[all-commits] [llvm/llvm-project] 47bdea: [ThreadSanitizer] Add fallback DebugLocation for i...

Marco Elver via All-commits all-commits at lists.llvm.org
Thu May 5 06:50:18 PDT 2022

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 47bdea3f7eb4bb70288e69635d73807c5d03dacc
  Author: Marco Elver <elver at google.com>
  Date:   2022-05-05 (Thu, 05 May 2022)

  Changed paths:
    M llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
    A llvm/test/Instrumentation/ThreadSanitizer/missing_dbg.ll

  Log Message:
  [ThreadSanitizer] Add fallback DebugLocation for instrumentation calls

When building with debug info enabled, some load/store instructions do
not have a DebugLocation attached. When using the default IRBuilder, it
attempts to copy the DebugLocation from the insertion-point instruction.
When there's no DebugLocation, no attempt is made to add one.

This is problematic for inserted calls, where the enclosing function has
debug info but the call ends up without a DebugLocation in e.g. LTO
builds that verify that both the enclosing function and calls to
inlinable functions have debug info attached.

This issue was noticed in Linux kernel KCSAN builds with LTO and debug
info enabled:

  | ...
  | inlinable function call in a function with debug info must have a !dbg location
  |   call void @__tsan_read8(i8* %432)
  | ...

To fix, ensure that all calls to the runtime have a DebugLocation
attached, where the possibility exists that the insertion-point might
not have any DebugLocation attached to it.

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D124937

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