That's fine for an `icmp`, but with
`-bonus-inst-threshold=2` a `speculatable` call can be a bonus
instruction too, and an inlinable call in a function with debug info
must have a `!dbg` location, otherwise the inliner can't set up the
inlined-at scope. The verifier rejects the module with "inlinable
function call in a function with debug info must have a !dbg location".

The clone now uses `Instruction::dropLocation()`, which is what
`speculativelyExecuteBB` in the same file already does. Non-call
instructions still lose their location as before, while calls get a line
0 location in the function's scope, so nothing misleading shows up when
stepping and the IR stays valid. `dropLocation()` needs the parent
function, so the clone is inserted into the predecessor before its
location is updated. An earlier attempt at this swap (674f57870f4c) was
reverted after buildbot crashes; the clone was still unparented when
`dropLocation()` ran there, which would explain them.



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